A Specialist Periodical Report
Organophosphorus Chemistry Volume 5
A Review of the Literature Published between July ...
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A Specialist Periodical Report
Organophosphorus Chemistry Volume 5
A Review of the Literature Published between July 1972 and June 1973
Senior Reporter
S. Trippett, Department of Chemistry, Universffy of Leicester Reporters R. S. Davidson, University of Leicesfer N. K. Hamer, University of Cambridge
D. W. Hutchinson, University of Warwick R. Keat, Universify of Glasgow
J. A. Miller, Universify of Dundee
D. J. H. Smith, University of Leicesfer J. C. Tebby, North Staffordshire Polyfechnic B. J. Walker, Queen’s University
of Belfast
0 Copyright 1974
The Chemical Society Burlington House, London, W I V OBN
ISBN : 0 85186 046 X Library of Congress Catalog Card No. 73-268317
Printed in Great Britain by Adlard & Son Ltd. Bartholomew Press, Dorking
Foreword
The pattern set in previous volumes has been continued, although increasing activity in several areas has required more selectivity on the part of Reporters. The year under review has in general been one of consolidation with few major advances. However, it did see the start of publication of the new ‘Kosolapoff’ replacing the first edition1 which has been an essential hand-book for all organophosphorus chemists since it appeared in 1950. Now edited jointly by Gennady Kosolapoff and Ludwig Maier the new edition,2 so far in four volumes, is a worthy successor to its one-volume predecessor. October 1973 1
a
S. Trippett
G . M. Kosolapoff, ‘OrganophosphorusCompounds’, Wiley, New York, 1950. ‘Organic Phosphorus Compounds’, ed. G. M. Kosolapoff and L. Maier, Wiley-Interscience, New York, 1973, vol. 1 4 .
V
Contents Chapter 1 Phosphines and Phosphonium Salts By D. J. H. Smith 1 Phosphines Preparation From Halogenophosphines and Organometallic Reagent From Metallated Phosphines By Reduction Miscellaneous Reactions Nucleophilic Attack on Carbon Ac:tivated olefins Activated acetylenes Carbonyls Nucleophilic Attack at Halogen Nucleophilic Attack at Other Atoms Miscellaneous 2 Phosphonium Salts
Preparation Reactions Alkaline Hydrolysis Additions to Vinylphosphonium Salts Miscellaneous
1
1 1
1 1 4 5 7 7 7 8 9 10 12 13 15 15 18 18 21 24
3 Phosphorins Preparation Reactions
25 25 28
4 Phospholes Preparation and Reactions Physical Measurements
30 30 32
Chapter 2 Quinquecovalent Phosphorus Compounds By S. Trippett
34
1 Ligand Reorganization and Structure
34
2 Acyclic Systems
35
vi
Contents 3 Three-membered Ring
37
4 Four-membered Rings
37
5 Five-membered Rings Phospholans and Phospholens 1,3,2-Dioxaphospholans 1,3,2-Dioxaphospholens 1,2-0xaphospholens 1,3,2-0xazaphospholens 1,3,5-Oxazaphospholens Miscellaneous
39 39 40 42 44 44 46 47
6 Six-membered Ring
49
7 Six-co-ordinate Species
49
Chapter 3 Halogenophosphines and Related Compounds By J. A. Miller
52
1 Halogenophosphines Physical Aspects Reactions Electrophilic Attack by Phosphorus Nucleophilic Attack by Phosphorus Biphilic Reactions Miscellaneous Reactions
52 52 53 53 56 56 59
2 Halogenophosphoranes
60 60 62 63
Structure and Bonding Preparation Reactions
Chapter 4 Phosphine Oxides, Sulphides, and Sefenides By J. A. Milter
70
1 Introduction
70
2 Preparation From Secondary Phosphine Oxides or from Phosphinites
70 70
vi i
Contents By Grignard and Related Reactions By Oxidation of Phosphines By Miscellaneous Routes
3 Reactions and Properties
Chapter 5 Tervalent Phosphorus Acids By B. J. Walker 1 Introduction
72 73 76 79
83
83
2 Phosphorous Acid and Derivatives Nucleophilic Reactions Attack on Saturated Carbon Attack on Unsaturated Carbon Attack on Nitrogen Attack on Oxygen Attack on Halogen Electrophilic Reactions Rearrangements Cyclic Esters of Phosphorous Acid Miscellaneous Reactions
83 83 83 86 98 99 101 103 105 105 109
3 Phosphonous and Phosphinous Acids and Derivatives
111
Chapter 6 Quinquevalent Phosphorus Acids By N. K. Hamer
112
1 Phosphoric Acid and Derivatives Synthetic Methods Solvolyses of Phosphoric Acid Derivatives Reactions of Phosphoric Acid Derivatives
112 112 115 121
2 Phosphonic and Phosphinic Acids and Derivatives Synthetic Methods Solvolyses of Phosphonic and Phosphinic Esters Reactions of Phosphonic and Phosphinic Acid Derivatives Miscellaneous
127 127 130 132 138
...
Contents
Vlll
Chapter 7 Phosphates and Phosphonates of Biochemical Interest 141 By D. W. Hutchinson 1 Introduction
141
2 Mono-, Oligo-, and Poly-nucleotides Mononucleotides Nucleoside Polyphosphates Oligo- and Poly-nucleotides Analytical Techniques and Separation Methods
141 141 150 152 156
3 Coenzymes and Cofactors
157 157 158 158
Nucleoside Diphosphate Sugars Vitamin Be and Related Compounds 0ther Coenzymes 4 Naturally Occurring Phosphonates
160
5 Oxidative Phosphorylation
161
6 Sugar Phosphates
163
7 Phospholipids
164
8 Enzymology
165
9 Other Compounds of Biochemical Interest
167
Chapter 8 Ylides and Related Compounds By S. Trippett 1 Methylenephosphoranes
Preparation Reactions Halides Carbonyls Miscellaneous
170
170 170 172 172 174 179
2 Phosphoranes of Special Interest
181
3 Selected Applications of Ylides in Synthesis Natural Products Macrocyclic Compounds Miscellaneous
188 188 191 192
ix
Contents
4 Selected Applications of Phosphonate Carbanions
194
5 Ylide Aspects of Iminophosphoranes
197
Chapter 9 Phosphazenes By R. Keaf
200
1 Introduction
200
2 Synthesis of Acyclic Phosphazenes From Amides and Phosphorus(v) Halides From Azides and Phosphorus(m) Compounds 0ther Methods
200 200 202 205
3 Properties of Acyclic Phosphazenes Halogeno-derivatives Alkyl and Aryl Derivatives
207 207 210
4 Synthesis of Cyclic Phosphazenes
213
5 Properties of Cyclic Phosphazenes Halogeno-derivatives Amino-derivatives Alkoxy- and Aryloxy-derivatives Alkyl and Aryl Derivatives
217 217 219 222 223
6 Polymeric Phosphazenes
225
7 Molecular Structures of Phosphazenes Determined by X-Ray Diffraction Methods
226
Chapter 10 Photochemical, Radical, and Deoxygenation Reactions By R. S. Davidson 228 1 Photochemical Reactions
228
2 Phosphinidenes and Related Species
229
3 Radical Reactions Structure a-Cleavage Reactions B-Scission Reactions
230 23 1 232 233
Contents
X
Relative Ease of a- and &Scission Reactions Other Aspects of the Chemistry of Phosphoranyl Radicals
4 Deoxygenation Reactions Ozone and Ozonides Molecular Oxygen Hydroperoxides and Peroxides Oxaziridines and Oxadiazoles Sulphoxides Mono- and Poly-sulphides and Elemental Sulphur N-Oxides, Nitroso- and Nitro-compounds
Chapter 11 Physical Methods By J. C. Tebby
234 234 238 238 239 239 240 241 242 243 247
1 Nuclear Magnetic Resonance Spectroscopy Chemical Shifts and Shielding Effects Pho~phor~s-31 BP of PI1 compounds BP of PII1 compounds BP of P I V compounds BP of Pv compounds Isotope effects on 8p Carbon-13 Hydrogen-1 Studies of Equilibria, Reactions, and Solvent Effects Pseudorotation Restricted Rotation Inversion, Non-equivalence, and Configuration Spin-Spin Coupling JVP) and JPM) JPC) lJ(PH) J(PCnH) JPXCnH) Relaxation Times, Paramagnetic Effects, and N.Q.R. Studies
247 247 247 248 248 250 252 253 253 254 254 256 258 259 260 261 262 263 264 266
2 Electron Spin Resonance Spectroscopy
269
3 Vibrational Spectroscopy Stereochemical Aspects Studies of Bonding
270 273 274
268
xi
Contents
4 Microwave Spectroscopy
275
5 Electronic Spectroscopy
275
6 Rotation and Refraction
278
7 Diffraction
279
8 Dipole Moments, Conductance, and Polarography
282
9 Mass Spectrometry
284
10 pKand Thennochemical Studies
287
11 Surface Properties
289
Author Index
290
Abbreviations
AIBN DBN DBU DCC DMF DMSO g.1.c. HMPT NBS n.q.r. PPi
TCNE THF t .l.c.
bisazoisobutyronitrile 1,5-diazabicyclo[4,3,0]non-5-ene l,S-diazabicyclo[5,4,0]undec-Sene dicyclohexylcarbodi-imide NIV-dimethylformamide dimethyl sulphoxide gas-liquid chromatography hexamethylphosphoric triamide N-bromosuccinimide nuclear quadrupole resonance inorganic pyrophosphate tetracyanoethylene tetrahydrofuran thin-layer chromatography
I Phosphines and Phosphonium Salts BY D. J. H. SMITH
1 Phosphines Preparation.-Many of the papers published in the year under review on the preparation of phosphines were minor variations of well proven routes. A number were concerned with making novel polyphosphines or cyclic phosphines for use as ligands. The preparation and reactions of phosphinesl and poly(tertiary phosphines) have been reviewed. From Halogenophosphines and Organometallic Reagent. Bis(dialky1aminoph0sphine)acetylenes (1) have been obtained by the reaction of acetylenedimagnesium dibromide with the appropriate chloropho~phine.~ BrMgC-CMgBr
RC-CLi
-I- (R12N)R2PCl
+
Ph,PCI
(RlaN)R2PCrCPR2(NRl,)
(I) Ra = R1,N or Me
* RC-CPFhs ‘B!oHlo (2) R = CHr= CH,H, Me, or Ph
‘B:OH, (3)
Pa14
-
+
/
pyridine
CH,(SH)s
_ _ _ f
CHI
‘s-P-s (4) 24%
The new carbaborane-containing ligands (2) have been synthesized by treatment of chlorodiphenylphosphinewith the carbaboran-1-yl-lithiums (3). Some of these phosphines are stable to atmospheric ~ x y g e n . ~ The reaction of methanedithiol with diphosphorus tetraiodide in the presence of pyridine gave the new phosphorus-sulphur heterocycle (4).6 From Metallated Phosphines. Sodium diphenylphosphide, prepared by the L. Maier, in ‘Organic Phosphorus Compounds’, ed. G. M. Kosolapoff and L. Maier, Wiley-Interscience, 1972, Vol. 1, p. 1. R. B. King, Accounts Chem. Res., 1972, 5, 177. W. Kuchen and K. Koch, 2. anorg. Chem., 1972,394,74. L. I. Zakharkin, M. N. Zhubekova, and A. V. Kazantseu, J. Gen. Chem., (U.S.S.R.), 1972,42, 1013. M. Baudler, K. Glinka, U. Kelsch, H. Sandmann, and W. Heller, Phosphorus, 1972, 2, 161.
1
2
Organophosphorus Chemistry
addition of sodium to a dioxan solution of ethyl diphenylphosphinite, when added to 1,2-dichloroethane gave a high yield of the diphosphine (5).6 The chiral diphosphine (6) containing a dioxolan ring, which has been used as a ligand in asymmetric catalysts, has been synthesized from the corresponding tosylate by reaction with sodium diphenylph~sphide.~ Ph2PNa
ClCHgCH &1
PhPCH2CH2PPh2 (5) 94%
H
H
V
C
N
(7) [Me,N=CHCI]+ Cl- 3. R2PLi + (R2P),CHNMeB (8) R = Me, Et, or Ph (9) Me,NCH(OMe),
+ R2PH
(10)
(2-Cyanophenyl) diphenylphosphine (7) has been prepared by the dropwise addition of 2-chlorobenzonitrile to a stirred, refluxing, solution of lithium diphenylphosphide.8 Aminophosphinomethanes (8) are obtained from the reaction of the corresponding phosphide with the salts (9) or the dimethyl acetals (10). These phosphines can also be made directly from (10) and the secondary pho~phine.~ Dipotassium triphenylcyclotriphosphanecan be prepared by metallation of pentaphenylcyclopentaphosphane (1 1) with a stoicheiometric amount of potassium in benzene.lo Reaction with iodine at - 78 "C followed by decomposition gave pure triphenylcyclotriphosphane (12), which is stable below - 20 "C but rearranges to the more stable (1 1) at higher temperatures. Mann has shownll that the dilithiotriphosphane (13), obtained by the action of lithium on (1 1) or dichlorophenylphosphine, reacts with o-bromo-
K
(PhP),
K,(PhP),
A
KB(PhP)J2
-
(PhP),
(1 1) (12) * H. Nohira, M. Taniguchi, and K. Shimamura, Jap. P. 72 47 014/1972 (Chern. A h . , 1973, 78, 84534). H. B. Kagan and T.-P. Dang, J. Amer. Chem. SOC.,1972,94, 6429. D. H. Payne and H. Frye, Inorg. Nuclear Chem. Letters, 1972, 8, 73. K. Issleib and M. Lischewski, J. Organometallic Chem., 1972, 46, 297. l o M. Baudler and M. Bock, 2. anorg. Chern., 1973, 395, 37. 1 ' F. G. Mann and A. J. H. Mercer, J. C.S. Perkin I, 1972, 1631.
Phosphines and Phosphoniunz Sults
+ PhP-P-PPh
3
+ m ” Y h
B’/PPh Li
(13)
Ph
chlorobenzene in a two-step process to give the triphosphane (14). Similarly, refluxing (11) with potassium in THF followed by addition of 1,2-dichloroethane12 gave the 1,2,3-triphosphane (15). The addition of an equimolar amount of j3-propiolactone to a benzene solution of ethylzinc diphenylphosphide gave a crystalline material, formulated as (16), which probably arises from initial acyl-oxygen bond cleavage followed by 1,4-addition of the ph0~phide.l~ 0
EtZnPPh,
+
CHa-C=O
I
CHa-0
t
II
+ EtZnOCHaCH8CPPh8
J. 0
Ph2PCHBCH=COZnEt
I
ll
f-
CH2=CHCPPhB
+ EtZnOH
PPha (16)
Acylphosphine (17) can be prepared by the reaction of diphenyl(trimethy1sily1)phosphine and oxalyl chloride. The interesting dione (18) was obtained in a similar reaction.14 Aromatic acid chlorides also react with diphenylM. Baudler, J. Vesper, and H. Sandmann, Z. Naturforsch., 1972, 27b, 1007 (Chem, Abs. 1973, 78, 16106). J. Boersma and J. G. Noltes, Rec. Trav. chim., 1973, 92, 229. H. J. Becker, D. Fenske, and E. Langer,!Chem. Ber., 1973,106, 177.
In
la
4
Organophosphorus Chemistry 2Ph2PSiMes
+
2Ph2PSiMe,
+
ClOCCOCl
O
x
c1
ArCOCl
+
o
Ph2PCOCOPPh2 (17)
+ O x o
Ph ZP
c1
PhaPSiMe3
ArCOPPh2
II
II
Ph2P-SPh
+ CH2=C=O O'hCH38'H (20)
+
CFBCOCl
+ Me3SiC1 0
0 PhS02Cl 3. 2Ph2SiMe, -+
PPh2
4- Ph2P-OH
(PhCHJ2PCOCHa . pyridine
(PhCH2)2PCOCFS
(trimethylsily1)phosphine to give acylphosphines, but benzenesulphonyl chloride gave the diphenylphosphinic ester (19).15 Acylation of dibenzylphosphine (20) can conveniently be carried out by reaction with keten or trifluoroacetyl chloride in the presence of pyridine.ls Ketens add to germyl- or silyl-phosphines to give the phosphorylated alkenoxy-germanes or -silanes (21).17 Diketen also reacts to yield (22), by isomerization of the initial adduct ; hydrolysis of (22) gave phosphorylated p-diketones. By Reduction. An improved procedure for the preparation of phenylphospiiine by the reduction of dichlorophenylphosphine with lithium aluminium hydride at - 78 "C has been reported.ls A number of polyphosphines, containing primary, secondary, or tertiary phosphorus, e.g. (23), have been prepared by the addition of a phosphine across the double bond of an unsaturated phosphorus ester, followed by reduction with lithium aluminium hydride.ls H. Kunzek, M. Braun, E. Nesener, and K. Ruhlmann, J. Organometallic Chem., 1973, 49, 149. l6 R. G. Kostyanovskii, Y . I. El'natanov, L. M. Zagurskaya, K. S. Zakharov, and A. A. Fomichev, Bull. Acad. Sci., U.S.S.R., 1973, 21, 1841. 1 7 C. Couret, J. Satge, and F. Couret, J. Organometallic Chem., 1973, 47, 67. la R. C. Taylor, R. Kolodny, and D. B. Walters, Synrh. Inorg. Mefal-org. Chem., 1973, 3, 175. R. B. King and J. C. Cloyd, 2. Naturforsch., 1972, 27b, 1432 (Chem. A h . , 1973, 78, 72 298). 16
5
Phosphines and Phosphonium Salts R'sMPEt2
R'sMPEt,
+ R*ZC=C=O
+ CH,=C-CH, I
I
0-c=o MeCCH2CPEt2
II
0
II
0
10 R1,M-O-C=CHCOpEt2 t
Me (22)
R1= Et or Me; R2= H or Ph; M = Ge or Si Phenylsilane was found to be the best reducing agent for converting the phosphorus acid or ester (24) into the secondary phosphine.aO
Miscellaneous. Silylphosphine (25) has conveniently been prepared in good yield by the reaction of silane and phosphine with a catalytic amount of iodine.21 Tris(hydroxymethy1)phosphine (26) can be produced quantitatively by passing phosphine into a solution of formaldehyde in methanola2or ~ y l e n e ~ ~ at 75-90 "C under pressure. C. N. Robinson, W. A. Pettit, A. William, T. 0. Walker, E. Shearon, and A. M. Mokashi, J. Heterocyclic Chem. 1972, 9, 735. I. H. Sabhenval and A. B. Burg, Inorg. Nuclear Chem. Letters, 1972, 8, 27. la R. F. Stockel and W. F. Herbes, Ger. Offen. 2158823 (Chem. Abs., 1973,78,43702). ** R. F. Stockel and W. F. Herbes, U.S.P. 370432$/1972 (Chem. Abs., 1973, 78,43703).
Organophosphorus Chemistry
6
PH3
+
HCHO
*
(HOCHd3P (26)
Trimethylphosphine can be prepared by passing a mixture of hydrogen chloride, methyl chloride, and phosphorus vapous over a charcoal catalyst at 360 "C and subjecting the resulting trimethylphosphonium chloride to alkaline hydr~lysis.~~, 25 The phosphabicyclo[3,3,1Inonane (27) is formed when a mixture of tris(hydroxymethyl)phosphine, formaldehyde, cyanamide, and polyphosphoric acid is kept at room temperature.26 Mislow has prepared optically active arsines by modification of his phosphine ~ynthesis.~' Treatment of the arsinite (28) with organo-lithium reagents gave the optically active arsines directly.
2PrLi
MeAsPr
I
Ph
Condensation of 1-phenylphosphorinan-4-onewith various phenylhydrazones, followed by cyclization in situ with acid, yielded the phosphorinoindoles (29), which quaternize on phosphorus when treated with alkyl halides.28 A series of phenylphosphorino[3,3-dlpyrimidines, e.g. (30), has been prepared from the phenylphosphine (3 l).29 H. Staendeke, Ger. Offen. 2116439/1972 (Chem. A h . , 1973,78,16309). H. Staendeke, Ger. Offen. 2 116355/1972 (Chem. A h . , 1973, 78, 43704). 8 6 D. J. Daigle, A. B. Pepperman, and F. L. Normand, J. Heterocyclic Chem., 1972,9,715. 3 7 J. Stackhouse, R. J. Cook, and K. Mislow, J. Arner. Chem. SOC., 1973, 95, 953. * e K. C. Srivastava and K. D. Berlin, J. Org. Chem., 1972, 37, 4487. ** T. E. Snider and K. D. Berlin, J. Org. Chem., 1973, 38, 1657.
24
as
Phosphines and Phosphoniurn Salts
+
CH(0Et)s
7
-'
Reactions.-Nucleophilic Attack on Carbon. Activated olefins. Phenylphosphine reacts with terminally unsaturated carboxylic esters to yield diesters from which the carbon-phosphorus heterocycles (32) can be prepared by the acyloin condensation in the presence of trimethylsilyl The structure of the adduct formed from the reaction of trialkylphosphines with para-substituted benzylidenemalononitriles has been shown to be a zwitterionic species (33) by the use of high-resolution n.m.r. spectrosc~py.~~
.(33) R = Et or Bu 'O
s1
J. W. von Reijendam and F . Baardman, Tetrahedron Letters, 1972, 5181. C. A. Fyfe and M. Zbozny, CanadJ. Chem., 1972,50, 1713.
0rganophosphorus Chemistry
8
Several 6-oxa-2-phospha-adamantanes,e.g. (34), have been synthesized using a double Michael addition of a primary phosphine to cyclocta-2,7dienone. The resulting ketones were converted into the corresponding alcohols, which were cyclized to (34) with lead tetra-a~etate.~~
oo 4-
PhCH2PH2 + PhCH,#’
O=P-
I
Q
Pb(OAc),
O=P
I
CHzPh
CHtPh
(34) Activated acetylenes. The reaction of diphenylvinylphosphine with dimethyl acetylenedicarboxylate affords either a 1 : 1 adduct or a 1 : 2 adduct depending upon the reaction conditions. Hydrolysis of the adducts The phosphine oxide (35) was also produced gave (35) or (36), re~pectively.~~ by hydrolysis of the zwitterionic adduct obtained from the reaction of trans-1 ,2-bis(dipheny1phosphino)ethylene and dimethyl acetylenedicarboxylate. The authors also confirmed previous that the cis-isomer gives a 1,4-diphosphorin (37). A preliminary account has appeared of the generation of benzyne in the presence of unsaturated phosphine~.~~ The bisphosphine (38) was surprisingly
X
I
PhzP:>
CI
Ql
_.)
X
X = COzMe
8a
GXX
%
PhZ
X
I1
X
I
PhzPCHzCH=CCH2X (35) 23%
xfix
X
I*
0
Ph 2
Y. Kashman and E. Benary, Tetrahedron, 1972, 28, 4091. M. Davies, A. N. Hughes, and S. W. S. Jafry, Canad. J. Chem., 1972, 50, 3625. M. A. Shaw, J. C. Tebby, R. S. Ward, and D. H. Williams, J. Chem. SOC.(C)., 1970, 504.
Phosphines and Phosphonium Salts
9
X
.X
I
ph2pl C
PhaP
+ 11'1 C
I
X
X = C0,Me
(37)
obtained from diphenylvinylphosphineand o-benzenediazonium carboxylate, whereas trans-l,2-bis(diphenylphosphino)ethylene gave the expected ylide (39) when added to N-nitrosoacetanilide in the presence of potassium acetate.
NO
I
NCOMe
Carbonyls. Another report of the preparation of 1,3-0xaphosphorinans (40),by the acid-catalysed condensation of 3-hydroxypropylphenylphosphine with aldehydes and ketones, has appeared.s6 The reaction of diphenylphosphine with hexafluoroacetone gave an adduct, readily oxidized to the phosphine oxide (41), which isomerizes in the presence of base.36Dialkoxyphosphines have been showns7to add in a similar fashion to aldehydes to form the adducts (42). The full report of the inversion of alkene stereochemistry via epoxides and reaction with lithium diphenylphosphide has appeared.38 K. Issleib, H. Oehme, and M. Scheibe, Synth. Inorg. Metal-org. Chem. 1972, 2, 223. A. F. Janzen and 0. C. Vaidya, Canal. J. Chem. 1973,51,1136. N. B. Karlstedt, M. V. Proskurnina, and I. F. Lutsenko, Zhur. obshchei Khim., 1972, 42,2418 (Chem. Abs., 1973, 78,88475). E. Vedejs and P. L. Fuchs, J. Amer. Chem. SOC.,1973, 95, 822.
*I
sB
s8
Organophosphorus Chemistry
10 PhPH(CH2),0H
+
n
R1R2C0 -+
+
H20
PhpXo R1 R2 (40) R1= Et or Ph; RZ = H or Me; R*-RB = (CH,), or (CH2h
0 OH PhzPH
+
(CF3)zCO
-r)
Ph?PC(CF3), I
II I
(01 _+
Ph2P--C(CFS),
/,
OH
pyridine
Ph2P-O-CH(CFS)
II
2
0 (41)
Nucleophilic Attack at Halogen. The halogenation of nucleoside hydroxygroups by reaction with carbon tetrahalides and triphenylphosphine has been studied in some Primary hydroxy-groups react more rapidly than secondary hydroxy-groups, the stereochemistry of the latter reactions depending upon the halide used. An interesting side-product obtained during the bromination of thymidine in DMF with triphenylphosphine-carbon tetrabromide was the bromide (43). In the absence of thymidine the salt (44)was obtained. The reaction of 1,3-distearoylglycero1 with triphenylphosphine-carbon tetrachloride gave the 2-chlorodeoxy-derivative(45) with only a trace amount of the 3-chlorodeoxy-isomer derived from acylo~y-migration.~~ Aldehydes can be conveniently converted into dibromoalkenes (46) by the use of the triphenylphosphine-carbon tetrabromide reagent.41 Chlorination of epoxides with triphenylphosphine-carbon tetrachloride gave cis-l,2dichloroalkanes. Reaction with ( + )-propene oxide showed that inversion of configuration had occurred at both carbon atoms. Bromination using carbon tetrabromide was also successful, but was much less stere~specific.~~ The salts (47) are formed when bis(dipheny1phosphino)amine and carbon tetrachloride are treated with a m i n e ~ Cyclocondensation .~~ to the triazadiphosphorins (48) takes place when bifunctional amidines are used. *@J. P. H. Verheyden and J. G. Moffatt, J . Org. Chem., 1972, 37,2289. 'O
4a 43
R. Aneja, A. P. Davies, and J. A. Knaggs, J.C.S. Chem. Comm., 1973, 1 10. E. J. Corey and P. L. Fuchs, Tetrahedron Letters, 1972, 3769. N. S. Isaacs and D. Kirkpatrick, Tetrahedron Letters, 1972, 3869. R. Appel and G. Saleh, Annalen, 1972, 766, 98.
Phosphines and Phosphonium Salts
11
CHZOCOR
I CHOH
Ph,P-CCI,
F
I CH~OCOR
RCHO
CHZOCOR I ClCH I
Ph,P-CBr,
(Ph2P)aNH
RCH=CBra (463 R = Ph, n-C,H,,, or
+ 2CC11, + 2RNHa
_.f
NH 4 3RC, 3. (Ph2P)BNH NH!4
[RNH-(PhdP-N-P(PhJ-”R]+ C1(47). R = H, But, or PhNH
+ 2CC14
Pha N-P
R-C,
4
‘“
N=P’ Phz (48) R = H, Me, Ph, ‘Me2N,or EtO
In a full paper the authors withdrew their earlier statement that the azirine (49) had been detected by i.r. spectroscopy in the reaction of azirine derivatives (50) with triphenylphosphine-carbon tetrachloride. However, they still
believe that (49) is an intermediate.44 The kinetics of the reduction of or-halogenobenzyl phenyl sulphones (51) with triphenylphosphine have been studied. Although the bromides react substantially faster than the chlorides, the iodides react slower than the bromides, an effect that may be due to the large drop in energy that can be
I4
T.Nishiwaki and F. Fujiyama, J.C.S. Perkin I, 1973, 817.
Organophosphorus Chemistry
12
H I PhSOaC-X
H I + 4- PhsP * [PhSOaq-XPPha]
HO
PhSO&H&
I
3.
Ar
PhsPO
+ HX
gained by bond formation in going from the phosphorus-bromine to the phosphorus-iodine bond.45 Nucleophilic Attack at Other Atoms. Benzoylation of glycosides has been described, using the diethyl azodicarboxylate-triphenylphosphine complex as the activating agent (see Scheme l).4s
Scheme 1
u
0
0
11
II
"p
BuSC ).c.O
II 0
BU
T-O\
2c\c-o/ 0 II
/ PPhs
\
Bu,d ' 0 'C'
+ PhsPO
II
0
(52)
Bu2C=C=0
+ Ph,PO
Treatment of di-n-butylmalonyl peroxide with triphenylphosphine gave an intermediate phosphorane which breaks down to give the malonyl anhydride (52) and di-n-butylketen.47 The stoicheiometry and the rate constants of the reaction of triphenylphosphine with ozone have been measured at various temperatures (see Chapter 10, Section 2).48 45
47 48
B. B. Jarvis and J. C. Saukaitis, Tetrahedron Letters, 1973, 709. G. Alfredsson and P. J. Garegg, Acta Chem. Scand., 1973, 27, 724. W. Adam and J. W.Diehl, J.C.S. Chem. Comm., 1972,797. S . Razumovskii and G. D. Mendenhall, Canad. J. Chem., 1973,51, 1257.
Phosphines and Phosphoniirm Salts
13
Triarylphosphines react with thionyl chloride to give initially the phosphine oxide and sulphur dichloride. Further reaction affords triarylphosphine dichloride and sulphur, or phosphine sulphide, depending upon the ratio of the reactants.4DTriphenylphosphine forms two 1 : 1 adducts with sulphuryl chloride.6oInfrared spectroscopy indicates that one has phosphorus bound to sulphur and the other, more stable, adduct has phosphorus bound to oxygen. Miscellaneous. Linear free energy correlations have been found for the barriers to pyramidal inversion of phosphines with arsines, amines, sulphonium salts, and other species.61The slopes of the correlation lines are a measure of the relative sensitivities of the inversion centres to structural modification. The inversion barriers of a number of phosphines have been reported. They include the acylphosphines (53) and (54),18the silylphosphine (55),62 the triarylphosphine (56),63 and the phosphines (57).64 Me
(PhCH,),PCOCH, (53) 81.9 kJ mol-I
(PhCH2)2COCF3 (54) 67.7 kJmol-’
I ,Si(OMe)S But Si -P Me I ‘SiMe3 (55)
c 43.5 kJmol-l
(Me,CH),P-X (57) X = CN, CH=CHCN, or CH=CHCO,Me > 109 kJmol-l
(56) 134.6 kJ mol-l
The rates of reaction of a series of triarylphosphines with or-bromoacetophenones have been defe~mined.~~ Tris-m-substituted triphenylphosphines react ‘significantly’ faster than predicted from their Hammett 0 values, an effect that the authors claim is due to steric acceleration of the reaction.
‘@ E. H. Kustan, B. C. Smith, M. E. Sobeir, A. N. Swami, and M. Woods, J.C.S. Dalton, 61
6a 68 64
66
1972,1326. A. J. Banister, B. Bell, and F. Leonard, J. Inorg. Nuckar Chem., 1972,34, 1161. R. D. Baechler, J. D. Andose, J. Stackhouse, and K. Mislow, J. Amer. Chem. Sac., 1972,94, 8060. 0. J. Scherer and R. Mergner, J. Organometallic Chem., 1972,40, C64. R. Luckenbach, Phosphorus, 1973,2,293. R. G. Kostyanovskii, Y . I. El’natanov, L. M. Zagurskaya, and K. S. Zakharov, Bull. Acad. Sci., U.S.S.R.,1973,21, 1844. G. B. Borowitz, D. Schuessler, W. McComas, L. I. Blaine, K. B. Field, P. Ward, P. Rahn, B. V. Rahn, W. Glover, F. Roman, and I. J. Borowitz, Phosphorus, 1972,2,91.
14
OrganophosphorusChemistry
The reaction of secondary phosphines with di-t-butylmercury gave high yields of tetraorganodiphosphines via intermediate (58), which was isolated when di-t-butylphosphine was used.66 2RzPH
+ ButzHg
(R2P)zHg RAP2 (58) R = Ph, Et, or But *
1,2-Diphenyldiphosphine has been found6' to exist in equilibrium with pentaphenylcyclopentaphosphine and phenylphosphine when the latter reagents are heated in pyridine at 100 "C:
+
SPhPH, (PhP)5 f 5(PhPH)2 Ring-opening occurs when the bicyclic phosphines (59) are treated with sulphur in boiling benzene.68 Dichloroketen can be generated from the reaction of the trichloroacetates (60) with triphenylpho~phine.~~ Treatment of the tosylhydrazone (61) with sodium amide in toluene gave 1-phenylphosphorin-3-ene and the oxide (62), which arose from oxidation of the phosphine by the tosyl group.6o
CS~*~-p (59)
R = H, Me, Br, or OMe
RSMOCOCCIS -t- PhaP 4R,MCI+ PhsPO f - [Cl~C=C=O] (60) R3M= Me& Bu,Sn, or Me,Sb
6'
3- NaNH,
Ph
ST
6a
7% 00 +
Ph
Ph
M. Baudler and A. Zarkadas, Chem. Ber., 1972, 105, 3844. J. P. Albrand and D. Gagnaire, J. Amer. Chem. SOC.,1972, 94, 8630. E. S. Kozlov, A. I. Sedlov, and A. V. Kirsanov, J . Gen. Chem., (U.S.S.R.), 1972,42,517. T. Okada and R. Okawara, J. Organometallic Chem., 1972, 42, 117. D. L. Morris and K. D. Berlin, Phosphorus, 1972, 1, 305.
Phosphines and Phosphoniurn Salts
15
The chemical shifts of a number of five-membered cyclic phosphines have been measured and discussed in detail (see Chapter 11, Section 1).61 Ab initiu calculations on phosphine using three different Gaussian basic sets, with and without the addition of d-orbitals, have been compared.62 The factors which control the reactivity of cyclic tervalent phosphorus compounds have been discussed in terms of the effect on the ring strain between ground state and the transition The chemiluminescence of lithium phosphides has been studied (see Chapter 10, Section l).64 2 Phosphonium Salts
Preparation.-A comprehensive review of the preparation of phosphonium salts is now available.6s Markl’s method for the synthesis of cyclic phosphonium salts (Scheme 2) has been found to be generally applicable to the synthesis of C-methylated rings.66 7 BrCH2(CH2)XH Br H CCH2Br
+f“ Ph2P-FPh2
__f
21’
Ph,P+- PPh2
J\
Scheme 2
Cyclic phosphonium salts have been made by cyclization of the esters (63) using phenyl-lithi~m.~~ The pKa values of these salts are more than 4 units lower than the corresponding acyclic compounds. + / (CH2) n CO &t
PhZP, CHS (63) O1 O8
66
+
PhLi
.+/ (CH z)nCO 2 E t --+ Ph2P,
CH2-
+/
(CH,)fa\
-+ PhzP\cH,/c=*
J. J. Breen, J. F. Engel, D. K. Myers, and L. D. Quin, Phosphorus, 1972, 2, 55. J.-B. Robert, H. Marsmann, L. J. Schaad, and R. R. Van Wazer, Phosphorus, 1972, 2, 11. R. Greenhalgh and R. F. Hudson, Phosphorus, 1972, 2, 1. R. A. Strecker, J. L. Snead, and G. P. Sollott, J . Amer. Chem. Soc., 1973,95, 210. P. Beck, in ‘Organic Phosphorus Compounds’, ed. G. M. Kosolapoff and L. Maier, Wiley-Tnterscience, 1972, Vol. 2, p. 189. K. L. Marsi, D. M. Lynch, and G. D. Homer, J . Heterocyclic Chem., 1972, 9, 331. G. Aksnes and H. Haugen, Phosphorus, 1972, 2, 155.
16
Organophosphorus Chemistry
7-Methylhexahelicenehas been resolved by conversion to the phosphonium a pure diastereomeric salt of which was obtained by salt formation salt (a), with silver D( -) hydrogen dibenzoyltartrate. Alkaline hydrolysis gave the pure hydrocarbon.sa
i, NBS ii, MesP
N-(Chloromethy1)carboxamide.s readily react with triphenylphosphine to give high yields of the phosphonium salts (65).69 In a related reaction, the ureidomethylphosphonium salts (66) were prepared by displacement of methanol from the corresponding methoxymethylureas with triphenylphosphine in the presence of acid.'Os71 The tosylate group in (67) was displaced dire~tly'~ by triphenylphosphine at 140 "C. RCONHCH2Cl 3. Ph3P -+
RCONHCH2$PhSC1' (65) R = CF3, CC13,or Ph
.O
0
/ \
/ \
It
I1 C
R1-N
I
R2
C
NCH20R1 +'Ph,P
I
'-% R1-N
R'
PhZPCH20Ts
II 0
+ Ph3P
140 "C
I R2
N-CH2hh3
I
R3
X-
-t
PhZPCHzPPh3 OTSII 0
(67)
1,4-Diphosphoniacyclohexadiene systems (68), having an alkyl and a phenyl group on each phosphorus atom, have been synthesized from acetylenic phosphines and hydrogen chloride in cold acetic The exocyclic dienes (69) could be obtained by thermal isomerization of (68). w 71
M. S. Newman and C. H. Chen, J. Org. Chem., 1972,37, 1312. B. S. Drach, E. P. Suridov, and A. V. Kirsanov, J. Gen. Chem. (U.S.S.R.), 1972,42,942. H. Petersen and W. Reuther. Annulen, 1972, 766, 58. H. Petersen, W. Reuther, U.S.P. 3658804/1972 (Chem. Abs.. 1972, 76, 153923). W. Wegener and P. Scholz, 2. Chem.. 1972, 12, 103 (Chem. Abs., 1972, 77, 34627). M. S. Chattha and A. M. Aguiar, J. Org. Chem. 1973, 38, 1611.
Phosphines and Phosphonium Salts
Bu\
17
HCI
PC-CR
ph'
\
R
\
(69)
R = alkyl
Pr
Acetylenic phosphines and bromoketones form 4-phosphoniapyran derivatives (70).74 Cyclic phosphonium salts (71) are also obtained from acetylenic phosphines by reaction with nitrilimine~.~~ Phosphonium salts, e.g. (72), containing a P-P linkage are formed from tertiary phosphines and phosphorus oxy~hloride.~~
;fFfR8
3. R*COCHBrR8
PhPR4C,CR1
R1 (70)
PhzPCECP'
4-
-
+ R'--C=N-N-Ph
t
Et$H C1-
NPh
-
c1-
C=N
(71)
EtaP ,+POCls
Ra B r' R1= Jkyl or aryl
R'. = H, Me,or Ph R2 = P-OSNC~H~, Et02C, or Ph
+
EtaP-PC12 I1 0
c1-
(72) 74
l6
M. Simalty and M. H. Bebazaa, Bull. SOC.chim. France, 1972, 3532. L. A. Tamm, V. N. Chistokletov, and A. A. Petrov, J. Gen. Chem. (U.S.S.R.), 1972, 42, 1920. E. Lindner and H. Beer, Chem. Ber., 1972, 105, 3261.
Organophosphorus Chemistry
18
A further report on the isolation of diacylmethyltriphenylphosphonium salts (73) by the action of hydrogen chloride or trifluoroacetic acid on the corresponding phosphorane has appeared." The addition of triphenylphosphine to the methyleneiminium salts (74) gave the phosphonium salts (75), which are in equilibrium with the starting materials but can be isolated at low femperat~res.~~ The phosphonium salts (76) are formed in high yield when a solution of phenol and carbon tetrachloride in ethylene dichloride is treated with triphenylphosphine followed by antimony pentachl~ride.~~ Chloramination of some heterocyclic tertiary phosphines with chloramine has been described.*O
Ph,P=C,
/
COMe
COR
[RaN=CH2]+ X-
HX
S
+ Ph3P
I ,COMe Ph3PCH, XCOR (73) X = C1 or CF3C02 R = Ph, Me, or OMe
+ * R2NCH2PPh3
(74)
PhOH
+ CCI4 + Ph3P
X' (75) X = C1 or Br R2N = morpholino or piperidino
SbC15
(PhO$Ph, SbC1,'(76)
Reactions.-Alkaline Hydrolysis. The sterochemistry of the alkaline hydrolysis of the phosphonium salts (77) has been reported.*l The small energy differences between the possible phosphorane intermediates is emphasized by the fact that the reaction, with loss of R, proceeds with partial inversion or retention of configuration depending upon the nature of R and whether the reaction is run under heterogeneous or homogeneous conditions. Me\,,+ Ph-P-R (77) R = PhCH2, p-CF3CBHdCH2, Ph,CH, or CH,CH=CH,
("y) R' R' (78) R = Et or Me n=4or5
T. A. Mastryukova, I. M. Aladzheva, E. I. Matrosov, and M. I. Kabachnik, J. Gen. Chem. (U.S.S.R.), 1972, 42, 1461. l o H. Boehme and M. Haake, Chem. Ber., 1972,105,2233. 7 0 H. Teichmann, M. Jafkowski, and G. Hilgetag, J. prakt. Chem., 1972,314, 129 (Chem. A h . , 1972, 77, 152274). S. E. Frazier and H. H. Sisler, Inorg. Chem., 1972, 11, 1431. ** R. Luckenbach, Phosphorus, 1972, 1, 293.
7 p
Phosphines and Phosphonium Salts
19
The alkaline hydrolyses of several tetra-alkylphosphonium salts using potassium hydroxide in aqueous DMSO have been studied.s2 Ring strain is the major factor governing the rate of reaction and the ratio of ring-opened against ring-retained products for the cyclic salts (78). Hydrolysis of the spirophosphonium salt (79) with lithium hydroxide surprisingly gave the rearranged oxide (80) with only a minor amount of the expected
$4 R I
R
R
LiOH
\
I/
R
R (79) R = H or Me R
R
R
4-
R
Q I
I
R
R
There appears to be a small preference for attack of hydroxide ion opposite the bulky menthyl group in the alkaline hydrolysis of the acyclic dialkoxyphosphonium salts (81). The ability of the intermediate phosphorane to undergo pseudorotation as opposed to direct loss of an alkoxide group is determined primarily by the leaving-group ability of the alkoxide. In these reactions when methoxide is in the apical position of the frst-formed phosphorane, pseudorotation is virtually n~n-existent.~~ The results of a study of the stereochemistry of the reaction of the phosphonium tetrafluoroborate (82) with various nucleophiles indicate that there is reversible phosphorane formation in competition with nucleophilic attack at carbon (the product-forming step). There appears to be a correlation 8s B4
K. L. Marsi and J. E. Oberlander, J. Amer. Chern. SOC.,1973, 95, 200. D. Hellwinkel and H.-J. Wilfinger, Chern. Ber., 1972, 105, 3878. K. E. DeBruin and J. R. Petersen, J. Org. Chern., 1972, 37, 2272.
20
Organophosphorus Chemistry
between the classification of the nucleophile as hard or soft and its ability to induce racemization by nucleophilic attack at p h o s p h o r u ~ . ~ ~ Me,, .,OR1
' h P (81)
P \OR2
R1,Re = Me, Et, or Menthyl
OMenthyl Ph,, I .P-OMe
(82)
Z&
Hydrolysis of alkoxy(methy1thio)phosphonium salts, with displacement of the methylthio-group, proceeds with retention of configuration, which is consistent with attack opposite the alkoxy-group to give the intermediate (83) which loses SMe directly from the equatorial position or pseudorotates before losing the SMe from the apical position.as Ph\
~
Ph\ ,OMenthyl
,OMen thy1
/=\
Me SMe SbClc
P
Me/ O \
..
\
OR
Phi I ;P-SMe
Ph\ ,OMe P But' O \ SbCI;
The presence of a ferrocenyl group bonded to phosphorus causes a marked depression in the rate of decomposition of phosphonium salts compared with the phenyl analogue. The effect is attributed to direct interaction between the electrons occupying an hag orbital of the ferrocenyl group and a 3d orbital on phosphoru~.~' The alkaline hydrolysis of 1,2,2,3,4,4-hexamethyI-l-phenylphosphetani~m bromide leads to a ring-expanded oxide, which has been formulated as (84). However, X-ray diffraction of the product obtained by reduction of (84)and quaternization with methyl bromide indicates a structure (85) in which K. E. DeBruin and S. Chandrasekaran, J. Amer. Chem. SOC., 1973,95,974. N. J. De'Ath, K. Ellis, D. J. H. Smith, and S. Trippett, Chem. Comm., 1971, 714. W. E. McEwen, A. W. Smalley, and C. E. Sullivan, Phosphorus, 1972, 1, 259.
21
Phosphines and Phosphonium Salts
(84)
Me Me
o// 'Me
rearrangement of the methyl groups has taken place.88This is very surprising, especially since X-ray diffraction of the product obtained by aromatization of the oxide with palladium+harcoal has been shown to be (86), in which the original methyl sequence has been maintained.8g The exchange of CH2OH groups between tetrakis(hydroxymethy1)phosphonium chloride and the corresponding phosphine in the presence of a limited amount of NaOD (Scheme 3) has been studied using variabletemperature n.m.r. spectrosc~py.~~ 4-
-OD
(HOCH2),P C1- C (HOCH&P
+ CHaO
Scheme 3
Additions to Vinyt'phosphonium Salts. The use of a number of substituted vinylphosphonium salts for the synthesis of heterocyclic compounds has been in~estigated.~~ The phosphonium zwitterion (87) could be isolated from the reaction of isopropenylmethyldiphenylphosphoniumbromide with sodium salicyloxide. /I-Acylvinylphosphonium salts react with diazomethane to form ylides which yield 4-acylpyrazoles (88) upon addition of potassium hydroxide.92
91
J. N. Brown, L. M. Trefonas, and R. L. R. Towns, J. Heterocyclic Chem., 1972,9,463. Mazha-ul-Haque, J . Chem. Soc. (B)., 1970, 71 1 . S. E. Ellzey, jun., W. J. Connick, jun., G. J. Boudreaux, and H. Klapper, J. Org. Chem., 1972, 37, 3453. E. E. Schweizer, A. T. Wehman, and D. M. Nycz, J. Org. Chem., 1973,38,1583. E. Zbiral and E. Bauer, Tetrahedron, 1972, 28, 4189. B
22
Organophosphorus Chemistry BrPh2P-C=CH2 +
I
I
aCHO '
+
+
0-
Me Me
CH=CH
+/
Ph2P \
Me
(87)
+
+ CH2Na
Ph,P-CH=COR
+
+ PhSP-CH-CHCOR
I
\
NkN,CH2
HqcoR + t
KOH
PhJQ
N\N H (88) R = Me or Ph
Ph,P=C-C-COR / 29 kJ rnol-l, which would be the highest barrier yet observed between topomeric phosphoranes. Details have appeared l2of the preparation and low-temperature 1°F n.m.r. L. S. Bartell and V. Plato, J. Amer. Chem. SOC.,1973, 95, 3097. J. I. Musher, Tetrahedron Letters, 1973, 1093. ' C. G . Moreland, G . 0. Doak, and L. B. Littlefield,J. Amer. Chem. SOC.,1973,95,255. ' T. A. Furtsch, D. S. Dierdorf, and A. H. Cowley, J . Amer. Chem. SOC., 1970,92, 5759. (a)D . L. Wilhite and L. Spialter, J. Amer. Chem. SOC.,1973, 95, 2100; (b) A. Rauk, L. C. Allen, and K. Mislow, ibid., 1972, 94, 3035. * M. Sanchez, J. Ferekh, J. F. Brazier, A. Munoz, and R. Wolf, Roczniki Chem., 1971, 45, 131. l o M. Eisenhut, R. Schmutzler, and W. S. Sheldrick, J.C.S. Chem. Comm., 1973, 144. l1 A. H. Cowley and R. W. Braun, Inorg. Chem., 1973,12,491. I * R. G. Cavell, R. D. Leary, and A. J. Tomlinson, Inorg. Chem., 1972,11,2578.
Organophosphorus Chemistry
36
CF3
(CF,),PO 3- (Me,Si),O
-+- F,C--P,
I ,,0SiMe3 I OSiMe,
CF3 (7)
R'PF4 I- Me,SiOR2 -+ R1PF3(OR2)+ Me,SiF (8)
of the phosphorane (7). At - 140 "C the signals due to the apical CF3groups show additional splitting which could be due to restricted rotation of these groups, caused in turn by restricted rotation round the PO bonds. The thermally stable monoalkoxyfluorophosphoranes (8 ; R1= Me or Ph) have been obtained as shown when R2is either an electron-attractinggroup or isobutyl or ne0penty1.l~The barrier to equivalence of the fluorines (ca. 52.3 kJ mol-1 with R2= CH,CCl,) has been contrasted to the higher barriers (> 63 kJ mol-l) found in analogous amino- and alkylthio-derivativesand has been attributed to the high electronegativity of the alkoxy-group. However, in the pseudorotations (9)7-?(11) leading to equivalence of the fluorines, the high-enery y phosphorane in all cases is (10) and the barrier might therefore be expected to be independent of the nature of the substituent X. The preparation and 19Fand 31Pn.m.r. of the phosphoranes (12) have been described.l* Full accounts have appeared of the preparations and properties la
D. U. Robert, G. N. Flatau, C. Demay, and J. G. Riess, J.C.S. Chem. Comm., 1972, 1127.
M. J. C. Hewson and R. Schmutzler, 2. Naturforsch., 1972, 27b, 879.
37
Quinquecovalent Phosphorus Compounds
of the fluoro- 15, alkoxy-, l6 and aryloxy-phosphoranesl6 R13MePX (X = F, OR2, or Oh). 35Cl N.q.r. of the chlorophosphoranes CC13PCl,, (CCl,),PCl,, and (CC13)2PC12NH2shows1’ that in all cases the trichloromethyl groups are apical; J(16NH)in the last compound is consistent with sp2-hybridizednitrogen. 3 Three-membered Ring
The azine (13) reacts with trialkyl phosphites and with trisdimethylaminophosphine to give 1 : 1 adducts of considerable thermal stability, formulated as the phosphoranes (14) on the basis of their lH and leFn.m.r. and their i.r. (CFJ&=N-N=C(CF3)2
+ R3P
(13)
(CF3)2C--N--N=C(CF&
‘4 R3
(1 4) and mass spectra; no 31Pn.m.r. data were given.l8These are the first quinquecovalent phosphoranes reported in which the phosphorus is part of a threemembered ring.
4 Four-membered Rings Two mechanisms have been proposedl9for the decomposition of the phosphite ozonides (15) to give phosphate esters and singlet oxygen. The preferred route is via the phosphorane (17), formed by pseudorotation of the initial ring-
0 I
(1 8)
(1 9)
H. Schmidbauer, K.-H. Mitschke, W. Buchner, H. Stuhler, and J. Weidlein, Chem. Ber., 1973, 106, 1226. l 8 H. Schmidbauer, H. Stuhler, and W. Buchner, Chem. Ber., 1973,106, 1238. l7 E. S. Kozlov S. N. Gaidamaka, G . B. Soifer, Y. N. Gachegov, and A. D. Gordeev, J . Gen. Chem. (U.S.S.R.), 1972, 42, 748. l 8 K. Burger, J. Fehn, and W. Thenn, Angew. Chem. Internat. Edn., 1973, 12, 502. L. M. Stephenson and D. E. McClure, J. Amer. Chem. Soc., 1973,95,3074. l5
38
Organophosphorus Chemistry
opened species (16). The rate of decomposition by this route is affected by substituents; in general, the less apicophilic the apical RO group in (16), the faster the reaction. If, however, the phosphorus is part of a five-membered ring, e.g. (18), then pseudorotation of the initial ring-opened species (19) to a phosphorane analogous to (17) becomes a high-energy process because of the need to force the ring into a diequatorial position. In these circumstances a relatively slow decomposition of (19) occurs, the rate of which is insensitive to substituents. The Witting intermediate (20) has been assigned a 1 ,Zoxaphosphetan structure20on the basis of its positive 31Pchemical shift. Above 5 “C it gave the expected cyclo-octene and phosphine oxide.
BF4-
(20) 31P e62.8 p.p.rn.
The bicyclic phosphoranes (24; X = O or S) were obtained21 from the tervalent phosphorus compounds (21 ; X = 0 or S) and hexafluoroacetone (HFA) via the cyclic iminophosphoranes (22). Diphenylvinylphosphine similarly gave the 1,2-oxaphosphetan (23). The phosphoramidite (25) with HFA gave the 1,3,2-0xazaphosphetan (26), the intermediate iminophosphorane being formed in this case by proton transfer in the initial adduct.
HFA
(Ph0)zPNHPh (25)
HNPh (Ph0)ZP \OCH(CF3)2
HFA
O--C(CF3)2
I I
OCH(CF3)z (26)
ao
I
(PhO),P-NPh
E. Vedejs, K. A. J. Snoble, and P. L. Fuchs, J . Org. Chern., 1973, 38, 1178. E. Duff, P. J. Whittle, and S. Trippett, J.C.S. Perkin I, 1973, 972.
QuinquecovalentPhosphorus Compounds
39
The variable-temperature lSFn.m.r. of the diazadiphosphetidines (27)--(29) prepared as shown are consistent 23 with concerted pseudorotation at the two phosphorus atoms. Me
Me /N \
3 MeLi
/PF,
F,P\
/
N Me
2MePF,
+
,PFMe, N
Me Me N MeF,P, /PF2Me
\
MeF,P,
N
/ \
N
Me (27)
Me N \ PhF,P, /PF2Ph -+ N Me /
+ MeN(SiMe,),
3- PhN(SiMe,),
Me N \ 2MeF,P ,PFIPh \ N Me (28) Me N / \ --+ MeF,P, P F 2 M e N Ph (29) /
The diazadiphosphetidine (30) dimerized23when kept at 130 "C for seven days. The dimer soluble in carbon tetrachloride was formulated as the cubane-like molecule (31) and the insoluble portion as the salt (32). Vacuum sublimation of the latter gave a tricyclic compound thought to be (33). (MeNPF,),
-% (MeNPF8)4
(30)
5 Five-membered Rings
Phospholans and Phospho1ens.-Whereas the strained phosphonium salt (34) with phenyl-lithium gave24the stable quinquecovalent phosphorane (39, the relatively unstrained salt (36) with the same reagent gave only the ylide (37). pp
0. Schlak, R. Schmutzler, R. K. Harris, and M. Murray, J.C.S. Chem. Comm., 1973,23. K. Utvary and W. Czysch, Monatsh., 1972,103,1048. E. W. Turnblom and T. J. Katz, J.C.S. Chem. Comm., 1972, 1270.
OrganophosphorusChemistry
40
Cyclo-octa-l,5-diene and triphenylphosphine were formed on thermolysis of (35).
6 '6 +
+
Ph,P
Br-
__t PhLi
Fragmentation of the cis-3-phospholen (38) gave25a trans,trans-hexa-2,4diene. The reaction was 99% stereospecific and is probably a concerted disrotatory process, as is the corresponding addition of halogenophosphines to d i e n e ~ . ~ ~ * Attempts to detect asymmetric induction in the reaction of the (inactive) phosphonium ion of the optically active salt (39) with 2,2'-dilithiodiphenyl were Similarly, the optically active salt (40) with bromine gave racemic phosphorane (41). The rates of reaction of the o-phenylene phosphonites (42) with butadiene 27 were in the order H>ClzMe%Me,N and were some 80 times greater than for the corresponding ethylene phosphonites. Hydrolysis of the phosphoranes (43; R = H or Me, X=Cl) gave high-boiling compounds regarded as the hydroxyphosphoranes (44) ; acetylation of the analogous compound (44;R or X = H) gave a diacetate formulated as (45). No slP n.m.r. data were given.
1,3,2-Dioxaphospholans.-The equilibria between the spirophosphoranes (46) and the corresponding phosphites (47) have been studied28 at 100 "C. In general the quinquecovalent form is stabilized by substitution of the rings by methyl or phenyl. With unsymmetrically substituted phosphoranes the less*I
*a
aa
(a) C . D. Hall, J. D. Bramblett, and F. F. S. Lin, J. Amer. Chem. SOC., 1972, 94, 9264; (b) A. Bond, M. Green, and S. C. Pearson, J. Chem. SOC.( B ) , 1968,929. D. Hellwinkel and H. J. Wilfinger, Phosphorus, 1972, 2, 87. F. V. Bagrov, N. A. Razumova, and A. A. Petrov, J. Gen. Chem. (U.S.S.R.), 1972,42, 782. D. Bernard, C. Laurenco, and R. Burgada, J. Organometallic Chem., 1973,47,113.
Quinquecovalent Phosphorus Compounds
41
' p =
p+ p-
2p-
p+ p-
(39)
bI+
blx
Reagents : i, 2,2'-dilithiodiphenyl;ii, 2'PtI-
MeCOCIJAr = Ph,R = H
$
3
0
OCOMe
OCOMe
Organophosphorus Chemistry
42
substituted ring opens preferentially. The unsubstituted bisethylenephosphorane is present to the extent of only 50% at 100 "C. For an account of phosphoranyl radicals derived from spirophosphoranes and from other species, see Chapter 10. 1,3,2-Dioxaphospholens.-New 1,2-dicarbonyl compounds used in the formation of quinquecovalent phosphoranes include the o-quinones (48) 29 and
(50)
(51)
(49)30 and perfluor~biacetyl.~~~ 32 Variable-temperature 19Fn.m.r. studies32 on the adducts from pefluorobiacetyl have given data on the energetics of the required to make the CF groups equivalent pseudorotations (50) ;-'(51) when A is more apicophilic than B and hence on the relative apicophilicities of a range of groups A and B. The trimethyl phosphite-biacetyl adduct (52) did not react with isothiocyanates, but with acyl isothiocyanates gave33 the 2-oxazoline-4-thiones(54), presumably via the intermediate betaines (53). With 2-thiazoline-4,Ediones (55) the adduct (52) gave carbon monoxide, trimethyl phosphate, and the thiazolones (57). The carbon monoxide is probably formed by fragmentation
'0
s1
aa
M. M. Sidky and F. H. Osman, J. Chem. U.A.R., 1 9 7 1 , 1 4 , 2 2 5 (Chem. Abs., 1972,77, 139 898). M. M. Sidky, M. R. Mahran, and L. S. Boulos, J. Indian Chem SOC., 1972,49,383. F. Ramirez and H. J. Kugler, Phosphorus, 1973, 2, 203. J. I. Dickstein and S. Trippett, Tetrahedron Letters, 1973, 2203. F. Ramirez, V. A. V. Prasad, and H. J. Bauer, Phosphorus, 1973, 2, 185.
43
Quinquecovalent Phosphorus Compounds
of the intermediates (56) as shown. Reaction of the trimethyl phosphite-biacetyl adduct (52) with ethylene glycol to give the spirophosphorane (58) is exothermica4to the extent of about 8 kJ mol-l. Me Me
m M 0 o, + O N Q P R
0,
@Me),
I
(53)
(52)
+ (HOCHha
(59)
__f
’’ F. Ramirez, K. Tasaka, and R.Hershberg, Phosphorus, 1972, 2.41.
OrganophosphorusChemistry
44
The phosphorane (59) fragments 2Sasterospecifically to trans,trans-hexa-2,4diene and the phosphonite (60) with AG*-105 kJ mol-I. This activation energy was explained in terms of the need to place the phospholen ring diequatorial before the fragmentation becomes a symmetry-allowed process. However, Hoffmann’s reasoning35applied to this case shows that the allowed process for loss of diene is from an apical-equatoriaI position. 1,Z-0xaphosphoIens.-Methyl vinyl ketone reacts 60 times faster with the ethylene phosphonite (61) than it does with the o-phenylenephosphonite (62),
as expected if the phosphonites are acting as nucle~philes.~~ The spirophosphoranes (64; R = H or Me) have been obtained3’ from the six-membered cyclic phosphite (63) and both acrolein and methyl vinyl ketone. The nonequivalence of the methylene protons of the oxaphospholen ring in the n.m.r. spectrum of (64; R=Me) at room temperature led to the suggestion that OMe
(63)
(64)
R
= H o r Me
pseudorotation in this compound is slow under these conditions. However, the lack of symmetry in this molecule precludes these protons from becoming equivalent by normal pseudorotation processes.
1,3,2-Oxazaphospholens.-Improved preparations of the spirophosphoranes derived from ephedrine and norephedrine have been described.38The effects of substituents on the positions of the equilibria between the spirophosphora6
36
87
38
R. Hoffmann, J. M. Howell, and E. L. Muetterties,J. Amer. Chem. SOC.,1972, 94, 3047. N. A. Razumova, M. P. Gruk, and A. A. Petrov, J. Gen. Chem. (U.S.S.R.), 1972, 42, 2109. B. A. Arbuzov, Y. M. Mareev, V. S. Vinogradova, and Y. Y. Samitov, Doklady Chem., 1973, 205, 618. R. Contreras, R. Wolf, and M. Sanchez, Synth. Znorg. Metal-org. Chem., 1973,3, 37.
Quinqueco valent Phosphorus Compounds
45
anes (65), (66), and (67) and the corresponding ring-opened species, e.g. (68), have been studied.SgThe unsaturated ring and aryl substituents favour the quinquecovalent form so that there is no evidence for the tervalent form in solutions of the phosphorane (69). H
Me
Me
(67)
(69) The bicyclic phosphoranes (70), obtained as shown, exist entirely in the quinquecovalent form in
(70)
R
= Me or 3,4-Me2C,H,
The spirophosphoranes (71) and (72) derived from ( - )-ephedrine equilibrate in solution by a process involving five successive pseudorotations. The
(71) a@ ‘O
(72)
C. Laurenco and R. Burgada, Compt. rend., 1972,275, C, 237. D. Houalla. J. F. Brazier M. Sanchez and R. Wolf Tetrahedron Letters. 1972.2969.
Organophosphorus Chemistry
46
isomer (71) is obtained in a pure state on crystallization and its mutarotation has been followed in benzene solution at different ternperat~res,~~ leading to activation parameters for the conversion of (71) into (72) of AG*=99.1 kJ mol-l, AH*= 95.3 kJ mol-l, and AS* z 13 J K-l mol-l. These agree with data previously obtained from n.m.r. studies. The quasi-enantiomers (73) and (74), containing one (-)-ephedrine and one (+)-norephedrine residue, are in equilibrium in benzene with a half-life at 30 "C of 11.4 min. Arguments have been presented for assigning the absolute configuration shown in (74) to the pure isomer obtained on crystallization.
(74)
(73)
1,3,5-Oxazaphospholens.-Details have appeared of the trapping with dip~larophiles~~ and with isocyanides44 of the nitrile ylides formed on thermal decomposition of the phosphoranes (75). In the absence of dipolarophiles, the nitrile ylide (76) d i m e r i ~ e dto~ give ~ (73, probably as shown.
(75)
@ NH
\
F,C
CF, (77)
41
4s 44 46
A. Klaebe, J. F. Brazier, F. Mathis, and R. Wolf, Tetrahedron Letters, 1972,4367. R. Contreras, J. F. Brazier, A. Klaebe, and R. Wolf, Phosphorus, 1972, 2, 67. K. Burger and J. Fehn, Chem. Ber., 1972, 105, 3814. K. Burger, J. Fehn, and E. Muller, Chem. Ber., 1973, 106, 1. K. Burger, K. Einhellig, G. Suss, and A. Gieren, Angew. Chem. Internat. Edti., 1973, 12, 156.
47
Quinquecovalent Phosphorus Compounds
Miscel1aneous.-Further examples have appeared of the use of amidoximes 46s 47 and of acyl hydrazides4*in the preparation of spirophosphoranes. The catechol liberated in the reactions of amidoximes with the cyclic phosphoramidite (78; X = Me,N) leads to the formation of stable six-co-ordinate species (see p. 49). In the proton n.m.r. spectrum of (79; R=Ph) at room
H
+ RIC(:NOH)NH,
1
RsC(:NOH)NHI
H
H
ZPNMe,
+ RCONHNH.2
-
H H
' l o 'ilR N" H
temperature, the methyl groups show three signals in the ratio 2 : 1 : 1, which separate into four equal signals in the presence of the shift reagent Eu(fod)3. Four different methyl absorptions would result if pseudorotations which place the five-membered rings diequatorial were, as expected, slow on the n.m.r. timescale. However, the proton n.m.r. spectrum of (79; R=Me) shows only two signals in the methyl region (apart from the hydrazide methyl) even in the presence of shift reagent. L. Lopez, M.-T. Boisdon, and J. Barrans, Compt. rend., 1972,275, C, 295. L. Lopez and J. Barrans, Compt. rend., 1973,276, C, 1211. R. Wolf, M. Sanchez, D. Houalla. and A. SchmidDeter. C o m t . rend.. 1972.275. C, 151.
48
Organophosphorus Chemistry
Amidrazones (80) also 4g give spirophosphoranes with trisdimethylaminophosphine or with cyclic phosphoramidites, e.g. (81).
RC(:NH)NHNH,.
+
MeCN
(MeaN),P
(80)
HHH
NIN 2
R r \p/ R N"/ \ N " N H H
The bis(trimethylsily1) thioether (82) with fluorophosphoranes gave lo the monocyclic phosphoranes (83), except with tetrafluorophosphoranes which gave the spirophosphoranes (84) and PF5, from which the salt (85) was obtained.
+
RnPF5-
PF6 and the sulphur di-imide (86) gave50 a small amount of a phosphorane,
S3N5PFS, to which the structure (87) has been assigned. The compound shows two different fluorine environments in its 19Fn.m.r. spectrum at 35 "C. This would not be expected for a molecule such as (87), in which a rapid pseudorotation to a topomeric trigonal bipyramid would lead to equivalence of the fluorines. Fragmentation of the intermediate phosphorane (88) has been proposed 61 to account for the deoxygenation of methyl p-tolyl sulphoxide by triphenylphosphine catalysed by tosyl isocyanate. 50
61
Y. Charbonnel and J. Barrans, Compt. rend., 1972, 274, C, 2209. H. W. Roesky and 0. Petersen, Angew. Chem. Internat. Edn., 1973,12,415. D. C. Garwood, M. R. Jones, and D. J. Cram, J. Ainer. Chem. SOC.,1973,95,1925.
49
Quinquecovalent Phosphorus Compounds F
PF,
+
I
- N\S=NTF //S=N,.,
Me3SiN=S=NSiMe, (86)
I
N\s4N
(87) 1-5%
ArSOMe
+ TsNCO + Ph,P
-+
,O\C=NT~ PhaP, 'S / \ Ar Me
0
(88)
Ar = p-MeC,H,
.1
Ph3P0
+ ArSMe + TsNCO
For the formation of quinquecovalent phosphoranes in the deoxygenation of nitro-olehs, see Chapter 10.
6 Six-membered Ring Following an investigation of the kinetics of the reduction of styrene ozonide with phosphitesYs2 the oxyphosphoranes (89) were proposed as intermediates in these reactions.
7 Six-co-ordinate Species A growing number of six-co-ordinate phosphorus-containing anions have been prepared. While these undoubtedly owe their stability partly to their spiro-nature, their very existence suggests that six-co-ordinate species may be much more important as reaction intermediates than has so far been recognized. The two by-products obtained from the reactions of amidoximes with the phosphoramidite (90) were also obtained46directly from (90) and catachol in acetonitrile. One (91) was the dimethylammonium salt of the known tris(ophenylenedioxy) phosphate anion; the other was formulated, on the basis of its 31Pchemical shift and PH bond, as the salt (92). This salt, on refluxing in 62
J. Carles and S. Flisziir, Canad.J , Chem., 1972, 50, 2552.
50
0rganophosphorus Chemistry
HO(92) 31P 99 p.p.m.
+
J(PH) = 800 Hz
1
51
Quinquecovalent Phosphorus Compounds
xylene, gave (91) and presumably hydrogen. The triethylammonium analogue (94) of (92) was subsequently in quantitative yield from the spirophosphorane (93) and catechol in the presence of triethylamine. Similar salts (95) were obtained from phenol and from alcohols, while with pyrrolidine the spirophosphorane (93) gave the salt (96). The amidoxime-derived spirophosphorane (97) with the aminoalcohol (98) gave4' the internal salt (99), which decomposed in polar solvents.
cyn PhCHz N H
+ HOCH2CMe2NH2 (981
0
I
(97)
CH2CMe2&H, (99)
Salts (101), similar to the above but containing carbon bonded directly to phosphorus, have been obtaineds4from the phosphonites (loo), catechol, and triethylamine in ether at room temperature. On heating they gave the phosphoranes (102), triethylamine, and hydrogen and were undoubtedly intermediates in previously reported reactions.66 A full account has appeared6sof the X-ray analysis of the salt (103).
(101)
31P
$113.5 p.p.m.
(R =
(103) 68 64 66
6a
Me)
(102)
R. Burgada, D. Bernard, and C. Laurenco, Compt. rend., 1973,276, C, 297. M. Wieber and K. Foroughi, Angew Chem. Internat. Edn., 1973, 12,419. M. Wieber and W. R. Hoos, Monatsh., 1970.101, 776. H. R. Allcock and E. C. Bissell. J. Amer. Chem. SOC.,1973,95,3154.
?
J
Halogenophosphines and Related Compounds BY J. A. MILLER
1 Halogenophosphines No major new developments have been reported this year, and the quantity and content of the literature is very similar to last year. Since publication in the field of Group IV phosphines has dropped this year, the chemistry of these compounds has been included in this section. Two reviews of phosphorushalogen compounds have appeared.’,
Physical Aspects.-& initio calculations on phosphorus trifluoride3 and difluoropho~phine~ have appeared, and the results compared3 with data from photoelectron spectra. An electron diffraction study has been made of the silylphosphines(l), and the Si-P bond length found to decrease slightly in the sequence n = 0 > n = 1 > YE = 2, while the C-P-Si bond angles are consistently 100k 1 o.6 The related silylamines(2) show relatively large changes in Si-N-C bond angle and in basicity, over the series n = 3 to n = 0, and the authors relate these contrasts to differences in bonding between nitrogen and phosphorus.6
Cyanodifluorophosphine (3) has a shortened C-P bond, and the P-C-N atoms are not collinear, as deduced from microwave studies.6 Infrared and Raman spectra have been reported for chlorodi-t-butylphosphine(4a) and fluorodi-t-butylphosphine (4b)’, and for difluoroiodophosphine (5a).8 and of Photoelectron spectra of a series of difluorophosphines (5b)--(5d),Q H. A. Klein and H. P. Latscha, Chem.-Ztg., 1973, 97, 77. R. H. Tomlinson, in Mellor’s ‘Comprehensive Treatise on Inorganic and Theoretical Chemistry’, Longmans, London, 1971, vol. 111, suppl. 111, pp. 438-535. L. J. Aarons, M. F. Guest, M. B. Hall, and I. H. Hillier, J.C.S. Faraday IZ, 1973, 69, 643. I. Absar and J. K. Van Wazer, J. Amer. Chem. SOC.,1972,94,6294. C . Glidewell, P. M. Pinder, A. G. Robiette, and G. M. Sheldrick, J.C.S. Dalton, 1972, 1402. P. L. Lee,K. Cohn, and R. H. Schwendeman, Znorg. Chem., 1972,11, 1917. ’ R. R. Holmes, G. T. K. Fey, and R. H. Larkin, Spectrochim. Acta, 1973 29A, 665. C . R. S. Dean, A. Finch, and P. N. Gates, J.C.S. Dalton, 1972, 1384. S . Cradock and D. W. H. Rankin, J.C.S. Faraday ZI, 1972, 68, 940.
52
53
Halogenophosphines and Related Compounds
the silyl derivatives (6) and (7),1° have been determined. In the latter paperlo the spectra are related to thermodynamic properties, such as basicity, by assignment of the low ionization potential band to the phosphorus lone pair. F,PCN
F,PR
(But),PX
(5) a ; R = I b; R = halogen C ; R = NH, d; R .= pseudohalogen e; R = NHSiH, f; R = Br
(4) a ; X = C1 b;X=F
(3)
.(H3Si)3M (6) M = N, P, or As
H2PSiH3
g;
(7)
R
= C1
The n.q.r. spectra of a series of dichlorophosphines(8) have been described.ll The following halogenophosphines have been subject to detail n.m.r. studies : dichloro(t-buty1)phosphine (9) [lineshape analysis and 3J(PCCH) values],le difluorophosphines (5c) and (5e) (double-resonance studies and sign of .I),'* and the borane complex (10) of tetrafluorodiphosphine (temperature dependence).l* RPCl (8)
R = CI, Ph, CH,Ph, or Me
ButPCl a
FzPPFs,BH,
(9)
(10)
Reactions.-The selection of the contents for the subdivisions of this section is not always clear cut, sometimes being based on mechanistic assumptions (made either by the original author or by the present Reporter), with which the reader may or may not agree. This is especially true of the reactions classified as biphilic. Electrophilic Attack by Phosphorus. Two standard reactions of acetylide reagents with halogenophosphines have been published. The first was used in preparation of difluoro(prop-1-yny1)phosphine (1 l), which was then converted into a phosphorane (see Halogenophosphorane section).ls Similar displacement of both chlorines from dichloro(t-buty1)phosphine (9) gave 75 % of the tertiary phosphine (12), from which the phosphabenzene (13) was prepared.le S. Cradock, E. A. V. Ebsworth, W. J. Savage, and R. A. Whiteford, J.C.S. Faraday 11, 1972, 68, 934. l1 P. Biryukov, K. V. Nikoronov, E. A. Gurylev, and A. Y . Deich, Zhur. obshchei Khim., 1972,42, 1223. J. B. Robert and J. D. Roberts, J. Amer. Chem. SOC.,1972, 94, 4902. l a D. W. W. Anderson, J. E. Bentham, and D. W. H. Rankin, J.C.S. Dalton, 1973, 1215. H. L. Hodges and R. W. Rudolf, Inorg. Chem., 1972.11, 2845. l * E. L. Lines and L. F. Centofanti, Znorg. Chem., 1973, 12, 598. G . Mark1 and D. Matthes, Angew. Chem. Internat. Edn., 1972, 11, 1019. lo
C
Organophosphorus Chemistry
54 F,PBr
+
LiCECMe + F,PC-CMe
(50 ButClz
+ PhC=CMgBr
--+
(1 1) Bu'P(C=CPh),
(9)
(12)
t
(1 3)
1 -Cyclopentadienyldifluorophosphine(1 4)has been prepared and suggested to be a fluxional molecule at temperatures above 25 OC.17 The principal evidence for this comes from n.m.r. studies, which reveal that above 25 "Cthe fluorines show coupling to five equivalent lH nuclei, and the J(FH) value falls from 11.5 to 2.5 H2.l'
A number of ligand-exchange reactions with Groups IV and VI compounds have been described this year. An extensive study of exchange between the difluorophosphines (5f) and (5g) and various silyl and germyl derivatives (15) was undertaken in order to examine the hypothesis that electronegative ligands prefer (in the thermodynamic sense) bonding to silicon rather than to germanium.lS The reactions of (5g) were difficult to interpret, but those of (5f) were generally consistent with theory, e.g. excess bromodifluorophosphine (5f) exchanged with 65% of (15a), but not at all with (15b).ls Bis(trifluoromethy1)chlorophosphineexchangeschlorine to give the ester (16).19Phosphorus trichloride reacts with (17) to exchange all the chlorines, although there are redox side reactions.20 2F,PBr + (H,M)20 BrMH3 -t (FJ')@ (5f)
(CFMCI
+ .(Me,Si),S
CF,N=SF,
-
(15) a; M = Si b; M = Ge
+ PCI:,
_cf
(CF&PSSiMe3 (1 6)
CF,N=SCI,
+ Me,SiCl + PF3
(1 7) J. E. Bentham, E. A. V. Ebsworth, H. Moretto, and D. W. H. Rankin, Angew. Chem. Internat. Edn., 1972, 11, 640. D. E. J. Arnold, J. S. Dryburgh, E. A. V. Ebsworth, and D. W. M. Rankin, J.C.S. Dalton, 1972, 2518. K. Gosling and J. L. Miller, lnorg. Nuclear Chem. Letters, 1973, 9, 355. M. D. Vorobiev. A. S. Filatov, and M. A. Englin, Zhur. obshchei Khim., 1972, 42, 1942.
55
Halogenophosphines and Related Compounds
The reactions of aryl amines with phosphorus trichloride are complex, and are a matter of some controversy.21sa2 A careful study of the reactions with excess phosphorus trichloride has shown that the main pathway involves two stages, and ultimate formation of the 2 : 2 adduct (18).23Phosphorus trifluoride reacts with NN'-dimethylethylenediamine to give the cyclic phosphine (19).24The formation and hydrolysis of the complex of phosphorus trichloride (and oxychloride) with pyridine have been studied.2S ArNH,
+ PC13
250c:
100
ArN(PC19 ) 2
* 20 "C
ArN-PCI
1
1
CIP -NAr
-
N H Me +PF, NHMe
(18)
Me "\F
ld Me
Difluorophosphine a i d e (20) has been prepared from either (5a) or (5f),26927 but there seems to be some disagreement in detail about its stability. Phosphorous acid fluorides (21) result from the hydrolysis of dihalogenophosphines in the presence of hydrogen fluoride.28The products of reactions between phosphorus trichloride and tertiary arsine sulphides are dependent upon the substituents on the ~ u l p h i d eFor . ~ ~example, triphenylarsine sulphide (22) simply desulphurizes, whereas dialkyl analogues (23) are converted into arsoranes.2s F,PX
+
( 5 ) a;
N3- -+
x
F,PN, (20)
= I
f ; X = Br 0
RPCIt
+
HF
+ HzO
R,PhAs(S)
+ PC13
(23) Ph,As(S)
+ PCI,
-
--+
II
RPHF
(21) RJ'hAsCI,
Ph3As
+
+
2HC1 [PSI
+ CI,P(S)
(22) H.-J. Vetter and H. Noth, Chem. Ber., 1963, 96, 1308. * a S. Goldschmidt and H.-L. Krauss, Annalen, 1955,595, 193. ** A. R. Davies, A. T. Bronsfield, R. N. Haszeldine, and D. R. Taylor, J.C.S. Perkin 1, 21
1973, 379. I4
I6
8B
S. Fleming, M. K. Lupton, and K. Jekot, Inorg. Chem., 1972, 11, 2534. R. G. Makitra, M. S. Makaruk, and M. N. Didych, Zhur. obshchei Khim., 197242,1877. E. L. Lines and L. F. Centofanti, Inorg. Chem., 1972,11,2269. S . R. O'Neill and J. M. Shreeve, Inorg. Chem., 1972, 11, 1629. U. Ahrens and H. Falius, Chem. Ber., 1972, 105, 3317. G. M. Usacheva and G. Kh. Kamai, Zhur. obshchei Khim., 1971,41,2705.
56
Organophosphorus Chemistry
Nucleophilic Attack by Phosphorus. The reaction of halogenophosphines with alkyl halides, in the presence of Lewis acids, has been a most useful source of a variety of organophosphorus halides.30A study of the intermediate complex in the reaction of t-butyl chloride with dichloro(methy1)phosphine (24) has confirmed31that it is a 1 : 1 complex, as originally
+ AICI,
BdCl
3- MePCI, -+
[ButMePCI,]~~AICI,-
(24)
Trimethylsilyldiphenylphosphine(25) reacts with aromatic acid chlorides to produce aroyldiphenylphosphines,which are generally not very stable to the reaction conditions32- see Phosphine Oxide chapter. French workers have made further studies of the insertion reactions of silyl- and germylphosphines with carbonyl compounds. Glyoxal is converted into the phosphines (26) and (27),33while keten gives the phosphine (28)34 with Group IV phosphines. 0
Me,,SiPPh,
II + ArCCl
0 d
Me,SiCl
+
I1
ArCPPh,
(25)
PEt,
I
R,MOCHCH=O (26) M = Si or Ge
CH=O
I
.CH2=C=0
+ RjSiPEt,
-
R,SiOC
/
PEt,
\CH, (28)
Biphilic Reactions. The mechanistic complexities of the reactions of halogenophosphines with ambident electrophilic carbonyl compounds are well illustrated by the problem of the reaction of dichlorophosphines (29) with acrylic acid, to produce the tertiary phosphine oxides (30). Two suggestions in the literature have involved an initial nucleophilic phosphorus reaction, I*
*'
'* 14
A. M. Kinnear and E. A. Perren, J . Chem. SOC.,1952, 3437. J. I. Bullock, N. J. Taylor, and F. W. Parrett, J.C.S. Dalton, 1972, 1843. H. Kunzek, M. Braun, E. Nesener, and K. Ruhlmann, J. Organometallic Chem.. 1973, 49, 149. C. Couret, J. SatgC and F. Couret, Inorg. Chem., 1972, 11, 2274. C. Couret, J. Satgt and F. Couret, J. Organometallic Chem., 1973, 47, 67.
57
Halogenophosphines and Related Compounds
or at the acidic However, the either at the @-carbonof the carbonyl oxygen has been suggested to displace halogen from electrophilic phosphorus in the first step.37The electrophilic phosphorus suggestionappears to have been eliminated by the results of competitive reactions for acrylic acid between the phosphines (29; R=Et) and (29; R=Ph), from which the latter was recovered unchanged (85 %).38 Moreover, in reactions of (29; R = Et) with a mixture of acrylic and methacrylic acids, the latter failed to compete.88 Assuming that the reaction pathway does not vary with the phosphine used, and that the first stage is rate-determining, the schemes outlined [for (29; R=Et)] are compatible with the new results.
RPCI,
+ CH,=CHC02H
CI
Nucleophilic P
I+ I
Et PCH,CH=C
H EtTCl, OCCH=CH,
I1
0
OH
CI
Nucleophilic P at acidic H
/O\
I JEt\+ 0 c1, p z o
Cl-
c1 0
I II
EtPOCCH=CH2
+ HCI
0
II
0
It
EtPCH ZCHZCCI I
The reactions of halogenophosphines with aldehydes to yield ct-halogenoalkylphosphoryl compounds present similar difficulties in mechanism. In the reactions of phosphorus trihalides with a range of aldehydes, bis-cc-halogenoalkyl ethers (31) and gem-dihalides (32) have been shown to be successive intermediates leading to the phosphonyl dihalides (33).39The known formation of (31) or (32) from the reactions of aldehydes with electrophilic halides like boron trichloride or thionyl chloride suggests a similar role for the phosphorus trihalides, and the relative rates of the reactions of phosphorus trichloride with p-substituted benzaldehydes have confirmed this ~uggestion.~~ 8b
ao 37 3B
3g
V. K. Khairullin and R. R. Shagidullin, Zhur. obshchei Khim, 1966,36, 289. T. Kh. Gazizov, M. A. Vasyanina, A. P. Pashinkin, N. P. Anoshina, E. I. Gol'dfarb, and A. N. Pudovik, Zhur. obshchei Khim., 1971, 41, 1857. V. S. Tsivunin and N. I. D'Yakonova, Zhiir. obshchei Khim., 1970, 40, 1995. T. Kh. Gazizov, A. P. Pashinkin, G. V. Dmitrieva, L. L. Tuzova, V. K. Khairullin, and A. N. Pudovik, Zhur. obshchei Khim., 1972, 42, 1730. J. A. Miller and M. J. Nunn, Tetrahedrotz Letters, 1972, 3953.
58
RCH=O 4 PX,
--
(RCHXj20
0 RCHX~~X, (33)
Orgarlophosphorus Chemistry
(3 1)
RCHX~ (3 2)
Aryldichlorophosphines react with carboxylic acid acylals to give phosphinic chlorides (34), although no evidence for mechanism has been OEt
ArPCI,
0
I II + MeCHOCOMe + ArPCH(0EtjMe + I
MeCOCl
c1 (3 4)
A detailed investigation of the reaction between tetraiododiphosphine (35) and benzyl chloride (Scheme 1) has enabled the authors to explain the formation of phosphorus trichloride and of polybenzylated phosphorus compounds, after hydroly~is.~~
312PC1
=i= 2PI, +
+ PCIs (PhCHz)zPI2CI
0 PhC€i,C{
H20''*
II
(PhCH,),POH
(PhCH,),fPCI TzCl
1 H,O
f
(PhCH,),P= 0
Scheme 1
Phosphorus tri-iodide is formed in an equilibrium with tetraiododiphosphine P-P bond(35) when the latter is treated with organic ~ u l p h i d e sFurther .~~ 40
41
4a
M. B. Gazizov, D. B. Sultanova, A. I. Razumov, G. N . El'Nikova, and L. P. Ostamina, Zhur. obshchei Khim., 1972, 42, 21 12. L. P. Zhuravleva, and M. I. Z'Ola, Zhur. obshchei Khim., 1972,42, 526. N . G. Feshchenko, Zh. K. Gorbatenko, and T. V. Kovaleva, Zhur. obshchei Khim., 1972, 42, 284.
Halogenophosphines and Related Conzpormds
59
forming and -breaking reactions of amines and of elemental sulphur have also been Cyclic phosphine oxides (36) result from the reaction of a, w-di-iodides with the di-iododiphosphine (37).4'*
(38) X = halogen
Treatment of hexafluoroacetone with halogenophosphines yields 1,3,2dioxapho~pholans,~~ presumably of the general type (38) - details not available. Oxidations of phosphorus trifluoride with oxygen, sulphur, or selenium,46 and of phosphorus tri-iodide and (35) with selenium, 47 have been reported see Phosphine Oxide chapter. Miscellaneous Reactions. Phosphorus trichloride and aluminium chloride ring-open the silacyclobutane (39) to give the phosphonous dichloride (40).48 The equilibrium reaction leading to the mixed diphosphine-p-oxide (41)lies well to the right,49in accordance with the n-acceptor theory of such exchanges.60
(39)
(('F,),POP(CF:,)2
+
F,PC)PF,
(CF,),POPF, (41)
44
46
'' '* Ls
N. G. Feshchenko, T. V. Kovaleva, and A. V. Kirsanov, Zhur. obshchei Khim., 1972, 42, 287. N. Ya Derkach, I. M. Kononenko, and A. V. Kirsanov, Zhur. obshchei Khim., 1971, 41, 2806. V. N. Volkovitskii, I. L. Kununyants, and E. G. Bykhovskaya, Zhur. Vsesoyuz. Khim. obshch. im. D.I. Mendeleeva, 1973, 18, 112. A. P. Hagen and E. A. Elphingstone, Znorg. Chem., 1973, 12, 478. M. Baudler, B. Volland, and H.-W. Valpertz, Chem. Ber., 1973, 106, 1049. E. F. Bugerenko, A. S. Petukhova, and E. A. Chernyshev, Zhur. obshchei Khim., 1972, 42, 168. R. G. Cave11 and A. R. Sanger, Znorg. Nuclear Chem. Letters, 1973, 9,461. A. B. Burg and J. S. Basi, J . Amer. Chem. SOC.,1963, 90, 3361.
60
Organophosphorus Chemistry
Phosphorus trifluoride reacts with the nitroxide radical (42) as shown.61 The effect of FeIII and CuI or CuII additives, and of solvent, on the formation of (43) by y-irradiation of cyclohexene in the presence of phosphorus triN-Silylaminodifluorophosphine (44) has been chloride has been prepared from (5c) and its n.m.r. spectrum
+
(CF,),N6
PF,
-
(CF,),NOPF,
(42)
H,,SiBr
+
(43) H,SiNHPF,
H,NPF,
(44)
(5c)
2 Halogenophosphoranes Structure and Bonding.-The question of 4s and/or 4p orbital participation in bonding in phosphoranes has been investigated in a series of calculations based on phosphorus pentafl~oride.~~ It appears that the promotion energy to the 4s orbital is greater than that for the 3d orbital, and the author concludes that the former are not likely to be important in bonding.54 Two years ago it was suggested66that the temperature dependence of the n.m.r. of the phosphorane (45a) could not be rationalized in terms of Berry pseudorotation (BPR), and that an intermolecular route might be operating. This matter has been re-examined for the phosphorane (45b), and temperature and solvent dependence of its n.m.r. spectrum found to be compatible with a BPR process.68The suggest that the original work56may have been complicated by the presence of hydrogen fluoride, formed via the glass n.m.r. cells. In a more theoretical approach to the same problem, arguments have been made for the intermolecular pathway, via octahedral intermediate^.^' RrPF, (45)
a;
b; c;
R R R
= Me = Ph = NH,
C. S.-C. Wang and J. M. Shreeve, Inorg. Chem., 1973, 12, 81. E. I. Babkina and I. V. Vereshchinskii, Zhur. obshchei Khim., 1972, 42, 1285. s3 D. E. J. Arnold, E. A. V. Ebsowrth, H. F. Jessep, and D. W. H. Rankin, J.C.S. Dalton, 1972, 1681. 6 4 R. G. A. R. Maclagan, J.C.S. Faraday 11, 1972, 68, 1 1 17. l 6 T. A. Furtsch, D. SDierdorf, and A. H. Cowley, J. Amer. Chem. SOC., 1970, 92, 5759. I* C. G. Moreland, G . 0. Doak, and L. B. Littlefield, J . Amer. Chem. SOC.,1973, 95,255. 6 7 J. 1. Musher, Tetrahedron Letters, 1973, 1093.
Halogenophosphines and Re Iated Compounds
61
Further support has appeared for the view5* that x-donors prefer an equatorial site in a trigonal bipyramid, and that, when so placed, the donor will have its donor orbital in the equatorial plane. Thus the n.m.r. of the phosphorane (4%) indicates that the hydrogens are axially oriented, and coupled strongly to the axial fluorines [as in structure (46)69].
(46)
Phosphorus pentachloride (47) has received an unusually high share of attention over the past year. A long overdue study of the effect of solvents on the various equilibria involving (47) and ionic species has appeared.60From laser Raman spectra, and freezing point depression data, it has been shown that, in polar solvents, (47) is ionizing in two different ways, and that the two equilibria are largely dependent upon concentration of (47). In benzene, (47) is monomeric, and the alleged dimer in carbon tetrachloride appears to be non-existent and incorrectly characterized because of solid-solution formation.6O F a g
-
k14
predominant at >0.03 mol 1-
PCI:, -
predominant at 10.03 mol I-' 4
6CI4 El
(47)
A study has been made of the reversible association between (47) and solvents containing carbonyl or ether functions.61Other reports have appeared on the dissociation and stability of (47),62its Raman spectrum in anhydrous hydrochloric its n.q.r. and on the heat capacity of (47).66 The X-ray photoelectron spectrum of phosphorus pentafluoride confirms the trigonal-bipyramidal structure and the relatively longer axial P-F bonds.66An electron diffraction study of the fluorophosphorane (48) has been made.67 Me,PF,
(48) rD .SO
a
'* Oa
Oa
R. Hoffmann, J. M. Howell, and E. L. Muetterties,J. Amer. Chem. SOC.,1972,94,3047. E. L. Muetterties, P. Meakin, and R. Hoffmann, J . Amer. Chem. SOC.,1972,94,5674. R. W. Suter, H. C. Knachel, V. P. Petro, J. H. Howatson, and S. G . Shore, J. Amer. Chem. SOC.,1973,95, 1474. V. G. Rozinov, V. V. Rybkina, and E. F. Grechkin, Zhur. obshchei Khim., 1972, 42, 1167. L. D. Polyachenok and 0. G. Polyachenok, Zhur. $2. Khim., l973,47,498B. P. V. Huong and B. Desbat, Bull. SOC.chim. France, 1972, 2631. H. Chinara and N . Nakamura, Bull. Chem. SOC.Japan, 1973, 46, 94. H. Chihara, M. Nakamura, and K. Masukane, Bull. Chem. SOC.Japan, 1973, 46, 97. R. W. Shaw, T. X. Carroll, and T. D. Thomas, J. Amer. Chem. SOC.,1973, 95,2033. H. Yow and L. S. Bartell, J. Mol. Structure, 1973, 15, 209.
62
Organophosphorus Chemistry
Preparation.-Details have appeared of the preparation of tetra-alkylfluorophosphoranes (49) from ylides, and of the structures of the phosphoranes.68 The related addition of methanol to methylene ylides yields tetra-alkylalkoxyphosphoranes (50),69which are unusual in that one alkyl group is axial in the trigonal-bipyramidal structure. These decompose thermally, but the pathway depends on the substituents. R,P=CH,
M e 0 !I
d R,MeP(OMk)
(50)
R =Me
Me,P=O
R = Ph
McPPh,
+ CzHs
RR,MePF (49)
+
McOPh
Prop-l-ynyltetrafluorophosphorane (5 1) has been prepared from the corresponding ph0~phine.l~ The fluorophosphoranes(45b) and (52) have been prepared using molybdenum hexafl~oride.~~ Phosphorus trichloride converts dialkyl(pheny1)arsine sulphides into the corresponding dichloroarsorane
(53).29 F,PC-CMe
+
SbF,
SbC'3+
F,PCfCMe
(51) Ph,PCl
+
MoF, -+ Ph,PF,
(45b)
Silicon-exchange routes to phosphoranes are being increasingly used in preparative phosphorane work. For example, tetrafluorophosphorane (54) has been synthesized by an improved route via trimethyl~ilane,~~ and its n.m.r. spectrum analysed for a trigonal-bipyramidalstructure with axial f l u o r i n e ~ . ~ ~ The fluorophosphorane (55) can be prepared from N-trimethylsilyl-2-methylp y r r ~ l e and , ~ ~ the n.m.r. spectrum (non-equivalent axial fluorines) appears to conform to the z-donor theories advanced a year
q1
H. Schmidbaur, K.-H. Mitschke, W. Buchner, H. Stiihler, and J. Weidlein, Chem. Ber., 1973, 106, 1226. H. Schmidbaur, H. Stiihler, and W. Buchner, Chem. Ber. 1973, 106, 1233. F. Mathey and J. Bensoam, Compt. rend., 1972, 274, C, 1095. A. H. Cowley and R. W. Braun, Znorg. Chent., 1973, 12, 491. M. J. C. Henson, R. Schmutzler, and W. S. Sheldrick, J.C.S. Chem. Comm., 1973, 190.
Hulogenophosphines and Related Compounds Me,SiI-E
+ PF,
63
+ F,PH
Me,SiF
(54)
A number of alkoxy and related fluorophosphoranes have been prepared by the routes indicated. The alkoxyphosphoranes (56)73 and (57)74are stable only when substituted as shown. The phosphorane (58) has a structure intermediate between a trigonal bipyramid and a square pyramid.75 Me,SiOR2 3. R'PF,
tEpp.fR1PF30R2 R1 = Me or Ph
(56)
R,P(X)Y
+
(Me,Si),O
=
'*
R ,P(Y)(OSiMed 2 (57) stable when
I
R = Y = C F 3
R,P(O)OSiMc, , ,*SSiMe3
'SSiMe,
L"
Reactions.-The cis-addition of phosphorus pentachloride to acetylenes has been confirmed, although the reactions are not always clean, as shown by the additions to propyne (59) and but-l-yne (60),in which the additional products appear to result from reaction of hydrogen chloride with the initial a d d u ~ t . ' ~ 75
74
76 76
D. U. Robert, G. N. Flatau, C. Demay, and J. G. Reiss, J.C.S. Chem. Comm., 1972, 1127. R. G. Cavell, R. D. Leary, and A. J. Tomlinson, Znorg. Chem., 1972, 11, 2578. M. Eisenhut, R. Schmutzler, and W. S. Sheldrick, J.C.S. Chem. Comm., 1973, 144.
A. V. Dogadina, K. S. Mingaleva, B. I. Ionin, and A. A. Petrov, Zhur. obshchei Khim., 1972,42,2186.
Organophosphorus Chemistry
64
i 3-
0
I1
McCFI= CC1C H 21' C:1
The en-yne (61) reacts with phosphorus pentachloride to give the adduct (62). 77 Styrene and phosphorus pentachloride react to give distyryltrichloroto form the phosphinic phosphorane (63), which has now been chloride (64), and not the corresponding phosphinous ~hloride,'~ on treatment with methyl phosphorodichloridite.
Details of the reaction between phosphorus pentachloride and acetals of or-keto-acids include mechanistic studies. The intermediate oc-chloroaceta1 (65) is formed almost instantaneously at below 0 "C, and CO and HCl simultaneously evolved.goStereochemical studies of the acetal ring-opening indicate that this step involves inversion. The suggested mechanismgois consistent with the original observation that alkaline hydrolysis of the B-chloroacetate (66) gives an epoxide with the same absolute stereochemistry as the diol from which the original acetal was derived.
7'
ao
A. V. Dogadina, B. I. Ionin, and A. A. Petrov, Zhur. obshchei Khim., 1972, 42, 1919. V. S. Galeev, Ya. A. Levin, Zhur. obshchei Khirn., 1972, 42, 1496. Y.A. Levin, V. S. Galeev and N. V. Evdokimova, Byul. Izohret., 1969, no. 2. M. S. Newman and C. H. Chen, J. Org. Chem., 1973,38, 1173.
Halogenophosphines and Related Compounds
65
0
LO
+ C1- +
II
MeCO\6H
The cleavage of 1,3-dioxolans (67a) by phosphorus pentachloride has been claimeds1 to involve 2-chlorodioxolan intermediates [cf. (66), above]. The products are normally vinylphosphonic dichlorides (68) and their formatione2 from 2,2-dimethyl-l,3-dioxolan(67b) suggests that another route is more likely - as ref. 82 would also indicate. 2-Ethyl-l,3-dioxolan (67c) yields the dichloride (69).8s 0
II
ClCH,CH,OCH=C
/ \
PCl * (69)
Me
For (67Qt
(67)a; R1 = H; R2 = H or alkyl b; R1 = R2 = Me C; R' = H ; R 2 = Et
CI(CH,),OC(Me)= CHPCII (68)
The bisperoxide (70) reacts with phosphorus pentachloride to yield the vinylphosphonic dichloride (71).84 Santonin (72) chlorinates in stages on treatment with phosphorus pentachloride or thionyl chloride.86
86
K. A. Petrov, M. A. Raksha, and V. L. Vinogradov, Zhur. obshchei Khim., 1966, 36, 7151. S. V. Fridland, S. K. Chirkunova, and T. V. Zykova, Zhur. obshchei Khim., 1972, 42, 117. S. V. Fridland, L. K. Dalmatova, and S. K. Chirkunova, Zhur. obshchei Khim., 1972, 42, 1916. A. I. Shreibert, F. V. Mudryi, L. M. Mudraya, and A. K. Brel, Zhur. obshchei Khim., 1972,42, 1867. A. Frohlich, K. Ishikawa, and T. B. H. McMurry, Tetrahedron Letters, 1973, 995.
66
Organophosphorus Chemistry 0
(Bu'OO),CHMe
II
+ PCI,
-% ButOOCH=CHPCI, (71)
(70)
A comparison has been made between the reactions of pyridine N-oxide (73) and nitrosobenzenes (74) with phosphorus pentachloride.86 Neither reaction is clean, but the N-oxide tends to deoxygenate, whereas (74) is halogenated predominantly in the para-position by an unidentified species.ss
1
(mainly)
-0 (73)
o
N
=
O PCI,
(74)
*
n
N
=
O
+ others
c1 (mainly)
Phosphorus pentachloride with hydrogen chloride has been found to be efficient in the cyclization of benzonitrile to the sym-triazine (75).87 Adipic acid diamide (76) reacts with phosphorus pentachloride as shown.ss The reaction of sulphur tetrafluoride with phosphorus pentachloride yields a salt-like product, formulated as (77) or (7Qs9 ** R. C. Duty and G. Lyons, J. Org. Chem., 1972,37,4119. S. Yanagida, M. Yokoe, M. Ohoka, and S. Komori, Bull. Chem. SOC.Japan, 1973, 46, 306.
H. A. Klein and H. P. Latscha, Z . anorg. Chem., 1973,396,261. L. N. Markovskii, E. A. Stukalo, and A. V. Kirsanov, Zhur. obshchei Khim., 1972,42, 2581.
Halogenophosphines and Related Compounds
67
Ph I
PCI,-HCI
PhCSN
x;l
Ph
Ph
(75)
(76)
2PC15
+
+ [C13F6PS] (?) either (77) kF68a,
3SF4
SCI4
or (78) C1,SF SF,
Trifluoroacetamide reacts with phenyltetrafluorophosphorane to give (79).g0The same phosphorane reacts with diphosphine disulphides, but only the disulphide (80) gave one pair of products.B1The N-trirnethylsilylirnide derivatives (81),92 (82),92 and (83) 93 react as indicated with phosphorus
pentafluoride. 0 PhPF,
+
0
II
CF3CNH2
II
__f
PhPF2=NCCF3 (79)
S
PhPF,
l p ,
+ RP,
II
b*
es
+
II
,PR
PhPF2
S
0
Me,S=NSiMe3
II
PF,
-
qs 'S
S
S
+
I
.F
a
PF,
G. Gzieslik and 0. Glemser, 2.anorg. Chem., 1972, 394, 26. R. K. Harris, J. R. Woplin. M. Murray, and R. Schmutzler, J.C.S. Dalton, 1972, 1590. R. Appel, I. Ruppert, and F. Knoll, Chem. Ber., 1972,105,2492. H. W. Roesky and 0. Petersen, Angew. Chem. Internat. Edn., 1973, 12,415.
68
Organophosphorus Chemistry
The reactions of dihalogenophosphoranes, or their chemical equivalent, continue to be exploited in general organic synthesis. Dibromotriphenylphosphorane (84) deoxygenates the ether (85), and the resulting dibromide is readily a r o m a t i ~ e d Benzoins .~~ may be oxidized to benzils by (84).96
0
II
ArCCH(0H)Ar
+ Ph,PBr,
-
00
II II
ArCCAr 3- Ph3P 2HBr
+
wMe mMe (84)
+ Ph3PBr,
+ Ph3P=0
_j
Me
Me
(84)
(85)
Br
rilicap
Epoxides are converted into cis-1,Zdihalides by refluxing with a solution of triphenylphosphine in carbon tetrachloride or tetrabr~mide.~~ The reaction involves inversion at both epoxide carbon atoms, and a reasonable rationale is outlined for cyclohexane epoxide (86) in carbon tetrachloride.
0 0
+ Ph3$CCI, C1-
1 CC13
1
'' J. DeWit and H. Wynberg, Rec. Trav. chim.,1973, 92,281. *' T.-L. Ho, Synthesis, 1972, 697. "
N. S. Isaacs and D. Kirkpatrick, Tetrahedron Letters, 1972, 3869.
69
Halogenophoshines and Related Compounds
The 2-chlorination of 1,3-distearoylglyceroI (87) by triphenylphosphine in carbon tetrachloride proceeds stereospecifically, again with inversion.s7 An extensive investigation of the reaction of triphenylphosphine in carbon tetrahalide-dimethylformamide with nucleoside hydroxy-functions has been published.98 Tris-NN-dimethylaminophosphine in carbon tetrachloride converts methyl a-O-glucopyranoside (88) quantitatively into an isolable alkoxyphosphonium salt.BB CHzOR CHOH I
I
CHzOR PhsP-CCId
*
I I
Cl--CH
CH2OR
CHzOR
(87) R = stearoyl C1- +P(NMe&
HQ
+ (Me,N),P HOQMe OH
w
-
I
0
CCId
HO QMe OH
R. Aneja, A. P. Davies, and J. A. Knaggs, J.C.S. Chem. Comm., 1973,110. J. P. H. Verheyden and J. G. Moffatt, J. Org. Chem., 1972,37, 2289. B. Castro, Y. Chapleur, B. Gross, and C. Selve, Tetrahedron Letters, 1972, 5001.
4 Phosphine Oxides, Sulphides, and Selenides BY J. A. MILLER
1 Introduction
As no significant work on physical aspects of phosphine oxides has appeared over the current year, this section has been omitted. The chapter has been divided into sections on the preparation and on the reactions and pmperties of phosphine oxides, and comment made on spectra or other physical properties where appropriate.
2 Preparation From Secondary Phosphine Oxides or from Phosphinites.-Diphen ylphosphine oxide (l), as its magnesium ester, has been converted into tertiary phosphine oxides by reaction with carbonyl compounds1 such as acetone and crotonaldehyde. With ag-unsaturated ketones,l$ however, the preferred reaction is a 1,4-addition, as with the ketone (2), which yields the bis-oxide (3).l In the same paper,l details have appeared of the generation of the anion of diphenylphosphine oxide from benzyl diphenylphosphinylformate (4). Trapping of this anion by benzoyl chloride yielded diphenylphosphinylbenzyl diphenylphosphinate (3, probably produced via the highly reactive3benzoyldiphenylphosphine oxide (6). Another group4 has obtained the ester (5) from benzoyl chloride and trimethylsilyldiphenylphosphine(7) - see Halogenophosphines, Chapter 3. Further studies of the rearrangement of propargyl and related phosphinites to allenic phosphine oxides have been reported by French workers.sss The rearrangement is known' to be stereospecific, and this has been used to determine the stereochemistry of acetylenic alcohol^.^ The propargyl-ally1 alcohol (8) was found, as expected, to rearrange via the triple bond only.6 The P. F. Cann, S. G. Warren, and M. R. Williams, J.C.S. Perkin I , 1972, 2377. P. F. Cam, D. Howells, and S. G . Warren, J.C.S. Perkin 11, 1972, 304. a See J. A. Miller, in 'Organophosphorus Chemistry' ed. S. Trippett (Specialist Periodical Reports), The Chemical Society, 1971, vol. 2, pp. 56-58. H. Kunzek, M. Braun, E. Nesener, and K. Ruhlmann, J. Organometallic Chem., 1973, 49, 149. D. Guillerm and M. L. Capmau, Tetrahedron, 1972, 28, 3559. M. Huche and P. Cresson, Tetrahedron Letters, 1972, 4933. ' A. Sevin and W. Chodkiewicz, Bull. SOC.chim. France, 1969, 4016.
70
Phosphine Oxides, Sulphides, and Selenides
71
0
0 0
0 Ph,POEt
+
I1
ClCOCH,Ph
-+
I1 II
Ph2P--COCHfPh
[ph2i]
+
C02 + ICH,Ph
+
Me3SiC1
0
II
Ph2PSiMe, 3- PhCOCl + PhCPPhs
(7)
I
H 2 0 [O]
Y (5)
bis(dipheny1phosphine) oxide (9) has been synthesized and an n.m.r. study made of its hindered rotation (by a variable-temperature method).* A re-examination of the reaction between p-benzoquinone and diphenylphosphine oxide (1) has confirmed the originallostructural assignment to the phosphine oxide product (10). The related reaction of chlorodiphenylphosphine yields p-hydroxyphenyl diphenylphosphinate (1 1). The authors were D. Howells and S. G. Warren, Tetrahedron Letters, 1973, 675. I. M. Magdeev, Y. A. Levin, and B. E. Ivanov, Zhur. obshchei Khim., 1972,42,2415. I. G . M. Campbell and I. D. R. Stevens, Chem. Comm., 1966, 505; J. Chem. SOC.(C), 1971, 1836.
72
Organophosphorus Chemistry
M e C f C C H ( 0 H)CH=C H Mc (8)
Me
CH=CHMe
f
Ph,PC&
.CH=CHMe
0
0
II
Ph ,P--?H-CMe
1
I1
,PPh 2
not able to rationalize the difference in reaction pathway, although there is close analogy in the reactions of tetracyclone (12), which gives conjugate addition products with the oxide (l), but is attacked at the carbonyl oxygen by tertiary phosphines.ll 0
il
PPh 2
Q Q qK 0 ’
@IPh2 OH
i, Ph,PCI ii, H,O
0
OH
Ph
Ph
0
By Grignard and Related Reactions.-1 -Phosphabicyclo[2,2,1Iheptane 1-oxide (13) has been synthesized12 by the route outlined, and detailed europium shift-reagent and 13C n.m.r. studies reported.13 These bridged oxides are See J. A. Miller in ‘Organophosphorus Chemistry’, ed. S. Trippett (Specialist Periodical Reports), The Chemical Society, 1973, vol. 4, p. 77. l’ R. B. Wetzel and G. L. Kenyon, J . Amer. Chem. SOC.,1972,94,9230. l 8 R. B. Wetzel and G. L. Kenyon, J.C.S. Chem. Comm., 1973,237. l1
Phosphine Oxides, Sulphides and Selenides
73
characterized by exceptionally large values of 3J(PCCH) coupling constants, e.g. (13) has a value of 28 Hz (see Physical Methods, Chapter 11). A related cyclization of a dibromide has been used in the preparation1*of novel 1,2,3-triphenyIphosphiren 1-oxide (14), from bis(cc-bromobenzy1)phenylphosphine oxide (1 5), using DBN as a double dehydrobrominating agent. The three-membered ring may be cleaved thermally or by alkali. Vinylphosphine oxides (16) may have been synthesized l6 by Grignard reactions of bis(P-bromoethyl)phosphinyl chloride (17) in the presence of base.
PhC,CPh
0
0
II (BrCH2CH,),PCI
+ RMgX
(1 7)
EtsN
II
+ (CHZ=CH)ZPR (16)
By Oxidation of Phosphines.-Standard
oxidation procedures have been described for the formation of several unusual phosphine oxides, e.g. (18), and hence (19);16(20)17and (21);18(22),lgand (23).20
l4
E. W. Koos, J. P. V. Kool, E. E. Green, and J. K. Stille, J.C.S. Chem. Comm., 1972, 1085.
l6
lB
Y. A. Levin, R. I. Pyrkin, and M. M. Gilyazov, Zhur. obshchei Khim., 1972, 42, 1166. Y. Kashman and E. Benary, Tetrahedron, 1972, 28,4091. K. C. Srivastava and K. D. Berlin, f. Org. Chem., 1972,37,4487. F. Mathey, G. Muller, and H. Bonnard, Bull. SOC.chim. France, 1972, 4021. Z . N. Mironova, E. N. Tsvetkov, L. I. Petrovskaya, V. V. Negrebetskii, A. V. Nikolaev and M. I. Kabachnik, Zhur. obshchei Khim., 1972, 42, 2152. G. Mark1 and D. Matthes, Angew. Chem. Internat. Edn., 1972, 11, 1019.
74
oo v
Organophosphorus Chemistry
+ PhPHz
i, base
____f ii, HIOt
Ph-P
ll
i,BH;
.
ii, Pb(OAc)d
0
i, RZ2NHin
R'nP(CH2OAc) 3 - 8
aq. M~OH-KOH
ii, HzOI
F
11
R1,1P(CH,NR2,),-, (22) R1 = cycloalkyl
ButPCl,
+ PhCECMgBr
-+
ButP(CGCPh), 1HdL
0
II
ButP(C=CPh) (23)
Phosphine Oxides, Sulphides, and Selenides
75
Treatment of the bicyclic phosphine (24) with sulphur results in ring cleavage when Ar=p-MeOC,H,, but in no reaction when Ar=pOZNCeH,! 21 1,2,3-Benzotriphospholesreact with sulphur to produce either a monosulphide or a disulphide, and 31Pn.m.r. was used to assign the structures (25) and (26), respectively.22 ZH,OH
Ph
D t .
V
P
’ Ph
W
P
.S
’ Ph
1
A useful development in this year’s synthetic work on phosphine sulphides is the report of a one-step conversion of a phosphine oxide into the corresponding sulphide by treatment of the former with boron trisulphide.2s It appears that the conversion is highly stereospecific, and the phosphine sulphide product (27) has retained stereochemistry at phosphorus.
Two reports of phosphine selenide preparation from selenium have appeared. Trifluorophosphineselenide (28) is unstable but can be manipulated (mass spectrum given) in a vacuum line in the dark.24The corresponding OP
as 24
E. S. KOZIOV,A. I. Sedlov, and A. V. Kirsanov, Zhur. obshchei Khim., 1972, 42, 519. F. G. Mann and A. J. H. Mercer, J.C.S. Perkin I, 1972, 1631; B. E. Maryanoff, R. Tang, and K. Mislow, J.C.S. Chem. Comm., 1973, 273. A. P. Hagen and E. A. Elphingstone, Inorg. Chem., 1973,12,478.
76
Organophosphorus Chemistry
reactions of phosphorus tri-iodide or tetraiododiphosphine give isolable products, the selenides (29), (30), and (31).25
PF,
+ Se
in vacuo
F,PSe (28)
By Miscellaneous Routes.-Benzyne and pentaphenylphosphole 1-oxide (32) yield the bicyclic oxide (33), which on pyrolysis yields tetraphenylnaphtha1ene.26The other pyrolysis product, phenylphosphinidene oxide (34), was trapped by the reactions outlined below, although trapping with isoprene or acetylenes failed.26
J.
Ph
0
II
PhP(SEt)z 0
II
PhPOMe
I
OH
.
Et,S,
[PhP=O]
+
ph@ Ph
(34)
MeY
J
Ph
CB2=C(OEt),
0 II
(Et 0),PPh
Two rearrangements are described which lead to the phosphepin 1-oxide ( 3 9 , from the bicyclic phospholan 1-oxide (36), or the isomeric phosphepin 1-oxide (37).27 Phospholes have been shown to ring-expand to the oxides (38) on treatment with benzoyl chloride and alkali,28and the reaction found ID
1’
M. Baudler, B. Volland, and H.-W. Valpertz, Chem. Ber., 1973, 106, 1049. J. K. Stille, J. L. Eichelberger, J. Higgins, and M. E. Freeburger, J. Arner. Chem. Soc., 1972,94,4761. G. Mark1 and G. Dannhardt, Tetrahedron Letters, 1973, 1455. F. Mathey, Tetrahedron, 1972, 28, 4177.
Phosphine Oxides, Sulphides, and Selenides
77
to be general except for R = But, in which case the product is the phosphol-3ene 1-oxide (39).29 The rearrangement reaction has been rationalized as shown, and resembles other ring-expansion reactions of p h o s p h ~ l e s31. ~ ~ ~ AI,O, or
Et,N
>
Three papers have appeared on the synthesis and synthetic utility of halogenoalkylphosphine oxides, such as tris-(2-~hloroethyl)phosphineoxide (40) and bis-(2-chloroethyl)chloromethylphosphine oxide (41).32-34 A summary of these reactions is shown. Another reaction leading to a-halogenoalkylphosphineoxides (42) is that between aldehydes and halogenoph~sphines.~~ With phosphorus trihalides, the pathway to the oxides (42)has been shown to be quite complex, and, for simple aldehydes, the oxide products are formed in the final stage of the ao
88
36
F. Mathey, Tetrahedron, 1973, 29, 707. A. N. Hughes and C. Srivanavit, Canad. J. Chem., 1971,49,879. M. Schlosser, Angew. Chem., 1962, 74,291. L. Maier, Phosphorus, 1972, 1,237. L. Maier, Phosphorus, 1972,1,245. L. Maier, Phosphorus, 1972, 1, 249. J. A. Miller and M. J. Nunn, Tetrahedron Letters, 1972, 3953.
0rganophosphorus Chemistry
78 (HOCH,CH&CH,OH
CI-
pH 1 - 3 y
0
II
(HOCH2CH1)3P=0
(HOCH,CH,) 2PCH,0H
k16
p. (40)
\RO- or
R3NJ
(CHZ=CH)3P=O
0
0 (CH,=CH),P, II
(ClCH,CH,),P=O
(RXCH ,CH 2)3P=0 X = SorO
~
II
Et,N
(CICH,CH,) 2PCH2Cl
CH,Cl
(41)
k-
in ether
0
It
(RXCH,CH,) 2PCHzCl
sequence - details of the role of the halogenophosphine appear in the previous chapter. Phosphorus oxychloride and tertiary phosphines react to give complex salts (43), which are decomposed hydrolytically to phosphine An interesting hydrolysis reaction yields the oxide (44)in what appears to be a stepwise rea~tion.~' ArCH=O
+ PX3
-
0
II
(ArCHX),O + ArCHX2 -+ ArCHXPXz
(42)
A compilation of 13Cn.m.r. data on phosphetan and phospholan oxides and 39 The analysis of sulphides has appeared, together with synthetic 13C n.m.r. spectra has been used to determine the number and identity of stereoisomers in reaction mixtures, and details of 13C shifts and l3GS1P a' as
E. Lindner and H. Beer, Chem. Ber., 1972, 105, 3261. F. G. Mann and A. J. H. Mercer, J.C.S. Perkin I, 1972, 2548. G. A. Gray and S. E. Cremer, J. Org. Chem., 1972, 37, 3458. G. A. Gray and S. E. Cremer, J. Org. Chem., 1972, 37, 3470.
Phosphine Oxides, Sulphides, and Selenides
79
coupling appear in the Physical Methods chapter (Chapter 11). Triphenylstibine oxide (45) has been prepared by the two routes outlined, and the oxidation product ~haracterized.~~ The oxide (45) is monomeric in benzene solution. Ph,SbOH
-% Ph,Sb=O
3 Reactions and Properties
The lithium derivative of 3,4-dimethyl-l-phenylphosphol-3-en 1-oxide (46) reacts with benzonitrile to produce the new heterocycle (4nY4l which has been found to rearrange photochemically. Diazomet hyldiphenylphosphine oxide (48) has been shown to add to the carbonyl group of (49), and the resultant adduct converted to the ring-expanded derivative (50).43
0
II
Ph ZPCHN 2
R
c K $ =Ro
R (50)
(49) 40
43
W. E. McEwen, G. H. Briles, and D. N. Schulz, Phosphorus, 1973, 2, 147. F. Mathey, and J.-P. Lampin, Tetrahedron Letters, 1972, 1949. J.-P. Lampin and F. Mathey, Tetrahedron, 1972, 28, 5367. M. Regitz, W. Disteldorf, U. Eckstein, and B. Weber, Tetrahedron Letters, 1972, 3979.
80
Organophosphorus Chemistry
Further study of the oxidation of diarylphosphine oxides (51) by peroxide compounds (52) has shown that the rate-determining step varies with the nature of R in (52).44The 1,3-0xaphosphol-4-en1-oxide (53) is converted into the bicyclic oxide (54) on treatment with an excess of chlorine.21 Ar,P(OjH
+ ROO-
(51)
__f
Ar,P(O)OH
(52)
n
II 0
Ar
Ar
(53)
(54)
Enamines derived from the oxide (55) have been used in the synthesis of the fused heterocycles (56) and (57).45 The reaction between enamines and diazomethylphosphine oxides (58) does not yield the anticipated pyrazoline (by a 1,3-dipolar addition), but instead yields the phosphine oxides (59).48 Ph-N-N
6
R2NH
(R = cycloalkyl))
ON 'Ph
(55)
0
II
RzPCHN2
'4
46
+
\
,N.-CH=CMe,
-
(57)
0
II
RJT(N2)CH-CHMe,
R. Curci and F. Di Furia, Tetrahedron, 1972, 28, 3905. G. Mark1 and H. Baier, Tetrahedron Letters, 1972, 4439. W. Welter and M. Regitz, Tetrahedron Letters, 1972, 3799.
I
81
Phosphine Oxides, Sulphides, and Selenides
A neat deoxygenation of epoxides by triphenylphosphine selenide (60) has been rep~rted.~’ The reaction results in retention of the epoxide geometry, and is therefore complementary to the deoxygenations by diphenylphosphide (61) and other PI11 reagents, which lead to i n v e r s i ~ n . ~Last * ~ ~year ~ it was reported that the related reaction of triphenylphosphine sulphide (62), also catalysed by trifluoracetic acid, gives good yields of thi-irans,&Oand the contrast is clearly a matter of general interest.
R \Ph,P-
(61)
k.4,
7
CFJCO,H
Triarylphosphineoxides form complexes (63) with toluene-p-sulphonamide, and these are the final products of the reactions of triarylphosphines with chloramine-T Tertiary arsine sulphides are desulphurized by phosphorus Ar,P
+
ClNHSO, -Me
_.)
Ar,P=NSO,
(64)
1
//O”-H \ NH Ar3q -.0--s /
Po f--
Ar,P=O
+
H,NS02
@
Me (63)
Ar,As(S)
+ PCI,
(65)
R,ArAs(S)
+
-
PCI, -+
Ar,As
+ Cl,P(S)
R2ArAsC12
+ [PSI
(66)
6o b1
D. L. J. Clive and C. V. Denyer, J.C.S. Chem. Comm., 1973, 253. E. Vedejs and P. L. Fuchs, J. Amer. Chem. SOC.,1971, 93,4070. E. Vedejs and P,L. Fuchs, J. Amer. Chem. SOC.,1973,95, 822. T. H. Chan and J. R. Finkenbine, J. Amer. Chem. SOC.,1972,94,2880. D. W. Allen, F. G . Mann, and J. C. Tebby, J.C.S. Perkin I, 1972, 2793.
82
Organophosphorus Chemistry
trichloride (see Halogenophosphines, Chapter 3), although the reaction pathway is dependent upon the nature of the arsenic ligands, e.g. (65) and
(66).62 The following physical properties of phosphine oxides have been described during the year : electron paramagnetic resonancessand ultraviolet spectra of oxides (67);s4 n.m.r. spectra of the diphosphine disulphide (68);66 i.r. and Raman spectra of the series of compounds (69);66e.s.r. studies of radicals derived from (70);67 infrared studies of the oxides (71);68 dipole moments of the oxides (72);69and an investigation of the pKa values and other dissociation constants of acyclic phosphine oxides and phosphetan oxides.6o
58
s* 64 66 K8
67 K8
Kg
6o
G. M. Usacheva and G. Kh.Kamai, Zhur. obshchei Khim., 1971,41,2705. S . P. Solodovnikov, A. I. Bokanov, L. I. Chekunina, and B. I. Stepanov. Zzuest. Akad. Nauk S.S.S.R., Ser. khim., 1973, 205. L. I. Chekunina, A. I. Bokanov, and B. I. Stepanov, Zhur. obshchei Khim., 1972,42,995. R. Pantzer, W. Schmidt, and J. Goubeau, Z . anorg. Chem., 1973, 395,262. G. Hagele, R. K. Harris, and J. M. Nichols, J.C.S. Dalton, 1973, 79. A. R. Lyons and M. C. R. Symons, J.C.S. Faraday ZI, 1972, 68, 1589. E. I. Matrosov, E. N. Tsvetkov, D. I. Lobanov, R. A. Malevannaya, and M. I. Kabachnik, Zhur. obshchei Khim., 1972, 42, 1218. E. A. Ishmaeva, R. D. Gareev, G. E. Yastrebova, and A. N. Pudovik, Zhur. obshchei Khim., 1972, 42, 73. A. G . Cook and G. W. Mason, J. Org. Chem., 1972,37,3342.
Tervalent Phosphorus Acids BY 6. J. WALKER
1 Introduction Although the inevitable increase in the number of references appearing in this area has continued, the percentage of significant work has reached an all time low; there is probably a correlation between this and the unusual number of reviews which have appeared during the past year. These include coverage of reactions of tervalent phosphorus acid chlorides with unsaturated acids and amidesl and thermal rearrangements of esters of phosphorous and phosphonous acids.2 Oxidative imination of phosphorus(m) compounds has also been re~iewed.~ 2 Phosphorous Acid and its Derivatives Nucleophilic Reactions.-Attack on Saturated Carbon. The Arbuzov reaction has been investigated with a number of halides including chloroethers,4
(5)
(4)
R. K. Khairullin, Probl. Org. Fiz. Khim., 1971, 109 (Chem. Abs., 1972, 77, 126717). a A. N. Pudovik and I. M. Aladzheva, Khim. Primen. Fosfororg. Soedinenii, Trudy Vsesoyuz. Konf., 3rd., 1965, 98 (Chem. Abs., 1972,77, 74329). ' G . I. Derkach and I. N. Zhmurova, Uspekhi Khim. Fosfororg. Seraorg. Soedinenii, 1970, no. 2, 128 (Chem. Abs., 1973,78, 16260). ' T. F. Kozlova, A. F. Grapov, and N. N. Mel'nikov, Zhur. obshchei Khim., 1972, 42, 1282 (Chem. A h . , 1972, 77, 126778).
83
84
Organophosphorus Chemistry
cc-brom~silanes,~ and trichloromethylamines.6 a-Halogenoureas react with trialkyl phosphites to give the expected phosphonates (l), which were also formed in the reaction of a-hydroxyureas with dialkyl phosphites.' NNN'N'tetramethylchloroformamidiniumchloride (2) undergoes the expected initial reaction with tervalent phosphorus esters to give (3), for example, but this is followed by further dealkylation to (4). Finally, (4) and its analogues are converted into the corresponding anhydrides, e.g. (9,by further reaction with chloroformamidiniumchloride.8 The Arbuzov reaction has been extensively used as a preparative method, for example in the synthesis of 2-alkoxyvinylphosphonates(6); isocyanato0
(Et0)aP
+ XCH,CH(OR),
II
_.)
(EtO)zPCH2CH(OR)2
JA
0
II
(EtO),PCH=CHOR (6)
methylphosphonates (7),1° and, in combination with the Curtius reaction, aminophosphonic acids (8).11 Mixtures of geometrical and structural isomers 0 (EtO),P 3- Me&CH,NHCHO Br-
II
__f
(EtO),PCH,NHCHO
(9) were prepared by the reaction of the dibromide (10) with trialkyl phosphites.l%The photo-Arbuzov reaction has been used to prepare13the anilide of diethyl2-carboxyphenylphosphonic acid (1 1). High yields of 1-substituted n-alkyl chlorides and bromides, with no detectable rearrangement, have been
' E.g. Z. S. Novikova, S. N . Zdorova, and I.
F. Lutsenko, Zhur. obshchei Khim., 1972, 42, 112 (Chem. Abs., 1972, 77, 34633). a V. P. Kukhav, V. I. Pasternak, and A. V. Kirsanov, Zhur. obshchei Khim., 1972, 42, 1169 (Chem. A h . , 1972, 77, 101 790). ' H. Petersen and W. Reuther, Annalen, 1972, 766, 58. ' G. H. Birum and J. D. Wilson, J . Org. Chem., 1972,37,2730. L. Maier, 2. anorg. Chem., 1972, 394, 111. l o U. Schollkopf and R. Schroder, Tetrahedron Letters, 1973, 633. J. P. Berry, A. F. Isbell, and G. E. Hunt, J . Org. Chem., 1972, 37,4396. K . Bergesen and A. Berge, Acta Chem. Scand., 1972, 26, 2975. l a R. Kluger and J. L. W. Chan, J. Amer. Chem. SOC.,1973,95,2362.
Tervalent Phosphorus Acids BrCH,CHMeCH,CH,Br
+
(RO),P
(10)
Me Me
d ‘OR
0’ ‘OR (9)
obtained from the reaction of the corresponding diphenylphosphinite (12) with the appropriate halogen or hydrogen halide.l* Optically active octan-2-01 was converted into 2-chloro-octane by this method with no loss of optical purity. Further details of experiments suggesting a five-co-ordinate phosphorus intermediate in the Arbuzov reaction have appeared.l6 The reaction of the cyclic phosphite (13) with a large excess of alkyl iodide gave the expected
phosphonate (15 ) uia the suggested intermediate (14). Similar experiments with trityl tetrafluoroborate in place of alkyl halide, followed by decomposition of the intermediate (16) with iodide, suggest that the five-co-ordinated intermediate is formed directly from alkyl halide and phosphite and not via an alkoxyphosphonium salt. This is supported by the increasing amount of l6
H. R. Hudson, A. R. Qureshi, and D. Ragoonanan, J.C.S. Perkin I., 1972, 1595. C. L. Bodkin and P. Simpson, J.C.S. Perkin ZI, 1972, 2049. D
86
Organophosphorus Chemistry
trans-isomer in the starting phosphite (13) as the reaction proceeds, since reversible formation of a five-co-ordinate intermediate provides a route for cis-trans interconversions. However, similar results would presumably be obtained if a significant rate difference existed between cis- and transphosphites. Salts of dialkyl phosphites have been reacted with chlorosilanesl6and with 2-chl0roethyldiphenylphosphine~~to give the expected phosphonates. Perhaps surprisingly, a similar reaction with 1,2-dibromoethylcyanidegave1*
-
(EtQ), P-0
-
+ BrCH,CHBrCN
0
I1
---+ (EtO),PCH,CH,CN (1 7)
diethyl 2-cyanoethylphosphonate (1 7), presumably via debromination and addition. Attack on Umaturated Carbon. The reactions of tervalent phosphorus acid derivatives with carbonyl compounds have been reviewed.19 Literally dozens of reports of reactions of tervalent phosphorus nucleophiles with activated olefins have appeared, typical of which are additions to a,%unsaturated ketones,20p-benzoquinone,21pyrylium salts,22and to acrylic acid derivative^.^^ Surprisingly, dialkyl phosphites can be added2*to unactivated olefins (18) to give phosphonates (19), although the reaction may be E. F. Bugerenko, A. S. Petukhova, A. A. Borisenko, and E. A. Chernyshev, Zhur. obshchei Khim., 1973,43, 216 (Clzem. Abs., 1973,78, 1 1 1437). l 7 J. Gloede, J,prakt. Chem., 1972,314 281 (Chem. Abs., 1972,77 140222). B. A. Arbuzov, A. D. Novosel'skaya, and V. S. Vinogradova, Izoest. Akad. Nauk S.S.S.R., Ser khim., 1972, 1153 (Chem. Abs., 1972, 77, 101793). l* I. V. Konovalova and A. N. Pudovik, Uspekhi Khim., 1972,41,799 (Chem. Abs., 1972, 77, 48 545). *O E.g. B. A. Arbuzov, V. M. Zoroastrova, G. A. Tudrii, and A. V. Fuzhenkova, Izuest. Akad. Nauk S.S.S.R., Ser. khim., 1972, 2545 (Chem. Abs., 1973, 78, 84493); B. A. Arbuzov, E. N. Dianova, and V. S. Vinogradova, Zhur. obshchei Khim., 1972, 42, 750 (Chem. Abs., 1972, 77, 126777); R. S. Tewari and R. Shukla, Indian J. Chem., 1972, 10, 823. I1 I. M. Magdeev, Y. A. Levin, and B. E. Ivanov, Zhur. obshchei Khim., 1972, 42, 2415 (Chem. Abs., 1973, 78,72295). a z S. V. Krivun, 0. F. Voziyanova, and S. N. Baranov, Dopouidi Akad. Nauk Ukrain. R.S.R., Ser. B., 1972, 34, 529 (Chem. Abs., 1972, 77, 101765); S. V. Krivun, 0. F. Voziyanova, and S. N. Baranov, Zhur. obshchei Khim., 1972, 42, 58 (Chem. Abs., 1972, 77,48 587). la L. Maier, Helu. Chim. Acta., 1973, 56, 489. F. Bodesheim, E. Velker, F. Bentz, and N. Guenter, Chem.-Ztg., 1972, 96, 581 (Chem. Abs., 1973, 78, 29910). lo
87
Tervalent Phosphorus Acids 0
0
II
(RO) ,PH
+ CH,=C(CH
,OCOMe)
(1 8)
PhCH;
O
‘P/
II
--+(RO) ,P-CH,CH(CH
,OCO Me)
,
(1 9)
+ R3CH=CHC02R2
R1’ ‘H
PhCHz
\#0
R1’
‘CHR3CH,C0,R2
free radical in character. The reaction of benzyl secondary phosphinites with a/?-unsaturated esters in aprotic provides a new synthesis of phospholan-3-ones (21), while a similar reaction in ethanol gives the phosphine oxide (20), probably by the mechanism shown. Azaphosphole (23) and dihydroazaphospholopyridine(24) are the products from the reactions26of aminophosphine (22) with acrylonitrile and acrylic esters, respectively. Secondary phosphites add to b-nitrostyrene to give the expected phosphonate (25) and a highly coloured polymer.27Rather different reactions take place between the unsaturated nitro-ester (26) and tertiary phosphites.28A high-boiling product was shown to be a mixture of tautomers (27) and (28), while a lower boiling fraction gave after irradiation the N-hydroxyaziridine as 2a
17
28
R. Bodalski and K. Pietrusiewicz, Tetrahedron Letters, 1972, 4209. W. Zeiss and A. Schmidpeter, Tetrahedron Letters, 1972, 4229. T. A. Mastryukova, M. V. Lazareva, and V. V. Perekalin, Izuest. Akad. Nauk S.S.S.R., Ser. khirn., 1972, 1164 (Chem. Abs., 1972, 77, 101794). C. Shin, Y . Yonezawa, and J. Yoshimura, Tetrahedron Letters, 1972, 3995.
88
Organophosphorus Chemistry
(29). Reaction mechanisms involving respectively the aci- and nitro-forms of (26) are suggested. CH ,=CHCN
PhZP-N=C(OEt),
c
(22)
CN (23)
0
II
(R0)zPCHPhCHzNO 2 (25)
RCH,C=CHCO,Et I NO2
1-
(Et),OP=O
* RCH,C-CHCOzEt -I-
II
RCHz M r O p E t +RCH2HCOzE -OdN,
0
ihV
,P(OEt), 0 (27)
RCH2wco2Et N
OH (29)
HON, ,P(OEt), 0
(28)
t
89
Tervalent Phosphorus Acids
The addition of dialkyl phosphites to ethylthioacetylene2Bto give (30) occurs in the opposite sense to the analogous addition to ethoxyacetylene,ao which gives (31). A similar,31 but uncatalysed, addition of phosphite to dimethyl acetylenedicarboxylategives the phosphonate (32). 0
(MeO), P - 0
-
EtSC-CH
----+
II
(MeO),P-CH=CHSEt (30)
1
JEtoC-CH 0
II
(MeO),P-C=CH,
I
0
I1
(RO),PH
+
MeO,C-C~C-COzMe
-
0
II
(ROZ)P-C=CH-C02Me
I
C02Me (32)
As usual, the addition of secondary and tertiary phosphites to Schiff bases has been popular in the Russian literature and the references givens2 are typical. Gross and C ~ s t i s e l l ahave ~ ~ used the related reaction of dichloromethyleneaniline with phosphinites to prepare triphosphorylmethane derivatives (33). A highly convenient synthesis of an optically active a-aminophos0 R'2POR2
+ PhN=CCIz
II PhN=C(PR12)2
0 II RS,PH
0
It
0
II + PhNHC(PR 2) zPR3 (33)
phonic acid has been reported34 through the reaction of Schiff base (34), derived from optically pure a-methylbenzylamine, with diethyl hydrogen *@M. L. Petrov and A. A. Petrov, Zhur. obshchei Khim., 1972, 42, 2345 (Chem. Abs., 1973, 78, 58 548).
M. L. Petrov and A. A. Petrov, Zhur. obshchei Khim., 1972, 42, 1863 (Chem. Abs., a1
88
1973, 78, 29931). D. A. Nicholson, Phosphorus, 1972, 2, 143. E.g. N. S. Kozlov, V. D. Pak, and E. S. Elin, Vestsi Akad. Naouk Belarus. S.S.R., Ser. khim. Nauuk, 1973, 108 (Chem. Abs., 1973, 78, 97765): N. S. Kozlov, V. D. Pak, and E. S. Elin, Trudy Perm. Sel'skokhoz. Znst., 1970, 68, 19 (Chem. Abs., 1972, 77, 19742); E. E. Nifant'ev and 1. V. Shilov, Zhur. obshchei Khim., 1972, 42, 503 (Chem. Abs., 1972, 77, 101 769). H. Gross and B. Costisella, J . prakt. Chem., 1972, 314, 87 (Chem. Abs., 1972, 77, 126 763). W.F. Gilmore and H. A. McBride, J . Amer. Chem. Soc., 1972, 94, 4361.
Organophosphorus Chemistry
90 0
*
PhCH=N-CHMePh
II Wo)LPH ,40"c t
Pht H-NH-CH MePh I
(34)
(EtO),P=O
phosphite followed by acidic hydrolysis and hydrogenation. Although the - )-amine use of (R)-( +)-amine gives (- )-a-aminophosphonic acid, (9-( gives the (+)-isomer. The reaction of nitrilimines with ap-unsaturated phosphonites leads to phosphorus heterocycles; alkenylpho~phonites~~ give diazaphosphorins (39,
I Ar2
Ph,PNCO
+
PhCCI-NNHPh
(37)
Ft'N=
/FN Ph
and ethynylphosphonites36 give analogous products (36). A similar reaction of the 1,3-dipole derived from (37) with diphenylphosphinyl isocyanate3' gives the heterocycle (38). ES
36
s7
V. V. Kosovtsev, V. N. Chistokletov, and A. A. Petrov, Zhiir. obshchei Khim., 1971,41, 2649 (Chem. Abs., 1972, 77, 34630). L. A. Tamm, V. N. Chistokletov, and A. A. Petrov, Zhur. obshchei Khim., 1972, 42, 1864 (Chem. Abs., 1973, 78,29920). V. A. Galishev, V. N. Chistokletov, and A. A . Petrov, Zhtr. ohshckei Khim., 1972, 42, 1876 (Chem. Abs., 1973, 78, 29906).
91
Tervnletit Phosphorlis Acids
The reactions of isocyanates with tervalent phosphorus-nitrogen com~ pounds derived from primary amiiies have been extensively investigated3 8 39 by Hudson and Mancuso; a variety of products were isolated, depending upon the nature of both the isocyanate and the phosphorus Diphenylaminophosphines react to give the urea derivatives (39), but with Ph,PNHR
+ ArNCO
Ph,PNR.CO.NHAr (3 9)
(Et0)tPNHR
(40)
+ PhNCO
1
(EtO),PNR* CO *NHPh
(EtO),P NPh CO *NHR *
(41)
dialkyl phosphoramidites (40), rearrangement to the alternative urea (41) appears to be possible. 1-0xazaphospholine (42) undergoes ring-expansion to (43) with ethyl isocyanate; in the case of the reaction of dialkyl N-arylphosphoramidites with aryl isocyanates, yet another pathway is available to give a-aminophosphonates (44), probably via the mechanism shown. Kinetic
(EtO),PNHPh
+
PhNCO
__f
(EtO),P*NPhCO*NHPh
11 .NP h
PhN- C=NPh
0 NPh
I1 II
(EtO),P-C-N
H Ph
(44) aa 38
R. F. Hudson and A. Mancuso, Phosphorirs, 1972, 1,265. R. F. Hudson and A. Mancuso, Phosphorus, 1972, 1, 271.
92
Organophosphorus Chemistry
studies30 suggest that in all cases initial attack on the isocyanate is by phosphorus rather than by nitrogen, unlike similar reactions of phosphorus compounds, e.g. (43, derived from secondary amines, where initial attack appears to be by nitrogen.
0
II
R2PH
+ CH,(CN),
-
0 NH
II II
R,P-C-CH,CN
The addition of phosphinous acids to the cyano-group to give, e.g. (46), has been The now predictable large number of reports 41 of additions of secondary phosphites to aldehydes and ketones have appeared, mainly in the Russian literature. The reaction of diphenylphosphinite, either as its sodium or magnesium salt, with acetone has been thoroughly in~estigated~~ and shown to give the diphosphine dioxide (48) as well as the expected adduct (47); a similar product was obtained from reactions of the benzyl ester (49) with 0
PhzPz'
-
4- MeKO -+
II
Ph,P-C(QH)Me, (47) 0
+
II
(Ph,PCMe,CH .) ,CQ (48)
0
It
PhpPCO2CH,Fh
acetone and sodium iodide, presumably via debenzylation and decarboxylation to give the phosphinite anion. Further Russian on the reaction of A. N. Pudovik, T. M. Sudakova, 0. E. Raevskaya, and V. A. Fedechkina. Zhur. obshchei Khim., 1972, 42, 1727 (Chem. Abs., 1973, 78, 29923): A. N. Pudovik and T. M. Sudakova, Zhur. obshchei Khim., 1972,42, 1646 (Chem. Abs., 1972,77, 126754). d l E.g. R. S. Tewari and R. Shukla, Labdeu. ( A ) , 1971, 9, 112, (Chem. Abs., 1972, 77, 5574); A. N. Pudovik, M. G. Zimin, and A. A. Sobanov, Zhur. obshchei Khim., 1972, 42,2174 (Chem. Abs., 1973,78, 58543). P. F. Cann, S. Warren, and M. R. Williams, J.C.S. Perkin I , 1972, 2377. ** A. V. Fuzhenkova, A. F. Zinkovskii, L. Y . Savchenko, and B. A. Arbuzov, Zhur. obshchei Khim., 1972,42,999 (Chem. Abs., 1972,77,101773); ibid., p. 754 (Chem. Abs., 1972, 77, 101776).
4o
93
Terualent Phosphorus Acids
trialkyl phosphites with phencyclone (50) adds little to that published prev i o ~ s l y The . ~ ~ same authors have a thermographic study of the reaction of trialkyl phosphites with tetracyclone.
(50)
Similar reactions of aldehydes have been studied, for example diethyl phosphonous acid anilides react 46 with p-nitrobenzaldehyde to give the iminophosphites (51), and other similar work4’ by the same authors is noteworthy if only for the mistakes in the abstract. (R0)ZPNHPh
+ p-OzNCsH4CHO
(RO)zP( :NPh)OCH&H4N02-p (51)
Sidky and co-workers have investigated the reactions of both dL4*and triketones49with phosphites. The o-quinone (52) and trialkyl phosphite give the phosphorane (53), and a similar reaction with dialkyl phosphite gives the
phosphonate (54).48In the latter case alternative mechanisms are suggested, involving either attack of phosphite on the ring adjacent to the carbonyl group or attack on the carbonyl carbon itself followed by rearrangement. The triketone monohydrates (55) and (57) react with trialkyl or dialkyl phosphites A mechanism involving to give the phosphates (56) and (58), re~pectively.~~ initial dehydration to the triketone followed by attack of phosphite at carbonyl carbon is suggested. peri-Naphthinadantrione (59) also reacts with dialkyl phosphites to give a phosphate product (60), but with trialkyl phosphites a reduction to (61) takes place. 44
46
46
47
49
B. J. Walker, in ‘Organophosphorus Chemistry’, ed. S. Trippett (Specialist Periodical Reports), The Chemical Society, London, 1973, vol. 4, p. 94. A. V. Fuzhenkova, A. F. Zinkovskii, and B. A. Arbuzov, Zhur. obshchei Khim., 1972, 42, 491 (Chem. Abs., 1972, 77, 87367). A. N. Pudovik, E. S. Batyeva, and V. D. Nesterenko, Izvest. Akad. Nauk. S.S.S.R., Ser. khim., 1972, 510 (Chem. Abs., 1972, 77, 88604). A. N. Pudovik, E. S . Batyeva, V. D. Nesterenko, and N. P. Anoshina, Sbornik Nekot. Probl. Org. Khim.,1972, 6 (Chem. Abs., 1973, 78, 29909). M. M. Sidkey and F. H. Osman, Tetrahedron, 1973, 29, 1725. M. M. Sidky, M. R. Mahran, and W. M. Abdo, Tetrahedron, 1972, 28, 5715.
94
a,:
Organophosphorus Chemistry
0
+ (RO),PII II
Ph 3C
J or \
(RO) ,P=O
Ph,C
(Rh
' OH
Ph :%C
\
OH
'
0-
J (RO) .,P=O
Ph,C
Jk:: 0
(54)
+
\
(RO)3P
or 0 (55)
-
0
It
(RO) ,PH (56)
0
PhCQ-C(OH)z-COPh (57)
+ (RO),P or 0
I1
(R0)ZPH
I1
+ PhCO-CH-O-P(OR)z
I
co Ph
(58)
95
Terualent Phosphorus Acids
Phenacyl chloride reacts50 with dimethyl phosphite in the presence of piperidine to give dimethyl a-chloromethyl-a- hydroxybenzylphosphona te (62) and a-piperidylacetophenone, illustrating the different preferences of nitrogen and phosphorus nucleophiles. An analogous reaction takes place with benzoylacetonitrile. 0 PhCOCHzC1
II
+ (MeO),PH
OH 0
I
II
Ph-C-P(OMe),
I
CHzCi
3
+ PhCOCHzN n
Paulsen and Thiem have studied the reaction of both tertiary phosphites and secondary phosphite salts with a variety of 0-acetylated hexose 52 With heavy-metal salts of dialkyl phosphites the phosphonate 61
s2
M. A. Ruveda and S. A. de Licastro, Tetrahedron, 1972, 28, 6013. H. Paulsen and J. Thiem, Chem. Ber., 1973, 106, 115. H. Paulsen and J. Thiem, Chem. Ber., 1973, 106, 132.
96
Organophosphorus Chemistry
FH,OAc 0
II
BrHgP(OR), ______f.
or
0
II
AgP(OR),
A
OAc
J. CH,OAc
I
OAc (64)
(63) is the major product; however, reactions with trialkyl phosphites lead to mixtures of (63) and olefin (64).In some cases, depending on the orientation of the adjacent acetyl group, phosphates, e.g. (65), are obtained. CH,OAc
I
(65)
The reactions of both tertiary63 and phosphites with acid chlorides to give the expected acetyl phosphonates (66) have been reported. An analogous product (67) is obtained from the reaction of methyl chloroV. M. D’yakov, N. F. Orlov, G. S. Gusakova, and N. M. Zakharova, Kremniiorg. Mafer., 1971, 139 (Chem. Abs., 1973, 78, 43609). I. L. Knunyants,E. G. Bykhovskaya, and Y.A. Sizov, Zhur. Vesesoyuz. Khim. obshch. im. D . I . Mendeleeua, 1972, 17, 354 (Chem. Abs., 1972,77, 114504).
I8
Tervalent Phosphorus Acids
97 0
II
RCO-P(OR)z (66)
0 (RO),PNHAr
+
CIC0,Me
II
_t
ArNHP(OR)CO,Me
(67)
formate with dialkyl phosphorous acid amides.66Prentice et aZ.66have carried out an extensive study of the reactions of tervalent phosphorus acids with acylating agents and have shown that the initial products in a complex reaction are condensates, e.g. (68), of the phosphorous acid used.
Me (68)
The sterochemistry of the enol phosphates produced in the Perkow reaction has been determined.67 When the carbonyl compound is a ketone (69;
0
(R10)3P4 R2COCHXR3
II (RIO),PO’
11
1
/
(R10)2P0
(71)
R3
\C’
\& H I
R3
R2= alkyl) the (a-phosphate (70) predominates,whereas or-halogenoaldehydes (69; R2=H) give mainly (2)-phosphate (71). The isomer ratios are explained by steric effects in the initial intermediate, a conclusion which is supported by the mixtures of (E)- and (2)-phosphates obtained from methyl ketones. 66
67
A. N. Pudovik, E. S. Batyeva, and V. A. Al‘fonsov, Zhur. obshchei Khim., 1972, 42, 1235 (Chem. Abs., 1972,77, 114503). J. B. Prentice, 0. T. Quimby, R. J. Grabenstetter, and D. A. Nicholson, J. Amer. Chem. SOC.,1972,94,6119. E. M. Gaydon, Tetrahedron Letters, 1972, 4473.
98
Organophosphorus Chemistry
Although N-halogenosuccininiide and trialkyl phosphites form the phosphoramidates (72),68a similar reaction with acyclic N-halogenoamides gives
0
(72)
R2CN 3- HX (73)
II
(RIO).,PH
+ RIX
quite different products including the corresponding nitrile (73) and the dehalogenated amide (74). A mechanism involving an initial step identical to that in the Perkow reaction is po~tulated.~*b 0
II
(R'O).,PH
0
+ RTONHX
II
__f
(R'O)2PX 3- R2CONH2 (74)
A further alternative mechanism for the Michaelis-Arbuzov and Perkow reactions is proposed in a recent review ;69 the formation of a five-co-ordinate intermediate (75) would provide a route to both p-ketophosphonate and vinyl phosphate products. Attack on Nitrogen. The reactioneoof triethyl phosphite with the azide (77) provides a new route to 2-substituted quinolines, via the imidophosphorane (76).New, rather unstable, nucleotide derivatives (78) have been prepared61by (a) E. M. Gaydon, G. Peiffer, A. Guillemonat, and J. C. Traynard, Compt. rend., 1972, 275, C , 547; (6) J. M. Desmarchelier and T. R. Fukuto, J. Org. Chem., 1972, 37, 4218. I s P. Gillespie, F. Ramirez, I. Ugi, and D. Marquarding, Angew. Chem. Internat. Edn., 1973, 12, 91. O0 S. A. Foster, U. J. Leyshon, and D. G. Saunders, J.C.S. Chem. Comm., 1973, 29. G. Baschang and V. Kvita, Angew. Chem. Internat. Edn., 1973, 12, 70.
99
Tervalent Phosphorus Acids
R\+
c-0
J
U(OR),
X-
0
0
It
II
RCOCH,P(OR),
RC-O-P(OR)z
II
.
CH2
+ (EtO),P
o +
__t
N3
(77)
R4 N
the reaction of phosphoryl, sulphonyl, or acyl azides with the corresponding phosphite esters. A variety of products (80)--(83) have been isolated from the reaction of the quinonimine (79) with trialkyl phosphites.62Mechanisms involving initial attack of phosphite at nitrogen or at ring carbon account for all the products. Attack on Oxygen. The kinetics of the oxidation of diary1 phosphinites with butyl hydroperoxide, hydrogen peroxide, and p-nitroperoxybenzoicacid under basic conditions have been The bicyclic hydrazinodiphosphine (84) @a
M. M. Sidky and M. F. Zayed, Tetrahedron, 1972, 28, 5157. R. Curci and F. Di Furia, Tetrahedron, 1972, 28, 3905.
100
Organophosphorus Chemistry
MeT7';r
NMe
NMe
"""\,//
+
0-P(0Me)
I9
(MeO),P=O
+
Tervalent Phosphorus Acids
101
shows reduced nucleophilicity at phosphorus compared with tris(dimethy1amino)phosphine and only reacts with methyl iodide and selenium slowly.64 The endo-peroxide (85), prepared by photosensitized oxygenation of l-benzoxepin, is deoxygenated by trimethyl phosphite to give the unstable aldehyde (87), probably via the betaine (86).66 The decomposition of a large number of different phosphite ozonides to give oxygen and phosphate has been studied.66and the results suggest that two mechanisms are involved. Ozonides derived from phosphites with small rings, or bicyclic structures, decompose by simple extrusion of oxygen from the initially formed adduct (88) without rearrangement, but adducts from phosphites (89) without such
0-0
+
RO...I
P-0
0 3
1
L'OR R
\
0
&wo
pseudorotations
I
0
I
(RO)aP=O
+
0 8
restraints appear to decompose by a lower-energy pathway and show a much greater substituent effect. The last result is in agreement with a requirement for pseudorotation before decomposition. Attack on Halogen. In a series of papers a French group has studied the reaction of phosphites with a-halogen~nitriles~~-~~ and with cc-halogeno-
O7
'* 70
R. Goetze, H. Noth, and D. S. Payne, Chem. Ber., 1972,105, 2637. J. E. Baldwin and 0. W. Lever, J.C.S. Chem. Comm., 1973, 344. L. M. Stephenson and D. E. McClure, J. Amer. Chem. SOC.,1973,95,3074. R. Leblanc, E. Corre, and A. Foucaud, Tetrahedron, 1972, 28, 4039. M. Svilarich-Soenen and A. Foucaud, Tetrahedron, 1972, 28, 5149. R. LeBlanc, E. Corre, M. Soenen-Svilarich,M. F. Chasle, and A. Foucaud, Tetrahedron, 1972, 28, 4431. E. Corre, M. F. Chasle, and A. Foucaud, Tetrahedron, 1972, 28, 5055.
0rganophosp horus Chemistry
102
imides.?l*72 In the case of a-halogenonitriles, attack of phosphite appears to be at halogen and the initial products are iminophosphoranes although CN / (RIO),P 3. R2C(CN),Br + R2C \C--Br
I
in favourably substituted cases these may cyclize.6s When the nitrile also contains an adjacent ester group,Sgp7 0 further reaction of the initially-formed ion pair (91) can lead to N-phosphorylketenimines (92) and to vinyl phos-
J
0
II
R2C= C=N--P(OR')
I
+
o
OR^
II
I
R~C=C-O-P(OR
CO,R~ (92)
I
1)
,
CN (93)
phates (93). The same group is guilty of the contemporary, but reprehensible, habit of publishing very similar work in different journals with their study of the reactions of tervalent phosphorus with a-chlor~succinimides.~~~ 72 Initial
(R'O)aP f
Rs;Rsf *
0
OP(0R'))z
0
R4
Rk (94)
attack of phosphorus again appears to be at phosphorus and vinyl phosphates (94) are isolated. Treatment of bis(dipheny1phosphino)arnine (95) with carbon tetrachloride and various amines gave high yields of the imidophosphine (96). Triazadiphosphorines (97) were obtained from a similar reaction of (95) with bifuncn
M. F. Chasle-Pommeret, M. Leduc, A. Foucaud, M. Hassairi, and E. Marchand, Tetrahedron, 1973, 29, 1419. M. F. Chsde and A. Foucaud, Bull. SOC.chirn. France, 1972, 1535.
Tervnlent Phosphorus Acids HN(PPhJ2
103
+ RNH2
-k
‘CI4*
RNHP(Ph,)
II
C1-
N-P( Ph 3NHR
(95)
(96)
PhZ (97) tional amines, e.g. amidinesi and i ~ o u r e a s The . ~ ~ alkoxyphosphonium salts (99) have been prepared74 by the selective reaction of tris(dimethy1amino)phosphine in carbon tetrahalide with the primary hydroxy-group of the or-D-ghcoside (98). CHzOH
Q yy:
x-
CH,O$(NM~~)~
HOQOMe
HO
OMe OH
OH (99)
(98)
Phosphites react with dichlorofluoronitrosomethane to give adducts (100) of varying stability, probably by initial attack on halogen.7K c1
/
(RO),P 3- CC1,FNO + (RO),P,
ON=CFCl (1oo)
Electrophilic Reactions.-Transesterification reactions of both tertiary 76 and sec0nda1-y~~ phosphites with various diols have been studied and in the latter case the diphosphite product (101) reacted with a number of carbonyl compounds. 0 0
II
II
(MeO)PO(CH ,),OP(OMe) H H
(101) 74 76
77
R. Appel and G. Saleh, Annalen, 1972, 766, 98. B. Castro, Y. Cliapleur, B. Gross, and C. Selve, TetrahedronLetters, 1972, 5001. S. I. Malekin, V. I. Yakutin, M. A. Sokal’skii, Y. L. Kruglyak, and I. V. Martynov, Zhur. obshchei Khim., 1972, 42, 807 (Chem. Abs., 1972, 77, 100370). G . Borisov and K. Troev, Izvest. Otdel. Khim. Nauki, Bulgar. Akad. Nauk., 1971, 4, 369 (Chem. Abs., 1972,77, 100338). G. Borisov and K. Troev, Zzuest. Otdel. Khim. Nauki, Bulgar. Akad. Nauk., 1972, 5, 175 (Chem. Abs., 1973,78,43615).
0rganophosphorus Chemistry
104
Spirophosphoranes, e.g. (102), have been obtained from reactions of various phosphorous acid amides with amino-alcohols and aminophen01s.~~~2-Diethylamino-l,3,2-dioxaphospholanreactss1 with whydroxy-carboxylic acids to give phosphites (103), which react further with
(1 04)
excess hydroxy-acid to give spirophosphoranes (104). Treatment of (104) with diethylamine regenerated the phosphite (103). The 3',5'-cyclophosphite (106)
(107)
'*
R. Contreras, R. Wolf, and M. Sanchez, Synth. Znorg. Metal-org. Chem., 1973, 3, 37 (Chem. Abs., 1973,78,97757). A. N. Pudovik, M. A. Pudovik, S. A. Terent'eva, and E. I. Gol'dfarb, Zhur. obshchei Khim., 1972,42, 1901 (Chem. Abs., 1973,78,43606). M. A. Pudovik, S . A. Terent'eva, and A. N. Pudovik, Sbornik Nekot. Probl. Org. Khim., 1972, 10 (Chem. Abs., 1973,78,29908). M. Koenig, A. Munoz, R. Wolf, and D. Houalla, BUN. SOC.chim. Frunce, 1972, 1413.
Tervalent Phosphorus Acids
105
has been prepareds2 by a similar route from thymidine and the phosphoramidite (105). Oxidation of (106) gave thymidine 3',5'-cyc1ophosphates (107), which were mostly stable to phosphatases. Part of the complex maze of reactions of phosphorus trichloride with amines has been reinvestigated and dichlorodiazadiphosphetidines (log), previously not well characterized, have been prepared by reactions with primary aromatic a n ~ i n e s .A~ ~mechanism involving dimerization of an intermediate imine (108) is proposed (see also Chapter 3). The same group ArNHz
+ excessPC1, * AI-N(PCI~)~
I-,,
ArN-PCI
I I
-=
[ArN=PCI J
[ArN=PCI]
(108)
ClP-NAr (109)
has reported 84 a new general route to 1,3-bisarylsulphonyl-1,3,2,4-diazadiphosphetidines (110) from arylsulphonamides and phosphorodiamidous chloride in the presence of pyridine, probably via a similar mechanism. ArSOaNH2
+ (R1R2N)2PCI
pyridine ___+
ArS02N--PNR1R2
I
I
R1R2NP-NS02Ar (1 10)
Rearrangements.-The intermediate phosphinite ester (111) rearranges 86 by attack at the alkynyl rather than the alkenyl group to give the phosphine oxide (112). A similar [2,3J-sigmatropic rearrangement of (113) gave (1 14). Burgada and his co-workers have continued their investigations of ligand rearrangement in phosphoramidites with a study 86 of biphosphorus compounds of the type (1 15). R*CrC-CH(OH)CH=CHR*
+
Ph2PCl
** G. Bashang and V. Kvita, Angew. Chem. Znternat. Edn., 1973,12, 71. 8a
A. R. Davies, A. T. Dronsfield, R. N. Haszeldine, and D. R. Taylor, J.C.S. Perkin I , 1973, 379. F. L. Bowden, A. T. Dronsfield, R. N. Haszeldine, and D. R. Taylor, J.C.S. Perkin Z, 1973, 516. M. Huche and P. Cresson, Tetrahedron Letters, 1972, 4933. R. Burgada, H. Germa, and M. Willson, Tetrahedron, 1973, 29, 727.
Organophosphorus Chemistry
106 MeCR1=C=CHC(OH)MeR2 3- Ph2PCI
/9\ CMeR2
Ph,P..
II
__f
Ph,P-C-CH=CMeR2
II
C
/ \
Me
I
(113)
R1
(114)
R1
(115)
X, Y = 0 or NH CH,CI
I
-0
SPh
(116)
(117)
Cyclic Esters of Phosphorous Acid.-The cis-thiophenoxyphosphorinan(1 17) was formed stereospecifically in the reaction of benzenesulphenyl chloride with the bicyclic phosphite (1 1 6).87 Two groups have investigated the stereochemistry of 2-dimethylamino1,3,2-dio~aphosphorinans.~~~ Mosbo and VerkadeS8have shown that the mixture of phosphoramidites (119) and (120), formed from the reaction of tris(dimethy1amino)phosphine with the diol (118), has the dimethylaminogroup equatorial in the major isomer (120). The stereochemistries were deduced by oxidation to the corresponding oxides and a comparison of their (Me2W3P 3- CH,(CHMeOH), (118)
\ I
NMe, (1 19) 1
..I (120) 10
W. S. Wadsworth, jun., S. Larsen, and H. L. Horten, J . Org. Chem., 1973, 38, 256. J. A. Mosbo and J. G . Verkade, J. Amer. Chem. SOC.,1972, 94, 8224. W. G. Bentrude and H. W. Tan, J. Amer. Chern. Soc., 1972, 94, 8222.
Tervalent Phosphorus Acids
107 Me
PL g z M e
I
Me Meo,
PA z x M e
I1
OMe
0
dipole moments with phosphates (121) and (122) of known configuration. Similar results have been obtained for the 2-dimethylamino-5-butyl-l,3,2dioxaphosphorinans,89where n.m.r. shows the trans-isomer (123) to be more
stable than the cis-isomer (124). Since the equatorial preference of the dimethylamino-group is in contrast to that of other similar sized groups, a px-dn nitrogen-phosphorus interaction is suggested. The stereochemistriesof various halogenation reactions of cyclic secondary
cis
Organophosphorus Chemistry
108
and tertiary phosphites to give 2-chloro-4-methyl-2-oxo-1,3,2-dioxaphosphorinans (125) and (126) have been reported.g0The configuration of (125) and (126) were allocated on the basis of 31Pn.m.r. and J(PH) coupling constants, and the stereochemistry of substitution of halide in (126) was determinedgOsglby a variety of reaction cycles, for example that shown in the Scheme. These otherwise excellent papers are spoilt by the large number of
(-07; Scheme
typographical errors, including the miraculous interconversion of succinimide and phthalimide! Hydrolysis of the halogenophosphite (127) gives a mixture of secondary probably phosphites (128) and (129) which can be equilibrated by
I
OMe (131)
via the tervalent tautomer (130). The reaction of phosphite (131) with hydrogen bromide gave a 1 : 1 mixture of (128) and (129)through isomerization of the product, but allocation of stereochemistries was still possible on the basis of equilibration studies. A reversal of the previous assignment of stereochemistry for the phosphites (132) and (133) is suggested on the basis of comparisons with (128) and (129) and is consistent with proton chemical shifts in the presence of shift reagents. In both of the above cases the isomers so 91 Oa
W. Stec and M. Mikolajczyk, Tetrahedron, 1973, 29, 539. W. Stec and A. Lopusinski, Tetrahedron, 1973, 29, 547. J. A. Mosbo and J. G. Verkade, J. Amer. Chem. SOC., 1973, 95, 204.
109
Tervalent Phosphorus Acids
with equatorial hydrogen [(129) and (133)] react faster with both water and acetone than those with axial hydrogen, although this is not true for the 5,5-dimethyl isomers (134). The authors suggest that (129) and (133) are more readily converted to the tervalent tautomeric form than their isomers. Miscellaneous Reactions.-Both thallium([) and thallium(III) derivatives of diphenylphosphinite have been prepared.03 A variety of salts have been obtained from the dealkylation of dialkyl phosphites with Group I and I1 metal halides.04 A new route to peptides, involving reaction of suitably protected amino-acids (135) and (136) with diphenyl phosphite and pyridine, 0
II
(Ph0)ZPH
+ ZNHCHR’COPH + NHZCHRTOtX (1 35)
1
(136)
pyridine
0
N+ -0Ph I H-P-OCOCHR~NHZ HO’ ‘OPh (1 37) JNH,CHR‘CO,X
0
PhOH
II + CSH,N + ZNHCHR’CONHCHR‘COZX + PhOP-OH I
H
has been reportedQ6and by analogy with earlier workQ6presumably involves an intermediate (137). A new synthesis of allylic alcohols from ally1 sulphoxides (138) has been Oa
B. Walther, J. Organometallic Chem., 1972, 38, 237. and A. E. Mishkevich, Zhur. obshchei Khim., 1972, 42, 1930 (Chem. A h . , 1973,78,42458). N. Yamazaki and F. Higashi, Tetrahedron Letters, 1972, 5047. B. J. Walker, in ‘OrganophosphorusChemistry’, ed. S. Trippett. (Specialist Periodical Reports), The Chemical Society, London, 1973, vol. 4, p. 114.
@‘ V. V. Orlovskii, B. A. Vovsi, O6
110
Organophosphorus Chemistry 0
0
II
I1
i base
PhSCH,CR'=ZCH,
11,
PhS--CH K'-CR'=CH
N-)i
(1 3 8 )
/lMCO,,P
R'CH=CR'--CH,OH
developedg7and involves alkylation followed by reaction with trimethyl phosphite. The photochemical reaction of 2H-azirines (1 39) with diethyl A r p O N HCH ,Ar
NHCH,Ar2
N (139)
'0
1
0
Ar1C0.NHCH,C0.NHCH,Ar2 +&
Ar1-J&NHCH2Arz
(141)
(140)
phosphite gave benzamido-N-benzylacetamides(141).98The intermediacy of the isoxazole (140) is supported by its conversion to (141) on warming with diethyl phosphite. Tetramethylammonium t-butyl phosphonate (142) is a convenient phosphorylating agent for alkyl iodidesg9since the initially formed alkyl t-butyl Bu'O e Me,N
\pH
-*'
But0
0 _t RI
H '
0
\pN
RO/
\H
CF,CO,H
/OH
+ ROP,
11
0 (143)
H
ap;.. a*" (142)
+
0I-I
(144) Et,N
O7
(145) D. A. Evans, G. C. Andrews, T. T. Fujimoto, and D. Wells, Tetrahedron Letters, 1973, 1385; ibid., p. 1389. T. Nishiwaki and F. Fujiyama, J.C.S. Perkin I , 1972, 1456. A. Zwierzak and M. Kluba, Tetrahedron, 1973, 29, 1089.
Tervalent Phosphorus Acids
111
phosphonates readily give monoalkyl hydrogen phosphonates (143) on treatment with trifluoroacetic acid at room temperature. What is claimed to be the first stable intermediate containing six-coordinated phosphorus (145) has been isolated from the reaction of the o-phenylenephosphonite (144) with catechol in the presence of triethylamine.lOO
3 Phosphonous and Phosphinous Acids and Derivatives Extensive reviews of both phosphonousIo1 and phosphinouslo2acid derivatives have appeared. The kinetics of oxidation of phenylphosphonous acid by vanadium(v) have been studiedlo3and the rate of oxidation shown to increase with increasing hydrogen ion concentration. The results of a studylo4of catalysis of tetramethyl-D-glucosemutarotation by oxyacids, including benzenephosphinic acid, suggest that strong oxy-acids act as tautomeric catalysts for the mutarotation in non-polar solvents. 0
I\ I
RPH
F
(146)
Previously unknown phosphonous acid fluorides (146) have been prepared by the simultaneous reaction of dichlorophosphines with hydrogen fluoride and water.Io5The reaction of diphenylphosphinic acid with acetic anhydride 0
II
PhzPH
+ MeCO.O.COMe
pyridine
[Ph,P-O*COMe]
+ AcOH
(147)
0
II
PhZP-PPhz (148)
and pyridine to give tetraphenyldiphosphine monoxide (148) is thought to involve the acetoxyphosphine (147) as an intermediate.lo6 M. Wieber and K. Foroughi, Angew Chem. Internat. Edn., 1973, 12,419. A. W. Frank, Org. Phosphorus Compounds, 1972. 4,255. loa L. A. Hamilton and P. S. Landis, Org. Phosphorus Compounds, 1972, 4, 463. loS K. K. Sen Gupta, J. K. Chakladar, B. B. Pal, and D. C. Mukherjee, J.C.S. Perkin 11, 1973, 926. lo' P. R. Rong and R. 0. Neff, J. Amer. Chem. SOC.,1973,99,2896. I o 6 U. Ahrens and H. Falius, Chem. Ber., 1972, 105, 3317. l o 6 S. Inokawa, T. Tanaka, H. Yoshida, and T. Ogata, Chem. Letters., 1972,469. loo
lol
6 Q ui nquevale nt Phosphorus Acids BY N.
K. HAMER
1 Phosphoric Acid and Derivatives Synthetic Methods.-There has been comparatively little work reported in this area during the past year. A few new active esters have been investigated as phosphorylating agents and there have been some practical extensions in the use of protecting groups. AIso included are examples where either the reaction type or the product have novel features even when the preparative method is severely limited in scope.
(1)
x
= 0
(2)
x
=
s
The phosphorylated derivatives (1) and (2) of N-hydroxy- and N-mercaptosuccinimide, respectively, have been prepared and examined as potential phosphorylating agents.' Although (1) was obtained by condensation of N-hydroxysuccinimideand a dialkyl phosphate with DCC, this procedure was unsuccessful for (2), which is easily produced, however, by reaction of N-chlorosuccinimide on 00-dialkyl phosphorothioates. Compound (1) phosphorylated primary alcohols in the presence of 2,6-lutidine in tolerably good yields but is unfortunately very much less effective for phosphorylating nucleotides. The thio-ester (2) is also a phosphorylating agent but gives mixtures of several products with alcohols, possibly by dealkylation of reactants (or products) by the N-mercaptosuccinimide liberated. Among other reported phosphorylating agents the cyclic ester (3) appears to be an elegantly designed reagent a for the preparation of OS-diesters of phosphorothioic acid and thence, by iodine oxidation, of monoalkyl phosphates. Use of primary amines in the alcoholysis of the triester (4) demonstrates (as has been shown in several solvolytic studies) that amines prefer to react with T.M.Chapman and D. G . Kleid, J. Org. Chem., 1973,38,250. * M. Iio and M.Eto, Agric. and B i d . Chem. (Japan), 1973, 37, 115.
112
113
Quinquevalent Phosphorus Acids
*yyAc Y
(ArO),bO
phosphate esters bearing a relatively poor leaving group by general base catalysis rather than by nucleophilic attack. A phosphorylating intermediate is formed3 from the N-phosphorylated 1,4-dihydropyridine ( 5 ) on oxidation (Ce4+,Ph3C+,or 02-hv), but appears to be of little practical value. Irradiation of (5) under N2 also gives P-N cleavage but results in a much less efficient reaction. An improved procedure has been reported for the removal of the phenylthioethyl protecting group in polynucleotide syntheses.* Use of N-chlorosuccinimide in neutral aqueous solution results in oxidation to the sulphone 0
II R’ SII
0
0
It I
CH2CH20P-OR2
+ R20POa2-
0-
(7) S. Matsumoto, H. Masuda, K . 4 . Iwata, and 0. Mitsunobu, Tetrahedron Letters, 1973, 1733. ‘ K. L. Agarwal, M. Fridkin, E. Jay, and H. G. Khorana, J. Amer. Chem. SOC.,1973,95, 2020.
114
Orgunophosphorus Chemistry
(a,
which undergoes base-catalysed elimination with sodium hydroxide much more readily than the sulphoxide formed by periodate oxidation. A protecting group which is claimed to facilitate product isolation from phosphorylation The arylaminoprocedures by zwitterion formation (7) has been e~amined.~ group is readily removed by treatment with isopentyl nitrite.
Some new phosphorimides have been reported, of which (8) is formed by reaction of o-aminophenol with phosphorus pentachloride and may prove, on further investigation, a useful phosphorylating agent. With alcohols and a tertiary base it gives (9),which can also be made by reaction of o-azidophenol R-CBr(CN),
(R0)3p*
R-C
FN %-Br /
(RO),P=N (10)
and a dialkyl phosphorochloridite. Phosphorimides of the type (10) are also formed in reaction of several bromomalononitriles with trialkyl phosphates.' The most general route to N-phosphorylaziridines appears to be reaction of NN-dibromophosphoramidatediesters with an appropriately substituted olefin followed by treatment of product (1 1) with methoxide.8 ON-Ethanola-
(1 1 )
T. Hata, I. Nakagawa, and N . Takebayashi, Tetrahedron Letters, 1972, 2931. M. I. Kabachnik, N. A. Tikhonina, B. A. Korolev, and V. A. Gilyarov, Doklady Akad. Nauk S.S.S.R., 1972, 204, 1352 (Chem. Abs., 1972, 77, 101767). R. Leblanc, E. Corre, and A. Foucaud, Tetrahedron, 1972, 28, 4039. * A. Zwierzak and S. Zawadzki, Synthesis, 1972, 416.
115
Quinquevalent Phosphorus Acids
H 2 0 3PNHCH2CH20PO3H2
mine diphosphate (12) can be obtained9 in good yield by reacting the parent amine with phosphoric acid with removal of the water formed by distillation.
(13)
When the sulphenyl chlorides (13) are refluxed in toluene, the OOS-triesters are formed in a reaction which is presumably radical in nature.lO This reaction appears to be adaptable to other hydrocarbons which possess readily abstractable hydrogen atoms. Also prepared from the corresponding sulphenyl chloride and silver cyanide is the first reported phosphoryl thiocyanate ester (14)11 which, even at room temperature, isomerizes to the corresponding isothiocyanate(15). (Me $-CH
/p
H0
20) 2P\
(MeK-CH 20)2P\
SCN
NCS
(14)
(1 5 )
Finally, it has been reported that trifluoromethyl phosphorodifluoridate (16) is formed on reaction of trifluoromethyl hydroperoxide with the mixed anhydride (17).12 CFSOOH
+ F2P-O-PF2
II
__f
CFSOPOFS
0
Solvolyses of Phosphoric Acid Derivatives.-There has appeared a detailed review of quinquecovalent intermediates which may be involved in nucleophilic displacements on Pv acids and related While much of the basic material is not new the review makes a systematic attempt to derive some useful generalization on the behaviour of cyclic esters. In particular the authors point out that, in the most general case, the rates, stereochemistry, and position of cleavage are a function of many rate constants (most of which lo
I1 ' I I8
P. V. Laakso, U.S.P. 3697626 (Chem. Abs., 1973,78, 3745). Hercules Inc., Fr.P. 2082884 (Chem. A h . , 1972, 77, 151465). A. Lopusinski and J. Michalski, Angew. Chem. Internut. Edn., 1972, 11, 838. P. A. Bernstein and D. D. Desmarteau, J. Fluorine Chem., 1973, 2, 315. P. Gillespie, F. Ramirez, I. Ugi, and D. Marquarding, Angew. Chem. Internut. Edn., 1973, 12, 91.
116
Organophosphorus Chemistry
cannot be measured) and only with suitable simplifying assumptions can the available experimental data be rationalized. It seems probable that future work in this field will aim at establishing how many of these assumptions will prove to be legitimate. Some aspects of this question have also been discussed briefly by Brown and Hudson,14 particularly in those compounds where the phosphorus is present in a four- or five-membered ring. (Et0)zPOF
* (EtO),PO,H
+ HzO K
+ HF
= 106
Scheme 1
The hydrolysis (Scheme 1) of diethyl phosphorofluoridate has been shown to be reversiblelSwith an equilibrium constant of lo6,which is far larger than the value 4.3 found for phosphorofluoridic acid itself. This difference is plausibly attributed to smaller solvation energy of the diethyl ester relative to the free acid rather than to electronic effects. In this investigation the very small concentrations of diethyl phosphorofluoridate present at equilibrium were measured by its inhibition of cholinesterase. The rates of hydrolysis of several phosphorochloridate esters and amides have also been measured and the effect of substituents on the values of ACp* and AS*for the hydrolysis discussed.la Methanolysis of cyclic trimetaphosphate (18) under acidic conditions gives only monomethyl phosphate,17 suggesting that the linear polyphosphates
0
z :F
+ MeOPO,H,
+
II
MeOPOPO,H,
I
OH
R Y + MeOP--O--~-OP03 I
OH
I
OH
MeQPO,H,
resulting from the initial attack must solvolyse faster than (18). More surprising is the observation that monomethyl phosphate is also a major product under basic conditions; however, here there are also formed considerable quantities of the diphosphate (19) with a little of the linear triphosphate ester l4
l6
l7
R. F. Hudson and C. Brown, Accounts Chem. Res., 1972,5,204. H. C. Froede and I. B. Wilson, J. Amer. Clzem. SOC.,1973, 95, 1987. E. C. F. KO and R. E. Robertson, Cunud. J. Chem., 1973,51, 597. D. B. Trowbridge, D. M. Yamamoto, and G . L. Kenyon, J. Amer. Chem. Soc., 1972, 94, 3816.
Quinquevalent Phosphorus Acids
117
"o\p/o OH
"9( >,OH 04 \/\o (21)
~--a--b :;o: base
OH
b+ MeOP II
0
II
0
0 mH2
II
PhO-P-OSOa-
I
0(22)
(20). The phosphonate analogue (21) behaves as expected to give the same products of P-0 cleavage with both acid and base. Further studies of the mixed anhydride (22) have revealed that in acetonitrile containing a small amount of water the hydrolysis is catalysed by Mgz+, the catalysis falling with increasing water concentration in the medium.l* It appears that (22) forms a 1 : 1 complex with Mgz+, whose formation is inhibited by water which complexes more strongly with the cation. The hydrolysis of tris-2,6-dimethoxyphenylphosphate in the pH range 7M-HCl+ pH 7.5 proceeds through the neutral molecule and the conjugate acid.l9 Similar behaviour is shown by the corresponding diester whose rate, unlike that of diphenyl phosphate, shows a simple dependence on Ho.aoThe elimination of p-nitrophenate anion from (23)in base is strongly catalysed by
micelles of the quaternized ethanolamine (24),21but since the reactions of (23) with fluoride ion is not catalysed under these conditions it seems probable that (24) acts as a nucleophile, deriving assistance from the hydrophobic interactions of the long alkyl chain with the aryl groups. Investigations into the hydrolysis of monoaryl phosphates catalysed by alkaline phosphatase (from E. coli.) at pH 8 have shown22that the reaction is rather insensitive to substituents (p = + 0.43), that tris-buffer is phosphorylated under the conditions of the reaction, and that the enzyme is inhibited by phenylphosphonic acid. It was suggested that this enzyme-catalysed reaction involved co-ordination of the substrate to Zn2+but is different from the Znz+-catalysedsolvolysis of phenyl phosphoramidate, which has a negative p value. The cyclic mixed anhydride (25), prepared by pyrolytic elimination of methyl chloride from (26), is claimedz3 to be more reactive to hydroxylic nucleophiles than any other known phosphate ester. Attack, even by tertiary la
so s1
aa *a
E
W. Tagaki, Y. Asai, and T. Eiki, J. Amer. Chem. SOC.,1973,95, 3037. M. M. Mhala and S. Prahba, Indian J . Chem., 1972, 10, 1073. M. M. Mhala and S. Prahba, Indian J . Chem., 1972, 10, 1002. C. A. Bunton and L. G . Ionescu, J . Amer. Chem. SOC.,1973, 95,2912. A. Williams, R. A. Naylor, and S. G . Collyer, J.C.S. Perkin ZI, 1973, 25. F. Ramirez, S. Glaser, P. Stern, P. D. Gillespie, and I. Ugi, Angew. Chem. Internat. Edn., 1973, 12, 66.
Organophosphorus Chernisfry
118
(26)
OMe
)fJ
Me
(45)
(44) analogues of pyridoxal 5’-phosphate indicates that the 5’-phosphoryl residue is not essential for activity as the 5’-sulphate (45) shows substantial Insolubilized tryptophanase can be prepared by adding the soluble apo-enzyme to pyridoxal 5’-phosphate which has been attached to Sepharose through an aryl diazo-group (46).13* CHO
kinetics of the reactions between acetyl Coenzyme A
Other Coenzymes.-The
and orth~phosphatel~~ or a r ~ e n a t e suggest l ~ ~ that they are essentially similar and are random bimolecular in type. CoA antagonists, e.g. (47), have been
0
II I
RO-P-0-P, HO
0 ll,*Me OH
(47) R = (Adenos’ine 3’-phosphate)-S’-
HO* HO
OH
I. Y. Yang, P. G . G . Potti, and W. Korytnyk, Fed. Proc., l973,32,589Abs. E. Groman, Y. Z . Huang, T. Watanabe, and E. E. Snell, Proc. Nut. Acad. Sci. U.S.A., 1972, 69, 3297. la‘ S. I. Ikeda and S. Fukui,Biochem. Biophys. Res. Coinm., 1973, 52, 482. S. A. Kyrtopoulos and D. P. N. Satchell, Biochim. Biophys. Acta, 1972, 276, 376. lS0 S. A. Kyrtopoulos and D. P. N. Satchell, Riochim. Biophys. Acta, 1972, 276, 383.
la’
Phosphates and Phosphonates of Biochemical Interest
159
synthesized.13' Analogues of NAD+ which contain formycin (48), 2-aminopurine riboside, or 7-deazapurine riboside in place of adenosine are highly fluorescent in both the oxidized and reduced forms.138Yeast NAD+ pyrophosphorylase will catalyse the synthesis of the 2-amino- and 7-deaza-purine analogues from NMN+ and the respective nucleoside triphosphates. This method was not successful for the synthesis of the formycin analogue, which was finally synthesized chemically from NMN+, formycin 5'-phosphate and DCC; this chemical route was also successfully applied to the preparation of analogues of NAD+ which lack the ribose residue of the adenosine moiety
(49).139All analogues showed catalytic activity with a variety of dehydrogenases, as did a water-soluble, high molecular weight derivative of NAD+ which was prepared by linking the coenzyme to p01yethyleneimine.l~~ From an examination of the crystal structure of thiamine pyrophosphate hydrochloride (50), it has been suggested that the most acidic proton is on the
Me
a-phosphorus atom and that the bridging oxygen atom of the pyrophosphate is not involved in hydrogen-bonding.14132P-labelledphosphoenol pyruvate (51) has been obtained by the trichloroacetonitrile-promoted phosphorylation of b-chlorolactic acid by 32P-labelledorthophosphate in the presence of trieth~1amine.l~~ Presumably, a likely intermediate is (52), which is dehydrochlorinated in situ. M. Shimizu, 0. Nagase, Y. Abiko, T. Hosokawa, and T. Suzuki, Jap. P. 72 05 552 (Chem. Abs., 1972, 76,, 127 382.) la* D. C. Ward, T. Horn, and E. Reich, J. Biol. Chem., 1972, 247, 4014. R. Jeck and G. Wilhelm, Annalen, 1973, 531. 140 J. R. Wykes, P. Dunnill, and M. D. Lilly, Biochim. Biophys. Acta, 1972,286,260. l P 1 J. Pletcher and M. Sax, J. Amer. Chem. Soc., 1972,94,3998. 14' H. F. Lauppe, G. Rau, and W. Hengstenburg, F.E.B.S. Letters, 1972,25, 357. l*'
Organophosphorus Chemistry
160 CICH,CH(OH)CO,H
+
H,32P04
CC'BCN>
4 Naturally Occurring Phosphonates Two new syntheses of 2-aminoethylphosphonicacid (53)have been reported.145 Treatment of the hydrazidate of diethyl phosphonopropionic acid with nitrous acid will yield (53), as does the catalytic reduction of diethyl cyanomethylphosphonate in the presence of ammonia. Although the biosynthesis of (53) has been studied in detail in Tetrahymena p y r i f ~ r m i sno ,~~ studies ~ have been carried out until recently with animals. However, it has now been reported that (53) is not synthesized in rat liver as no incorporation of radioactivity
H O J PCH(OH)C,H H~ ' 0 (54)
(55)
into (53) from known precursors could be On the other hand, large amounts of (53) and the related (2-amino-l-hydroxyethy1)phosphonic acid (54) occur in the plasma membranes of a1110ebae.l~~ The synthesis has been reported of a homologue of an a-monoetherphosphonocephalinwhich occurs in 7'. pyrifo~mis.~'~ The antibiotic phosphonomycin (or, as it now appears to be called,148 14* 144
14'
140
14' 149
A. F. Isbell, J. P. Berry, and L. W. Tansey, J. Org. Chem., 1972, 37, 4399. M. Horiguchi, J. S. Kittredge, and E. Roberts, Biochim. Biophys. Acta, 1968,165, 164. J. A. Alhadeff, J. T. Van Bruggen, and G. D. Daves, jun., Biochim. Biophys. Acta, 1972,286, 103. E. D. Korn, D. G. Dearborn, H. M. Fales, and E. A. Sokoloski, J . Biol. Chem., 1973, 248, 2257. E. Baer and H. Basu, Canad. J . Biochem., 1972,50,988. P. J. Cassidy and F. M. Kahan, Biochemisfry, 1973, 12, 1364.
Phosphates and Phosphonates of Biochemical Interest
161
fosfomycin) (55) inhibits the formation of bacterial cell walls by preventing the transfer of an en01 pyruvate residue from phosphoenol pyruvate (51) to UDP-GlcNAc. Proteolytic digestion of the complex formed between ( 5 5 ) and the transferase enzyme yields (56), and hence (55) is probably bound to the transferase through a cysteinyl residue. Unlike the free enzyme, the transferase(55) complex is no longer inhibited by N-ethylmaleimide, which also indicates that a cysteinyl side-chain is involved in the formation of the complex. It is that covalent addition-elimination of a sulphydryl group across the C=C bond of (51) occurs during the enzymic reaction. Since (55) interferes with the reaction, both (51) and ( 5 5 ) must fit into the active site of the enzyme and it may be that the relatively flexible (51) is distorted during the reaction to assume a shape similar to that of (55). NH2
I
HOzCCHCH2CH2
I
0 II
(PhCH20)2PCHNZ
0
Me
'O\
!(*cli12Ph)2
(58)
New intermediates in the synthesis of ( 5 5 ) include (57)149 and (58).150 The latter reacts with acetaldehyde to give racemic (55). 5 Oxidative Phosphorylation Mitochondria1 electron transport and energy conservation have been reviewed151and the phosphorylation potential of respiring mitochondria has been determined.152In view of the large adverse phosphorylation potential which appears to arise in respiring mitochondria, it has been calculated that a redox potential difference of at least 350 mV between substrate (succinate) and oxygen is necessary for ATP synthesis to take place. An ATP-inorganic phosphate exchange similar to that catalysed by mitochondria can be simulated by a reaction system containing oxidized glyceraldehyde 3-phosphate dehydr0gena~e.l~~ The latter contains a E. J. Glamowski, C. B. Rosas, M. Sletzinger, and J. W. Wantuck, Fr. P. 2 074 329 (Chem. Abs., 1972,77,62 132). l*O R. A. Firestone, U.S.P. 3 668 197 (Chem. Abs., 1972, 77, 114 560). lr1 D. F. Wilson, P. L. Dutton, M. Erecinska, J. G. Lindsay, and N. Sato, Accounts Chem. Res., 1972, 5, 234. 16* E. C. Slater, J. Rosing, and A. Mol, Biochim. Biophys. Acta, 1973,292,534. lba W. S.Allison and L. V. Benitez, Proc. Nut. Acad. Sci. U.S.A., 1972, 69, 3004.
l4#
162
Orgunophosphorus Chemistry
sulfenic acid residue, and a model for mitochondria1 oxidative phosphorylation has been put forward (Scheme 4) which includes a sulfenyl-carboxylate
H2PO;
m
-rl-l--
OP03HADP . 7 ‘--r-rTHS SH C HS SH COZ-
0” ‘oPO3H-
+ B + H20
3. ATP
Scheme 4
anhydride as a non-phosphorylated ‘high energy’ intermediate and an acyl phosphate as a phosphorylated ‘high energy’ intermediate. (59 ; Oxidation of 1,4,5,6-tetrahydro-6-hydroxy-l-n-propylnicotinamide R = C,H,) by NNN’N’-tetramethyl-p-phenylenediamineand oxygen in aqueous pyridine in the presence of orthophosphate is accompanied by phosphoryl A possible reaction sequence is outlined in Scheme 5 and it is suggested that an intermediate similar to (60) may be formed in vivo from NADH.
E.J. H. Bechara and G . Cilento, Biochemistry, 1972,11, 2606.
Phosphates and Phosphonates of Biochemical Interest
163
6 Sugar Phosphates The synthesis and properties of carbohydrates which contain modified phosphate groupsfSShas been recently reviewed, as have methods for the determination of sugar The chemical synthesis of a number of sugar phosphates have been r e p ~ r t e d , and ~ ~ ~acetal - ~ ~ phosphonates ~ (61) have been prepared from 0-acetylglycosyl halides.lsl
I
c=o I
+ H,N -Lys-Aldolase
I
$
C=N-Lys-AAldoIase
I
CH2OH
CHzOH
4-H+
CH~OPO~H~
I I
C=N-Lys CHOH
1
-Aldolase
CH 20P03Hz
I
c=o I
HO-C-H
I I c=o
H-C-OH
E. E. Nifant’ev and I. P. Gudkova, Russ. Chem. Rev., 1972, 41, 850. H. G. Pontis and L. F. Leloir, Analyt. Chem. Phosphorus Compounds, 1972, 617. lK7 J. Stverteczky, P. Szab6, and L. Szab6, J . C . S. Perkin I, 1973, 872. lS8 J. S. Prihar and E. J. Behrman, Biochemistry, 1973, 12, 997. lse G. J. F. Chittenden, Carbohydrate Res., 1972, 25, 35. 160 E. M. Bessell and P. Thomas, Biochem. J. Mol. Aspects, 1973, 131, 77. 161 H. Paulsen and J. Thiem, Chem. Ber., 1973, 106, 115, 132. lS6
164
OrganophosphorusChemistry
The reaction of fructose 1,6-diphosphate with aldolase to give dihydroxyacetone phosphate (62) and glyceraldehyde 3-phosphate has been shown to proceed through the formation of a carbanion derived from aldolase and (62).lS2The aldolase-(62) complex reacts with tetranitromethane to give hydroxypyruvaldehyde phosphate (63), formed by oxidation of the complex, and D-5-ketofructose 1,6-diphosphate(64), which is presumably formed in an aldolase-catalysed condensation of the complex with (63). A phosphoryl enzyme intermediate is formed during the hydrolysis of glucose 6-phosphate by glucose 6-phosphatase,la3and pronase digestion of the intermediate liberates N-3-phosphorohistidine. It is unlikely that the phosphorohistidine transfers its residue to serine, as is commonly found in hydrolytic enzymes, as no phosphorylated serine could be detected in the enzymic digest. The structures have been determined of a cell wall phoso ~ of ~~ a phosphomannan ~~~~ phoropolysaccharideof a strain of S t a p h y Z o ~ and excreted by the yeast Hansenula holstis.lsS
7 Phospholipids The biosynthesis of lipids in bacterial membranes16s and phospholipid metabolismla7have been the subjects of recent reviews. lH N.m.r. studies168 reveal that glycerophosphatidyl choline, unlike glycerophosphatidyl ethanolamine, has the same conformation in solution as in the solid sfate.lS9Addition of praseodymium ions to lecithin vesicles enables phospholipids inside and outside the vesicle membrane to be differentiated,170as the 31Pn.m.r. chemical shifts of the two types of phospholipid are altered to different extents. 12Stearic acid nitroxide has been enzymically incorporated into the membrane phospholipids of rat liver microsomes. The spin-labelled lecithin produced was then isolated and used to examine the ordering of phospholipid layers in the membrane.171 In a simple synthesis of analogues of lecithin derived from ethylene glycol, the cis-glycol group in sn-glycero-3-phosphorylcholineis cleaved with periodate and the resulting phosphorylglycollaldehyde reduced with borohydride.17* A number of other phospholipids has been isolated and characterized during
H. J. Healy and P. Christen, J. Amer. Chem. SOC.,1972, 94, 7911. F. Feldman and L. G. Butler, Biochim. Biophys. Acta, 1972, 268, 698. l e d A. R. Archibald and G. H. Stafford, Biochem. J., 1972, 130, 681. lo6 R. K. Bretthauer, G. J. Kaczorowski, and M. J. Weise, Biochemistry, 1973, 12, 1251. l e e W. J. Lennarz, Accounts Chem. Res., 1972, 5, 361. Ie7 W. C. McMurray and W. L. Magee, Ann. Rev. Biochem., 1972, 41, 29. lea J. Dufourcq and C. Lussan, F.E.B.S. Letters, 1972, 26, 35. l a g M. Sundaralingam, Nature, 1968, 217, 35. V. F. Bystrov, Y.E. Shapiro, A. V. Viktorov, L. I. Barsukov, and L. D. Bergelson, F.E.B.S. Letters, 1972, 25, 337. A. Colbeau, P. M. Vignais, and L. H. Piette, Biochem. Biophys. Res. Comm., 1972, 48, lea
1495.
K. K. Yabusaki and M. A. Wells, Biochim. Biophys. Acta, 1973, 296, 546.
Phosphates and Phosphonates of Biochemical Interest
165
the past year,173-175and the identification of a ceremide aminophosphonate by g.1.c.-mass spectrometry has been achieved.178 8 Enzymology Enzymic phosphoryl group and the interconversion of active and inactive forms of enzymes178have been the subjects of recent reviews. Phosphoryl enzymes have been identified as intermediates in several enzymic reactions. For example, phosphoglycerate mutase, which catalyses the interconversion of 2- and 3-phosphoroglyceraldehyde,has been shown to give a phosphorylated intermediate both for the and human erythrocytelso enzymes. The phosphoryl enzyme in the latter instance is very sensitive to acid and may be a phosphorohistidine. Phosphoglucomutase is another enzyme which is phosphorylated while catalysing an isomerization reaction ;181 furthermore, this enzyme is inactivated by 1,2-anhydrohexitoI 6-phosphates (65).lS2A pyrophosphoryl enzyme, the first to be detected, is formed in pyruvate phosphate dikinase from Propionibacteria.lE3
I
CH20P03H2 (65)
17* 176
170
l7I
170 ‘*O
M. Matsumoto and M. Miwa, Biochim. Biophys. Acta, 1973, 296, 350. N. Shaw, P. F. Smith, and H. M. Verheij, Biochem. J., 1972, 129, 167. P. Kemp, R. M. C. Dawson, and R. A. Klein, Biochem. J , 1972,130,221. T. Matsubara and A. Hayashi, Biochirn. Biophys. Acta, 1973, 296, 171. J. F. Morrison and E. Heyde, Ann. Rev. Biochem., 1972, 41, 29. H. L. Segal, Science, 1973, 180, 25. H. G. Britton, J. Carreras, and S. Grisolia, Biochemistry, 1972, 11, 3008. Z. B. Rose and R. G. Whalen, J. Biol. Chem., 1973, 248, 1513. K. J. Schray, S. J. Benkovic, P. A. Benkovic, and I. A. Rose, J. Biol. Chem., 1973, 248, 2219. E. L. O’Connell and I. A. Rose, J. Biol. Chem., 1973, 248, 2225. Y. Milner and H. G. Wood, Proc. Nat. Acad. Sci. U.S.A., 1972, 69, 2463.
I66
Organophosphorus Chemistry
Yeast inorganic pyrophosphatase has been extensively studied recently. New methods of purification have been developed,184and with the availability of large amounts of crystalline enzyme the existence of two identical subunits has been demonstrated and a partial sequence of their N-terminal ends has been elucidated.186Proton relaxation rates measured by n.m.r. show that manganese can bind directly to the enzyme at two sites186and kinetic together with active-site mapping, have led to a possible mechanism of action for this enzyme.lS8In the active site (66), a pyrophosphate ion is bound to the enzyme by a magnesium ion and an arginine residue. The change in proton relaxation rates of water when manganese binds to pyruvate kinase in the presence of phosphoenol pyruvate (51) or its analogues has been used as a method for studying the active site of the lgo Phosphoryl co-ordination from (51) to an enzyme-bound manganese ion in the active site which was suggested by this n.m.r. technique is confirmed by 31P n.m.r. measurements. It is also suggested that co-ordination of the carboxy-group of (51) to an enzyme-bound potassium ion changes the conformation of the enzyme-Mn2+-(5 1) complex to its catalytically active form. Triose phosphate isomerase is another enzyme which has been studied extensively in the past year, and the isolation,1s1 pH dependence,lg2and active-site labellinglS3of this enzyme have been reported. The involvement of a glutamic acid residue in the active site has been demonstrated by the covalent labelling of the enzyme by bromohydroxy [14C]acetonephosphate.lS3 The importance of a glutamic residue is confirmed by its esterification by Dor L-glycidol phosphates (67)lg4and by the isolation of the active-site peptide containing a glutamate residue.lg5 Thymidylate synthetase catalyses the reductive methylation of dUMP to dTMP with the concomitant conversion of 5,1O-methylenetetrahydrofolic acid (68) into 7,8-dihydrofolic acid. The synthetase in the presence of (68) is rapidly inactivated by 5-fluoro-2’-deoxyuridylic acid,lg6and this is accompanied by the loss of the 5-fluorouridine chromophore in the ultraviolet ln4
B. S. Cooperman, N . Y . Chiu, R. H. Bruckmann, G. J. Bunick, and G . P. McKenna,
Biochemistry, 1973, 12, 1665. R. L. Heinrickson, R. Sterner, C. Noyes, B. S. Cooperman, and R. H. Bruckmann, J. Biol. Chem., 1973, 248, 2521. 1 8 0 B. S. Cooperman and N. Y . Chiu, Biochemistry, 1973, 12, 1670. lS7 J. W. Sperow, 0. A. Moe, J. W. Ridlington, and L. G . Butler, J. Biol. Chem., 1973,248, 2062. B. S. Cooperman and N. Y . Chiu, Biochemistry, 1973, 12, 1676. la9 T.Nowak and A. S. Mildvan, Biochemistry, 1972,11,2813. lSo T. Nowak and A. S. Mildvan, Biochemistry, 1972, 11, 2819. l B 1 S . J. Putman, A. F. W. Coulson, I. R. T. Farley, B. Riddleston, and J. R. Knowles, Biochem. J., 1972, 129, 301. l B f iB. Plaut and J. R. Knowles, Biochem. J., 1972, 129, 311. l B 8S. De la Mare, A. F. W. Coulson, J. R. Knowles, J. D. Priddle, and R. E. Offord, Biochem. J., 1972,129, 321. lo* K. J. Schray, E. L. O’Connell, and I. A. Rose, J. Biol. Chem., 1973, 248, 2214. I s 6 F. C. Hartman and R. W. Gracy, Biochem. Biophys. Res. Comm., 1973,52, 388. D. V. Santi and C. S. McHenry, Proc. Nut. Acad Sci. U.S.A., 1972, 69, 1855. la6
Phosphates and Phosphoitates of Biochemical Interest
167
spectrum. It is suggested that a covalent intermediate is formed between the synthetase and the 6-position of 5-fluorouracil ring (69).
R
(69)
Acetyl cholinesterase is inhibited by diethyl phosphor~chloridate~~~ and the chloridate of 1,3,2-dioxaphosphorinan 2-oxide (70).lg8 In marked contrast to inhibition by diethyl phosphoryl derivatives, inhibition of (70) is spontaneously and rapidly rever~ib1e.l~~ This difference in reactivity between the two phosphoryl enzymes may be due to steric strain in (70) caused by the binding of a comparatively large residue to the active site of the cholinesterase. 9 Other Compounds of Biochemical Interest The incorporation of geranylgeranyl pyrophosphate (71) into lycopene and other carotenoids appears to follow the same pathway as that taken during the incorporation of farnesyl pyrophosphate into ~ q u a l e n e .Head-to-head ~~~ condensation of two molecules of (71) leads to a cyclopropyl derivative, prelycopersene pyrophosphate (72),200which is enzymically converted, in the presence of NADPH, into lycopersene (73), a carotenoid precursor.2o1 Farnesyl pyrophosphate synthetase from pig liver is capable of synthesizing homologues of farnesyl pyrophosphate, e.g. (74), from 3-ethylbut-3-enyl pyrophosphate,202or homofarnesyl pyrophosphate (75) from 3-methylpent-2enyl p y r o p h ~ s p h a t e .A~ ~similar ~ enzyme has been isolated from pumpkin fruit.20* Organic polyphosphates markedly decrease the affinity of haemoglobin for oxygen and, for example, 2,3-diphosphoroglycerate (76) can act as a regulator for oxygen in tissues.206The binding of (76) to human haemoglobin has recently been studied by 31Pn.m.r.206and it has been shown that an a-chain binds to (76) before a p-chain. Pyridoxal phosphate has a similar effect to (76) on haemoglobin but other pyridoxine derivatives are inactive, suggesting that lo'
lo8 loo
aoo
Y.Ashani, P. Wins, and I. B. Wilson, Biochim. Biophys. Acta, 1972,284, 427. Y.Ashani, S. L. Snyder, and I. B. Wilson, Biochemistry, 1972, 11, 3518. E. Beytia, A. A. Qureshi, and J. W. Porter, J. Biol. Chem., 1973, 248, 1856. A. A. Qureshi, F. J. Barnes, E. J. Semmler, and J. W. Porter, J. Biol. Chem., 1973,248, 2755.
*01
F. J. Barnes, A. A. Qureshi, E. J. Semmler, and J. W. Porter, J. Biol. Chem., 1973,248, 2768.
*OS *Oa
lo'
K. Ogura, T. Koyama, and S. Seto, J.C.S. Chem. Comm., 1972, 881. A. Polito, G. Popjak, and T. Parker, J. Biol. Chem., 1972, 247, 3464. T. Nishino, K. Ogura, and S. Seto, J. Amer. Chem. Soc., 1972, 94, 6849. R. Benesch, R. E. Benesch, and C. I. Yu, Proc. Nat. A c ~Sci., . U.S.A., 1967, 59, 526. W. H. Huestis and M. A. Raftery, Biochem. Biophys. Res. Comm., 1972,49,428.
168
Organophosphorus Chemistry
Phosphates and Phosphonates of Biochemical Interest
169
CH,OPO,H,
I
CHOP03H2
I
COtH (76)
both the phosphoryl and the aldehyde groups are essential for binding.*07 Reduction of the haemoglobin-pyridoxal phosphate complex with borohydride gave a haemoglobin in which the pyridoxine residue was attached to the N-terminal valine of a p-chain. Reaction of pyridoxal phosphate with oxyhaemoglobin led to modification of an a-chain. Deuteriohaemin IX dimethyl ester derivatives in which a phosphodiester is the fifth ligand for iron have been prepared and are slowly hydrolysed in neutral aqueous solution to haematin-like OH I
OH
I
HN=CNHCH,OPOCH,CHCO,H
I
NH2
II
0
(1.3
I
HN=CNHCH,OPOCH,CHCO,H
I
NMe,
NH
I
II
NMez
0
H203P' (78)
.O
The stereochemistry of the ionic binding of phosphate to arginine residues in enzymes has been deduced from X-ray crystallographic studies with model guanidinium C O ~ ~ O U An ~ ~arginine-containing S . ~ ~ ~ phosphagen (77) and its N-phosphoro-derivative (78) related to lombricine have been isolated from an echiuroid worm.21o Biocidal organophosphorus compounds have been reviewedalland an antitumour agent, cyclophosphamide (79),has been shown to be metabolized in rabbits to the oxygenated form (80) and its hydrolysis product (81).212 R. E. Benesch, R. Benesch, R. D. Renthal, and N. Maeda, Biochemistry, 1972, 11, 3576. C. S. Russell, J. Landis, and N. Bocian, Arch. Biochem. Biophys., 1972, 153, 398.
F. A. Cotton, E. E. Hazen, jun., V. W. Day, S. Larsen, J. G. Norman, jun., S. T. K. Wong, and K. H. Johnson, J. Amer. Chem. SOC.,1973,95,2367. *la N. van Thoai, Y. Robin, and Y. Guillou, Biochemistry, 1972, 11, 3890. N. N. Mel'nikov, 2.Chem., 1972, 12, 201. ¶ l a A. Takamizawa, Y. Tochino, Y.Hamashima, and T. Iwata, Chem. and Pharrn. Bull. (Japan), 1972, 20, 1612.
*OD
Ylides and Related Compounds BY S. TRIPPETT
1 Methylenephosphoranes Preparation.-Electrolytic reduction at a mercury cathode in acetonitrile,
+
DMF, or HMPT of the cations Ph3PCHR1R2(R1=H, R2=PhC0 or Ph; R1 and R2= Ph) gave ylide, phosphine, and hydrocarbon:'
+
+
2e-
+
-
Ph,PCHR1R2 .-•Ph3P CHR1R2
+
-
Ph3PCHR1R2 CHR1R2+Ph3P=CR'R2 + CH2R1R2 Further examples of the use of epoxides as the source of base in olefin synthesis have appeared.2Particularly noteworthy is the synthesis of the furylolefin (1); previous attempts to prepare this from furfuraldehyde and preformed ylide had failed. Polymeric ylides have been used in stereospecific Ph,;(CH,),Me
Br-
+ O/ C\ H
O
0
PhMeC=CHPr 100%; 97.5% cis
*CHt-CH
+ PhCOMe (2)
Ph MeC=CH Pr 5 9 % ; cis: trans, 14 : 86
olefin ~yntheses.~ Thus the polymer (2) with acetophenonegave almost entirely cis-olefin under salt-free conditions and largely trans-olefin via the p-oxidoylide. Besides the expected olefins, cis- and trans-l-styrylazulenes and l-methyl-
a
J. M. SavCant and S. K. Binh, Bull. SOC.chim. France, 1972, 3549. J. Buddrus, Angew. Chem. Internat. Edn., 1972, 11, 1041. W. Heitz and R. Michels, Annalen, 1973, 227.
170
Ylides and Related Compounds
171
azulene were also obtained4 when the ylide (3) was generated using phenyllithium in DMF or dimethylacetamide and used in olefin synthesis. The benzaldehyde which leads to the styrylazulenes probably comes from the
PhLi
+ HCONMe2 --+PhCH(G)NMe,Li+
._f
PhCHO
+
Me,NLi
(4)
1Azc.*h3 AzMe
t
A z ~ H ,t AzCH,-PPh,-&-CHPh-NMe, ?
-6'.
A z = l-Azulenyl Scheme 1
adduct (4) of phenyl-lithium and a i d e while the l-methylazulene, which was not formed by hydrolysis of unchanged salt, could arise from attack of the adduct (4) on phosphonium salt, as shown in Scheme 1. In alcoholic solution, triphenylphosphine and dimethyl acetylenedicarboxylate gave6 the p-alkoxyphosphoranes (5). The effects of varying the Ph3P
+
MeO,CCECCO,Me -+
Ph,k(CO,Me)=CCO,Me . 0 . 1
Ph ,P=C(CO ,Me)C H(0R)CO ,Me +--
-t-
Ph,PC(CO,Me)=CHCO ,Me RO-
(5)
R1,P
+
R26=NRPh -+ R1,P=CR2-N=NPh (6)
* J. 0. Currie, jun., R. A. LaBar, R. D. Breazeale, and A. G. Anderson, jun., Annalen, 1973, 166.
I. F. Wilson and J. C. Tebby, J.C.S. Perkin I , 1973, 2830.
172
Organophosphorus Chemistry
substituents on the preparation of the azo-phosphoranes (6) from phosphines and nitrile-imines have been studied.g Attempts to generate the methylenephosphorane from trimesitylmethylphosphonium bromide gave7 the benzylphosphine (7), the product of the first recorded Stevens rearrangement of a phosphorus ylide. Similar rearrangements of other ylides are in general catalysed by nickel complexes. Reactions.-The synthesis of cyclic compounds using phosphorus ylides has been reviewed.* Halides. The gold complex (8) with increasing quantities of methylenetrimethylphosphorane gaveQsuccessively the salt (9), the salt (lo), and finally with an excess of reagent the complex (11). Similar products were obtained from the silyl-phosphorane Me,P=CHSiMe,, but the bis-silyl-phosphorane Me,P=C(SiMe,), gave only the analogue of (9). Copper(1) chloride and the silver complex [Me,PAgCl], with methylenetrimethylphosphorane gavelo the copper@ and silver analogues of (1 1) quantitatively. Me,PAuCI
+ Me,P=CH,
(8) +/ Me,P,
CH&CH:,
cH, LC
\+
PMe,
H’2
Ph,P=CHCOAr (12)
+
+
i
-
Me,PAuCH,PMe, CI(9)
1
Me,P=CH,
Me,kH,&CH26Me, CI-
Me,SiCI
(10)
+
Ph,PCH-CAr C1-
I
Me:,Si+O (1 3)
II
The phosphonium salts obtainedll from the stable phosphoranes (12) and trimethylchlorosilane show carbonyl absorption in the i.r. at 1480 cm-l and are formulated as (13). Heating gave back the starting materials and attempts to generate the corresponding ylides failed. Details have appeared12of the reactions of methylene- and silylmethylenephosphoranes with chloro- and dichloro-disilanes. S. P. Konotopova, V. N. Chistokletov, and A. A. Petrov, J . Gen. Chem. (U.S.S.R.), 1972,42,2406. F. Heydenreich, A. Mollbach, G. Wilke, H. Dreeskamp, E. G. Hoffmann, G. Schroth, K. Seevogel, and W. Stempfle, Israel J. Chem., 1972, 10, 293. H. J. Bestmann and R. Zimmermann, Chem.-Ztg., 1972, 96, 649. H. Schmidbauer and R. Franke, Angew. Chem. Internat. Edn., 1973,12,416. l o H. Schmidbauer, J. Adlkofer, and W. Buchner, Angew. Chem. Internat. Edn., 1973, 12, 415. l1 S. Kato, T. Kato, M. Mizuta, K. Itoh, and Y. Ishi, J. Organometallic Chem., 1973, 51, 167. H. Schmidbauer and W. Vornberger, Chem. Ber., 1972, 105, 3173. a
Ylides and Related Compounds 2 Ph,P=CHR
+
173
CGFC
Ph,P=CRC,jFS
+
-b
PhaPCHZR F-
(1 5 )
(14)
Hexafluorobenzene with the reactive phosphoranes (14; R = H or Ph) gavel3the ylides (15), isolated as a stable compound when R= Ph and trapped with p-nitrobenzaldehyde when R = H. A general alkylation of heterocyclic involves the reaction of nuclear-chlorinated heterocyclics with reactive phosphoranes to give ylides which are then hydrolysed. The ylides can also be used in olefin synthesis. In this way 4-chloro-2-methylquinoline CH=PPh
@Me
+ 2Ph3P=CH,
3
_j
CH=CHPh W
M
e
(17)
with methylenetriphenylphosphoranegave the ylide (16), hydrolysis of which gave 2,4-dimethylquinoline (79 %) and which with benzaldehyde gave the olefin (17; 69%). Similar reactions have been used16 in syntheses of quinine and related alkaloids. Full accounts have appearedla of the n.m.r. and alkylation of fomylstabilized phosphoranes. Cyclopropylacetic acid was obtained" as shown in Scheme 2. 2 D C H Z 6 P h , Br-
. .. *
[)C(CO,Me)=PPh,
+DCH,h,
CI-
Reagents: i, PhLi-ether; ii, CIC0,Me; iii, NaOH-H,O.
Scheme 2
*' l1
N. A. Nesmeyanov, S. T. Berman, and 0. A. Reutov, Izuest. Akad. Nauk S.S.S.R., Ser. khim., 1972, 605. E. C. Taylor and S. F. Martin, J. Amer. Chem. SOC.,1972, 94, 2874. E. C. Taylor and S. F. Martin, J. Amer. Chem. SOC.,1972, 94, 6218. C. J. Devlin and B. J. Walker, Tetrahedron, 1972, 28, 3501. A. Maercker and W. Theysohn, Annalen, 1972, 759, 132.
174
Organophosphorus Chemistry
Carbonyls. Studies on the kinetics of the reactions of p-nitrobenzaldehyde with phenacylidenetriphenylphosphoranelsand with a number of fluorenylideneph~sphoranes~~ led to the conclusion that the initial, ratedetermining, step involves a four-centred transition state of low polarity leading directly to a 1,2-oxaphosphetanand not to a betaine. However, the similar rates of reaction of benzaldehyde with the cyclic (18; R = P h or
QTO
Ph,P=CHR
Ph/ \CHR
(19)
(18)
C0,Et) and corresponding ‘acyclic’ ylides (19; R = Ph or C0,Et) led2*to the opposite conclusion: direct formation of 1,Zoxaphosphetans would be expected to lead to increased rates of reaction for the cyclic ylides (18) because of relief of angle strain at phosphorus. A high yield of stilbene was obtained21from benzaldehyde and benzyltri(2-fury1)phosphonium bromide in methanolic methoxide solution. Because of the high leaving-group ability of the 2-fury1 group, this implies that the
-I-
Fu,P-CHPh
I
LCHPh
MeO-
+ PhCHO
-I-
Fu,PCHIPhBr-
-
-
M&H
Fu,PO
+ PhCH=CHPh
+ FuaP-CHPh
I
HO-CHPh
*
Fu,$-CPh
II
CHPh (20)
vinylphosphonium salt (20) is not an intermediate. In contrast to the rearrangements observed in the reactions of methyltriphenylphosphonium salts with benzaldehyde in ethanolic ethoxide solution, the furylphosphonium salts (21 ; n= 1, 2, or 3) under the same conditions gave normal olefin syntheses.
Y
Ph2P(:O)CHPh*CH ,Ph
EtOH-NaOEt
Fu,Ph,-,,kH,
+ PhCHO
(21)
FunPh,-nPO
ao s1
+ PhCH=CHZ
G. Aksnes and F. Y. Khalil, Phosphorus, 1972, 2, 105. P. Frayen, A d a . Chem. Scand., 1972, 26,2163. I. F. Wilson and J. C. Tebby, J.C.S. Perkin I, 1972, 2713. D. W. Allen, B. G. Hutley, and T. C. Rich, J.C.S. Perkin I l , 1973, 820.
Ylides and Related Compounds
175
The use of sodium a-hydroxysulphonates (bisulphite addition compounds) in olefin syntheses instead of aldehydes leads to higher yields of purer products.22The t-butyldimethylsilyl group has been to protect hydroxygroups during reactions involving the use of ylides. It is rapidly removed at 25 "C in THF containing tetrabutylammonium fluoride. A striking demonstration that Wittig olefin syntheses using reactive ylides proceed under much milder conditions than normally employed was provided2* in the synthesis of the unstable cis-divinylcyclopropane(23). Addition of the aldehyde (22) to methylenetriphenylphosphorane in DMSO-isopentane at 5 "C,reaction, and quenching in brine at - 20 "Ctook about 1 min.
+
Ph,P=CH2
_.f
(23)
D
D
Ill
Ill
11
i' /
(26)
Besides the expected deuterioallene (25), the isomer (26) was also obtained when the ketone (24) labelled with deuterium at the free acetylenic position was treated with methylenetriphenylph~sphorane.~~ Scrambling of deuterium between the free acetylenic position and the methylenephosphoraae is presumably faster than addition of the phosphorane to the carbonyl. The la
l4 *&
G. Koszmehl and B. Bohn, Angew. Chem. Internat. Edn., 1973, 12, 237. E. J. Corey and A. Venkateswarlu, J. Amer. Chem. SOC.,1972, 94, 6190. J. M. Brown, B. T. Golding, and J. J. Stofko, jun., J.C.S. Chem. Comm., 1973, 319. P. Gilgen, J. Zsindely, and H. Schmid, Hell?.Chim. Acta, 1973,56,681.
176
4 /
0rganophosphor us Chemistry
0:"l \
same phosphorane did not react with the ketones (27) and (28). Among other unsuccessful olefin syntheses reported is that between the tetralone (29) and the ylides Ph3P=CH(CHz),COzR.26
d
+ Ph,P=CHCOMe
Me0
\
-+
(31)
(3 0)
+ 0
(32)
The olefins (32) and (35) were unexpected products from the reactions of the acetonylidenephosphorane (31) with the ketone (30) and the lactone
L (33)
(341,
O (35)
(33), respecti~ely.~~ They may be formed via attack of carbanions, e.g. (36), on ketophosphonium salt followed by elimination of phosphine oxide. CH 2-PPh
3
CH Z-PPha
c-oMe
Me
-
(36) I0
D. Taub, R. D. Hoffsommer, C. H. KUO,H. L. Slater, Z. S. Zelawski, and N. L. Wendler, Tetrahedron, 1973, 29, 1447. H. T. J. Chan, J. A. Elix, and B. A. Ferguson, Svnrheric Comm., 1972, 2, 409.
(32)
Ylides and Related Compounds
177
A new synthesis of terminal acetylenesz8is based on the reaction of aldehydes with dibromomethylenetriphenylphosphorane,formed in situ from carbon tetrabromide and triphenylphosphine, and treatment of the resulting dibromo-olefins with butyl-lithium or lithium amalgam (Scheme 3). 2 Ph3P
+ CBr,
RCHO
+
__f
Ph,P=CBr,
Ph,PBr, 4- Ph,P=CBr,
-+ RCH=CBr,
3RCzCLi 80-95 %
80-!90% 1Li-H.
RC-CH Scheme 3
The reaction between salicylaldehyde and the crotylphosphonium salt (37) in the presence of sodium hydride has now been to give a mixture of all four geometrical isomers of the diene (38). The same mixture was obtained
1 : 1.4
(40)
67%
starting from pure trans-crotyl salt. Among other olefin syntheses worthy of note were the use of muconic dialdehyde in the synthesis of aw-di-l-naphthyland cxw-di-2-naphthyl-polyene~~~ and the preparation31of the aldehydes (39) and (40) from benzylidenetriphenylphosphorane and a five-fold excess of 0-phthalaldehy de. The p-oxidoylide synthesis of allylic alcohols, using formaldehyde as the second carbonyl component, gave32the expected olefins (41) when the first ph3p=CHR1
PdxidoYlide_ synthesis '
R2R3C=CR1CHZOH
+
R2R3C(OH)CR1=CHz
(41)
(42)
Reagents: R2R3C0, -78 "C;BuLi, - 78 OC; H,CO, -78 "C;R.T. lo
ao
E. J. Corey and P. L. Fuchs, Tetrahedron Letters, 1972, 3769. R. Hug, H.-J. Hansen, and H. Schmid, Helu. Chim. Acta, 1972, 55, 1828. A. Yasuhara, S. Akiyama, and M. Nakagawa, Bull. Chem. SOC.Japan, 1972,45, 3638. A. A. Baum, J. Amer. Chem. SOC., 1972, 94,6866. M. Schlosser and D. Coffinet, Synthesis, 1972, 574.
178
Organophosphorus Chemistry
component was a long-chain aldehyde but also the olefins (42), formed by elimination of the oxygen derived from the formaldehyde, when the first component was a hindered aldehyde or a ketone. In extreme cases, e.g. with acetone as the first carbonyl reagent, only the olefins (42)were obtained. The use in analogous /?-oxidoylide syntheses of a nitrile instead of the second carbonyl compound gave the +unsaturated ketones (43).33
Reagents: i, R2RR3CO; BuLi; R4CN; ii, H-+-H20.
The reactive esters [44;X = H, CO,Et, CN or CH(OEt),] gave34the stable phosphoranes (45) with methylenetriphenylphosphorane, but the vinyl
Ph,P=CHR 3- XC0,Et
/ \
Ph,P=CHCQX
+ EtOH
(45)
(4)R = P h ,
PhCH = CH, or C0,Me
Ph,PO 3- RCH=CX(QEt) (46)
ethers (46) with other phosphoranes. Further examples have appeared36of the reaction of dichloromethylenetriphenylphosphoranewith aroyl cyanides to give 2-aryl-3,3-dichloroacrylonitriles.
0
0
I
0 +Ph,P=CHX (47)
\ I
XCH20CH2X (48) 58 -60%
The bipyrroles (48)were from NN-bisuccinimide and the stable ylides (47; X=CN or C0,Me) under vigorous conditions. Chromium hexacarbonyl and salt-free methylenetriphenylphosphorane gave3' the salt (49) in low yield from which the ylide-carbene complex (50) was obtained on 83 a4
M. Schlosser, D. Coffinet, and H. B. Tuong, unpublished work quoted in reference 32. M. Le Corre, Compt. rend., 1973, 276, C , 963. R. L. Soulen, S. C. Carlson, and F. Lang, J. Org. Chem., 1973, 38, 479. W. Flitsch and H. Peeters, Chem. Ber., 1973, 106, 1731. D. K. Mitchell and W. C. Kaska, J. Organometallic Chem., 1973, 49, C73.
Ylides and Related Compounds Cr(CO), 4- Ph,P=CH,
179 THF
---+
(CO),CrC@)CH=PPh, Ph,$Me (49) 0.3 % k&S02F
(CO),CrC(OMe)CH=PPh (50)
methylation. The tungsten analogue of (49) was obtained similarly but in high yield. MisceZZuneous. Metallation of the acetonylidenephosphorane (31) with butyl-lithium gave38 the anion (51), which with benzophenone and alkyl Ph3P=CHCOMe
BuLi-THF
Ph3P=CHCOCH2 Li+
(31)
(51) hh,CO
Ph 3P=CHCOCHZC(OH)Ph 2
y' Ph,P=CHCOCH,R
(52) 65%
RCHACHC0,Me
(53)
+ Ph,P=CMe, (54)
T
C0,Me
(55) 65-75
+ Ph3P=CHC02Et d 0 'R
(56)
-
%
0 C0,Et
a8--&H--6Ph3
R = HorMe
NC0,-
R
(57)
-co2 -EtOH
J. D. Taylor and J. F. Wolf, J.C.S. Chem. Comm., 1972, 876.
180
OrganophosphorusChemistry
halides gave the expected phosphoranes (52) and (53), respectively. The gem-dimethylcyclopropyl esters (55) were obtained39from ap-unsaturated esters and the isopropylidenephosphorane (54). Isatoic anhydrides and the ester phosphorane (56) gave40 the very stable phosphoranes (58), presumably via the intermediates (57). The synthesis of triazoles from azides and /?-ketoalkylidenephosphoraneshas been extended41 to include iV-vinyltriazoles, Both the triazoles (59) and products derived from the quinquecovalent phosphoranes (60) were obtained42from ester phosphoranes and aryl azides.
(59)
t
ArN,
+ Ph3P=CRC02Et
[
ph~>co2E~ ArN /N
--+Ph,P=NAr
+ [N,CRCO,Et]
k= Ph
JR=Me
(60) EtO,CCMe=CMeCO,Et
A rN= NN= CPhCO ,Et
Attack by methylenetrimethylphosphorane at the 3-position of the silacyclobutanes (61) gave43either the ylide (62; R=Me) or, when R=H, the cyclic ylide (63). Similar ring-opening of the disilacyclobutane (64)gave (65).
+O
Me,P=CH, Me,PhSiHMe
i R , --+ [Me,6(CH2),SiR~~H2J
H*
I ) (63) v
40
'l 4*
'*
4R =
Me,P( :CH,)(CH,),SiR,Me (62)
MeaP=CH, 3- M e , S p S i Me
89
-1
(61)
+
+ Me ,P(:CH,)CH ,Si Me &H,SiMe,
P. A. Grieco and R. S. Finkelhor, Tetrahedron Letters, 1972, 3781. D. T. Connor and M. von Strandtmann, J. Org. Chem., 1973, 38, 1047. P. Ykman, G. Mathys, G. L'Abbk, and G. Smets, J. Org. Chem., 1972,37, 3213. P. Ykman, G. L'Abbk, and G. Smets, Tetrahedron, 1973, 29, 195. H. Schmidbauer and W. Wolf, Angew. Chem. Internat. Edn., 1973, 12, 320.
Ylides and Related Cornpowids Ph3P=CH2
181
+ R1R2CHCH=NA1B~',
20 "C - -
(66)
R1R2C=CHCH=PPh,
(67)
+
Bui,AINH2 (68)
The alkylideneaminoaluminium compounds (66), obtained from diisobutylaluminium and nitriles, with methylenetriphenylphosphorane gaveQQ the allylidenephosphoranes (67), which were isolated by crystallization or used directly, sometimes after precipitation of the aminoaluminium (68) (OC),WC(OMe)Ph
+
Ph,P=CHR (70;
-
R = €1 or Me)
Ph (OC),W-C-OMe
4
WC-PPh,
K LA
PhCOCH,R -+!j$-
RCH=C(OMe)Ph
(711
(72)
by the addition of KNH2. The tungsten-carbene complex (69) with the ylides (70) gave45the vinyl ethers (71), from which the acylbenzenes (72) were obtained in high overall yield after hydrolysis. The carbene complex (73) (OC),WC(OMe)CH,
+ Ph,P=CH2
4
(OC),WC(OMe>cH, P h , k H ,
(73) could not be used in a similar reaction sequence because of proton abstracti~n.~~
2 Phosphoranes of Special Interest The structure of the phosphorane (74), obtained from dichlorophenylphosphine and diethyl malonate in the presence of triethylamine, has been confirmed by X-ray analysis.*' The same technique was used to that the product obtained on heating the adduct (77) of the carbophosphorane (76) and diphenylcarbodi-imidehad the structure (75) and was formed by migration of phenyl from phosphorus to nitrogen. 44 45 46 47 48
B. BogdanoviE. and S. Konstantinovi ', Synthesis, 1972, 481. C. P. Casey and T. J. Burkhardt, J . Amer. Chem. SOC., 1972, 94, 6543. C. P. Casey, S. H. Bertz, and T. J. Burkhardt, Tetrahedron Letters, 1973, 1421. W. Saenger, J. Org. Chem., 1973, 38, 253. F. K. Ross, L. Manojlovic-Muir, W. C. Hamilton, F. Ramirez, and J. F. Pilot, J. Amer. Chem. SOC., 1972, 94, 8739.
Organophosphorids Chemistry
182
(74)
Ph,P=C=PPh,
(75)
+ PhN=C=NPh
I
-+
,yc\. PhN
NPh
Reagents: i, Ph,P; ii, KOBu*; iii, RCHO,
Scheme 4
The 'anti-aromatic' phosphorane (78) was stable only below - 30 "C but reacted norinally with aldehydes (see Scheme 4).49 The deep red-violet phosphorane (79) was stable at room temperature under argon but reacted
(79) S . V. Krivun, 0. F. Voziyanova, and S. N. Baranov, J. Gen. Chem. (U.S.S.R.), 1972, 42, 289.
183
Ylides and Related Compounds
rapidly with oxygen to give the corresponding ketone and phosphine The ylide character of the 2-tropylmethylenephosphoranes(80) was by their normal reactions with aldehydes and with peracids (see Scheme 5).
fl
(80) iib = Me = \
O
M
1
H
e
0
-
0
(81) Reagents: i, BuLi-THF; ii, C,HllCHO.
Scheme 5
The olefin (8 1) was presumably formed via the aldehyde. Therquinquecovalent character of these phosphoranes was shownsa in their Diels-Alder reactions with dimethyl acetylenedicarboxylate and with maleimides (Scheme 6).
(80)
R
+
(MeO,CCi),
= Me or Ph
-
C0,Me
Meo+
P R Ph 3
Ar = p-MeOC,H,
%erne 6 61 62
M. Rabinovitz and A. Gazit, Tetrahedron Letters, 1972, 3361. I. Kawamoto, Y. Sugimura, and Y . Kishida, Tetrahedron Letters, 1973, 577. I . Kawamoto, Y. Sugimura, N. Soma, and Y. Kishida, Chern. Letters, 1972, 931.
184
Organophosphorus Chemistry
Well-defined products are obtaineP3 from trimethylsilylmethylenephosphoranes and ketones only if 'salt-free' ylide is used and the reactants are in the molar ratio of 2:3. Under these conditions the phosphorane (82; K1and R2= Ph) and benzophenone gave quantitative yields of diphenylethylene, tetraphenylallene, bis(trimethylsily1)ether, and phosphine oxide. The reactions involve silyl transfer in the initial adducts (83) and reaction of the resulting ylides (84)with more (82) to give ether and the phosphoranes (85) and (86).
R1,P=CHSiMe, 4- R 2 & 0
Ph,C=CH,
P-
__f
R1,PCH--CR2,
OSiMe,
I
+ Rr3P=CHCR2,
+ Ph,C=C=CPhl + 2Ph3P0
When R1and/or R2are methyi, proton transfer in (86) occurs before reaction with ketone. The cumulene (87) was obtaineds4from an olefin synthesis using propargyltriphenylphosphonium bromide and butyl-lithium as base, presumably uin the cumuleneylide as shown in Scheme 7. The same salt has previously been P h 3 k H & E C H Br- i ,Ph:IP=C=C=CH2
CH=C=C=CH,
56 % Reagents: i, ArCHO dioxan; ii, rri-CIC6H,C0,H.
Scheme 7
to give the expected ene-ynes with conjugated aldehydes in liquid ammonia. Silylation of the terminal acetylenic group also led to normal behaviour in olefin 56 b3 54
55 58
H. Schmidbauer and H. Stiihler, Angcw. Chem. Internat. Edn., 1973, 12, 321. E. J. Corey and R. A. Ruden, Tetrahedron Letters, 1973, 1495. K. Eiter and H. Oediger, Annnlen, 1965, 682, 62. N. N. Belyaev, M. D. Stadnichuk, A. A. Petrov, and A. N. Belyaev, J. Gen. Chem. (U.S.S.R.), 1972, 42, 710.
185
Ylides arid Related Compounds P h , k H , C E C H Br-
+
4-
Ph,P=NN=CHCOR
--+ Ph,PCH,CCH=PPh, Br-
II
NN=CHCOR
(88)
R
.f
I
I
Y
RPh,P
+
CH,
k‘
CH2=C=CH2
RPh,Pf
186
Organophosphorus Chemistry
Reaction of the propargylphosphonium salt with the iminosphosphoranes (88) gaves7 the phosphorane-phosphonium salts (89), which show great potential in heterocyclic synthesis. Thus the salt (89; K=Ph) on heating gave the pyridazine (93), and with sodium ethoxide and p-chlorobenzaldehyde the pyrazole (92) was obtained. Addition of the anilines (90; R = Ph or MeO) to the salt (87) gave the adducts (91), from which the quinolines (94) were obtained on treatment with sodium hydride. The Michael-Wittig reaction sequence, involving the addition of nucleophiles to vinylphosphonium salts and trapping of the resulting ylides, has been extended58 to include substituted vinylphosphonium salts. Among anomalous reactions observed were the formation of the 2-methylbenzopyran (100) instead of the expected 3-methyl isomer when the isopropenylphosphonium salts (95; R = Me or Ph) were fused with sodium salicyloxide (96). The corresponding allylidenephosphoranes (99) are known to give (100) under these conditions and they may have been formed from the betaines (97) either via allene or by rearrangements involving the three-membered phospkoranes (98). In solution (DMF or HMPT) only the 3-methylbenzopyran was obtained. The heterocycle (101) reacted as a methylenephosphorane with both p-nitrobenzaldehyde and diinethyl acetylenedicarboxylate (Scheme 8).59
Ph 2P(:O)N=CMeN=PPh ?.CH=CHC,H,NO ?-p Ph,
+
N-P
Me//
‘\jCO,Mc
Reagents: i, McOLCC1 CC0,Me; ii, p-O2NC6H,CHO.
Scheme 8
67
58 Kg
E. E. Schweizer, C . S. Kim, C. S . Labaw, and W. P. Murray, J.C.S. Chenz. C ’ o r m i . , 1973, 7. E. E. Schweizer, A. T. Wehman, and D. M. Nycz, J. Org. Chem., 1973,38, 1583. R. Appel, R. Kleinstuck, and K.-D. Ziehn, Chem. Ber., 1972, 105, 2476.
Ylides arid Related Compounds
187
The dienes obtainedGofrom the bisphosphonium salt (102) and benzaldehyde with lithium in HMPT or benzophenone with sodium in THF could have been formed via two-electron reduction of the salt to give the bis-ylide or by addition of the carbonyl radical anions as shown in Scheme 9 for I
Ph(CH=CH),Ph
(PhCH0)-' 3- (102)
-
0' I
PhCH
Ph, p
7+\
Ph,
0-
I
PhCH Ph(CH=CH),Ph
Phz
p v+\
t
Reagents: i, PhCHO-Li-HMPT; ii, Ph&O-Na-THF.
Scheme 9
benzaldehyde. Support for the latter route is provided by the formation of diene on reaction of the sodium ketyl from benzophenone with vinyltriphenylphosphonium bromide. Full details have appeared of the preparation and use in olefin syntheses of the salts (103),61(104),62(105),63 and of the salts (106)64 formed by the 4-
Ph ,PCH ,CH,CECSi Me,, 1-
(103) 6u 61
6L
64
Ph$a
Br-
R
( 104) E. Vedets and J. P. Bershas, J. Org. Chem., 1972, 37,2639. A. G . Fallis, M. T. W. Hearn, E. R. H. Jones, V. Thaller, and J. L. Turner, J.C.S. Perkin I , 1973, 743. K. Utimoto, M. Tamura, and K. Sisidoi, Tetrahedron, 1973, 29, 1169. J. A. Eenkhoorn, S. 0. de Silva, and V. Snieckus, Cunad. J. Chem., 1973,51,792. E. Hugl, G . Schulz, and E. Zbiral, Annalen, 1973, 278.
188
OrganophosphorusChemistry
(105)
(106) (Ph3P=CC0 2Me)2Hg
(107) addition of nucleosides and nucleoside bases to p-acylvinylphosphonium salts. Further information has been givens5on the use of the bisphosphorane (107) in the synthesis of divinylmercury compounds. Among other interesting phosphoranes used successfully in olefin synthesis (110),68 and (111),69 and those derived from the salts are (108),66 Ph ,P=CH(CH=kH),CO,Et
a:]
(108)
Ph ,P=CRICO
R?\
Ph&'=CRCOC( :NOH)Ar (109)
Ph,P=CHCOCH,Br (1 11)
Ph,;(CH,)60H I(112)
( I 13)
(1 l2)'O and (1 13).'l The last with &anexcess of paraformaldehyde and ethanolic sodium ethoxide gave 83% of 6-vinyluracil, which could not be obtained by methylenation of or0t aldehyde. 3 Selected Applications of Ylides in Synthesis Natural Products.-The synthetic sequence shown in Scheme 10 was de~eloped'~ in order to elaborate the cephalosporin nucleus (115) from the N. A. Nesmeyanov, A. V. Kalinin, V. S. Petrosyan, and 0. A. Reutov, Bull. Acad. Sci., U.S.S.R., 1972, 21, 1142. M. P. L. Caton, T. Parker, and G. L. Watkins, TetrahedronLetters, 1972, 3341. M. V. Khalaturnik, M. I. Shevchuk, and A. V. Dombrovskii, J. G m . Chem. (U.S.S.R.), 1972, 42, 982. A. S. Antonyuk, M. I. Shevchuk, and A. V. Dombrovskii, J . Gen. Chem. (U.S.S.R.), 1972,42, 1695. Y. A. Zhdanov and L. A. Uzlova, J. Gen. Cliern. (U.S.S.R.), 1972,42, 751. 7 0 R. K. Bentley, E. R. H. Jones, R. A. M. Ross, and V. Thaller, J.C.S. Perkfn I, 1973, 141. '' R. S. Klein and J. J. Fox, J . Org. Chem., 1972, 37, 4381. 7 * R. Scartazzini, H. Peter, H. Bickel, K. Heusler, and R. B. Woodward, Welv. Chim. Acta, 1972, 55, 408.
189
Ylides and Related Compounds R'CONH 0JxHslH20R2
I
4 C HIC 0 , B u '
OH
(114) R2 = COzCHZCC13
C1 Jiii
R 1 C o N ~ s ~ 2 0 H L
gJJNCC0,But
)=PPh,
PPh,
O
II
CO,But
R1coNB3CO,But
Reagents: i, CHO * C02 But; ii, SOCI2-pyridine; iii, PhaP-pyridine; ivy Zii-AcOH ; V, AQO-DMSO.
Scheme 10
t ii
P h 3 C N H ~ ' \COCHtPh 0
Reagents: i, reflux, piperidine; ii, reflux, dioxan.
Scheme 11
yPPh3
190
Organophosphorus Chemislry
p-lactams (1 14) obtained by the degradation of penicillins. Similar sequences were applied to the B-Iactams (116; n = Y 3 or 374)and (117)75(Scheme 11).
(1 18) 4-
Reagents: i, Ph,PCH,OMe CI-, KOBu'; ii, 20% HCI; iii, polyphosphoric acid.
Scheme 12
Dictamnine (118) has been synthe~ized'~ as outlined in Scheme 12 and the general route applied to the syntheses of related furoquinoline alkaloids and of oxaphenalene. The first stage in the synthesis of 'pear ester' involved reaction of hexylidenetriphenylphosphorane with the epoxy-aldehyde (1 19), the major product
(1 19)
15 : 85
being the tra~;l~,cis-isomer.~~ The acetylenic ester (121), prepared by pyrolysis of the P-ketoalkylidenephosphorane(120), was an intermediate in the synthesis78of various naturally occurring sulphur compounds from the family Arctotideae. AcO
QCOCI
AcO
+
Ph,P=CHCO,Me
*
Q
COC(CO,Me)=PPh,
(121) 63 7;
74
76 76 77
'*
R. Scartazzini and H. Bickel, Helu. Chim. A d a , 1972, 55, 423. R. Scartazzini, J. Gosteli, H. Bickel, and R. €3. Woodward, Helv. Chim. Acta, 1972,55, 2567. J. H. C. Nayler, M. J. Pearson, and R. Southgate, J.C.S. Chem. Comm., 1973, 5 8 . N. S. Narasimhan and R. S. Mali, Tetrahedron Letters, 1973, 843. G. Ohloff and M. Pawlak, Heh. Chim. A d a , 1973, 56, 1176. F. Bohlmann and W. Skuballa, Chem. Ber., 1973,106,497.
Ylides and Related Compounds
191
Among many other syntheses involving the use of ylides in key steps are those of the macrolide antibiotic ( k)-pyren~phorin,~~ ( - )-ylangocamphor and related compounds,80isomers of phytoene used in the establishment of its stereochemistry,8la number of polyenes related to carotenoids,82and various crepenyate, linoleate, and oleate esters labelled with 14Cand 3H.s3 Macrocyclic Compounds.-Cyclobutane-1 ,Zdione has been used in the synthesiss4of the interesting thiophen (122) and details have appeared86of
(122) 5 %
the synthesis of the corresponding [6,7]benzo-compound. A reinvestigationa6 of the ylide synthesis of the [12]annulene (123) gave both the &,cis (1.1 %)
(123)
and trans,trans (4.2%) isomers. The conformation of the latter has been determined by X-ray analy~is.~' A number of heteroannulenes have been prepared, some by conventional bisylide reactions, e.g. ( 1 2 4 p and others by construction of cco-diacetylenes
+ (Ph,PCH,),X
2Br(124) X = 0,S, or CH,
8s
84
n6 8a
E. W. Colvin, T. A. Purcell, and R. A. Raphael, J.C.S. Chern. Comm., 1972, 1031. E. Piers, M. B. Geraghty, F. Kido, and M. Soucy, Synthetic Comm., 1973,3,39. N. Khatoon, D. E. Loeber, T. P. Toube, and B. C. L. Weedon, J.C.S. Chern. Comm., 1972,996. E.g. U.S.P.3694491 (Chem. Abs., 1973,78,30033); G. W. Francis, Actu Chem. Scand., 1972,26,2969. G . C . Barley, E. R. H. Jones, V. Thaller, and R. A. Vere Hodge, J.C.S. Perkin 1, 1973, 151. P. J. Garratt and D. N. Nicolaides, J.C.S. Chem. Comm., 1972, 1014. P. J. Garratt and K. P. C. Vollhardt, J. Amer. Chem. SOC.,1972,94, 7087. K. Grohmann, P. D. Howes, R. H. Mitchell, A. Monahan, and F. Sondheimer, J. Org. Chem., 1973, 38, 808. I. Agranat, M. A. Kraus, E. D. Bergmann, P. J. Roberts, and 0. Kennard, Tetrahedron Letters, 1973, 1265. H. Ogawa and N. Shimojo, Tetrahedron Letters, 1972, 4129.
OrganophosphorusChemistry
192
+ (Ph$CH,),S
2Br-
LiO Et
(125) 15%
followed by oxidative cyclization. Among these were the bisdehydrothia[l7]annulene (125),89 the bisdehydroaza[l9]annulene (126; n = l),gOand the analogous [21 Iannulene (126; n = 2).91
Other macrocyclic compounds constructed with the use of ylides included (127)02and (128),93obtained as a mixture of geometrical isomers. Miscellaneous.-Further examples have appeared of the reactions of protected aldehydo- and keto-sugars with simple ylides in conventional olefin syntheses.94 89 O0
91
OP O* Or
R. H. McGirk and F. Sondheimer, Angew. Chem. Internat. Edn., 1972,11, 834. P. J. Beeby and F. Sondheimer, Angew. Chem. Internat. Edn., 1973, 12, 411. P. J. Beeby and F. Sondheimer, Angew. Chem. Internat. Edn., 1973,12,410. H. Ogawa, M. Kudo, and I. Tabushi, Tetrahedron Letters, 1973, 361. W. Carruthers and M. G. Pellatt, J.C.S. Perkin I, 1973, 1136. E.g. J. M. J. Tronchet and J. M. Chalet, Carbohydrate Res., 1972, 24, 263; J. M. J. Tronchet, B. Baehler, H. Eder, N. Le-Hong, F. Perret, J. Poncet, and J.-B. Zumwald, HeZv. Chiin. A d a , 1973, 56, 1310; N. Baggett, J. M. Webster, and N. R. Whitehouse, Carbohydrate Res., 1972, 22, 227.
Ylides and Related Compounds
193
Among polyenes synthesized with the use of ylides were a series of aw-diphenanthrylpolyenesg6and the thiophens (129; n=O, 1, or 2).96 An interesting methylenation was that of the nickel porphyrin complex (130).@'The sequence of reagents shown in Scheme 13 has been usedg8for the 'one-pot' conversion
Reagents: i, Ph,P=CHOMe; ii, H+-H,O; iii, Cr03.
sctrme 13 of adamantanone (1 3 1; R = H) into the carboxylic acid in 70-75 % yield and has also been appliedggto the ester (131 ; R = C0,Me). 4 Selected Applications of Phosphonate Carbanions The diastereoisomers of the p-hydroxyphosphonates (132; R = H or Me) have been obtained.loOTheir behaviour when treated with base demonstrated the direct interconversion of the diastereoisomers (132; R = H) and confirmed the reversibility of the reaction of phosphonate carbanions with carbonyl compounds. This was also shownlolin a study of the p-oxidophosphonateions (133), generated as shown in Scheme 14 from a-cyanovinylphosphonates. Protonation of the p-oxidophosphonate carbanion (134) gavelo2exclusively the less stable diastereoisomer of the p-hydroxyphosphonate (1 35). This contrasts with the protonation of p-oxidoylides, which gives the more stable isomers. Y. Takeuchi, A. Yasuhara, S. Akiyama, and M. Nakagawa, Bull. Chem. SOC.Japan, 1973, 46, 909. G . Manecke and M. Hartel, Chem. Ber., 1973,106, 655. Q' H. J. Callot, Tetrahedron, 1973, 29, 899. O 8 A. H. Alberts, H. Wynberg, and J. Strating, Synthetic Comm., 1972, 2, 79. A. H. Alberts, H. Wynberg, and J. Strating, Tetrahedron Letters, 1973, 543. loo B. Deschamps, G . Lefebvre, and J. Seyden-Penne, Tetrahedron, 1972, 28,4209. l o l D. Danion and R. Carrie, Tetrahedron, 1972, 28,4223. G. Lavielle, M. Carpentier, and P. Savignac, Tetrahedron Letters, 1973, 173. O6
194
Organophosphorus Chemistry (EtO),P( :O)CR(CN)CH(OH)Ph (1 32)
R1R2C=C(CN)P( :O)(OEt),
+
OH- --+
RIR*Ce(CN)P(:O)(OEt),
I
HO
11 R1R2C0 3. cH(CN)P( :O)(OEt),
R'R*CCH(CN)P(:O)(OEt),
I
0(133)
(PriO),P( :O)CHCICH(6)Ar
(PriO),P( :O)CClCH(6)Ar (1 34) p.0
(Pr '0) ,P(:0 ) CHCICH(0H)A c (1 35)
Among phosphonates used in conventional olefin syntheses were (136),lo3 (137),loPand the phosphonates (EtO),P(: O)R1 with R1= CH,(CH: CH),R2,lo5 P( :O)(OPh),
n
(EtO),P( :O)CHRN
WY
(136)Y= O o r C H 2
O,N
@ 0 (137)
CHBrC,H,NOz-p,l,Os or CH,SMe in a synthesisfo7 of ( i)-occidental, CH2SOzR,108CH,SMeR,loSa or CH,NC.loSb The last, with aldehydes in ethanolic sodium cyanide and with acetone in the presence of Cu,O, gave oxazolines. The bisphosphonate (138) gave vinylphosphonates,llO and the H. Bohme, M. Haake, and G . Auterhoff, Arch. Pharm., 1972,305,88. A. Yamaguchi and M. Okazaki, Nippon Kagaku Kaishi, 1973, 110 (Chem. Abs., 1973, 78, 84494). Io5 H. De Koning, A. Springer-Fidder, M. J. Moslenaar, and H. 0. Huisman, Rec. Trau. chim., 1973, 92, 237; H. De Koning, G . N. Mallo, A. Springer-Fidder, K. E. C. Subramanian-Erhart, and H. 0. Huisman, ibid., p. 683. Io6 A. Yamaguchi and M. Okazaki, Nippon Kagaku Kaishi, 1972,2103 (Chem. Abs., 1973, 78, 29372). l o * D. S. Watt and E. J. Corey, Tetrahedron Letters, 1972, 4651. l o 8 G. H. Posner and D. J. Brunelle, J. Org. Chem., 1972, 37, 3547. l o S (a) K. Kondo and D. Tunemoto, J.C.S. Chem. Comm., 1972,952; (b) U. Schollkopf and R. Schroder, Tetrahedron Letters, 1973, 633. ' l o W. F. Gilmore and J. W. Huber, tert., J. Org. Chem., 1973, 38, 1423.
loa
lo*
195
Ylides and Related Compounds [(EtO),P(:O)CH,I*P(:O)OEt
+ RCHO
NaH
-:RCH=CHP( :O)(OEt),
+ (EtO)zP( :O)CH,P(O,-)OEt
(138)
carbanion from the diazophosphonate (1 39) with carbonyl compounds gave acetylenes,lll probably formed uia rearrangement of the intermediates (140). BuLi-THF
(MeO),P( :O)CHN
(MeO),P(:O)CN,
____f
-80 "C
(139)
The dianion (142), formed on treatment of the phosphonate carbanion (141) with butyl-lithium, alkylated exclusively on the y-carbon with alkyl
(Ma),P( :O)eHCOCH,
(MeO),P( :O ) ~ H C O ~ H ,
BuLi
(141)
(1 42)
.1=
(MeO),P( :O)CM,COCH,R
xsiMe3
PhCOO P
h
C
Y
Ph
Me,SiCHP( :O)(OEt), hC0,Me
(143)
\p, [PhCOCH(SiMe3)P(:O)(OEt),]
PhCoNMezl
Me,Si-CHP( :O)(OEt),
1
-0-CPhNMe
Me3SiO-
-1
P(:O)(OEt),
(144)
+ PhC(NMe,)==CHP(:O)(OEt),
(145)
I PhCOCH,P(:O)(OEt), (146)
(147) 24%
halides.l12 With benzoyl chloride the phosphonate carbanion (143) gave118 the O-benzoylated product (144) of the expected phosphonate (145), but 118
lIS
E. W. Colvin and B. J. Hamill, J.C.S. Chem. Comm., 1973, 151. P. A. Grieco and C. S. Pogonowski, J. Amer. Chem. SOC.,1973, 95, 3071. F. A. Carey and A. S. Court,J. Org. Chem., 1972, 37,939.
196
Organophosphorus Chemistry
with methyl benzoate the phenacylphosphonate(146) was formed, presumably via desilylation of (145). With NN-dimethylbenzamide and (143) the vinylphosphonate (147) was obtained. To overcome the lack of reactivity of long-chain aldehydes towards the ester carbanion (148), this was acylated and the resulting 8-ketophosphonates reduced and then treated with base as in Scheme 15.114 trans-@-Unsaturated EtO,CCHP(:OXOEt),
A
RCOCH(CO,Et)P(:O)(OEt),
(148)
Jii
RCH(OH)CH(CO,Et)P( :O)(OEt) 2 tii
RCH=CHCO,Et Reagents: i, RCOCl; ii, NaBH, or H,-Pd; iii, NaOEt.
Scheme 15
ester was obtained irrespective of the isomer composition of the intermediate 8-hydroxyphosphonate. The nitrile-phosphorme carbanion (149), generated (EtO),P( :O)cHCN
ArCNO
(149)
(1 50) 25-3 1 %
H,W -P(:O)(OEt),
n
ArN,N9N
(151) 54-81
%
in ethanolic sodium ethoxide, with benzonitrile oxides gave the oxazoles (150) and with aryl azides the triazoles (151).l15Under the same conditions the ester carbanion (148) with aryl azides gave the diazophosphonates (152), and
(148)
+ ArN,
[
HO- P(:O)(OEt), ArNQN
]
--+ ArNHCOCN,P(:O)(OEt),
(1 52)
mixtures of the triazoles (154) and (155) were obtained from the carbanion (153) and aryl azides. 11* 116
G. Durrant and J. K. Sutherland, J.C.S. Perkin I, 1972, 2582. U. Heep, Annalen, 1973, 578.
197
Ylides and Related Compounds
PhCOCHP(:O)(OEt),
-
+ ArN,
(153)
0 P(:O)(OEt), PhftH
Ph/,\P( /N w-
ArN
ArN
:O)(OEt) 2
/N
' I 4
(154)
(155)
The formation of cyclopropanes from epoxides and the carbanion (148) has been shown to involve inversion of configuration at both carbon atoms.116 Terminal epoxides with the phosphonates (156) gave trans-cyclopr~panes.~~~
~
1
8
aF
f1 (EtO)2P(:O)CH2COCHONRa2
2NR'2
5 Ylide Aspects of Iminophosphoranes
Details have appearedlls of the formation of N-styryliminophosphoranesfrom the reactions of 2H-azirines with triphenylphosphine and tetrahalogenomethanes, e.g. (158) from (157). Besides the expected carbodi-imides, the
ArF?co2R
PhaP= C&
Ph,P=NCArl=C(CN)C,H,R-p
Ph,P=NCAr=CXCO *R
+ Ar2NC0
(1 59)
-
Ar*N=C=NCAr1=C(CN)CBH4R-p + NHArZ
Ar2
(161) lla 118
R. A. Izydore and R. G. Ghirardelli, J. Org. Chem., 1973, 38, 1790. M. Baboulene and G. Sturtz, Phosphorus, 1973,2, 195. T. Nishiwaki and F. Fujiyama, J.C.S. Perkin I, 1973, 817.
198
Organophospkorus Chemistry
isoquinolines (160) were obtained from the reactions of the iminophosphoranes (1 59) with aryl isocyanates. The carbodi-imides were not intermediates in the formation of (160) and cyclization of the initial adducts (161) was suggested. R *P(:NAr)OCH*C6H,WO 2-p (163) R2:27Ar R *P(:NAr)OCHPhCOPh
But (1 65)
But (166) 71-78%
The iminophosphoranes (1 63) and (164) were obtainedllDfrom the aminophosphines (162; R1= Ph or OR2) and p-nitrobenzaldehyde and benzil, respectively. The reactions presumably involve initial attack of the phosphines on carbonyl oxygen followed by proton transfer. Pyrolysis of the imines (165) gave the cyclic iminophosphoranes (1 66) and arene.120 The results of a kinetic investigation of the reactions of the iminophosphoranes R,P=NPh with p-nitrobenzaldehyde in various solvents were held121to be inconsistent with the formation of betaine intermediates. Instead the direct formation of four-membered covalent adducts was suggested.
The iminophosphoranes (1 67 ; R1= alkyl or aryl) with acyl halides gave122 the imidoyl halides (168 ; X = C1, Br, or I), whereas (167 ; R1= SiMe,) with A. N. Pudovik, E. S. Batyeva, and V. D. Nesterenko, Bull. Acad. Sci., U.S.S.R.,1972, 21,825; A. N. Pudovik, E. S. Batyeva, V. D. Nesterenko, and N. P. Anoshina, Sbornik Nekot. Probl. Org. Khim., Mater. Nauch. Sess., Inst. Org. Fiz. Khim., Akad. Nauk S.S.S.R.,1972,6 (Chem. Abs., 1973, 78, 29909). l a 0 H. B. Stegmann and G. Bauer, Synthesis, 1973, 162. lS1 P. Frsyen, Acta Chem. Scand., 1972, 26, 1777. E. Zbiral and E. Bauer, Fhosphorus, 1972, 2, 35.
11'
199
Ylides and Related Compounds
both acyl halides and acid anhydrides gave the acyliminophosphoranes (1 69).123The N-lithioiminophosphorane (170) has been treated with chloroand dichloro-disilanes to give a series of disilanyl-substituted amines, e.g. (171).124
Me,P=NLi
+
Me,Si,CI,
+ [Me,P=NSiMe,], (171)
(170) Ph3P=NNH,
% :- :
Ph,PO
+
N,
(172)
Oxidation of the aminoiminophosphorane (1 72) with mercuric oxide gave phosphine oxide and nitrogen,126but attempts to trap the supposed intermediate Ph3PN2were unsuccessful.
H. R. Kricheldorf, Synthesis, 1972, 695. H. Schmidbauer and W. Vornberger, Ckem. Ber., 1972,105, 3187. l a bK. Yamada and N. Inamoto, Bull. Ckem. SOC. Japan, 1972,45, 1559. l** 1*4
9 Phosphazenes BY R. KEAT
1 Introduction The past year has been notable for the number of reviews related to this topic. The most important of these is a monograph,l which gives an excellent comprehensive coverage of phosphazene chemistry, although it might disappoint those interested in the more general aspects of phosphorus-nitrogen chemistry, coverage of which is implied by the title. The same author has also given a review of recent developments in this field. Cyclophosphazene chemistry is covered in a new biannual review s e r i e ~and , ~ analytical aspects of this topic have been s ~ r v e y e dThe . ~ chemistry of linear halogenophosphazenes5 and trihalogenomonophosphazenes has been reviewed. The latter two reviews contain a useful collection of data from the extensive literature on this topic originating in the Soviet Union. 6s
2 Synthesis of Acyclic Phosphazenes From Amides and Phosphorus(v) Halides.-Surprisingly few examples of the Kirsanov reaction have been reported, and in most of these the formation of a phosphazene, X3P=NR, was accompanied by halogenation of the R group. For example, adipamide and phosphorus pentachlorideundergo the reaction :8
In this case it appears that chlorination of the keto- and methylene-groups is preceded by the formation of the -N=PC13 group. Previous observations concerning the formation of a dinitrile from the same reaction, but in the absence of a solvent, were also confirmed: PCI
H2N.CO(CH2)4CO-NH2-i&+ NC(CH,),CN
+
decomposition products
H. R. Allcock, ‘Phosphorus-Nitrogen Compounds’, Academic, New York, 1972. H. R. Allcock, Chem. Rev., 1972,72, 315. * D. B. Sowerby, in ‘MTP International Review of Science, Inorganic Chemistry, Series One’, ed. C. C. Addison and D. B. Sowerby, Butterworths, London, 1973, Vol. 2. J. M. E. Goldschmidt, in ‘Analytical Chemistry of Phosphorus Compounds’, ed. M. Halmann, Interscience, New York, 1972, p. 523. H. W. Roesky, Chem.-Ztg., 1972,96,487. a M. Bermann, Adu. Znorg. Chem. Radiochem., 1972, 14, 1. M. Bermann, Topics Phosphorus Chem., 1972, 7 , 31 1. H. A. Klein and H. P. Latscha, 2.anorg. Chem., 1973,396,261.
200
Phosphazenes
201
Hydroxy-groups in the side-chain R2 of the acetimides R1C(=NR2)NH2 are chlorinated when phosphazenylation of the NH2 group is effected by phosphorus pentachl~ride.~ Phosphinothioylamines are desulphurated by phosphorus(v) chlorides:lo
+
R1R2*P(S)*NH2 2R3PC1,
R1
+
R1RZ*P(S).NH2 2R3R4PC13
__f
R3
-i-
[ g; ] C1-
I =N-P-CI
CI-
+
R3R'P(S)CI
k 4
(Rl, R2, R3, and R4 included Me, Et, and Ph)
The reactions of these phosphazenyl derivatives are typified by that of [R1R2PCl=N.PR3C12]+CI-, which gave [(H2N)R1R2P=N.PR3(NH2)2]fC1-, R1R2PCI=N.PR3(0)CI, and R1R2P(OH)=N.P(0)R3(0H), on reaction with ammonia, sulphur dioxide, and formic acid, respectively. Perfluoroalkyl- and other halogenoalkyl-carboxylic acid amides have also been employed as substrates for somewhat modified Kirsanov reactions:ll. l 2
R*CO*NH2 + 2PhPF4 3. 2EtaN
4
R*CO*N=PF2Ph+ 2Eta&H PhPF5-
(R = CF3or n-C3F,; ref. €1) R*CO.NH, + 2PC15
R*CCI,*N=PC13
(R = CHBr,, ClCH,.CHCl, or ClCH,.CCI,; ref. 12)
Phosphazenes of the type C13P=NR generally give dichlorophosphinylamides, RNH.P(0)C12, on reaction with formic acid, but the latter series of halogenoalkyl derivatives gave N-phosphinylimides, RCCl[=N P(O)Cl,] with this reagent.12 The reaction of phosphorus pentachloride with ammonium chloride in the presence of boron trichloride leads to the formation of chlorophosphazonium V. P. Rudavskii and M. N. Kucherova, J. Gen. Chem. (U.S.S.R.), 1972, 42, 1283. A. Schmidpeter, N. Schindler, and H. Eiletz, Synth. Inorg. Metal-org. Chem., 1972, 2, 187. 1 1 G. Czieslik and 0. Glemser, Z . anorg. Chem., 1972, 394, 26. 1% V. P. Rudavskii and D. M. Zagnibeda, Farm. Zhur. (Kieu), 1972, 27, 35. 0
10
202
Organophosphorus Chemistry
tetrachloroborates, [CI(CI,P= N)12PC13]+ BC14-, rather than to products containing boron-nitrogen bonds.13 The degree of condensation, n, was shown by 31P and llB n.m.r. to be dependent on the temperature employed; thus at 75 "C in dichloroethane n is mainly 1, with some 2, but at ca. 130 "C products with n = 2,3, and higher values have been identified. Similar products were obtained from PCI4+BC1,- and ammonium chloride. Interesting new N-trimethylsilylphosphazeneswith considerable synthetic potential have been obtained from the lithio-derivative LiN(SiMe,), :14,l6 PC15
+ LiN(SiMe&
POC13
+ LiN(SiMe,),
-
C13P=N.SiMe3 .(Me,SiO)CI,P=N~SiMe,
(ref. 14) (ref. 15)
The latter monophosphazene, which may also be obtained in an impure form from the reaction of phosphoryl(v) chloride with N(SiMe&, is obviously isomeric with ClzP(0).N(SiMe3)2and is presumably formed partly as a result of the tendency of silyl groups to bond to oxygen where possible. It is worth noting, however, that the analogous fluoride F,P(O) .N(SiMe,), does not exist in the phosphazene form, so that the tautomer obtained reflects a rather subtle balance of electronic factors. From hides and Phosphorus(m)Compounds.-This class of reaction continues to provide a convenient route to a wide range of novel monophosphazenes. For example, 1,2,5-triphenylphosphole(1) eliminates nitrogen with the azides
RN, (R = Ar, ArSO,, MeS02, Et02C, or Ph,PO) to give the phosphazenes (2).16 The products were all thermally stable except for when R = o-nitrophenyl, which gave the analogous phosphole oxide and benzofurazan (3) on heating. The phosphite (4) may be converted into a phosphazene (3, with complete retention of configuration at phosphorus, on reaction with phenyl a2ide.l' This was deduced from the sequence of reactions shown in Scheme 1. Nucleoside 5 '-phosphite esters have been derivatized as monophosphazenes by reaction with phosphinyl and sulphonyl azides, and the aminophosphite la
l4
l6 l6 lq
lS
K. Niedenzu, I. A. Boenig, and E. B. Bradley, Z . anorg. Chem., 1972,393,88. E. Niecke and W. Bitter, Inorg. Nuclear Chem. Letters, 1973, 9, 127. G. Czieslik, G . Flaskerud, R. Hofer, and 0. Glemser, Chem. Ber., 1973, 106,399. J. I. G. Cadogan, R. Gee, and R. J. Scott, J.C.S. Chem. Comm., 1972, 1242. W. Stec and A. kopusiniki, Tetrahedron, 1973, 29, 547. G. Baschang and V. Kvita, Angew. Chem. Internat. Edn., 1973, 12,70.
Phosphazenes
203
Scheme 1
(MeO),P.N(SiMe,), eliminates nitrogen to give (7) on reaction l9 with trimethylsilyl azide at ca. 110 “C.The two trimethylsilyl signals in the lH n.m.r. spectrum of (7) coalesce at 98 “C,probably as the result of an intramolecular 1,3 trimethylsilyl group shift involving an intermediate of the type (8).
WesW2N, (MeO)2P*N(SiMe3),4- Me,SiN, -+
MeOTP=N-SiMe, Me0
SiMe, I
Me0 N \ / \ P:+ -SiMes
M&/ \.N/ I
%Me,
l8
0.J. Scherer and R. Thalacker, 2.Nuturforsch., 1972, 27b, 1249.
+ N2
204
Organophosphorus Chemistry
The azide synthesis has been used to advantage in the formation20of (9), a derivative which could not be obtained by the elimination of trimethylsilyl chloride between the urea derivative, [(Me,Si)MeN],CO, and PhN= PCI,NEt,. The feasibility of stepwise reactions between diphosphines and azides has The reaction of the tellurium azide been demonstrated, e.g. Scheme Cl,TeN, with triphenylphosphine does not result in the formation of a phosphazenyl-tellurium derivative (Scheme 3). 2 2 This is probably a result of the tendency of the Te-N bond to heterolyse (Scheme 4).
PhN=PYh
2
CH2*PhZP=NPh
Scheme 2
2CI,TeN,
+ 4Ph,P
__f
2[Ph3P-N=PPh,]+TeC1,2-
+ Te + 2N2
Scheme 3
CI,Te-N=N=N
+ Ph3P
-+
[CI,Te-N=N-N=PPh,] .e
C1,Te- 4- N=N=N-PPh,
Scheme 4
Phosphazenes fail to result from the reaction of acyl azides and phosphorus tri-i~ocyanate,~~ which gives instead a uretidinedione (Scheme 5). It is worth noting here that azides and ethoxycarbonylalkylidenetriphenylphosphormes, R0,C -CH=PPh3, form pho~phazenes;~~ this reaction is discussed further in Chapter 8. 30
$1
st a* 94
M. Bermann and J. R. Van Wazer, J.C.S. Dalton, 1973, 813. V. Yu. Kovtun, V. A. Gilyarov, and M. I. Kabachnik, Izvest. Akad. Nauk S.S.S.R., Ser. khim., 1972, 2612. N. Wiberg, G. Schwenk, and K. H. Schmid, Chem. Ber., 1972, 105, 1209. E. S. Gubnitskaya and G. I. Derkach, J. Gen. Chem. (U.S.S.R.), 1972, 42, 287. P. Ykman, G. L'Abb6, and G. Smets, Tetrahedron, 1973, 29, 195.
Phosphazenes
205
0
Scheme 5
Other Methods.-The synthesis of monophosphazenes from the reaction of nitriles with phosphorus pentachloride continues to be studied. With benzcitri rile,^^ as with acetonitrile, the products depend on the molar ratios of reactants and with three molar equivalents of phosphorus pentachloride the reaction is: PhCHZ.CN
+ 3PCIb
PhCCIy*CCI,N=-PCI3
With smaller proportions of phosphorus pentachloride, the olefmic deriva-
ph,
,c=c,
H
Cl
Ph,
/
N=PCI,
Cl
C=C
0
h=PCI3
C’l (1 1)
(10)
tives (10) and (11) are formed. PhCCl, CCl, .N=PCI, undergoes expected reactions with formic acid and with boron trifluoride: HCQ2H/
PhCCli C(CI)=N* P(O)C12
PhCCI,* CCIZ*N=PCI, BFh
PhCCl,.CCl,.N(~F,)i;Cl,
Bis(dipheny1phosphino)amines 2 6 and bis(dipheny1phosphino)methane 2 7 have both been utilized as substrates for condensation with ammonia and carbon tetrachloride (Scheme 6) (similar reactions have been carried out with HN(PPh,),
+ CCIJ +
H2C(PPh2), + CCIJ
NH,
+ NH3
-+
[H2NPh2P-NqPh2NH2]+C1[H2NPh2P-N=PMePh,]+Ci-
Scheme 6 p K
za 37
E. Fluck and W. Steck, Phosphorus, 1972, 1, 283. R. Appel and G. Saleh, Annalen, 1972, 766, 98. R. Appel, R. Kleinstiick, and K.-D. Ziehn, Chem. Ber., 1972, 105, 2476.
206
L)i~~aiiopliosphouus Chemistry
t-butylamine and phenylhydrazine in the presence of triethylamine). It was suggested that the latter salt is formed by the mechanism shown in Scheme 7.
Ph H2NPhzP-N=PMePh2
f--
H Phz H,N
Scheme 7
When more than one methylene group bridges the diphenylphosphinogroups, cyclic products are obtained (Scheme 8).
Scheme 8
A closely related method has also been used for the synthesis of cyclic phosphazenes (see Section 5). Interesting possibilities are also suggested by the reaction 38 of phosphines with N-chlorohexamethyldisilazane:
(X = Alk, Ar, or OAlk) By analogy with the reactioiis of N-chlorodialkylamines with phosphines, zB
A. M. Pinchuk, M. G. Suleimanova, and L. P. Filonenko, J . Gen. Chem. (U.S.S.R.), 1972, 42, 2111.
207
Phosphazenes
+
which give stable phosphonium salts R1,N .PR,Cl-, it was suggested that the
+
disilazane reaction proceeds uiu salts of the type (Me,Si),N.PR, C1-. Benzil and (EtO),P .NHPh give the thermally unstable phosphazene (EtO),P( :NPh)OCH(Ph)CH,Ph in diethyl ether solution.29 3 Properties of Acyclic Phosphazenes Halogeno-derivatives.-The alcoholysis30 of the diphosphazene C1,P =NCI,P=N-P(S)Cl, follows a course similar to that observed last year for CIF,P=N .P(S)F, in that a thioalkoxy- rather than an alkoxy-derivative is obtained :
(R = MeorEt)
Initial nucleophilic attack by the alcohol probably occurs at the CI,P=Ngroup, and the product rearranges to the thioalkoxy-derivative by an intramolecular exchange process. The triphosphazene Cl(Cl,P= hT)3P(0)C12 has also been alcoholized: C1(C1,P=N)3P(0)C12
ROH- Et3N +
HO [(RO) aP=N] ,P(O)(OR) 3.
(R = A l k o r A r )
Although the product is represented here as a hydroxyphosphazene, there is infrared evidence that this product is in equilibrium with its tautomer:
Alkyl chlorides were eliminated when the alkoxy-derivativeswere heated with triphenylsilyl chloride, and it was shown that silyloxy-groups are introduced at both terminal and bridging phosphorus atoms :
Thermal decomposition of the N-sulphonyl phosphazenes CIR2P= N * S0,X (R = Cl, Me, or Ph; X = F or C1) results32in the formation of phosphinyl chlorides, R,P(O)Cl, and oligomers of the type [NS(O)XIn, rather than the 29
30
31
32
A. N. Pudovik, E. S. Batyeva, and V. D. Nesterenko, Izvest. Akad. Nauk S.S.S.R., Ser. khim., 1972, 871. H. W. Roesky, Z . Nrtturforsch., 1972, 27b, 1569. A. A. Volodin, V. V. Kireev, V. V. Korshak, and E. A. Filippov, J. Gen. Chem. (U.S.S.R.), 1972, 42, 509. W. Naubold, E. Fluck, and M. Becke-Goehring, 2. anorg. Chem., 1973, 397, 269.
208
Organophosphorus Chemistry
phosphazenes (R2PN)nand the sulphuryl chlorides S02C1X. The ring compound (12) was obtained in 20% yield from the thermolysis products of C13P= N - S02C1. When compounds containing longer phosphazene chains were pyrolysed the range of products was more complex, as might be expected, e.g. Scheme 9. Both Cl,P=N - C(C1)= N - Cl,P= N S0,Cl and (CI3P=N)2-
(13)
Scheme 9 C=N.Cl,P=N -SO,CI gave phosphoryl chloride, C13P=N -SO,CI, and other unidentified products, whereas SO,(N= PCl, .N=PCI,), gave CI,P=NP(0)Cl2 and (14). Almost identical results for the decomposition of CI,P=N-Cl,P=N .S02C1have been reported by other workers,33who found that the preparation of (14), which was first reported last year, is best achieved by heating Cl,P=N.SO,Cl and Cl(Cl,P=N),SO,Cl in a 1 : 3 molar ratio, respectively. The infrared spectra of (12), (13), and (14) were also discussed. Thermal methods were also employed in the synthesis3.*of the novel cage compound (1 5) from the dimeric phosphazene (MeNPF3),. The formation of
(15) in a bomb at 130 "Cwas accompanied by the appearance of a salt formulated as (16), insoluble in carbon tetrachloride, which gave (17) on vacuum sublimation. An n.q.r. study 3 5 of the dimeric phosphazenes (1 8 ; R = Me, Et, or Ph) showed that the axial and equatorial chlorine atoms are readily ss
H. H. Baalmann, H. P. Velvis, and J. C . van de Grampel, REC.Trau. chin?., 1972,91,935. K. Utvary and W. Czysch, Monatsh., 1972, 103, 1048. R. Keat, A. L. Porte, D. A. Tong, and R. A. Shaw, J.C.S. Dalton, 1972, 1648.
209
Fhosphazenes .C1
distinguished, with the latter giving the higher-frequency signal, implying the least ionic character. Although it is well established that the foregoing dimeric phosphazenes contain a four-membered ring, the structures of dimeric N-cyanoalkylphosphazenes, WC(Alk),C .NPCl,],, are not necessarily similar 36 because the bulky N-substituent may well inhibit the formation of a ring analogous to that in (18). The N-cyanoalkyl dimers readily add hydrogen chloride to give compounds of structure (19), and in view of this it was suggested that the dimers have CIC-CAlk, II I N,+NH
CI-
structure (20), where the steric effects of the N-substituent may offer less restraint to dimer formation. This is consistent with the fact that absorptions characteristic of C = N and P-N are present in the infrared spectrum of (20). The N-chlorophosphazene (Cl,C),CIP= NCI can be obtained 37 by the route: (C13C),ClP--IUH i- Clz
pyridine:
(CI,C)2ClP=NCI
and is sufficiently thermally stable to be vacuum distilled. It undergocs a number of interesting reactions, which are summarized in Scheme 10. The infrared identification of the vibrational modes associated with the P-N bonds in these derivatives was also discussed. (C1,C),CIP=N
*
C1
pi>
(Cl ,C),ClP=N* PCI,
""*
(C13C),ClP(O)NH,
PCI,
*
(C1,C),CIP(O) N=PCI
3
(Cl,C)2CIP=N* P(0)Cl Scheme 10
aa
A. M. Yinchuk, I. M. Kosinskaya, and V. I. Shevchenko, 3. Gem. Chem. (U.S.S.R.), 1972, 42, 520. E. S. Kozlov and S. N. Gaidamaka, J. Gem Chem. (U.S.S.R.), 1972, 42, 101.
Organophosphorirs Chemistry
210
N-(Chloroalky1)phosphazenes behave 38 like aa-dihalogenoamines in forming adducts with Lewis acids: RCIZC. CIZC. N-PCI,
+
MCI,
--+
[RCItC * CIC=N* PCI,]-' MCIG+,
(MCln included AlCI'3,SbCI,, and FeCl,),
These adducts are extremely electrophilic and readily react with water, or even weakly basic organic compounds, for example, benzene: [C1,C*CIC=N*PCIJ+ SbClG- -I- PhH --+
[Cl,C*ClC(Ph)N=PCl3]SbCI,
The conditions required for the reaction of C13C- C1,C .N =PC13with benzene in the presence of Lewis acids have been studied in and several aryl trichloromethyl ketones have been synthesized by hydrolysis of the complexes formed : ArCO. CCI,
C1,C.ClCAr.N=PCl,.MCI,,
P-Bis(t-buty1dioxy)phosphazenes have been prepared 4o by the route : RN=PCI,Ph
+
2 NaOOBut
_j_
RN=PPh(OOBut),
(R = substituted vinyl group4oor ArSO,*l)
and their hydrolysis and acidolysis followed in detail. Predictable results 4 2 have been observed in the aminolysis, alcoholysis, and thioalcoholysis of N-(monofluoropheny1)phosphazenes : ArCO*N=PCI,
+ RNHz --+
ArCO.N=PCl,
+ XH
Et,N
Aikyl and Aryl Derivatives.-The 38
*
ArCO.N=P(NHR),
+ &H3RC1-
ArC0.N=PX3
N-lithiated phosphazene Me3P=NLi
V. P. Kukhar', V. Ya. Sernenii and A. V. Kirsanov, J. Gen. Chem. (U.S.S.R.), 1972, 42, 93.
40
V. P. Kukhar', A. P. Boiko, L. A. Zolotareva, and A. V. Kirsanov, J. Gen. Chem. (U.S.S.R.), 1972, 42, 270. A. G. Babyak, T. I. Yurzhenko, and N. D. Bodnarchuk, J. Gen. Clzem. (U.S.S.R.), 1972, 42, 533.
41
42
A. G . Babyak and T. I. Yurzhenko, J. Cen. Chem. (U.S.S.R.) 1972, 42, 529. V. P. Rudavskii, L. N. Sedlova, and M. N. Kucherova, J. Gen. Chem. (U.S.S.R.), 1972, 42,961
21 1
Plz ospliazenes
condenses with niethylchlorodisilanes in ether solution at ambient temperatures 4 3 to give N-disilanylphosphazenes: Mc,P=NLi
-t- McjSi,CI
2 Me,P=NLi
+ MelSi,C1,
-+
Me3P=N.Si,Me,
-* Me3P=N*SiMe2*SiMe,.N=PMe3
A disilane terminated by a methylenephosphorane as well as by a phosphazene was also synthesized (Scheme 11). There was no evidence from infrared and IH 1i.m.r. spectroscopy that conjugative effects could be transmitted from in these systems. nitrogen to a P-silicon atom (i.e. N-Si-Si) Me,Si2CI,
- Me,Si ,c, * Me ,P =N - Si Me Si Me ,C1
Me ,P=N Si Me Si Me
Me,P=CH,
/, -
Me,PCl
Me3P=N * Si Me Si Me - CH =PMe, *
Scheme11 The cleavage of silicon-nitrogen bonds in N-silylphosphazenes has also been accomplished44by PF5 and by PhPF,: 2 Ph3P=N.SiMe,
+ 2 RPF,
+
(R = F o r P h )
Suitable modification of the proportions of the reactants has enabled monophosphazeiiyl derivatives to be obtained also : R1,R2P=N-SiMc, + 2 PhPF, --+ [K',R'P=N.PPhF',I+[PhPF,]- + Me,SiF (R1
= R' = P h ; R 1 =
Me,Rz = ph)
N-Sulphinylphosphazenes form the subject of a patent application 4 5 and were synthesized by a simple condensation reaction : Ph,P=NH
+ p-RC,H4*SOCl +
Et,N + Ph,P=N.SO*CGH,R-/)
+ E t , i H C1-
(R = H'or Me)
The hydrolysis of N-sulphonylphosphazenes, Ar,P= N * SO, - C,H,Me-p obtained from the long established reaction of phosphines with chloramine-T, Is 44
H. Schmidbauer and W. Vornberger, Chem. Ber., 1972,105, 3187. R. Appel, I. Ruppert, and F. Knoll, Chem. Ber., 1972, 105, 2492. A. D. Josey, U.S.P. 3 647 856 (Chern. A h . , 1972,76, 141 023).
Organophosphorus Ciierriistry
21 2
results 4 6 in the formation of hydrogen-bonded adducts of the type formulated in structure (21).
91)
The factors affecting the formation of imines from the arylphosphazenes Ar1,P-NAr2 and aldehydes by a route analogous to the Wittig reaction have been examined further.47 Studies of the auxochomic action of the triarylphosphazenyl group, Ar,P=N-, have entailed the synthesis4* of an extensive range of azocompounds, Ar1Ar2Ar3P=N.CsH4-p-N=N.C6H4R, in which variation of the electron-donor properties of the Ar groups has but a marginal effect4'J on the parts of the electronic spectra associated with the azo-function. It is interesting that the Ph,P=CH- group is a better electron donor than the isoelectronic phosphazenyl group, P$P= N-,50 according to comparisons based on the electronic spectra of the azo-compounds Ph3P=X-C6H4-N=NC6H4R( X = N or CH), a finding that may be contrasted with the fact that the following phosphonium salts may be deprotonated by Ph,P=NH: e
I~h,P-CH,-C,l I,.N=N.C6H,R Br- -1- Ph3P=NH
-+
Ph ,P=CM*C,H4*N=N*C ,H i R
+
P ti ,,F"H Hr-
Hammett 0- constants have been calculated51for the K group in the azocompounds RCsHp.N=N.C6H4QM,from the results of titration of these weak acids with base. The CT- constant for the Ph,P=N- group was very similar to that of the NH2 or NMe, groups, 2s might have been expected from previous studies. Related results have been obtained 5 2 for compounds of the type Ar1Ar2Ar3P=N- C6H4K,in which features of the electronic spectra were related to o+ and 0- constants for the substituents in the Ar groups. The electronic spectra of the phosphazenes p-Q2NCGH4Ph,P=NCGH4K-p (R = H, NO2, or NMe,) have been The tautomeric equilibrium : t
1'1 ,P=N. CGH 1 * N=N H CG HJX
I
F?
Ph,%P--NI 1* C6H,*N=N CGH,X
D. W. Allen, F. G . Mann, and J. C . Tebby, J.C.S. Perkiti I , 1972, 2793. S. C. K. Wong and A. W. Johnson, J. Org. Chem., 1972, 37, 1850. I. N. Zhmurova, V. G. Yurchenko, and A. V. Kirsanov, J. Gen. Chem. (U.S.S.R.), 1972, 42, 1938.
I. N. Zhmurova, V. G . Yurchenko, A. P. Martynyuk, and A. V. Kirsanov, J. Gerr. Chcm. (U.S.S.R.), 1972, 42, 1942. R. I. Yurchenko, I. N. Zhmurova, L. N. Shpartun, and A. V. Kirsanov, J. Gen. Chem. (U.S.S.R.),1972, 42, 2350.
Phosphazenes
213
lies to the left when X = NOz, but is shifted well to the right with most other X s ~ b s t i t u e n t s .Different ~~ results were obtained for the azo-compounds Me2N-C6H4.N=N.C6H4X, which were protonated at the azo-group rather than at the dimethylamino-group. Measurements of pKa values of compounds of the type R1C6H4-CH=N.C6H4R2 indicate 55 that protonation occurs at the azomethine nitrogen atom when R1 = NMe,, but at the phosphazenyl nitrogen atom when R1 = N=PPh,. Molecular orbital calculations have been carried out 56 on monophosphazenes of the type R1,P=NR2, and the results related to the data obtained from electronic and infrared spectra. N-Phenyl-PPP-triphenylphosphazene, Ph,P=NPh, forms5’ a radical species on reaction with sodium dispersed in THF which shows clearly resolved hyperfine coupling to 14N and 31P nuclei, although it was not clear whether the radical present was the anion: Ph,P-A--Ph,
Ph,P-R-Ph
or the neutral species:
=+=
PhzP-N-Ph
PhZP-N-Ph
formed by elimination of phenylsodium. ESCA determination58 of nitrogen 1s and phosphorus 2p binding energies in salts of the type [Ph,P-N-PPh,]+ +
-
+
X- suggests that the cation is better represented as [Ph,P-N-PPh3]
+
rather
than [Ph,P=N=PPh,]. The two types of phosphorus atom in the N-diphenylphosphinylphosphazene Ph,P= N P(O)Ph, could not be distinguished by their 2p binding energies, also obtained 59 by ESCA. 6
4 Synthesis of Cyclic Phosphazenes Further examples6o of monophosphazenes which form part of a five-membered ring have been synthesized from N-phosphinoimines and electrophilic olefins in a 1,3-cycloadditionreaction (Scheme 12). The lH and 31Pn.m.r. spectra of these derivatives show that the tautomeric equilibrium in Scheme 13 lies 61
6a
68 64
55
67
s8
8o
V. P. Kukar’, I. N. Zhmurova, and R. I. Yurchenko, J. Gen. Chem. (U.S.S.R.), 1972, 42, 268. I. N. Zhmurova, R. I. Yurchenko, V. G . Yurchenko, A. A. Tukhar’, and A. V. Kirsanov, J. Gen. Chem. (U.S.S.R.), 1972, 42, 770. T. G. Edel’man and B. I. Stepanov, J. Gen. Chem. (U.S.S.R.), 1972,42, 1469. I. N. Zhmurova, R. I. Yurchenko, V. P. Kukhar’, L. A. Zolotareva, and A. V. Kirsanov, J. Gen. Chem. (U.S.S.R.), 1972, 42, 1947. V. P. Kukhar’, I. N. Zhmurova, L. A. Zolotareva, and A. A. Tukhar’, Zhur. org. Khirn., 1972, 8, 756. V. V. Penkovskii, Yu. P. Egorov, and D. P. Khomenko, Dopovidi Akad. Nauk. Ukrain. R.S.R., Ser. By 1972, 34, 155 (Chem. Abs., 1972,76, 153 040). T. Kauffmann, G. Ruckelshauss, and D. Glindemann, Chem. Ber., 1973,106, 1618. W. E. Swartz, J. K. Ruff, and D. M. Hercules, J. Amer. Chem. SOC.,1972, 94, 5227. W. J. Stec, W. E. Morgan, J. R. Van Wazer, and W. G . Proctor, J. Inorg. Nuclear Chem., 1972,34, 1100. A. Schmidpeter, W. Zeiss, and H. Eckert, Z . Naturforsch., 1972, 27b, 769. H
214
0rganophosphorus Chemistry
R‘ I
Me,P.N=C-OAlk
+
N, R2-CH=CR3 -+
Me,
(16)> (14). This order is in accord with the premise that a-scission occurs more readily from an apical than from an equatorial position. The greater length of apical bonds compared with equatorial bonds favours the a-scission process. Thus in the case of (14) no pseudorotation is necessary to bring an alkyl group into the required position for departure. In the case of (15), pseudorotation is necessary to bring an alkyl group into an apical position and this requires that alkoxy-groups be placed in equatorial positions. Since alkoxy-groups prefer to occupy apical positions, owing to the electronegativity of oxygen, there is a sizeable energy barrier to pseudorotation and consequently radical (15 ) is relatively stable. The process of pseudorotation for R. W. Dennis and B. P. Roberts, J. Organometallic Chem., 1972, 43, C2. D. Griller and B. P. Roberts, J. Organometallic Chem., 1972, 42, C47. l a A. G . Davies, R. W. Dennis, D. Griller, and B. P. Roberts, J. Organometallic Chem., 1972, 40, C33. l 4 A. G. Davies, D. Griller, and B. P. Roberts, J.C.S. Perkin 11, 1972, 2224.
l1
le
Photochemical, Radical, and Deoxygenation Reactions
233
radical (16) is not as unfavourable as that for (15) since it leads to a radical having an alkoxy and an alkyl group in apical positions. Hence radical (16) is less stable than radical (15). f3-Scission Reactions.-The ease of the B-scission reaction increases as the radical produced changes from primary to secondary, to tertiary, to ben~y1ic.l~ When very stable radicals, such as benzyl radicals, are produced, it probably makes little difference whether the benzyloxy-group occupies an apical or equatorial position. However, this is not likely to be the case for formation of less-stableradicals and it is proposed that p-scission occurs preferentially from equatorial p o ~ i t i o n s Thus . ~ ~ ~in~the ~ case where a phosphoranyl radical is produced by attack of a t-butoxyl radical and a &scission reaction ensues in which a t-butyl radical derived from the attacking butoxyl radical is produced, an intermediate pseudorotation step is required. The attacking t-butoxyl group will initially take up an apical position and therefore pseudorotation is necessary to bring it into an equatorial position for B-cleavage to occur. It has been previously reportedl6 that reaction of 13C-labelled radicals with tri-tbutoxyl phosphite produces a phosphate containing 75 % of the label. In this case pseudorotation must have taken place prior to the @-scissionreaction. However, in this particular case the barrier to pseudorotation will be small because identical groups are being exchanged. When a variety of ligands are present in the phosphoranyl radical, the ease of the p-scission reaction will be dependent upon the ease of placing the requisite alkoxy-group in an equatorial position. Thus the radical (15) does not readily undergo a p-scission reaction because this would require pseudorotation to a trigonal bipyramid having the alkyl groups, which are less apicophilic than alkoxy-groups, occupying apical positions. It is also argued that alkoxy-groups which contain a very bulky alkyl group will prefer to occupy apical positions. l4As a consequence,phosphoranyl radicals in which alkoxy-groups of widely differing size are present will undergo a @-scissionreaction to give a product in which the largest alkoxy-group is retained in the phosphorus-containingproduct. The ease with which phosphorany1 radicals undergo B-scission increases as the degree of substitution in the alkyl groups increases, e.g. the stability of the following radicals is in the order ButOP(OMe), > (ButO)P(OEt), > (ButO)P(OPri), > (ButO),P. ,8-Scission reactions of the radicals (17),14 (18),14and (19)9have been observed and in the case of (18) it was suggested that the ring probably occupies a diequatorial position.
I
0'
-"y*