3 Halogenophosphines and Related Compounds

BY J. A. MILLER

1 Introduction Halogenophosphine chemistry, over the year being reviewed, has nearly all been directed towards new examples of established reactions. In the halo- genophosphorane field, iodophosphoranes are fast emerging from the shadows of obscurity. Considerable effort is still being expended in structural studies of halogenophosphoranes. Overall, the field remains an active one, but aimed generally at consolidation of existing views.

2 Halogenophosphines Preparation.-Scarcely any significant synthetic work on halogenophosphines has appeared during the year, and none of it departs from established methods. Thus t-butyl(di-iodo)phosphine (1) has been prepared by halogen exchange.l A number of silylphosphines have been prepared via alkali-metal phosphides, e.g. (2),a (3),3 and (4) and (5).4

A micro-scale synthesis of highly active a3PCl, has been published.s

W P C ~ + 2 ~ i 1 bray+ B ~ ~ P I , (1) 93%

Ph,PNa + ClMR, --+ Ph,PMR, (2) R = Ph, M = Si56%

R = Ph, M = S n 4 2 %

RPLi, + 2C1SiMe3 -+ RP(SiMe,),

(3) Me

,Si, MeP L l l L W DU’,

Si. MePHLi MePHLi

+ - I I Me,SiC1, Me,Si ,

I PMe \ f -+ MeP’

But zS iCl, ‘si’ Butz

\ P / SiMe2 Me

(4) (5 ) 1 N. G. Feshchenko and E. A. Mel’nichuk, J . Gen. Chem. USSR (Engl. Transl.), 1978,48,329. 2 A. Antoniadis and U. Kunze, 2. Naturforsch., Teil B, 1979, 34, 116. 3 G. Becker, 0. Mundt, M. Rossler, and E. Schneider, Z. Anorg. Allg. Chem., 1978,443,42. 4 G . Fritz and R. Uhlmann, 2. Anorg. Allg. Chem., 1978, 442, 95. ti D. V. Woo, A. F. Rupp, and J. K. Poggenburg, J . Labelled Compd. Radiopharm., 1978,15,

117.

51

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

52 Organophosphorus Chemistry

Reactions with Alkenes and Alkynes.-Details have appeared of the preparation of phospha-steroids via cycloaddition to dienes.6a Cycloaddition was particularly facile in the 17-phospha-steroid series, and gave (6) after a hydrolytic work-up. The isomeric oxide (7) was formed in poorer yield, after hydrolysis of the complex formed over 21 days. Control of temperature and pH during hydrolysis resulted in the formation of A3-phospholen l-oxides (8) in the tricyclic series. A range of other cycloadditions of dichloro(methyl)phosphine, leading also to polycyclic phospholen oxides, is reported in the same paper?

( 6 ) 66%

(7) 21%

0 Me Me ,p

@ (i)MePCL,+ (ii) H,O +

Me0 \ Me0 \ Me0 \

(8) 5370 (both isomers)

Complex product mixtures can result when halogenophosphine-aluminium chloride complexes are treated with vinylcyclopropanes (9).8 In the absence of water, the products are either phosphorinens (lo), resulting from cycloaddition, or acyclic phosphine oxides (11). When water is added to these reactions, cyclo- addition is not observed, and the products are the oxides (12) and (13).8

Alkyne additions of phosphorus tribromide in the presence of oxygen continue to generate confusion. The latest contribution to this field describes the require- ment for oxygen to initiate addi t i~n,~ but, unlike other reports,1° describes the

6 C. Symmes and L. D. Quin, J. Org. Chem., 1979,44, 1048. 7 C. Symmes, J. Morris, and L. D. Quin, Tetrahedron Lett., 1977, 335. 8 Y. Kashman and A. Rudi, Tetrahedron Lett., 1979, 1077. 9 A. S. KrugIov, A. V. Dogadina, B. 1. Ionin, and A. A. Petrov, J. Gen. Chem. USSR (Engl.

Transl.) 1978, 48, 649. 10 V. Okamato and H. Sakurai. Chem. Lett., 1973, 599.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

Halogenophosphines and Related Compounds 53 0 -

Me dp(H)ph II

(10) R = Me or Ph (11) R = Ph c 1

products as vinylphosphines (14), i.e. oxygen is not incorporated. Furthermore, (14) generally seems to be one isomer, characterized on the basis of 3 J ~ ~ v a l u e s as the (E)-isomer. Previous considerations had suggested that the products had the (2) configuration.ll

"'">-i" 0 RC-CH + PBr, A R Br

(14) R = Ph, But, or BrCH, 50-70%

BufPC1, + 2BufCH,MgC1 __f BdP(CH,Buf),

(15)

Reactions with Carbaniom.-Grignard routes to the phosphines (15) la and to (16) and (17),13 as shown in Scheme 1, have been described. The preparation of (1 6) involved a cadmium reagent.

(minor) (major)

(16) Reagents: i, Mg; ii, CdCla; iii, PC13; iv, MeMgI.

Scheme 1 11 S. V, Fridland, J. M. Shchukareva, and R. A. Salakhutdinov, Zh. Obshch. Khim., 1976,46,

12 H. Quast and M. Heuschmann, Angew. Chem., Int. Ed. Engl., 1978, 17, 867. 13 L. D. Quin and L. B. Littlefield, J. Org. Chem., 1978, 43, 3508.

1232.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

54 Organophosphorus Chemistry

The substituted phenylmagnesium bromides (1 8) give monohalogeno- phosphines with phosphorus trichloride, and the failure to observe trisubstitution has been ascribed to steric fa~t0rs . l~ A related reaction of the internally complexed Grignard reagent (19) leads to the first (also see ref. 45) substantiated phosphor- anide anion (20).16 Chemical evidence for (20) includes its protonation to give a phosphorane. l6

X = Me 46% x = c1 35% X = OMe failed

(20)

Simple sodium enolates of ketones, on treatment with monohalogeno- phosphines, give phosphorus(n1) esters (21) or ketones (22). Ionizing solvents favour O-phosphinylation to form (21), as does a change in halogenophosphine from R=Pri to R=NEtZ.I6

R = NEt,, OEt, or Pri

Reactions with Functional Groups containing Oxygen and/or Nitrogen.-Di- phosphorus tetraiodide (23) is gaining more attention as a reagent that has general synthetic utility. Thus alkyl iodides can be prepared from alcohols using (23). The sequence works well for tertiary iodides, gives inversion in a secondary system, and generally is free from side-reactions that involve rearrangement of carbonium ions.17 The tetraiodide (23) also converts oxirans into alkenes and aldoximes into nitriles:l* see Scheme 2 for details. 14

16 1 6

ir

18

A. A. Shvets, 0. A. Moiseeva, and 0. A. Osipov, J . Gen. Chem. USSR (Engl. Transl.), 1978,48, 208. I. Granoth and J. C. Martin, J. Am. Chem. SOC., 1978, 100, 7434. 2. S. Novikova, A. N. Kurkin, and I. F. Lutsenko, J. Gen. Chem. USSR (Engl. Transl.), 1978, 48, 271. M. Lauwers, B. Regnier, M. Van Eenoo, J. N. Denis, and A. Krief, Tetrahedron Lett., 1979, 1801. u C11miti T Fnchita. A. Iwasa. and T. Mishina. Svnthesis, 1978, 905.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

Halogenophosphines and Related Compounds

RI (R is primary, secondary, or tertiary alkyl)

RCH=NOH P,I, RC-N (37-85%)

L

55

Scheme 2

Formamidine derivatives (24) are formed efficiently from cyanamides and phosphorus trich10ride.l~ Simple hydrazones are known to react with phosphorus trichloride to give 2H- 1,2,3 a2-diazaphospholes (25).20 Re-investigation of this reaction has revealed that the isomeric 1H-phosphole (26) is also formed.21 The isomers are not interconvertible, and an X-ray study of (26) suggests that it is similar to pyrazole in its n-electron distribution. 21

R , N C F N + PCl, 20"ct R,NC(CI)=NPCI, (24) 90-97%

MeNHN=CMe, + PCI, -+

(25) (26)

The silylamino-phosphines (27) have been prepared by standard methods.¶' Quaternization at phosphorus and treatment with base yields the phosphine imines (28), which result from a 1,341~1 migration in the ylide intermediate."

R2 Li Me I

(i) Me,SiNRZ I /./ R'PCl, RIP-N

R' = C1 or Ph 'SiMe,

(27) Rz = Me or Ph

(i) Me1 (i) BuLi I

le SiMe, /

CJ 'R2

19 V. I. Shevchenko, N. P. Pisanenko, and I. M. Kosinskaya, J. Gen. Chern. USSR (Engl.

80 J. Luber and A. Schmidpeter, Angew. Chem., Znt. Ed. Engl., 1976, 15, 111. 21 J. H. Weinmaier, J. Luber, A. Schmidpeter, and S. Pohl, Angew. Chem., Znt. Ed. Engl.,

22 J. C . Wilburn and R. H. Neilson, Inorg. Chem., 1979, 18, 347.

Transl.), 1978, 48, 1078.

1979,18, 412.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

56 Organophosphorus Chemistry

Dichloro(pentafluoropheny1)phosphine reacts with the silylated urea (29) to form the phosphorane (30) in high yield.23 Structural studies of (30) show that it is 21 % distorted from a trigonal bypyramid, towards a square pyramid.23

ArN NMe

0 K

(30) Ar = in-CF3-C6H4 87%

Arsenate esters (31) react with phosphorus(II1) chloridea4 or with arsenic(r1r) halides 2 4 9 26 to give a range of ligand-exchange and condensation products. A selection of these reactions is outlined in Scheme 3.

RCI +

ROPCI, (mainly) A (RO) ,A~Q ROA~CI,

(ROASQJ, 62-97%

(BuO),AsBr t BuOAsBr, F,AsOR

Reagents: i, PC13; ii, AsC13; iii, AsF3; ivy AsBrs. Scheme 3

Reactions with Carbonyl Compounds, Carboxylic Acids, and their Derivatives.- The phosphine oxides (32), (33), and (34) have been isolated from the reaction of di-t-butyl(ch1oro)phosphine with acetic acid. a6 Their formation presumably depends upon a pre-equilibrium (see Scheme 4), since an earlier study2’ of the reaction of acetyl chloride with di-t-butylphosphine oxide described the same products. These results resemble those previously reported for chloro(dipheny1)- phosphine with trifluoroacetic acid 28 and with acetic acid,2g and the product differences seem to be ascribable to the electronic effect of the CF, group, or to differences in reaction conditions. 23 H. W. Roesky, K. Ambrosius, and W. S. Sheldrick, Chem. Ber., 1979, 112, 1365. 24 V. S. Gamayurova, M. M. Aladzhev, R. M. Nigmatullina, and B. D. Chernokal’skii,

25 V. S. Gamayurova, M. M. Aladzhev, R. M. Nigmatullina, and B. D. Chernokal’skii, J.

26 T. Kh. Gazizov, V. A. Kharlamov, and A. N. Pudovik, Bull. Acad. Sci. USSR, Diu.

27 A. N. Pudovik and T. M. Sudakova, Dokl. Akad. Nauk. SSSR, 1970, 190, 1121. 28 J. A. Miller, in ‘Organophosphorus Chemistry’, ed. S . Trippett (Specialist Periodical

29 J. A. Miller, in ‘Organophosphorus Chemistry’, ed. S. Trippett (Specialist Periodical

J. Gen. Chem. USSR (Engl. Transl.), 1978, 48, 643.

Gen. Chem. USSR (Engl. Transl.), 1978, 48, 734.

Chem. Sci., 1978, 1418.

Reports), The Chemical Society, London, Vol. 8, p. 55.

Reports). The Chemical Society, London, Vol. 9, p. 55.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

Halogenophosphines and Related Compounds

0

Buf2PCl + AcOH @ But,POAc + HCl a But2PH + AcCl I1

kist illation

57

0 0 0 0 II I I II II

(B u',P),C(OH) Me + B u:PA c + B uf,PCH (Me)OPB u*,

(32) 12% (33) 23% (34) 27% Scheme 4

The same type of equilibria appear to be involved in the series of simplecarbonyl- addition reaction~~O-~~ outlined in Scheme 5. In each system, the product is an a-hydroxyalkyl-phosphinoyl chloride, probably formed by addition of a halide R(CI)P(O)H to the carbonyl compound in question.

0 I I I

EtPC1, + AcOH * EtPCl + AcCl

H

0 0

PhPCl, + PhPH + 2PhPH PhP I I 1 I

Cl OH 70%

0 0 0 I 1 1 1 R,C=O 11

PhPH + AcCl + PhPH ___f PhPC(OH)R, I I ref. 32 I OH c1 c1

R = Me 70% + AcOH R, = C,H,, 85%

Scheme 5

30 S. Kh. Nurtdinov, N. M. Ismagilova, T. V. Zykova, R. A. Salakhutdinov, and V. S.

31 N. A, Kardanov, N. N. Godovikov, and M. I. Kabachnik, Bull. Acad. Sci. USSR, Diu.

32 N . A. Kardanov, N. N. Godovikov, and M. 1. Kabachnik, Bull. Acad. Sci. USSR, Diu.

Tsivunin. J. Gen. Chem. USSR (Engl. Transl.), 1977, 41, 2447.

Chem. Sci., 1978, 1282.

Chem. Sci., 1978, 1720.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

58 Organophosphorus Chemistry

A related reaction of halogenophosphines in the presence of alkyl carbamates (35) leads to reasonable yields of a-amino-phosphorus(1v) products. 33 The carba- mate (35) clearly functions as an amino-group donor, but it is not known at which stage this becomes attached to the original carbonyl

Molecules possessing both a carbonyl group and an adjacent hydroxyl group are capable of forming cyclic and spirocyclic compounds with halogenophos- phines. Further examples of this behaviour come from the hydroxamic acids (36),*4 also studied earlier in 1977.36 A much more spectacular example comes from treatment of o-hydroxyacetophenone (37) with dichloro(pheny1)phosphine. *6

The phosphorane product (38) has an equatorial phenyl group in a slightly distorted trigonal b i ~ y r a m i d . ~ ~

0

(37)

PhPC1, Et,N benzene * Ph

The existence of the phosphorane (39) was discussed several years A re- examination of the acylation reactions of diphenyl(fluoro)phosphine has led to the isolation of (39).38 Another example has appeared of acylation of a silyl- phosphine, in this case the bisphosphine (40). 39 The phospha-alkene structure (41) has been confirmed by X-ray crystal analysis, the P--C bond lengths (1.69 and 1.85 A) being quite different.39

39 J. Oleksyszyn, R. Tyka, and P. Mastalerz, Synthesis, 1978, 479. 34 E. V. Hinrichs and I. Ugi, J. Chem. Res. (S) , 1978, 338. ~4 E. Fluck and M. Vargas, 2. Anorg. Allg. Chem., 1977, 437, 53 . 86 G. M. L. Cragg, B. Davidowitz, G . V. Fazakerley, L. R. Nassimbeni, and R. J. Haines,

a7 C. Brown, M. Murray, and R. Schmutzler, J. Chem. SOC. (C) , 1970, 878. 38 S. Neumann, D. Schomburg, G. Richtarsky, and R. Schmutzler, J. Chem. SOC., Chem.

sB G. Becker and 0. Mundt, Z. Anorg. Allg. Chem., 1978,443, 53.

J. Chem. SOC., Chem. Commun., 1978, 510.

Commun., 1978, 946.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

Halogenophosphines and Related Compounds

0 I1 PhCOF

Ph,POEt + PhCF d PhPF ____t

59

Similar phospha-alkene structures have been implicated in the reaction of the bis(trimethylsily1)phosphine (42) with phosgene.40 This reaction is known'l to lead to poly(phenyl)phosphines, and two intermediates, (43) and (44), the latter of uncertain structure, have now been suggested to be involved.

OSiMe, cocl, / COCJ

\

Ph (43)

PhP(SiMe,), pentaner PhP-C * [(PhP),(COSiMe,)l, P-%Me,

/ cw/ (44)

(42)

COCl PhPCL, I (PhP),

n = 4 o r 5

Reactions with Phosphorus(m) Compounds.-l,2-Bis(phosphino)ethane (45) reacts with a range of halogenophosphines (X = C1 or Br ; R = C1, Ph, or Me) to give 1,2,5,6-tetraphosphabicyclo[3.3.O]octane (46).4a The best yield of the reductive dimer comes from dichloro(methyl)phosphine, and detailed spectral evidence in support of structure (46) has been pre~ented.'~

More straightforward are the reactions of di-isopropyl(iodo)phosphine (47)4a and bis(dimethy1phosphino)methane (48),44 as outlined.

(46) 55% when R = Me and X = C1

40 R. Appel and V. Barth, Angew. Chem., Int. Ed. Engl., 1979,18,469. 4 1 M . Baudler, B. Carlsohn, W. Bohm, and G. Reuschenbach, Z. Naturforsch., Tell B, 1976,

42 M. Baudler, M. Warnau, and D. Koch, Chem. Ber., 1978, 111, 3838. 4a M. M. Kabachnik, A. A. Prishchenko, Z . S. Novikova, and I. F. Lutsenko, J. Gen. Chem.

44 H. H. Karsch, 2. Naturforsch, Teil B, 1979, 34, 31.

31,553

USSR (Engl. Transl.), 1978, 48, 1088.

3*

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

60 Organophosphorus Chemistry

0 II

Pri2PI + (RO),P + (RO),PPPri,

(47)

PMe, PMe, I I

(Me,P),CH, + 2Me,PCI _+ Me,!-;Me, 2C1'

(48)

Miscellaneous Reactions.-Perhaps the greatest surprise in this year's literature is the simplicity of the preparation of the first acyclic phosphoranide anions, (49) and (50).46 These are made from dicyanophosphide ion (51) or from tricyano- phosphine (52). The salts of (49) and (50) are stable, and, when complexed with crown ethers, they can be isolated and handled.46

X@(CN), X-

P(CN), - ( 5 2 ) (SO) X = C1, Br, or I

Me,N Me,N HN(PF2), i BrSiH, --+- H,SiN(PF,), F,PNHSiH, + BrSiH, (H,Si),NPF2

(53) (54)

The silylamino-phosphines (53) and (54) have been prepared from fluoro- pho~phines,~~ as shown. Bis(trimethylsily1)mercury (55) converts chloro- phosphines into diphosphines in fair yield.47 Chloro(di-t-buty1)phosphine (56) forms a gold@ complex, from which the anhydride (57), as its gold complex, can be prepared.48 Complexation is believed to stabilize the normally labile phos- phinous anhydride structure; however, see ref. 49.

(Me,Si),Hg + &PCl --+ KPPR, But,PCl + ClAdCO - C1AuP(But2)C1 (55 ) 50-70% (56) 1 ow0

wy

BU~~POPBU t2

(57) 60%

A. Schmidpeter and F. Zwaschka, Angew. Chem., Int. Ed. Engl., 1979,18,411. E. A. Ebsworth, D. W. Rankin, and J. G. Wright, J. Chem. SOC., Dalton Trans., 1979,1065. S . V. Ponomarev, A. A, Stepanov, V. N. Sergeev, and I. F. Lutsenko, J. Gen. Chem. USSR (Engl. Transl.), 1978, 48, 207. H. Schmidbaur, A. A. M. Aly, and U. Schubert, Angew. Chem., Inf. Ed. Engl., 1978, 17, 846. V. L. FOSS, Yu, A. Veits, V. A. Solodenko, and I. F. Lutsenko, J. Gen. Chem. USSR (Engl. Transl.), 1976, 46, 1606.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

Halogenophosphines and Related Compounds 61

Further carbene-insertion reactions of germylphosphines have been reported. Thus (58) has been prepared, and the analogous reaction of a diastereomeric mixture of the germaphospholans (59) suggests that the insertion does not affect the relative configuration at phosphorus and germanium. 6o

Me,GePMe, + Hg(CF,), __f Me,GeCF,PMe,

(5 8)

Me C c k M e + Hg(CF,), --+

f’ ‘Ph Ph Ph

(59)

The chemistry of phosphorus trichloride in oleum has been investigated.6l The influence of dichloro(pheny1)phosphine on vinyl polymerization reactions has been reported. 62,s8 Physical Aspects.-A detailed INDO M.O. study of the phosphines (60) has been published.64 The ground-state conformations of the parent phosphine (ma) and the fluorophosphine (Ob) are each calculated to have the lone pair on phosphorus orthogonal to the plane of the phenyl ring. With the chlorophosphine (6Oc) the relatively bulky halogen is preferred staggered to the ring, and the lone pair on phosphorus is in the plane of the ring. The preference of the chlorine to be remote from the ring is reflected in the relatively high rotational barrier (2.3 kcal mol-l) for (6Oc), compared to that (0.53 kcal mol-l) for (60b).s4

The phosphines (61) have been studied by 3sCl n.q.r. and 13C n.m.r. methods.56

PhPR, (CF,) n PC1, -n (60) a; R = H

b ; R = F c; R = C1

(61) n = 1 or 2

3 Halogenophosphoranes Preparative and Structural Aspects.--Over recent years, iodophosphoranes have only rarely been reported, and could indeed have been regarded as chemical curiosities. This year, however, has seen a number of preparative studies, and we may expect synthetic applications of their reactivity to be reported in the next year or so. Pride of place in the current work goes to the Russian group who

50 J. Escudi6, C. Couret, and J. Satgk, Bull. SOC. Chim. Fr., Part 2, 1978, 361. 51 K. B. Dillon, M. P. Nisbet, and T. C. Waddington J . Chem. SOC., Dalton Trans., 1979,

52 T . Ogawa. J. Gallego, and M. Inoue, Eur. Polym. J., 1978, 14, 825. 58 N. D. Kazakova, L. B. Iriskina, Z . K. Ibrasmeva, and S. R. Rafikov, Izv. Akad. Nauk

54 W. J. E. Parr, J. Chem. Soc., Faraday Trans. 2, 1978,74, 933. 5s P. Dagnac, J.-L. Virlichie, and G. Jugie, J. Chem. Soc., Dalton Trans., 1979, 155,

883.

SSSR, 1978,20,49.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

62 Organophosphorus Chemistry

have reported the first preparation of phosphorus pentaiodide (62).66 Phosphorus pentaiodide has had an interesting history, as reference to standard phosphorus texts will It is a black-brown solid, and stable in dark, dry conditions, but dissociates in solution to some extent. The pentaiodide reacts with -OH, -NH2, and -SH compounds, and its conversion into the salt (63) was used to characterize (62). 66

Me1 8PhCH,NH, pc4 + MI - PI5 (PhCH,NH),PI

(62) (6 3)

87-92% Other routes to iodophosphoranes involve oxidative addition to phosphorus(rII),

as for (64)l and (65).43 The latter preparation is somewhat surprising, since the product might have been expected to be a salt [the n.m.r. data on (65) are not decisive on this point].43

New fluorophosphoranes include the first acyl-fluorophosphorane (39).58 X-Ray analysis reveals that (39) is a distorted tbp, and that the plane of the \ C=O is only 3.1” out of the equatorial plane at phosphoru~.~~ Dialkoxy- / (trifluoro)phosphoranes (66) have been prepared as shown, and found to dis- sociate readily at temperatures above 0 oC.68 The structural criteria for ease of ionization are discussed, and impressive multinuclear variable-temperature n.m.r. data for (66) have been pre~ented.~~

benzene 20 O C

Pri,PI -t Me1 ether_ Pri,P(Me)I, BufPI, + I, - ButPI, (64) 93% ( 6 5 ) 100%

F Ph Ph.., I *-

P-c‘ Ph‘I \b

F

(39) R = CH,CCl,

or CH2CF3

The amino(fluoro)phosphoranes (67)69 and (68)60 have been prepared by standard routes. At low temperature, (67) shows (by l@F n.m.r.) non-equivalent fluorines, and this has been ascribed to restricted rotation about the PV-N bond.69 In the phosphorane (68), the -CCl, groups are equatorial.60 66 N. G. Feshchenko, V. G. Kostina, and A. V. Kirsanov, J. Gen. Chem. USSR (Engl. Transl.),

1978, 48, 196. 57 Sometimes PIS receives cautious mention, as in J. R. Van Wazer, ‘Phosphorus and its

Compounds’, Interscience, New York, 1958, Vol. 1 ; or in H. Remy ‘Treatise on Inorganic Chemistry’, Elsevier, New York, 1956, Vol. 1. More often, however, PI5 is ignored, even in recent texts, such as D. E. C. Corbridge, ‘Phosphorus’, Elsevier, Amsterdam, 1978; or R. H. Tomlinson in “Mellors’ Comprehensive Treatise on Inorganic and Theoretical Chemistry”, Vol. 8, supp. 111, section XVI, p. 528.

ti* F. Jeanneaux and J. G. Riess, Tetrahedron Lett., 1978, 4845. LW D. W. Rankin and J. G. Wright, J. Chem. SOC., Dalton Trans., 1979, 1070. ao E. S. Kozlov, L. G. Dubenko, and M. L. Povolotskii, J. Gen. Chem. USSR (Engl. Trand.),

1978,48, 1734.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

Hcllogenophosphines and Related Compounds 63

F Y.. I ’JI

F,PN(SiH,), + PF, __f P-N’ (54) F‘I ’PF,

(67) 95% F

c1 F

(Cl,C),P--NH + HF + H,N-P’ CCl, I I - 0

I ’CCl, F

(68)

Cavell’s group has reported the fluxional behaviour of a series of trifluoro- methylphosphoranes. Thus the phosphorane (69) shows an exchange barrier of AG2& = 8.8 kcal mol-l, while (70) has a very low barrier (1-3 kcal mol-l), sufficient to indicate that a &I, ground state is not the reason for the equivalent fluorines.61 In the series of phosphoranes (71), barrier heights for exchange of CF3 increase as X varies, in the order F < C1< OMe < SMe < NMe, < Me.@,

Other structural work reported during the year includes a study of the solvent dependence of the 31P nuclei in the phosphoranes (72),63 a study of the solid-state

n.m.r. spectra of the phosphoranes (73),64 and an electron-diffraction study of the phosphorane (74).66 X-Ray crystal structures for the hexaco-ordinate derivatives (75) and (76) have appeared.66, 67

XQPCL HC=CPF,

61 N. T. Yap and R. G. Cavell, Inorg. Chem., 1979, 18, 1301.

68 B. V. Timokhin, V. I. Dmitriev, V. I. Glukhikh, and N. A. Korchevin, J. Gen. Chem.

64 B. V. Timokhin, V. I. Dmitriev, and V. I. Glukhikh, J . Gen. Chem. USRR (Engl. Transl.),

65 M. Oberhammer, J. Mol. Struct., 1979, 53, 139. b6 W. S. Sheldrick and M. J. C. Hewson, 2. Narurforsch., Ted B, 1978, 33, 834. G7 W. S. Sheldrick, J. A. Gibson, and G.-V. Roschenthaler, Z. Naturforsch., Teil B, 1978,33,

R. G. Cavell, J. A. Gibson, and K. I. The, Inorg. Chem., 1978, 17, 2880.

USSR (Engl. Transl.), 1978, 48, 1160.

1978,48, 1160.

1102.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

64 Organophosphorus Chemistry

Me

Me F

Reactions of Ha1ogenophosphoranes.-The view that substitution reactions in phosphoranes occur by nucleophilic attack opposite the leaving-group 68 has been challenged by Trippett et al., following work on the spirophosphorane (77; X = Cl).69 This phosphorane and its substitution products (77; X= NMe,), (77; X = OPh), and (77; X = Me) are all configurationally relatively stable at - 78 "C, and hence the observed retention or inversion of configuration (resulting from substitution) can be related to the mode of entry of the nucleophile in each case. It turns out that inversion is the dominant reaction mode of (77; X=C1) with dimethylamine, but that inversion and retention are much more closely balanced in reactions of (77; X= Cl) with PhO- or Me-.69

\ I/X

1'0 o \ 0-P

Cl

(77) X = C1, NMe,, OPh, or Me

Spirophosphoranes (78)70 and (79)71 have been prepared by displacement of fluoride from the appropriate fluorophosphoranes. Structural details are dis- cussed in each of these papers: see Chapter 2.

A review of the chemistry of phosphorus pentachloride has appeared.72 The usual catalogue of reactions of phosphorus pentachloride with a l k e n e ~ , ~ ~ - ~ ~

6s F. Ramirez, G. V. Loewehgart, E. A. Tsolis, and K. Tasaka, J. Am. Chem. SOC., 1972, 94, 353 1. S. Trippett and R. E. L. Waddling, Tetrahedron Lett., 1979, 193.

107. 70 G.-V. Roschenthaler, K. Sauerbrey, and R. Schmutzler, 2. Naturforsch., Teil. B, 1979, 34,

71 W. Althoff, R. 0. Day, R. K. Brown, and R. R. Holmes, Inorg. Chem., 1978, 17, 3265. n S. V. Fridland, Russ. Chem. Rev. (Engl. Transl.), 1978, 47, 742.

74 S. V. Fridland and A. I. Efremov, J. Gen. Chem. USSR (Engl. Transl.), 1978, 48, 285. 75 M. A. Kazankova, T. Ya. Satina, V. D. Lun'kov and I. F. Lutsenko, J. Gen. Chem. USSR

S. V. Fridland, Yu. K. Malkov, L. A. Eroshina, and R. A. Salakhutdinov, J. Gen. Chem. USSR (Engl. Transl.), 1978, 48, 38.

(Engl. Transl.), 1978, 48, 58.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

Halogenophosphines and Related Compounds 65

F3cq (78) F3C

F3C

cF3 CF,

OSiMe, Ph'

OSiMe, f FZ(Ph)P% c,",'*"

alkynes, 75,76 ether^,^^^^^ or metal a l k y l ~ ~ ~ has appeared, and a summary is presented in Scheme 6. In general, these are concerned either with fine mechan- istic detail or with reactions which give complex product mixtures. Perhaps the reaction leading to the vinylphosphonic dichloride (80) is an exception, made the more interesting by the efficient conversion of (80) into a functionalized keten acetal(81).

i, ii ref. 74

PhCH-CH, ---+ PhCHClCH,PCI, 57-90%

i, iii RT--COR' ref. 75 h

R'O PCL?

0 II 0

(80) 60-7676 (81) 45-60%

Reagents: i, PC15; ii, PH3; iii, S02; ivy RSOH, pyridine; v, NaOR1, RlOH; vi, POCh, heat;

Scheme 6 (part)

vii, Cl2, I2 catalyst; viii, ROH, KzC03.

76 S. V. Fridland and Yu. K. Malkov, J. Gen. Chem. USSR (Engl. Transl.), 1978, 48, 325. 7 7 S. V. Fridland, A. I. Efremov, G. P. Anisimova, and R. V. Nuretdinova, J. Gen. Chem.

78 M. A. Pericas and F. Serratosa, Tetrahedron Lett., 1978, 2603. 7O V. I. Dmitriev, B. V. Timokhin, A. V. Kalabina, and V. V. Samorodov, J . Gen. Chem.

USSR (Engl. Transl.), 1978, 48, 1993.

USSR (Engl. Transl.), 1978, 48, 42.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

66 Organophosphorus Chemistry

i. iii ref. 17

Reagents: i, PC15; ii, PH3; iii, S02; iv, RSOH, pyridine; v, NaOR1, RlOH; vi, POC13, heat; vii, Cl2, I2 catalyst; viii, ROH, KzC03.

Scheme 6 (continued)

Further study of the reaction of phosphorus pentachloride with arylhydroxamic acids confirms the phosphoranes (82) and (83) as p r o d ~ c t s . ~ ~ ~ ~ ~ Reactions in which halogenophosphoranes act as electron-pair acceptors have been des- cribed,8OP8l and the effect of 100 % sulphuric acid on pentahalogenophosphoranes has been investigated.82

Reactions of Halogenophosphoranes Relevant to Organic Synthesis.-Examples of synthetic use of the reactions between phosphines and positive halogen compounds continued to be described, although little new ground has been broken. Thus, details of the conversion of allylic alcohols into allylic chlorides (84) have ap- peared, 83 and the only serious drawback to this system appears to be the difficulty in removing carbon tetrachloride, a by-product.

(84)

Further investigation of Chlorination by polymer-supported phosphine-carbon tetrachloride systems has revealed an unexpected rate enhancement, in com- parison to rates of similar reactions in This has been ascribed to a co-operative assistance by adjacent phosphine residuesYs4 as outlined in Scheme 7.

K. B. Dillon, R. N. Reeve, andT. C. Waddington, J. Chem. SOC., Dalton Trans., 1978,1318- 81 K. B. Dillon, R. N. Reeve, and T. C. Waddington, J. Chem. SOC., Dalron Trans., 1978,1465. ci2 K. B. Dillon, M. P. Nisbet, andT. C. Waddington, J . Chem. SOC., Dalron Trans., 1978, 1455- 83 R. 0. Magid, 0. S. Fruchey, W. L. Johnson, andT. G. Allen, J. Org. Chem.. 1979,44,359. a4 C. R. Harrison and P. Hodge, J . Chem. SOC., Chem. Commun., 1978, 813.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

Halogenophosphines and Related Compounds

Ph Ph

67

c1-

Scheme 7

Mechanistic aspects of the involvement of alcohols in chlorination reactions of triphenylphosphine and carbon tetrachloride have been discussed.a6 The authors have studied the intermediate (85), and suggest that its breakdown involves an S N ~ displacement on the ion-pair derived from (85).8L

The work of Appel's group on peptide synthesis using phosphine-hexachloro- ethane systems has passed the racemization test for several amino-acids, provided that l-hydroxybenzotriazole (86) is present .86 Impressive yields have been obtained in a synthesis of bradykinin (outlined in Scheme 8) that is based on the same coupling

NHX NH* I 1 (Me,N),P + C13C-CC1, + R'CHC0,H + RTHCOY

NHX R2 I I

(Me,N),P=O + R'CHCONHCHCOY 82-95%

(X and Y are protecting groups)

Scheme 8

A related reaction of the phosphine (87) leads to the bis-ylide (88).88 The di- chlorophosphorane (89) has also been used in peptide coupling.89 85 L. A. Jones, C. E. Sumner, B. Franzus, T. T.-S. Huang, and E. I. Snyder, J. Urg. Chem.,

86 R. Appel and L. Willms, Chem. Ber., 1979,112, 1057. 8' R. Appel and L. Willms, Chem. Ber., 1979,112, 1064. 88 R. Appel and K. Waid, Angew. Chem., Int. Ed. Engl., 1979, 18, 169. 89 E. Vilkas, M. Vilkas, and J. Sainton, Tetrahedron Lett., 1978, 2933.

1978,43, 2821.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online

68 Organophosphorus Chemistry

Ve c1 c1 1 I

Ph,PCHPPh, + CC14 I_) Ph2P=C=PPh, I (88) 90% a';; Me SiMe,

(87) (89)

Primary and secondary thiocyanates (90) and isothiocyanates (91) and acyl- isothiocyanates (92) have been prepared via phosphoranes generated in sit~.~O Conversion of o-acyl-anilines (93) into 2-thioxo-l,2-dihydroquinazolines (94) has been achieved in good yields using bis(thiocyanato)triphenylpho~phorane.~~ Exchange of halogen from alkyl, benzyl, and activated aryl chlorides or bromides has been achieved using the fluorophosphoranes (95).92 Elimination is the main side-reaction.

0

(93) (94) 62-88%

R'X + RZ,P(Me)F R'F +' R2,;(Me) X-

(95)

00 J. Burski, J. Kieszkowski, J. Michalski, M. Pakulski, and A. Skowronska, J. Chem. SOC.,

91 Y. Tamura, T. Kawasaki, M. Tanio, and Y. Kita, Synthesis, 1979, 121. 9f J. Bensoam, J. Leroy, F. Mathey, C. Wakselman, and I. Cercoa, Tetrahedron Lett., 1979,

Chem. Commun., 1978, 940.

353.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n 04

Mar

ch 2

013

Publ

ishe

d on

31

Oct

ober

200

7 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/9

7818

4755

4314

-000

51

View Online