6 Quinquevalent Phosphorus Acids

BY R. S. EDMUNDSON

Reviews published during the year cover such topics as organic monothio- pyrophosphates ;l reactions of monothio-, monoseleno-, and selenothio- phosphorus acids with aliphatic diazo-compounds ; alkylidenediphosphonic acids;3 the synthesis and reactions of heterocyclic compounds possessing the P-N-N linkage;4 and hydrogen phosphonates. The types of reactions which have been reviewed include 1,3-dipolar reactions of organophosphorus com- pounds;g the formation of phosphonic and phosphinic esters by the addition of tervalent phosphorus esters to unsaturated ~ysterns;~ the imideamide re- arrangement in organophosphorus chemistry;s phosphorylation by cyclic enediol phosphate^;^ and stereochemical aspects of the participation of pentaco-ordinate intermediates in nucleophilic substitution reactions at a phosphoryl centre.l0

Of relevance to the material in the present Chapter are the reviews by Kabachnik et al. on investigations into optical isomers in solution, using n.m.r. techniques,ll and associated diastereoisomers of organophosphorus compounds. l2

Published lectures cover aspects of the chemistry of phosphor~hydrazidesl~ and of phosphorus-sulphur compounds; l4 the preparation of cr-aminoalkyl- phosphonic acids and their synthetic applications ;lS a-cuprophosphates;le and developments in phosphorus-nitrogen heterocyclic chemistry.17

1 J. Michalski, W. Reimschdssel and R. Karninski, Russ Chem. Rev. (Engl. Transl.), 1978,

2 T. A. Mastryukova and M. I. Kabachnik, Izu. Akad Nauk. SSSR, Ser. Khim., 1978, 2040

8 M. V. Korsakov and B. A. Ivin, Khim.-Farm. Zh., 1978,12,25 (Chem. Abs., 1978,89,59 920). 4 J. P. Majoral, Synthesis, 1978, 557. 5 E. E. Nifant'ev Russ. Chem. Rev. (Engl. Transl.), 1978, 47, 835. 6 N. G. Khusainova and A. N. Pudovik, Russ. Chem. Rev. (Engl. Transl.), 1978, 49, 803 7 A. N. Pudovik and I. V. Konovalova, Synthesis, 1979, 81. 8 V. A. Gilyarov, Russ. Chem. Rev. (Engl. Transl.), 1978, 49, 870. 9 F. Ramirez and J. F. Marecek, Acc. Chem. Res., 1978, 11, 239.

47, 814.

(Chem. Abs., 1979,90, 5371).

10 A. Okruszek, Wiad. Chem., 1977,31, 503 (Chem. Abs., 1979,90, 102 836). 11 M. I. Kabachnik, T. A. Mastryukova, E. I. Fedin, M. S. Varsberg, L. L. Morozov,

P. V. Petrovskii, and A. E. Shipov, Russ. Chem. Rev. (Engl. Transl.), 1978, 49, 821. 1% M. I. Kabachnik, Phosphorus Sulfur, 1977, 3, 239. 13 J. P. Majoral, R. Kraemer, and J. Navech, Actes Congr. Int. Composes Phosphores, ls t ,

14 J. Michalski, Actes Congr. Int. Composes Phosphores, Zst, 1977 (publ. 1978), p. 63 (Chem.

1s G. Lavielle and A. Dehnel, Actes Congr. Int. Composes Phosphores, ls t , 1977 (publ. 1978),

16 F. Mathey and P. Savignac, Actes Congr. Int. Composes Phosphores, Zst, 1977 (publ. 1978),

17 J. I. G. Cadogan, Lect. Heterocycl. Chem., 1978, 4, 17.

1977 (publ. 1978), p. 653 (Chem. Abs., 1978, 89, 59 841).

Abs., 1978, 89, 109 675).

p. 503 (Chem. Abs., 1978, 89, 109 743).

p. 617 (Chem. Abs., 1978,89, 146 979).

104

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Quinquevalent Phosphorus Acids 105

As in previous Reports, the sections headed ‘General’ cover papers which describe work on phosphonic or phosphinic acids derivatives as well as on those of phosphoric acid, or which describe compounds having more than one type of ‘phosphyl’ function within the same molecule.

1 Synthetic Methods General.-A series of 6,7-dihydro-SH-dibenzo[d,f][ 1 , 3,2]diazaphosphepines (1 ; R = alkyl, aryl, or aryloxy) l8 and the more unusual 4-(diethoxyphosphiny1)- tetrahydro-l,3,Zbenzoxazaphosphorines (2; X= 0 or S) l9 have been prepared by conventional reactions.

The reactions which take place between phosphorus isocyanatidites and various 2-oxo-compounds have been recorded previously (see ‘Organophosphorus Chemistry’, Vol. 8, p. 107), but exemplification has been rather meagre. Further examples have now been reported which demonstrate an interesting spectrum of reactivity. When diethyl phosphoroisocyanatidite and diethyl trichloro- acetylphosphonate react together, only the Perkow product (3; Z= Y = OEt; R3 = Et) is produced, but with diethyl chloroacetyl- or dichloracetyl-phosphonate the reactions lead to mixtures of the linear Perkow compounds (3 ; Y = 2 = OEt, R1 = H, R2 = H or C1, respectively, R3 = Et) and the 5-(diethoxyphosphinyl)- 1,3,2-oxazaphospholidin-4-one 2-oxides (4; Y = OEt, R1 = H, R2 = H or Cl).20 Interaction of dimethyl trichloroacetylphosphonate and methyl phosphorodi- isocyanatidite gives the Perkow product (3 ; Y = NCO, Z = OMe, R1 = R2 = C1, R3 = Me) together with the 1,3,2-oxazaphospholen-4-one ( 5 ; 2 = NCO).21 With diethyl chloroacetyl- or dichloroacetyl-phosphonate, the same di-isocyanatidite

0 CR’R’ I I I1 ,OR3

I Z Y-P-o-c-P(o)\

Et NCO (3) (4) ( 5 )

18 M. S. R. Naidu and C. D. Reddy, Bull. Chem. SOC. Jpn., 1978, 51,2156. 19 T. P. Zeleneva, S. I. Patlina, and E. E. Nifant’ev, Zh. Obshch. Khim., 1978,48, 465 (Chem.

20 I. V. Konovalova, L. A. Burnaeva, N. V. Mikhailova, and A. N. Pudovik, Zh. Obshch.

21 I. V. Konovalova, L. A. Burnaeva, N. K. Novikova, M. V. Cherkina, T. G. Monakhova,

Abs., 1978, 88, 170 248).

Khim., 1978,48, 739 (Chem. Abs., 1978,89,43 622).

and A. N. Pudovik, Zh. Obshch. Khim.. 1978,48,746 (Chem. Abs., 1978,89,109 732).

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106 Organophosphorus Chemistry

gives (3 ; Y = NCO, Z = OEt, Rf = H, R2 = H or Cl, R3 = Et), and in the case of the dichloracetylphosphonate the bicyclic compound (6) is also obtained. 23

Reactions between dialkyl phosphoroisocyanatidites and acyl cyanides or related compounds (including halogen-free a-oxophosphonic esters) exemplify the phosphonatephosphate 24 Thus, the intermediacy of the ‘phosphate’ species (8) is clearly suggested by the formation of the 1,3,2- oxazaphospholidin-4-ones (1 1) as the major product from trimethylpyruvo- nitrile, even though initial formation of the ‘phosphonate’ species (7) is to be expected, and indeed, its participation is evidenced by the production of the 1,3,4-oxazaphospholidine derivatives (9) and (lo), both of which are formed as mixtures of diastereomers.

O

-% (Meo),~-OcR1R2 1

NCO NCO

(8)

(a) R’ = Me, R2 = C0,Et (b) R’ = Me, R2 = P(O)(OEt), (c) R1 = Me, R2 = CN

1

Phosphoric Acid and its Derivatives-An effective way to convert alkyl bromides into alkyl phosphates consists in heating the bromide with potassium di-t-butyl phosphate followed by removal of the t-butyl groups with trifluoroacetic acid.26 Activation of an alcohol as the 2-alkoxybenzoxazole, and subsequent treatment with diphenyl hydrogen phosphate, is an attractive phosphorylation method since purification of the diphenyl alkyl phosphate is facilitated by the ease of removal of the benzoxazalone formed. 26

Crystalline 2,4dinitrophenyl dihydrogen phosphate has been prepared for the first time. In aprotic solvents, this compound undergoes slow conversion into cyclic trimetaphosphoric acid, while on alcoholysis it yields alkyl dihydrogen phosphate^.^' Ramirez ef aZ.2s have also described a synthesis of magnesium tri- and di-alkyl pyrophosphate salts. Methyl pyrophosphates and dimethyl pyro-

32 I. V. Konovalova, R. D. Gareev, L. A. Burnaeva, N. V. Mikhailova, N. K. Novikova, and

*a I. V. Konovalova, R. D. Gareev, T. A. Faskhutdinova, L. A. Burnaeva, and A. N. Pudovik,

*4 I. V. Konovalova, R. D. Gareev, L. A. Burnaeva, T. A. Faskhutdinova, and A. N. Pudovik,

26 M. Kluba and A. Zwierzak, Synthesis, 1978, 770. 46 Y. Watanabe and T. Mukaiyama, Chem. Lett., 1978, 349. a7 F. Ramirez and J. F. Marecek, Synthesis, 1978, 601. 28 F. Ramirez, J. F. Marecek, Yu Fen Chaw, and T. McCaffrey, Synthesis, 1978, 519.

A. N. Pudovik, Zh. Obshch. Khim., 1978,48, 1700 (Chem. Abs., 1978, 89, 163 660).

Zh. Obshch. Khim., 1978,48, 1460 (Chem. Abs., 1978, 89, 179 929).

Zh. Obshch. Khim., 1978,48, 284, 1013 (Chern. Abs., 1978, 89, 43 601, 109 753).

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Quinquevalent Phosphorus Acids 107

phosphates are demethylated by a magnesium bromide-THF complex which attacks only one of two methyl groups attached to the same phosphorus atom, and which also distinguishes between methyl and higher alkyl groups.

Further examination of the attempted preparation of phosphorodichloridates from fluorinated benzylic alcohols (see ‘Organophosphorus Chemistry’, Vol. 9, p. 102) has shown that the successful synthesis of the desired compounds (12) can be achieved when reactions are carried out at temperatures lower than those previously used. 2s Other compounds have been obtained from extensively fluorinated aliphatic alcohols by reaction with phosphorus pentoxide. 30 A study of the reactivity of phenyl phosphorodichloridate towards ao-diols has con- firmed the reluctance of 1,Zdiols to cyclize to 1,3,2-dioxaphospholans in a satisfactory manner, whereas other diols yield compounds containing six- to nine-membered rings quite easily.31 In such difficult cases, the use of N-phos- phoryl imidazolides might be advantageous (see ‘Organophosphorus Chemistry’, Vol. 10, p. 141).

(14) R‘ = Et (15) R’ = Me,% (16) R‘ = H

Examples of the 1,3,4,2-dioxazaphosphole system (1 3 ; e.g., RZ = Cl or Oalkyl) have been synthesized via pentaco-ordinate compounds by conventional

An improved method for the preparation of diammonium acetyl phosphate has been described.33 Dialkyl hydroxy- and dihydroxy-cyclohexyl phosphates are obtained in good yields from hydroxycyclohexene epoxides by the reaction of these with dialkyl hydrogen phosphate^.^^ The yield of tris- (trimethylsilyl) phosphate from phosphorus pentoxide and hexamethyldisiloxane can be improved considerably when the reactants are heated together at 200°C in an Reaction between diethyl enol phosphates (14) and bromo- trimethylsilane yields the bis(trimethylsily1) esters (1 5), ethanolysis of which affords the free en01 phosphoric acids (16); the latter are conveniently isolated as their anilinium Phosphorylation of alcohols by the cyclic enediol phosphate (17; R= H) in aprotic solvents proceeds faster than do those reactions

z9 L. S. Zakharov, E. I. Goryunov, L. L. Morozov, V. A. Svoren, E. P. Lur’e, T. M. Shcherbina, and M. I. Kabachnik, Izv. Akad. Nauk SSSR, Ser. Khim., 1978, 2090 (Chem. A h . , 1979, 90, 22 468).

30 A. V. Fokin, V. A. Komarov, A. F. Kolomiets, A. I. Rapkin, K. I. Pasevina, T. M. Potarina, and 0. V. Verenikin, Izu. Akad. Nauk SSSR, Ser. Khim., 1978, 1574 (Chem. Abs., 1978, 89, 146 350).

31 C. L. Penney and B. Belleau, Can. J . Chem., 1978, 56, 2396. 32 E. V. Hinrichs and I. Ugi, J . Chem. Res. (S) , 1978,338; J. Chem. Res. ( M ) , 1978,3973. 33 J. M. Lewis, S. L. Haynie, and G . M. Whitesides, J . Org. Chem., 1979, 44, 864. 34 T. H, Chan and P. Di Raddo, Tetrahedron Lett., 1979, 1947. 35 Czech. P. 173 33211978 (Chem. Abs., 1979, 90, 6533). 3° T. Hata, K. Yamada, T. Futatsugi, and M. Sekine, Synthesis, 1979, 189.

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108 Organophosphorus Chemistry

which involve the ester (17; R= alkyl). However, the latter reactions are catalysed by trifluoroacetic acid and are then faster than those involving the cyclic diester. Both types of reaction involve protonation of the phosphoryl group and proceed through phosphorane intermediate^.^^

Some interesting observations regarding the formation and use of cis- and trans-isomers, (1 8) and (19) respectively, of 2-methoxy-4,5-diphenyl-I ,3,2- dioxaphospholan-2-thione have been reported in preliminary form. In the preparation of these compounds by reaction between meso-hydrobenzoin and thiophosphoryl chloride, the stereochemistry of the product depends upon the quantity of pyridine used to remove HCI. The cis-dioxaphospholan predominates if pyridine is used in smaller quantity, whereas if pyridine is used in excess the trans-form of product predominates, suggesting conversion of the kinetically favoured form into the thermodynamically more stable one. Cyclic chiral esters from (1 R,2S)-1,2- [l -180]dihydroxy-l ,2-diphenylethane were used to prepare chiral methyl [180]phosphorothioates. 38 A useful route to (+ )-(R)-2,2'- dihydroxy-1 , l '-binaphthyl is based on the acid-catalysed transesterification of the previously resolved dithiophosphoric acid (20) with isopropyl alcohol,aa

Scheme 1 summarizes reactions which have been used to prepare sterically hindered dialkyl (e.g., neopentyl, neopentylene) phosphoroselenocyanatidates (22) from amine salts of phosphoroselenoic acids (21). These products are reasonably stable, and are converted into the isomeric phosphoroisoseleno- cyanatidate (23) only when heated.40

37 F. Ramirez, J. F. Marecek, H. Tsuboi, and Y . Chaw, Phosphorus Sulfur, 1978, 4, 325. $8 R. L. Jarvest and G. Lowe, J . Chem. SOC., Chem. Commun., 1979, 364. s9 E. W. Hoffmann, W. Kuchen, W. Poll, and H. Wunderlich, Agnew. Chem., Int. Ed. Engl.,

40 W. J. Stec and B. Uznanski, Synth. Commrcn., 1978, 8, 473. 1979, 18, 415.

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Quinquevalent Phosphorus Acids

Se

(RO),POse Et&H

109

(21) 1 l-Me$iCl

0 (RO),P( 0) SeCN (RO),P(O)NCSe 4

(23) (22)

Reagents: i, MeaSiCl; ii, ClCN; iii, heat.

Scheme 1

N-Su bst i t u t ed N-a1 k y 1 t hioace t yl phosphor amida tes have been prepared by the addition of dialkyl hydrogen phosphates to alkylthioketenimines, as shown in reaction (l).41 N1-Alkyl-ureas are phosphorylated on N-2 by phosphoryl

chloride in liquid sulphur or via the N2-sodio-derivatives in aceto- nitrile. 43 The reaction between phosphorochloridothionates and isothiouronium salts gives the N-phosphorylated compounds (24).44 An ingenious scheme

(R*O),P(S)Cl + (H,N),CiR2 X‘ _t (R’O),P(S)N=C(SR’)NH, (24)

(Scheme 2) allows synthesis of several phosphorus-containing pyrimidines and related Other heterocyclic systems, i.e. (26) and (27), which, in principle, are merely cyclic hydrazides have been obtained by conventional reactions.46

It EtOCH=CHP(NCO), ‘* u : - 1)

-- “NH, ‘OEt OF- ‘ fT

(25; R = CO,CH,Ph)

Reagents: i, PhCHzOH; ii, NH3; iii, H2,Pd.

Scheme 2

41 Yu. G. Gololobov and L. I. Kruglik, Zh. Obshch. Khim., 1978,48,2225 (Chem. Abs., 1979,

42 W. Schaffrath, J. Tschufrig, S . Uhlmann, and H. A. Lehmann, 2. Chem., 1978,18,179. 43 W. Schaffrath, R. Schumann, and H. A. Lehmann, 2. Chem., 1978, 18, 180. 44 L. Kuruc, S. Truchlik, and S . Kovak, Chern. Zuesti, 1978, 32, 524 (Chem. Abs., 1979, 90,

45 P. A. Bartlett, J. T. Hunt, J. L. Adams, and C. E. Gehret, Bioorg. Chem., 1978, 7 , 421. 48 J. P. Majoral, M. Revel, and J. Navech, Phosphorus Suwur, 1978, 4, 317.

90, 86 665).

186 328).

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110 Organophosphorus Chemistry

(26) X = 0 or NMe (27)

The search continues for more biologically active derivatives and analogues of the anti-cancer drug cyclophosphamide. 4-Aryl-cyclophosphamides 47 and 4-alkylthio-cyclophosphamides 48 have been prepared, the latter from the 4-hydroxy-cyclophosphamide and thiols in the presence of trifluoroacetic acid ; for many of these compounds the separation of diastereoisomers was achieved, and assignments of relative configurations have been claimed. Diastereoisomers of 5-bromo-cyclophosphamide have also been separated, but in this case their relative configurations could not be assigned on the basis of lH n.m.r. spectral data with any degree of certainty. Treatment of 5-bromo-cyclophosphamide with sodium hydride afforded stereoisomers of ‘3,5-dehydro-cyclophosphamide’ (28). 49 The cis- and trans-isomers of 4,6-dimethyl-cyclophosphamide have served as model compounds in a study of the solution stereochemistry of cyclophos- phamide using spectroscopic techniques; assignment of the stereochemistry at phosphorus in the dominant conformations is somewhat dubious, however. The (R)- and (S)-enantiomers of isophosphamide (29) have been obtained by resolution of the diastereoisomers (30) and their subsequent hydrogenolysis. 61s 6 a

(29) R = H (30) K = PhCHMe

Phosphonic and Phosphinic Acids and their Derivatives.-2-Methyl-3-nitropyridint differs from other nitro-2- and -4-methylpyridines in its behaviour towards mixtures of phosphorus oxychloride and pentachloride. Thus it forms the phosphonic dichloride (3 l), which, on hydrolysis, yields 2-dichloromethyl 3-nitropyridine, whereas other nitro-methylpyridines yield the corresponding trichloromethylpyridine. 63 The complexes formed when 4-(pyridinium)-pyridine salts are treated with phosphorus trichloride are alcoholysed to esters of 1-(4’-pyridy1)-1,2-dihydropyridine-2-phosphonic acids ; the same pyridinium salts form pyridine-4-phosphonic acids when treated with phosphorous acid.64

Yun-Er Shih, Jy-Shih Wang, and Chao-Tung Chen, Heterocycles, 1978, 9, 1277. 48 T. Hirano, W. Klesse, and J. H. Heusinger, Tetrahedron Lett., 1979, 883. 49 S. M. Ludemann, G. Zon, and W. Egan, J. Med. Chem., 1979, 22, 151. 5O D. W. White, D. E. Gibbs, and J. G. Verkade, J. Am. Chem. SOC., 1979, 101, 1937. 61 S. M. Ludemann, D. L. Bartlett, and G. Zon, J. Org. Chem., 1979, 44, 1163. 5 1 R. W. Kinas, K. Pankiewicz, W. J. Stec, P. B. Farmer, A. B. Foster, and M. Jarman,

58 T. Kato, N. Katagiri, and A. Wagai, Tetrahedron, 1978, 34, 3445. 54 R. Roduszek and J. S. Wieczorek, Synthesis, 1979, 452, 454.

Bull. Acad. Pol. Sci., Ser. Sci. Chim., 1978, 26, 39 (Chem. Abs., 1978, 89, 109 387).

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Quinquevalent Phosphorus Acids 111

The lY4-thiaphosphorin 4-oxide (33) is prepared from the sulphide (32) by reaction with phosphorus pentachloride and hydrolysis of the intermediate complex. 66 The reaction between 1,3-dibenzoylpropane and hypophosphorous acid yields the tetrahydropyranylphosphonic acid (34). 56

1,2-0xaphospholen derivatives are obtainable with some facility, starting with tetrahydropyranyl propargyl ether and proceeding according to the steps summarized in Scheme 3.67 The A3-1 ,Zoxaphospholen (35) undergoes ring opening when treated with phosphorus pentachloride, affording the (E)-l,3- butadienylphosphonic dichloride (36).6*

0 II

0 I1

+ (THP)OCH,C=CP(OBU), L HOCH,C=CP(OB~), i, ii (THP)OCH,C=CH

P

* Spontaneous steps

Reagents: i, EtMgBr; ii, CIP(0)(OBun)2, THF, benzene; iii, TsOH, MeOH; iv, Pd/BaSOr,

Scheme 3

THP = te trahydropyranyl

quinoline, MeOH.

A phosphorus-containing analogue of a-pyrone, i.e. (37), has been reported. This substance forms 1:l adducts with the usual dienophiles, although with some difficulty, and under pyrolysis conditions such adducts afford a polymer derived from the postulated mesitylmetaphosphonate (38). The choice of mesityl

55 Ya. P. Shaturskii, E. L. Kalinina, and P. S. Makovetskii, Zh. Obshch, Khim., 1978, 48, 224 (Chem. Abs., 1978, 88, 170 238).

56 V. I. Vysotskii, A. S. Skobun, and M. N. Tilichenko, Zh. Obshch. Khim., 1978,48,2442 (Chem. Abs., 1979,90, 121 722).

57 Y . Machida and I. Saito, J. Org. Chem., 1979, 44, 865. 58 Kh. M. Angelov, T. S. Mikhailova, V. M. Ignat’ev, V. I. Zakharov, A. V. Dogadina,

B. I. Ionin, and A. A. Petrov, Zh. Obshch. Khim., 1978, 48, 1487 (Chem. Abs., 1978, 89, 163 671).

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112 Organophosphorus Chemistry

(37) mes = 2,4,6-trimethylphenyl

group as substituent rested upon the possibly enhanced stabilization of labile intermediate^.^^ The monomeric anhydrides (39) are reported to be formed in high purity when alkoxyvinylphosphonothioic dichlorides are treated with aqueous triethylamine, or, better, with pyridine. The anhydrides react with ethylene oxide to give the isomeric ring esters (40) and (41).60

Y

(39) (40) X = S, Y = 0 (41)X = 0, Y = S

The formation of the macrocycle (42) from methylphosphonic dichloride and the appropriate phenol is accompanied by that of the ‘dimer’ (43), which exists in two conformations.61

I Me

Various simple active-methylene compounds have been C-phosphorylated using diethyl phosphorochloridate.62 Cyclic esters of arylphosphonic acids have been prepared by reaction between cyclic phosphorochloridites and aryldia- zonium fluoroborates in the presence of copper(1) bromide; treatment of the intermediate ‘Croft’s complex’ with H,S leads to the corresponding thio- phosphonic s-Alkyl-phosphonates have been synthesized using reactions

69 I. Sigal and L. Loew, J. Am. Chem. SOC., 1978,100,6394. 60 K. A. Petrov, L. V. Treshchalina, and A. Sulaimanov, Zh. Obshch. Khim., 1978, 48, 101

(Chem. Abs., 1978, 89, 136 735). 61 T. N. Kudrya, A. S. Shtepanek, and A. V. Kirsanov, Zh. Obshch. Khim., 1978, 48, 927

(Chem. Abs., 1978, 89, 197 645); K. B. Yatsimirskii, E. I. Sinyavskaya, and T. N. Kudrya, Dokl. Akad. Nauk SSSR, 1978,240, 100 (Chem. Abs., 1978, 89, 109 744). D. L. Comins, A. E. Jacobine, J. L. Marshall, and M. M. Turnbull, Synthesis, 1978,309. Z. E Golubski and Z. Skrowaczewska, Synthesis, 1979, 21.

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Quinquevalent Phosphorus Acids 113

exemplified in Scheme 4; the choice of the disulphones as starting materials rather than the corresponding sulphoxides or sulphides was the result of their greater rea~tivity.~

phHso2Me (MeO),P(O)CHPhCH( SO,Me), -b (MeO),P(O)CHhlePh H S0,Me

Reagents: i, (MeO)ZP(O)H; ii , Raney nickel,

Scheme 4

Phosphonates in the 1,3,2-0xathiaphospholen series (44) have been prepared from phosphonic dichlorides and MeCOCH,SCN.66 Amongst the phosphorus acids resolved this year are ethyl phenylphosphonothioic acid, by brucine,g6 and alkyl ethylphosphonoselenoic acids, using either quinine or br~cine.~? Alkyl- phenylphosphinic acids are obtained by the alkylation of lithiated phenyl- phosphinous acids;68 chiral alkyl methylphenylphosphinates have been obtained by treatment of the phosphinic chloride with L-proline ethyl ester, followed by the acid-catalysed alcoholysis of the separated diastereoisomeric phosphinic The novel cyclic phosphinic ester (46) is produced when the ester (45) is chlorin- ated and the product subjected to dehydrochlorination with triethylamh~e.~~ The structure of 1,3-dihydro-l-hydroxy-3-methyl-l,2,3-benziodoxaphosphole (47; R = OH), prepared from 2-bromoacetanilide through several steps and via ethyl methyl(2-iodophenyl)phosphinate, has been confirmed by structural technique^.^

64 M. Yamashita, T. Miyano, T. Watabe, H. Inokawa, H. Yoshida, T. Ogata, and S.

~35 Zh. M. Ivanova, T. V. Kim, and Yu. G. Gololobov, Zh. Obshch. Khim., 1978, 48, 2376

6* Japan. Kokai 78 33 042 (Chem. A h . , 1978,89, 163 739). 67 I. A. Nuretdinov, N. A. Buina, E. V. Bayandina, and M. A. Giniyatullina, Tezisy Dokl.-

68 M. E. Garst, Synth. Commun., 1979, 9, 261.

70 V. K. Khairullin, A. A. Bredikhin, S. F. Makhmutova, and M. A. Vasyanina, Zh. Obshch.

7 l T. M. Balthazor, J. A. Miles, and B. R. Stults, J. Org. Chem., 1978, 43,4538.

Inokawa, Bull. Chem. SOC. Jpn., 1979, 52, 466.

(Chem. Abs., 1979,90, 72 121).

Vses. KonJ’Stereokhim. Konform. Anal Org. Neftekhim. Sint.’ 3rd., 1976, p. 89 (Chem. Abs., 1978, 89, 6365).

T. Koizumi, H. Amitani, and E. Yoshii, Synthesis, 1979, 110.

Khim., 1978,48, 1276 (Chem. Abs., 1978, 89, 129 592).

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114 Organophosphorus Chemistry

l-Ethoxy-A3-2, l-benzoxaphospholen 1-oxide (48), postulated as an inter- mediate in the hydrolysis of diethyl 2-~arboxyphenylphosphonate, has been synthesized from the latter via the corresponding chlorocarbonyl compound. It is converted by phosphorus pentachloride into ethyl 2-chlorocarbonylphenyl- phosphonic chloride, a reaction that allows the synthesis of the corresponding cyclic aza-compound (49) to be effected by aminoly~is.~~

0

(48) X = 0 (49) X = NR

Interest in the chemistry of aminoalkyl-phosphonic acids and their derivatives continues unabated. Savignac has reported a new and novel synthesis of o-aminoalkyl-phosphonic acid esters which employs the diethoxyphosphinyl group to protect the nitrogen. This sequence, starting from o-aminoalkyl bromides (Scheme 5), is likely to be of wide applicability since it allows the

Rt R' I I

H,NCH(CH,),Br i, (EtO),P(O)NHCH(CH,),Br

R' \ R1 I I

(EtO),P(O)NRZCH(CH,),P(O)(OEt), d- (EtO),P(0)NHCH(CH2),P(O)(OEt),

R' + I

H,NCH(CH,),P(O)(OH)O-

Reagents: i, (Et0)2P(O)Cl; ii, (Et0)3P; iii, NaH, R2X; iv, H30+.

Scheme 5

synthesis of compounds having various lengths of the aminoalkyl chain and, in principle, it also allows branching at any point on that chain. In addition, the products may be N-s~bstituted.~~ Compounds similar to (50) are obtained by the addition of hydrogen phosphonates to N-diphenylphosphinylimines, which in turn may be obtained from oximes and chlorodiphenyIphosphine.74

Another very useful general synthetic sequence (Scheme 6) is based on the initial reaction between the copper derivatives of phosphonic esters (51 ; R1 = H

It J. A. Miles and R. W. Street, J. Org. Chem., 1978, 43, 4668. ' 8 D. Brigot, N. Collignon, and P. Savignac, Tetrahedron, 1979, 35, 1345. 74 B. Krzyzanowska and W. J. Stec, Synthesis, 1978, 521.

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Quinquevalent Phosphorus Acids 115

(EtO),P(O)CIIR'Cu

(51)

/R2 + (EtO),P(O)CHR'CH,C=C /R2

I 'x3

+ X1CH,(irC,x3

X ( 5 2)

(EtO),P(O)CHR'(CH,),CHMeNH, - (EtO),P(0)CHK*(CH;),COR2 (54) n = 1 o r 2

Reagents : i, HzS04; ii, NaBHsCN,NH40Ac

Scheme 6

or Me) and the allylic halides (52; X1= C1 or Br; X2, XS=H or halogen); the unsaturated phosphonates (53) are formed without the troublesome side- reactions, e.g. elimination, previously encountered in this area. Subsequent reactions, as indicated, yield the 3- or 4-aminoalkyl-phosphonic esters (54).76

X,P(Y)CHLiCl A X,P(Y)CHClCH(OLi)R' X,P(Y)CH,COR

X = EtO or Me,N Y = O o r S

i v y = 0 -1 X,P( O)CH2CH R'N R2R3

Reagents: i, RlCHO, at -70 "C; ii, base: iii, H30+; iv, R2R3NH, NaBH3CN.

Scheme 7

A recent direct synthesis of 2-oxoalkyl-phosphonates from aldehydes (Scheme 7) 76

allows for the similar preparation of 2-aminoalkyl-phosphonic As an alternative to the dealkylation of esters with HCI, oxoalkyl-phosphonic esters have been dealkylated to the free acids by initial reaction with iodotrimethyl- silane and subsequent methanolysis of the bis(trimethylsily1) esters.78

The initial reaction in Scheme 7 is unusual insofar as ketones yield epoxy- phosphonates. cis-l,2-Epoxypropyl-phosphonic acid has been resolved with phenylet h~lamine.?~

a-Aminoalkyl-phosphonic acids are synthesized directly from aldoximes and HsP02, albeit in relatively poor yields.80 The aminoalkyl-phosphinic acids (55)

75 P. Savignac, A. Breque, F. Mathey, J.-M. Varlet, and N. Collignon, Synth. Commun.,

76 P. Savignac and P. Coutrot, Synthesis, 1978, 682. 77 J.-M. Varlet, N. Collignon, and P. Savignac, Synth. Commun., 1978, 8, 335. 78 J. Zygmunt, P. Kafarski, and P. Mastalerz, Synthesis, 1978, 609. 7@ Tokkyo Koho 78 24 407 (Chem. Abs., 1979,90, 6534). 10 R. M. Khornutov and T. I. Osipova, Izv. Akad. Nauk SSSR, Ser. Khim., 1978, 1951

1979, 9, 287.

(Chem. Abs., 1978, 89, 197 655).

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116 Organophosphorus Chemistry

are prepared by a route starting with aldazines and phosphonous acid ethyl ester, the product subsequently being hydrolysed with acid.*l Sodium dialkyl phosphites add to imino-thioethers (56) in yet another sequence leading to a-aminoalkyl-phosphonic acids (Scheme 8). Thus, the use of (56; R1 = Me, R2 = C02Et) leads to 1-aminoethyl-phosphonic acid (59; R1= Me),82 while the use of the camphoric acid derivative [56; R1 = PhCH2, R2 = (57)] and separation of the diastereomeric derivatives (58) yields enantiomers of (1-amino-Zphenyl- ethy1)phosphonic acid (59; R1 = PhCH2).83 a-Aminobenzyl-phosphonic acid has been resolved using phenylethylamine.s4

CO- 0 II

(HO),PCHR'NH,

(57) Reagents: i, (EtO)zP(O)Na; ii, Raney nickel; iii, H30+.

Scheme 8

Issleib et aLes have usefully summarized the types of products obtainable from various types of aldehydes on reaction with ammonia, and have used some of these to prepare esters (58; R1=CHR3R4, R2=H) as well as various imino- diphosphonic esters. Evidently, in those reactions between hydrogen phos- phonates and aldimines or related compounds, di-4-methylbenzyl hydrogen phosphonate offers advantages for the preparation of aminoalkyl-phosphonic acids having groups that are sensitive to hydrolysis or to hydrogenolysis; the benzyl groups may be removed with formic acid.86 1-Guanidinobenzyl-phosphonic acids (61) have been prepared by aminolysis

of the isothioureido compounds (60) prepared from aromatic aldehydes,

,P(O)(OH),

'NHC=NH ArCH -

X (60) X = SR' (61) X = NR2R3

C. Wasielewski, K. Antczak, and J. Rachon, Pol. J . Chem., 1978, 52, 1315 (Chem. Abs., 1978, 89, 163 655). K. Kotynski and W. J. Stec, Pol. J . Chem., 1978,52,659 (Chem. Abs., 1978,89,43 630).

a3 A. Kotynska and W. J. Stec, J. Chem. Res. (S ) , 1978, 41. 8' M. Hoffmann, Pol. J. Chem., 1978,52, 851 (Chem. Abs., 1978, 89, 129 590). 85 K. Issleib, K. P. Doepfer, and A. Balszuweit, 2. Anorg. Allg. Chem., 1978,444,249. *6 J. Lukszo, J. Kowalik, and P. Mastalerz, Chem. Lett., 1978, 1103.

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Quinquevalent Phosphorus Acids 117

thiourea, and triphenyl pho~phi te .~~ A synthesis of unesterified carbamoyl- or thiocarbamoyl-phosphonic acids, isolated as their anilinium salts, starts from isocyanates or isothiocyanates and involves their initial reaction with tris(tri- methylsilyl) phosphite (Scheme 9).ss For the isocyanates, the intermediates (62) are isolable and can be converted into the free acids (63; X=O). For the isothiocyanates, the intermediates (62; X = S) cannot be isolated, although the acids (63; X= S) may be, and prolonged heating of the reaction mixture leads to the formation of alkyl isocyanide and tris(trimethylsily1) phosphorothionate.

X

-b R'NHCP0,H- H$Ph II 1 (6 3)

X = O o r S (62) Reagents: i, (Me3SiO)sP; ii, MeOH, PhNHz.

Scheme 9

The reaction between N-acyl-isoquinolinium salts and trimethyl phosphite in the presence of NaI yields dimethyl (2-acyl-l,2-dihydroisoquinolinyl)-l- phosphonates ; a similar sequence operates for the quinoline series.89

The synthesis of (2-amino-1 -hydroxyalkyl)phosphonic acids is discussed in two reports, the first of which considers the hydrogenation of (l-hydroxy-2- nitroalky1)phosphonic acid esters and subsequent acidolysi~.~~ The second report concerns the reactions shown in Scheme 10; this appears to be much more general in its scope and in the availability of starting material^.^^

Reagents: i, (MeO)zP(O)H; ii, NH2NHz.

Scheme 10

The cyclic m-aminophosphonic amides (64) have been claimed as the products obtained from the reaction of acylaminoalkyl nitriles and a mixture of phos- phorous acid and phosphorus trichloride in d i o ~ a n . ~ ~ Some related five-membered- ring compounds are obtainable from benzaldimines and phosphoro-mono-

81 J. Oleksyszyn and R. Tyka, Pol. J. Chem., 1978,52,1949 (Chem. Abs., 1979,90,104 066). 88 M. Sekine, H. Yamagata, and T. Hata, Tetrahedron Lett., 1979, 3013. 89 K. Akiba, Y. Negishi, and N. Inamoto, Synthesis, 1979, 5 5 . 90 A. V. Seryukova, G. M. Baranov, and V. V. Perekalin, Zh. Obshch. Khim., 1978, 48, 522

Q1 T. Tone, Y. Okamoto, and H. Sakurai, Chem. Lett., 1978, 1349. Q8 Ger. Offen. 2 738 720/1979 (Chem. Abs., 1979, 90, 204 252).

(Chem. Abs., 1978, 89, 24 455).

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118 Organophosphorus Chemistry

and -di-isocyanatidites (see also refs. 22 and 24);g3 in connection with the latter reagents, it might be mentioned that dimethyl phenylacetylphosphonate yields the 1,2,4-oxazaphospholidin-5-one 2-oxide (65). 24

2 Reactions General.-Under normal conditions, (pheny1thio)trimethyIsilane fails to react with phosphates or phosphonates, but, on addition of phenylthiolate and dicyclohexyl-18-crown ether, O-dealkylation takes place readily, and in an easily controllable, stepwise sequence.g4 As an alternative to the use of phos- phorus pentasulphide, a 1 : 1 mixture of sulphur and red phosphorus reacts with a variety of phosphoryl compounds at 120470°C to yield the corresponding t hiophosphoryl compounds.

2-Hydroxyethyl phosphorothiolates and phosphonothiolates rearrange at room temperature to the O-Zmercaptoethyl compounds. The rates of these reactions depend upon the size of substituents on phosphorus as well as on the degree of substitution in the hydroxyethyl side-chain; 1,3,2-oxathiaphospholans are thought to be intermediate^.^^

S R1R2PSzH

+ PhzCN,

I I Ph,C=S +' R*R*P(S)H B-, [s2ir] % Ph,CHSPR'R2 f-

(66) (67)

The base-catalysed rearrangement of thiophosphonates, as represented by the structure of the intermediate ion (66), to thiophosphate has been observed. The structure assigned to the products (67) was confirmed by treatment of the hydrogen phosphorodithioate with diphenyldiaz~rnethane.~~ Further studies on the reactions between diazo-compounds and a variety of dialkyl, diaryl, alkyl- (alkoxy), and aryl(a1koxy)phosphino-thionic acidsg8 and -selenoic acids,gg using diazomethane and diphenyldiazomethane in particular, has shown that the 93 1. V. Konovalova, R. D. Gareev, L. A. Burnaeva, M. V. Cherkina, 0. A. Molchanova, and

94 Y. Takeuchi, Y. Demachi, and E. Yoshii, Tetrahedron Lett., 1979, 1231. 95 V. K. Khairullin, M. A. Varyanina, and S. F. Makmutova, Zh. Obshch. Khim., 1978, 48,

96 0. N. Nuretdinova and F. F. Guseva Izv. Akad. Nauk SSSR, Ser. Khim., 1978, 2142

97 A. N. Pudovik, I. V. Konovalova, M. G. Zimin, and T. A. Dvoinishnikova, Zh. Obshch.

08 T. A. Mastryukova, A. B. Uryupin, and M. I. Kabachnik, Zh. Obshch. Khim., 1978, 48,

99 T. A. Mastryukova, J. Michalski, A. B. Uryupin, Z. Skrzpczynski, and M. I. Kabachnik,

A. N. Pudovik, Zh. Obshch. Khim., 1978, 48, 1940 (Chem. Abs., 1979,90, 23 176).

1993 (Chem. Abs., 1979,90, 6470).

(Chem. Abs., 1979,90, 54 419).

Khim., 1978,48,490 (Chem. Abs., 1978, 89,43 607).

2174 (Chem. Abs., 1979,90, 86 527).

Zh. Obshch. Khim.. 1978.48, 1447 (Chern. Abs., 1978,89, 196 559).

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Quinquevalent Phosphorus Acids 119

ratio of S(Se)- to 0-alkylation products depends upon the nature of the substi- tuents on phosphorus. S(Se)-Alkyl esters are formed via the diazonium cation and ambient p hosp hino- t hioat e(-selenoa t e) anion. The 0 -a1 k y 1 esters are obtained through the phosphorus-containing anion and its reaction with a carbo-cation, an increase in the stability of which leads to more 0-alkyl product.

Dithioacids (68; Rf = Ph or 0-alkyl) react with imino-ethers or aldimines to give the salts (69; R3 = OEt or H) initially. The main product of further reaction is the substituted-aminoalkyl dithioester (70); in the case of the imino-ethers, however, protonation of (69) leads ultimately to the S-ethyl dithiol(n)ate ester. The latter, together with dithioacetals, are formed also from aldimines. In the case of iminoethyl ethers, loss of ethanol affords the carbonyl compound (71) which, through protonation with (68), gives carboxamides and trithiopyro- phosph(in)ates (Scheme 1 1). loo The disulphide bond in bis(phosphinothioy1) disulphides is cleaved by diethylmercury, when the products are the S-ethyl- and the S-ethylmercuri-derivatives of the appropriate dithiophosphoric acid. lol

R*,PS,H + RZR3C=NR4 @ [ RzR3C=NHR4]' R',PS; _3 RZR3C-SP(S)R'z I

(6 8) NH R4 (70)

H: R' = Ph or 0 alkyl R3 = OEt \ R1 = Ph or Oalkyl

R4 = PI1 or Me

R',P(S)SEt + R2CONHR4

P hC H H 2R4 P hCIi A IJ R4

R1$(S)SR4 +- s-P"o + S--p\--

0-

I 1 A-0

I h 0 I S rllkyl

R',P(SjNHCPh (7 1) S II -.-.\ 168)

PhCONH, + [R',P(S)],S

Scheme 11

Full experimental details and results regarding the stereochemistry of reaction between chlorine or sulphuryl chloride and thiono-(and seleno-)esters have appeared. Phosphorus-3 1 n.m.r. spectroscopy indicates unambiguously that phosphonium species are intermediates and, depending on the substituents on phosphorus, they undergo nucleophilic displacement of ligands to give an alkyl halide and phosphorochloridate or the analogous halogen-containing compound (Scheme 12). Loss of sulphur also occurs in the last and most important step. If, for any reason, nucleophilic displacement should fail to take place, then sulphenyl chlorides are produced. lo2

100 M. G. Zimin, N. G. Zabirov, R. A. Cherkasov, and A. N. Pudovik, Zh. Obshch. Khim., 1978, 48, 1020 (Chem. Abs., 1978, 89, 108 424); ibid., 1978, 48, 1943 (Chem. Abs., 1978, 89, 215 502).

101 N. N. Mel'nikov, B. A. Khaskin, and 0. D. Sheluchenko, Zh. Obshch. Khim., 1978,48, 1657 (Chem. Abs., 1978,89, 163 700).

107, J. Michalski, J. Mikolajczak, and A. Skowronska, J. Am. Chem. Soc., 1978,100,5386.

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120 Organophosphoriis Chemistry

SCL R'RZP'

\\o

Scheme 12

Isomerization of the allylic phosphinoselenoates (72) to the phosphoryl compounds (73) takes place during distillation, and can be followed by 31P n.m.r. spectroscopy. The mode of rearrangement is not of the customary Claisen type, since there is no 'inversion' of the allylic group, but the observed data are consistent with a process of transalkylation in an ion pair (74) or with intra- molecular alkylation according to (75).lo3

Se 0 II

R' R?P SeCH,CH=CR3R4 R'R2POCH,CH=CCR3R4 heat b II

Modro et aZ. have examined the cleavage of P-N and N-C bonds in a series of amides X,P(O)NHR, where X is alkyl, aryl, Oalkyl, or Oaryl, in acidic media.Io4 For N-alkyl groups other than But, competition between the two degradation pathways is a function of the ability of that alkyl group to form the corresponding carbo-cation. For the N-But compounds, competition depends on substrate structure and properties of the reaction medium.

Hydroxyiminopyridinium salts (76; R = heptyl or dodecyl; X = halogen, MeSO,, etc.) are much more effective accelerators of hydrolysis of neutral esters such as (77) and (78) than are non-micellar salts. However, they are ineffective in catalysing reactions of the oxirnate ion with positively charged esters such as (79).lo6

10s I. A. Nuretdinov, N. A. Buina, and E. V. Bayandina, Zh. Obshch. Khim., 1978, 48, 1073

10' T. A. Modro, M. A. Lawry, and E. Murphy, J . Org. Chem., 1978, 43, 5000. lo5 J. Epstein, J. J. Kaminski, N. Bodor, R. Enever, J. Sowa, andT. Higuchi, J. Org. Chem.,

(Chem. A h . , 1978, 89, 108 488).

1978,43,2816.

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Quinquevalent Phosphorus Acids 121

ACH=NOH ( EtO),P(O)OC,H,NO,-~ Me(EtO)P(0)sC2H,NPri2

lpJ R x'

(76) (7 9 )

A study of the kinetics of reaction of a series of 4-nitrophenyl esters with butylamine suggests that the displacement of the 4-nitrophenoxyl ion occurs through a pentaco-ordinate intermediate that is broken down by a second molecule of amine. lo6 Dialkyl t-butylperoxy phosphates and alkyl t-butylperoxy alkylphosphonates react with cycloalkenes under thermal or photolytic condi- tions, in the presence of copper(1) bromide, to give cycloalkyl phosphates or O-cycloalkyl phosphonates.lo7 Reactions of Phosphoric Acid and its Derivatives.-Mixed anhydrides containing phosphorus-halogen bonds, as exemplified by (80), react with alcohols, in- cluding t-butyl alcohol, at the anhydride bond.lo8

A variety of phosphoric halides, amides, and thioesters have been dealkylated with halogenotrialkylsilanes. Of the latter, iodotrimethylsilane is more effective than the bromide (see also refs. 36, 78, 153, and 154). The N- and S-containing functions are unaffected, and some selectivity of the reagent action is observed. Thus (81), with bromotrimethylsilane, loses those groups attached to the phosphoryl centre, whereas the corresponding iodosilane dealkylates at both centres.log

,OCHC( SiMe&=CH,

I 1 S 0 ll ll

(R'O),P--O-P( OR?, (E t O)P( 0) OCH,C=CH,

(81) HJP' (82)

EtOP(O)(OH), EtOP(O), 0' &Et,

The 2-trimethylsilyl-2-propenyl moiety is a new protecting group for phos- phoric acids; the group is relatively stable to acids and may be removed from, e.g. (82), by hydrogenolysis or with tetraethylammonium fluoride.

Triallyl phosphate allylates nucleic acid bases in aqueous medium at 60°C.111 Heating methyl aryl phosphorochloridates or phosphorochloridothionates, or

lo6 V. E. Bel'skii, L. S. Novikova, L. A. Kudryavtseva, and B. E. Ivanov, Zh. Obshch. Khim.,

lo' G. Sosnovsky and G. A. Karas, 2. Naturforsch., Tcil B, 1978, 33, 1165, 1177. 108 F. Effenberger, G. Koenig, and H. Klenk, Angew. Chem., 1978, 90, 740. loQ J. Chojnowski, M. Cypryk, and J. Michalski, Synthesis, 1978, 777. 110 T.-H. Chan and M. Di Stefano, J . Chem. SOC., Chem. Commun., 1978, 761. 111 T. Tanabe, K. Yamauchi, and M. Kinoshita, Bull. Chem. SOC. Jpn., 1979, 52, 259.

1978,48, 1512 (Chem. Abs., 1978,89, 179 154).

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122 Organophosphorus Chemistry

treatment of aryl phosphorodichloridothionates with triethylamine, results in the formation of the dimeric anhydrides (ROPZ,),, where Z is 0 or S, (see also ref. 6O).ll2 In the glycosylation of phosphorothioselenoic acids by glycosyl bromides, the ratio of Se- : S- reaction product depends upon reaction conditions and equilibration between product species at higher temperatures.l13 Related compounds have been obtained by the addition of hydrogen phos- phorodithioates to glycals, a sequence which has potential in the synthesis of 't-deoxy-~-thio-cc-~-sugars.~~~ Alcohols can be thiophosphorylated with phosphoro(di)thioic acids in the presence of Ph,P-CC1,-Et,N mixtures. Using

n.m.r. spectroscopy, it proved possible to show that, within the range - 50 to + 30°C, phosphonium salts were formed as intermediates from neopentyl alcohol. The formation of several by-products was explained by postulating a series of equilibria involving different phosphonium salts (cf. Scheme 12). llS

In the presence of aluminium chloride, bis(diaryloxyphosphinothioy1) disul- phides will thiophosphorylate aromatic hydrocarbons, while the corresponding tetra-alkoxy-compounds possess alkylating capacity under the same conditions. 116 Bis(dialkoxyphosphinothioy1) tri- and tetra-sulphides are mono-desulphurized by various compounds of tervalent phosphorus, but the final reaction mixtures are complex. l7

A series of papers describes an examination of the action of phosphoro- dithioic acids on nitriles and imines (see also ref. 100 and Scheme 11). The reaction between 00-di-isopropyl hydrogen phosphorodithioate and ethyl benzimidate follows the reactions shown in Scheme 11 and yields OO-di- isopropyl S-ethyl phosphorodithioate and benzamide as the major products through a S to N rearrangement step, (71 ; R1 = OPri) and thiobenzamide being the minor products.ll* The initial product from the same dithioacid and cyano- acetic ester, i.e. (83; R= CH,CO,Et), also rearranges; eventually it gives

(Pr'O)$(S)SCR==NH -% (Pr'O),P(S)NHCSR _t RCSNH, + [(Pr'O),P(S)],S

(83)

thiocarbamoylacetic acid and tetraisopropyl trithiopyrophosphate. 11* The latter is also formed when 00-di-isopropyl hydrogen phosphorodithioate reacts with acyl nitriles. In this case, a further reaction seems to take place between the intermediate (84) and more dithioacid; the same intermediate, when acted upon by more acyl nitrile, affords compound (85). 00-Dimethyl hydrogen phos-

112 K. D. Dzhundubaev, A. S. Sulaimanov, and B. Batyrkanova, Zh. Obshch. Khim., 1978,

11s M. Michalska, 1 . -0 . Krezel, and J. Michalski, Tetrahedron, 1978, 34, 2821. 114 J. Borowiecka and M. Michalska, Carbohydr. Res., 1979, 68, C8. 115 B. Mlotkowska and A. Zwierzak, J. Prakt. Chem., 1978, 320, 777. 116 N. N. Mel'nikov, B. A. Khaskin, and I. V. Poluyan, Zh. Obshch. Kliim., 1978, 48, 1902

117 N. A. Tolmacheva, B. A. Khaskin, and N. N. Mel'nikov, Zh. Obshch. Khim., 1978, 48,

118 M. G. Zimin, N. G. Zabirov, R. A. Cherkasov, and A. N. Pudovik, Zh. Obshch. Khim.,

11* A. N. Pudovik, R. A. Cherkasov, M. G. Zimin, and N. G. Zabirov, Zh. Obshch. Khim.,

48, 2037 (Chem. Abs., 1979,90, 22478).

(Chem. A h . , 1979, 90,22 473).

1078 (Chem. Abs., 1978, 89, 107 963).

1978,48,225 (Chem. Abs., 1978, 88, 136268).

1978,48,926 (Chem. Abs., 1978, 89, 107958).

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Quinquevalent Phosphorus Acids 123

phorodithioate is more reactive in its behaviour with aroyl nitriles in the absence of solvents, and with pyruvonitrile the products are pyruvic amide, 00s- trimethyl phosphorodithioate, and polymeric methyl metadithiophosphate. 2o

Amidoximate readily dephosphorylates 4-nitrophenyl phosphates at pH 8-1 3 in a pattern which, qualitatively at least, resembles that for deacylation.lal Diphenyl 4-nitrophenyl phosphate loses the 4-nitrophenoxy-group when treated with phenoxide anion in micelles of cetyltrimethylammonium bromide. 122

The full paper on the 'three-phase test' for the detection of metaphosphate intermediates using polymer-bound substrates (see 'Organophosphorus Chemistry', Vol. 7, p. 121) has appeared.123 Ramirez' group continues to link its study of the chemistry of cyclic phosphate esters with the search for reactive intermediates in phosphate reactions. The cyclic ester (86; R = Me) methylates nicotinamide, and gas-phase pyrolysis of the resulting methyl carbamoyl- pyridinium salts of the acid (86; R=H) yields (87) and its decarboxylation product (88), of which (88; R = Me) seems to be pyrolysed still further to acetoin together with, presumably, methyl metaphosphate. A similar process seems not to occur for the acid (88; R=H).124

Ramirez and Mareceklea have also examined the behaviour of 2,ddinitro- phenyl dihydrogen phosphate and several of its quaternary ammonium salts in protic and aprotic solvents in the presence of added alcohols or water. They concluded that the acid and its monoanion react via oxyphosphorane inter- mediates, but that the dianion reacts via a monomeric metaphosphate ion, PO,-. They emphasize that they do not regard the formation of cyclic trimeta- phosphoric acid as necessarily being an indication of the involvement of mono- meric metaphosphate in phosphorylation processes.

120 R. A. Cherkasov, G. A. Kutyrev, A. A. Karelov, E. G. Yarkova, and A. N. Pudovik,

1 2 1 C. A. Bunton and G. Cerichelli, J. Org. Chem., 1979, 44, 1880. 122 C. A. Bunton, G. Cerichelli, Y . Ihara, and L. Sepulveda, J. Am. Chem. SOC., 1979, 101,

123 J. Rebek, Jr., F. Gavina, and C. Navarro, J. Am. Chem. SOC., 1978, 100, 8113. 124 S. Meyersen, E. S. Kuhn, F. Ramirez, J. F. Marecek, and H. Okasaki, J. Am. Chem. SOC.,

125 F. Ramirez and J. F. Marecek, J. Am. Chem. Soc., 1979, 101, 1460.

Zh. Obshch. Khim., 1978, 48, 1025 (Chem. Abs., 1978, 89, 108 425).

2429.

1978,100,4062.

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1 24 Organophosphorus Chemistry

Amongst the hydrolysis studies reported during the year are those on dimethyl 1,2-dibromo-2,2-dichloroethyl phosphate (giving not only dimethyl hydrogen phosphate and bromodichloroacetaldehyde but also methyl dihydrogen phosphate);126 methyl ethyl aryl phosphorothionates in alkaline rnedium;l2? and methyl aryl hydrogen phosphates in an alkaline medium.128 The cis- and trans-isomers of 2-4'-nitrophenoxy-5-chloromethyl-5-methyl-1,3,2-dioxaphos- phorinan undergo attack by aryloxy anions with both retention and inversion of configuration. Retention is favoured by a high degree of ion association, and the product ratio depends on the nature of cation and solvent. The results were interpreted in terms of a square-pyramidal intermediate, with the anion-cation complex spanning the phosphoryl bond. 129

(89) cis: R' = OP(O)(OEt),, R2 = H trans: R' = H, R2 = OP(O)(OEt),

In the reaction between cis- or trans-stereoisomers of the ally1 phosphates (89) and the aluminium-containing nucleophilic reagents Me2AlX (X = OPh, SPh, or NHPh), s N 2 attack at the ol-position generally predominates for each of the three reagents. The isomeric composition of the product mixture and the extent of 01- us. y-substitution (sN2 vs. S N ~ ' reaction) depend on solvent. Reactions in THF give ratios which are closer to 1:l than for other solvent systems examined. 130

Kinetic data have been obtained for the bromination-dephosphorylaiion of phosphoenol pyruvate.131 When diethyl 2,2-dichloro-l-ethoxyvinyI phosphate is treated with organolithium compounds and then allowed to react with carbonyl compounds, 1-chloro-1 ,Zunsaturated esters are obtained.132 Enol phosphates are cleaved to the corresponding alkene by the action of finely divided titanium metal. 133 Active-methylene compounds are C-acylated by carboxylic acids in the presence of diethyl phosphorocyanidate. 13* The polymer- ization of 2-alkoxy-2-oxo-l,3,2-dioxaphospholans using organometallic initiators has been discussed in terms of pentaco-ordinate intermediates. 135

126 R. Jentzsch and G. W. Fisher, J. Prakt. Chem., 1978, 320, 634. 127 G. G. Lykhina and L. A. Pershina, Izv. Tomsk. Politekh. Inst., 1977,238, 161 (Chem. Abs.,

138 M. Younas and S. S. Bokhari, Pak. J. Sci. Ind. Res., 1978, 21, 111 (Chem. Abs., 1979,

139 M. Bauman and W. S. Wadsworth, J. Am. Chem. SOC., 1978,100, 6388. 130 S. Ozawa, A. Itoh, K. Oshima, and H. Nozaki, Tetrahedron Lett., 1979, 2909. 131 N. V. Volkova, I. I. Semenyuk, E. P. Zhuchenko, L. I. Budarin, and A. A. Yasnikov,

1m F. Karrenbrock, and H. J. Schafer, Tetrahedron Lett., 1979, 2913. 135 S. C. Welch and M. E. Walters, J . Org. Chem., 1978, 43, 2715. 134 T. Shiori and Y. Hamada, J. Org. Chem., 1978, 43, 3631. 135 J. Libiszowska, K. Kaluzynski, and S. Penczek, J. Polym. Sci., Polym. Chem. Ed., 1978, 16,

1978, 89, 179 158).

90, 71 411).

Teor. Eksp. Khim., 1978, 14, 380 (Chem. Abs., 1978, 89, 89 760).

1275.

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Quinquevalent Phosphorus Acids 125

cis-2-Chloro-5-methyI-3-phenyl-l,3,2-oxazaphospholidine 2-oxide undergoes methanolysis or phenolysis with retention of configuration at Compounds derived from ephedrine continue to provide scope for the study of the mechanism, and particularly of the stereochemistry, of reactions at phosphoryl or thiophosphoryl centres in compounds that contain phosphorus as part of a five-membered ring. The stereoisomer (90) of the 2-methyl 2-thione undergoes

stereospecific ring opening when acted upon by phenyl- or ethyl-lithium ; acidolysis of the initial product yields methylphenylphosphinothioic acid. However, the 2-thione that is epimeric at phosphorus is not so stereospecific in its mode of action.137 Treatment of (2R, 4S, SR)-2-chloro-3,4-dimethyl- 5-phenyl-l,3,2-oxazaphospholidine-2-thione (91) [from ( - )-ephedrine] with sodium ethoxide [to give (92)] followed by methanol under acidic conditions routinely gives @)-ethyl methyl hydrogen phosphorothionate (93-R) in > 60 % yields. By reversing the order of reaction with alcohols, (91) affords (934). Scheme 13 attempts to summarize reactions of these two hydrogen phosphoro- thioates; most steps appear to proceed with a high degree of stereoselectivity. lS8 2-Anilino 2-thiones based on the same ring system undergo P-N bond cleavage in the Staudinger-Wittig reaction with full retention of configuration at

The dihydro-1,2,6-phosphadiazine (96; X= 0, R1= Et, R2= H) is brominated to (96 ; X = 0, R1 = Et, R2 = Br), which in turn reacts with amines by replacement of the bromine. The reaction of the diones with phosphorus pentasulphide gives the corresponding dithiones, which on methylation give (97; R2 = SMe) and on ammonolysis give (97; R2 = NH2).14* N-Phosphoryl-imidazolides are better reagents than the corresponding

chlorides for the dehydration of aldoximes to nitriles. 141 The benzimidazolides

(96) (98) R = OPh (99) R = NHPh

189 M. A. Pudovik, M. D. Medvedeva, A. A. Musina, and A. N. Pudovik, Zh. Obshch. Khim.,

137 C. R. Hall, T. D. Inch, and I. W. Lawston, Tetrahedron Lett., 1979, 2729. 158 C. R. Hall and T. D. Inch, J. Chem. Soc., Perkin Trans. I , 1979, 1104. 139 K. Lesiak and W. J. Stec, 2. Naturforsch., Teil By 1978, 33, 782. 140 I. S. Levi, L. D. Garaeva, E. M. Osipova, and M. N. Preobrazhenskaya, Khim. Geterotsikl.

141 M. Konieczny and G. Sosnovsky, Z. Naturforsch., Teil B, 1978, 33, 1033,

1978, 48,464 (Chem. Abs., 1978, 88, 189 910).

Soedin., 1978, 972 (Chem. Abs., 1979, 90, 6367).

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126 Organophosphorus Chemistry

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Quinquevalent Phosphorus Acids 127

(98) and (99) have received some attention with regard to their phosphorylating ability. For the tris(benzimidazo1ide) (98/99; n = 3), reaction with aliphatic and aromatic amines takes place easily, but with more difficulty in the case of alcohols and phenols. Replacement of two benzimidazole groups by PhNH, i.e. (99; n= l), allows for ready phosphorylation of alcohols, phenols, and amines through loss of the anilino-groups. The phenoxy-compound, (98 ; n = l), also reacts with alcohols and amines, when PhO- is lost, but when this is heated with aniline it is benzimidazole which is

For the series of diary1 phosphoramidates (loo), S N ~ hydrolysis in aqueous ethanol at 30-50°C predominates over alcoholysis, but there appears to be effective transmission of inductive effects of substituent groups through phos- phorus. 143 Acid-catalysed methanolysis of the phosphoramidates (101 ; R = NHPh or NHCH2Ph) proceeds with complete inversion of configuration at phosphorus, whereas in the presence of BF, some configurational retention is observed, this being attributed to kinetic

(100) (101)

The rearrangement of triethyl N-phenylphosphorimidate to diethyl N-ethyl- N-phenylphosphoramidate has been investigated; the initial alkylation product, (102), formed under kinetically controlled conditions, rearranges to the thermo- dynamically more stable phosphoramidate (103) under the influence of Rx,

RzX ,O R2 / (EtO),P(O)NHR' (EtO),P\ + (EtO) N R' 'NRR~

(102) (103)

ZnX,, 12, EIX, or MeCOX (X= halogen).145 Zwierzak has continued his investi- gations into the properties of diethyl NN-dichlorophosphoramidate and has shown that it adds easily to a-pinene and norbornene, and that it is possible to prepare amines derived from these hydrocarbons thereby.146 A lack of space does not permit a full listing of papers relating to the uses of HMPT; for the most part, they refer to the use of the compound as a solvent in, for example, reactions of NaBH,CN 14' and lithium di-isopropylamide 14* and in de-methoxy- carbonylations;14s there has been some discussion regarding the general role of HMPT as a solvent in nucleophilic substitution reactions.160 142 G. L. Matevosyan, R. M. Matyushicheva, and P. M. ZavIin, Zh. Obshch. Khim., 1978,

48, 941, 928, 2433 (Chem. Abs., 1978,89, 129 449,43 244, 121 488). 143 F. Kasparek and J. Mollin, Collect. Czech. Chem. Commun., 1978, 43, 3420. 144 T. Koizumi, Y. Kobayashi, and E. Yoshii, Heterocycles, 1978, 9, 1723. 145 B. C. Challis, J. A. Challis, and J. N. Iley, J. Chem. Soc., Perkin. Trans. 2, 1978,813. 146 B. Olejniczak, K. Osowska, and A. Zwierzak, Tetrahedron, 1978, 34, 2051. 147 K. Yamada, N. Itoh, and T. Iwakuma, J. Chem. Soc., Chem. Commun., 1978, 1089. 14* E. S. Stratford and N. D. Aggarwal, J . Org. Chem., 1979, 44, 1570. 149 S. Yameda, T. Kawase, Y. Yasuda, and Z . Yoshida, J. Org. Chem., 1979, 44, 1728. 150 R. S. Glass and R. J. Swedo, J. Org. Chem., 1978, 43, 2291.

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128 Organophosphonu Chemistry

Reactions of Phosphonic and Phosphinic Acids and their Derivatives.-A mixture of a carboxylic acid R1C02H and diphenylphosphinic chloride in the presence of a tertiary amine will C-acylate diethyl sodiomalonate; when treated with R2MgX, the same reactants yield the ketones R1COR2.1S1 Aromatic carboxylic acids, phenols, amines, and sodium sulphinates are methylated when heated with dimet h yl me thy1 p hosp hona te.

Dialkyl phosphonates are dealkylated by iodotrimethylsilane.153, 15* Di- (hydroxymethy1)phosphinic acid yields an ester when treated with trialkyl orthoformate in DMF. The esters afford their di(trimethylsily1) ethers with the usual reagents. lK5 Di(hydroxymethy1)phosphinic acid reacts at all three reactive sites when treated with trialkylsilane in the presence of colloidal nickel.156

When 00-dimethyl trimethylsilylmethylphosphonate is heated at 250 "C, a mixture of dimethyl methylphosphonate (22 %) and O-methyl 0-trimethylsilyl methylphosphonate (41 %) is obtained. The intermediate formation of the ylide (104) has been postulated, to account for the formation of 00-dimethyl 0-trimethylsilyl phosphate (50 %) and Ph2C=CH2 (71 %) when the reaction is carried out in the presence of added benzophenone.lS7

R" k- D 3

151 A. S. Kende, D. Scholz, and J. Schneider, Synth. Commun., 1978, 8, 59. 152 P. Sutter and C. D. Weis, Phosphorus Sulfur, 1978, 4, 335. 153 Y. Machida, S. Nomoto, and I. Saito, Synth. Commun., 1979, 9, 97. 154 G. M. Blackburn and D. Ingleson, J. Chem. SOC., Chem. Commun., 1978, 870. 155 V. D. Romanenko, P. P. Kornuta, and L. N. Markovskii, Zh. Obshch. Khim., 1978, 48,

156 M. S. Sorokin, N. F. Orlov, and M. G. Voronkov, Zh. Obshch. Khim., 1978, 48, 2053

I57 A. Sekiauchi and W. Ando, Chem. Lett., 1978, 1385.

1182 (Chem. Abs., 1978, 89, 109 758).

(Chem. Abs., 1979, 90, 6472).

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Quinquevalent Phosphorus Acids 129 Because of the resultant extensive tautomerism, the course and end-point of

the reaction between C-phosphorylated acetaldehydes and active-methylene compounds can vary. Thus if, in the initial product (105), R1 and R2 are branched alkyl groups or X = S , the forward reaction ceases at that point. For more acidic active-methylene compounds such as cyanoacetic ester or dimedone, further reaction between the initial condensation product and active-methylene com- pound can occur, and in the case of cyanoacetic ester the final product is then (108).158 For less acidic active-methylene compounds the final position of tautomeric equilibrium depends on the nature of the dicarbonyl compound and on the nature of substituents on When Rf is OMe and R2 is Me, cycIization can take place to give 2-methoxy-2-oxo-3-methyl-4-substituted- 2,l-oxaphosphorin (109; X = 0), presumably through (107).16811s0 The azaphosphorine (109; X = NH) is formed similarly.lao

Several addition reactions of vinyl- and allenyl-phosphonates have been recorded. Sulphenyl chlorides add to allenylphosphonates at room temperature to give the compounds (l1O),ls1 and other allene compounds have been hydro- chlorinated with chlorosilanes in the presence of chloroplatinic acid to give, e.g., (111).la2 A study of the kinetics of the 1,3-cycloaddition of aryl azides to allenylphosphonic acid derivatives has indicated that the phosphorus atom allows the transmission of substituent electronic effects.ls3

R'2P(0)CH=C=CHKZ + PhSCl Rz= + R',P(O)CH(SPh)CCl=CH,

MeSiHCI, R' = C1, R*= Me I

Cl,P( 0 ) C H,CCl=CHMe (E t O),P(0)CR'=C=CR2R3

(1 11) (112)

The year has seen a number of communications by Russian authors which, to some extent, have paralleled those by Macomber et al., (see 'Organophosphorus Chemistry', Vol. 10, p. 144) although certain differences are also to be noted. Chlorination of diethyl propadienylphosphonate (1 12; R1 = R2 = R3 = H) gives both cyclic, i,e. (113; R1=R2=R3=H), and acyclic products, i.e. (114) and both (2)- and (E)-(115).164 However, the esters (112; R1=Me, Ra=R3=H)

158 M. P. Sokolov, B. G. Liorber, A. I. Razumov, V. V. Moskva, Z. Ya, Bulatova, and T. V. Zykova, Zh. Obshch. Khim., 1978,48,1032 (Chem. Abs., 1978,89,109 754).

159 M. P. Sokolov, B. G. Liorber, A. 1. Razumov, V. V. Moskva, Z. Ya. Bulatova, T. V. Zykova, and R. A. Salakhutdinov, Zh. Obshch. Khim., 1978,48, 1036 (Chem. Abs., 1979, 90, 5385).

160 A. I. Razumov, B. G. Liorber, M. P. Sokolov, T. V. Zykova, and R. A. Salakhutdinov, Zh. Obshch. Khim., 1978,48, 51 (Chem. Abs., 1978, 88, 121 316). N. G. Khusainova, E. A. Berdnikov, and A. N. Pudovik, Zh. Obshch. Khim., 1978, 48, 694 (Chem. A h . , 1978, 89, 43 608).

162 L. L. Erokhina, N. K. Skvortsov, and V. 0. Reikhsfel'd, Zh. Obshch. Khim., 1978, 48, 231 (Chem. Abs., 1978, 89,43 597).

163 N. G . Khusainova, Z . A. Bradikhina, E. S. Sharafieva, and A. N. Pudovik, Zh. Org. Khim., 1978,14, 2555 (Chem. A h . , 1979,90, 103 222).

164 T. S. Mikhailova, Kh. M. Angelov, V. M. Ignat'ev, A. V. Dogadina, V. I. Zakharov' B. I . Ionin, and A. A. Pettov, Zh. Obshch. Khim., 1977, 47, 2701 (Chem. Abs., 1978, 889 136 730); B. I. Ionin and A. A. Petrov, ibid., 1978,48,55 (Chem. Abs., 1978,88, 121 317).

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130 Organophosphorus Chemistry

and (1 12; R1 = R3 = H, R2 = Me) give the corresponding cyclic ester (1 13 ; R3=H) only as a mixture of cis- and trans-isomers. It was suggested that the influence of substituents on the course of the reaction is substantial, and the

formation of both the ions (116) and (117) was considered possible. In contrast to the results of Macomber et al., addition of HCl to the phosphonate (112; R1=H, Ra=Me) gives the ester (118), with none of the free cyclic acid (118; R1=H),ls5 but this may be a small point of difference, being the result of difference in acid strength or time of contact.

Me

(E tO),P(O)CH=CCl~H, (E tO),P( O)CH=&--CH,CI

2-Aminovinyl-phosphonates and -phosphinates add to activated carbon- carbon double bonds only if the nitrogen carries a free hydrogen.166 Aniline adds to 2-nitrovinyl-phosphonates to give l-anilin0-2-nitroethyl-phosphonates.~~~ 00-Dimethyl vinylphosphonothionate adds sodio diethyl thiophosphite in the expected manner, but it reacts with tripropylstannane to give a mixture of isomeric addition products.les The reactivity displayed by nitrones towards substituted vinylphosphonates increases with increasing electrophilicity of the vinyl double bond. lsB

Further details of the previously reported Pummerer rearrangement of a-phosphorylated sulphoxides, with transfer of chirality from sulphur to carbon, have appeared. 170

Alkylphosphonates with free a-hydrogens can be aminated by KNHz in NH3 (l), and also nitrated using lithium di-isopropylamide in THF followed by propyl nitrate, although yields are low and several by-products are formed, including dialkyl propyl phosphate and nitr0a1kene.l~'

165 T. S. Mikhailova, V. M. Ignat'ev, B. I. Ionin, and A. A. Petrov, Zh. Obxhch. Khim., 1978,48,701 (Chem. Abs., 1978, 89,41 837). A. I. Razumov, B. G. Liorber, M. P. Sokolov, A. Yu. Alikin, T. V. Zykova, T. A. Tarzivolova, and R. A. Salakhutdinov, Zh. Obshch. Khim., 1978, 48, 310 (Chem. Abs., 1978, 89, 6370).

167 L. A. Khidkova, M. G. Ivanova, G. M. Baranov, and V. V. Perekalin, Zh. Obshch. Khim., 1978,48, 1290 (Chem. Abs., 1978, 89, 109 779).

168 F. V. Bagrov and N. E. Galkina, Zh. Obshch. Khim., 1978, 48, 1422 (Chem. A h . , 1978, 89, 109 781).

169 B. A. Arbusov, A. F. Lisin, E. N. Dianova, and Yu. Yu. Samitov, Izu. Akad. Nauk SSSR, Ser. Khim., 1978, 2588 (Chem. Abs., 1979,90, 87 580).

170 M. Mikolajczyk, A. Zatorski, S. Grzejszczak, B. Costisella, and W. Midura, J . Org. Chem., 1978,43,2518.

171 H. Feutr. W. D. Van Buren. and J. B. Grutzner, J . Org. Chem., 1978,43, 4676.

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Quinquevalent Phosphorus Acids 131 A novel rearrangement occurs when the phosphinic amide (119) is treated

with alkoxide, being initiated by loss of a proton from the anilin~-group.'~* Treatment of the quaternary ammonium methylphosphonate (120) with t-butoxide anion yields a rearranged product (121). 173

The reaction between benzylideneaniline and dialkyl phosphites to give anilinobenzylphosphonates, e.g. (1 22; M = H), is already documented. Should the sodio diethyl phosphite be employed instead, the phosphoramidate (123 ; M = H) is formed via its sodio derivative, and an aminophosphonatephos- phoramidate rearrangement thus occurs. It becomes possible to isolate the intermediate (122) if the reaction is carried out under mild conditions. When

(122; M =Na) is heated, it undergoes rearrangement, and the product, when treated with methyl iodide, yields (123 ; M = Me). When (122; M= H) is treated with sodamide, a carbanion is produced which, however, when similarly methylated, reacts at carbon. The initial product (125) from the addition of diethyl hydrogen thiophosphite to the phosphonate (124) can, and does, rearrange in the two different ways indicated.174

172 K. A. Petrov, V. A. Chauzov, T. S. Erokhina, and 1. V. Pastukhova, Zh. Obshch. Khim.,

1 7 3 S . Kano, S. Hibino, and Y . Tanaka, Heterocycles, 1979, 9, 1257. 174 A. N. Pudovik, I. V. Konovalova, M. G. Zimin, and T. A. Dvoinishnikova, Zh. Obshch.

1977,47, 2749 (Chem. Abs., 1978, 88, 105 478).

Khim., 1978,48, 1241 (Chem. Abs., 1978, 89, 146984).

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132 Organophosphorus Chemistry

S 0

(E tO),PCHPhNPhP(OE t)2

0 S

(Et O),PCHPhNPhP(OEt),

0 S=P(OEt), II II ll

I 1 II + (EtO),FCPh=NPh + NaSP(OEt1, -+

(124)

(125)

When diphenylphosphinic hydrazide is treated with alkyl bromides in the presence of solid NaOH-K,CO,, alkylation occurs on N-1, allowing, by acido- lysis of the products, the preparation of N-alkyl-hydrazines. 175

The properties of silicon-containing organophosphorus compounds are beginning to prove useful in organic synthesis. The present example is based on the previously recorded reaction between silyl phosphites and aldehydes or ketones to give silyloxymethylphosphonates. Here, the phosphite (1 26), carefully chosen with regard to the alkyl groups of the trialkylsilyl group so as to preclude the possibility of migration of the silyloxy-group during reaction, reacts with saturated or unsaturated aldehydes to give (127) or (128) respectively. When treated with butyl-lithium, both (127) and (128) form anions which contain a disguised carbonyl group. The paper 176 contains several examples of applications of such anions.

0 0 OSiEt, I1 I

(Me,N),P-CHCH=CHR II

(Me,N),POSiEt, (Me,N),PCHR(OSiEt,)

Compounds possessing the 1,3,2,5-oxazadiphospholidine ring system (1 29) have been prepared as indicated.17?

0

+ R'O-P /c' heat (R'O),P( 0)C HRzNR3P 'OR?

(12%

Alkyl diphenylphosphinodithioates (1 30) are cleaved by alkyl- and aryl- lithiums to yield sulphides. In the specific case when R1=allyl, the products include allylbenzene (70 %) and traces of allyldiphenylphosphine sulphide, produced via Wittig rearrangement of the ester and loss of s ~ 1 p h u r . l ~ ~

1 7 5 B. Mlotkowska and A. Zwierzak, Tetrahedron Lett., 1978, 4731. 176 D. A. Evans, J. M. Takacs, and K. M. Hunt, J. Am. Chem. SOC., 1979,101, 371. 177 E. A. Suvalova, Zh. M. Ivanova, L. F. Kasukhin, M. P. Ponomarchuk, and Yu. G.

Gololobov, Zh. Obshch. Khim., 1978, 48, 1281 (Chem. Abs., 1978, 89, 109 778). 178 K. Koda, F. Hanafusa, and N. Inamoto, Bull. Chem. SOC. Jpn., 1978, 51, 818.

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Quitiquevalent Phosphorus Acids 133

The products of reaction between cycloalkenylphosphonothioic dichlorides and H,S have been assigned the structure (131) on the basis of their failure to react with ethanol; the more commonly described anhydrides, e.g. (1 32), undergo ring opening when treated with ethan01.l'~ The dithiophosphinic anhydride (1 32) has been employed in the preparation of thioketones,lsO thiocarbox- amides,lsl and thio- and dithio-esters,ls2 and in the conversion of sulphoxides into disulphides. la3 Salicylamides and (1 32) in HMPT yield the corresponding thiosalicylamides together with low yields of the 4H-1,3,2-benzoxazaphos- phorine derivatives (133; X = O or S).18*

S

(131) ri = 0 or 1

Examples of equilibria between 2-hydroxyphenyl esters of monocyclic phos- phonic and related acids and their spirobicyclic pentaco-ordinate tautomers continue to appear,ls5*la6 and the possibility that phosphorane-type compounds might act as intermediates in the reactions of tetraco-ordinate phosphorus esters continues to receive attention. However, papers have appeared which reflect the care needed in the experimental techniques and in the interpretation of results. Thus, Sigal and Westheimer ls7 allowed diphenyl methylphosphonate to hydrolyse in acidic 60 : 40 dimethoxyethane-water ; exchange of oxygen with

0. N. Grishina, N. A. Andrew, and E. I. Babkina, Zh. Obshch. Khim., 1978, 48, 1537 (Chem. Abs., 1978, 89, 163 675).

180 B. S. Pcdersen, S. Scheibye, N. H. Nilsson, and S. 0. Lawesson, Bull. SOC. Chim. Belg., 1978, 87, 223 (Chem. Abs., 1978, 89, 128 559).

181 S. Scheibye, B. S. Pedersen, and S. 0. Lawesson, Bull. SOC. Chim. Belg., 1978,87,229,299 (Chem. Abs., 1978, 89, 108 050, 109 787).

182 B. S. Pedersen, S. Scheibye, K. Clausen, and S. 0. Lawesson, Bull. SOC. Chim. Belg., 1978, 87, 293 (Chem. Abs., 1978, 89, 109 786). J. B. Rasmussen, K. A. J~rgensen, and S. 0. Lawesson, Bull. SOC. Chim. Belg., 1978, 87, 307 (Chem. Abs.. 1978,89, 109 788).

184 S. Scheibye, B. S. Pedersen, and S. 0. Lawesson, Bull. SOC. Chim. Belg., 1978, 87, 299 (Chem. Abs., 1978, 89, 109 787).

lS5 G. Kemp and S. Trippett, J . Chem. SOC., Perkin Trans. I , 1979, 879. I. Granoth and J. C. Martin, J. Am. Chem. SOC., 1978, 100, 5229.

lS7 I. Sigal and F. H. Westheimer, J . Am. Chem. SOC., 1979, 101, 752.

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134 Organophosphorus Chemistry solvent took place at approximately 8 % of the rate of hydrolysis, a finding which was explained by postulating bipyramidal intermediates. However, the importance of rigorous purification of solvents was demonstrated by Haake and co-workers,lss who have repeated their earlier experiments on the alkaline hydrolysis of methyl di-isopropylphosphinate in dimeth~xyethane-~H,O. They found that the induction periods, previously ascribed to the setting up of the phosphorane intermediate, are merely a function of the solvent, involving as they do the presence of peroxides in the dimethoxyethane. It is felt that the hydroxyl-assisted hydrolysis of the oxime of diethyl 2-oxopropylphosphonate could be the result of involvement of phosphorane intermediates. lSg

The rates of hydrolysis of aryl diphenylphosphinates lgo and aryl diphenyl- phosphinothionates lgl in alkaline medium have been measured.

For a series of w-diethoxyalkyl-phosphonates, the rate of acid-catalysed Al-type hydrolysis in dioxan decreases rapidly as the length of the alkyl chain decreases.lg2 Where the acetal moiety is cyclic, the rate of acid-catalysed hydro- lysis depends on the size of the acetal ring, but the results are in accord with a blend of mechanisms, neither specifically A1 nor A2.1D3

Three papers have been devoted to the study of the hydrolysis of simple acylphosphonates. Dimethyl acetylphosphonate in water is rapidly cleaved to acetic acid and dimethyl phosphite, the rate being first order in each of OH- and phosphonate, the tl12 at pH 7 and 25°C being about 3 s. In the initial stage the substrate is evidently rapidly hydrated at the carbonyl centre as a result of the strong withdrawal of electrons by the phosphoryl A series of dimethyl aroylphosphonates behaves similarly, although at pH > 6 the carbonyl- hydration step becomes slow compared with conversion into products, and the kinetics are complex.1g6 Other authors la6 have examined diethyl benzoyl- phosphonate in acidic media; the more acidic the medium the slower the hydrolysis to benzoic acid and diethyl phosphite through initial hydration of the carbonyl group. In approximately molar HCl solution, removal of ethoxy- groups also occurs. A mechanism has been proposed in which hydration at the phosphoryl bond is in equilibrium with that at the carbonyl centre.

Electrolysis of diethyl dichloromethylphosphonates (1 34) in the presence of aldehydes or ketones and using a mercury cathode yields the alkenes (135).lD7

(EtO),P(O)CCJR' + R2R3C0 4 R2R3C-CR'C1

(134) R' = C1 or C0,Et (135)

188 J. Rahil, R. D. Cook, and P. Haake, J. Am. Chem. SOC., 1979, 101, 1322. 189 P. Livant and M. Cocivea, J. Org. Chern., 1978, 43, 3011. loo B. L. Finkel'shtein, Yu. I. Sukhorukov, and B. I. Istomin, Urg. React. (Tartu), 1977, 14,

191 G. D. Eliseeva, B. I. Istomin, and A. V. Kolabina, Zh. Obshch. Khim., 1978, 48, 1901 181 (Chem. Abs., 1978, 89,41 817).

(Chem. Abs., 1978, 89, 179 146). S. Yanai, D. Vofsi, and M. Halmann, J. Chem. Soc., Perkin Trans. 2, 1978, 517.

lo$ S. Yanai, D. Vofsi, and M. Halmann, J. Chem. SOC., Perkin Trans. 2, 1978, 511. lQ4 R. Kluger, D.. C. Pike, and J. Chin, Can. J. Chem., 1978, 56, 1792. lD5 R. Kluger and J. Chin, 3. Am. Chem. Soc., 1978, 100, 7382. lo8 K. S. Narayanan and K. D. Berlin, J. Am. Chem. SOC., 1979, 101, 109. le7 G. Karrenbrock, H. J. Schtiffer, and I. Langer, Tetrahedron Lett., 1979, 2915.

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Quinquevalent Phosphorus Acids 135 The polymer (1 36), obtained using the ring-opening Arbusov reaction

indicated, is thermally depolymerized to give 5,5-dimethyl-2-phenyl-1,3,2- dioxaphosphorinan 2-oxide.

Further details of the acidolysis of alkyl aryl(diazoalky1)phosphinates with HCI (see also ‘Organophosphorus Chemistry’, Vol. 8, p. 128) to give erythro- and threo-alkyl aryl(a-chloroalky1)phosphinates together with alkenes have been presented.lsg Alkenes are also formed in high yields during the photolysis of the alkyl phenyl(1 -diazopropyl)phosphinates. 2oo Photolysis of dimethyl cc- diazobenzyl-phosphonates (1 37) gives products that are temperature-dependent. Reaction in alcohols at room temperature leads to O-H insertion products; in a frozen alcohol matrix at - 196”C, insertion into C-H takes place.2o1

0 II RCH,OH

(MeO),P(O)CHPh +* (MeO),P-CPh - ho * (MeO),P(O)CHPh

RCHOH I l l

N* I OR

(137)

Isomerization of C-phosphorylated vinylcarbenes has been shown to give cyclopropenes, allenes, acetylenes, indenes, and butadienes. 202

Full details have appeared of Harger’s work on the stereochemical effects of CI- on the hydrolysis of N-aryl methylphenylphosphinic amides, and dealt with in last year’s Report.20S

198 G. Singh, J . Org. Chem., 1979, 44, 1060. 199 R. D. Gareev and A. N. Pudovik, Dokl. Akad. Nauk SSSR, 1978,240, 1115 (Chern. Abs.,

500 R. D. Gareev, and A. N. Pudovik Zh. Obshch. Khim., 1978, 48, 226 (Chem. Abs., 1978,

201 H. Tomioka, T. Inagaki, S. Nakamura, and Y . Izawa, J. Chem. SOC., Perkin Trans. I ,

202 W. Welter, A. Hartmann and M. Regitz, Chem. Ber., 1978, 111, 3068. a03 M. J P. Harger, J. Chem. SOC., Perkin Trans. I , 1979, 1294.

1978, 89, 109 789).

88, 136 025).

1979, 130.

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