Oxodimethoxyphosphoranesulfenyl Chloride1

(1; R1 = R2 = OMe)

[13894-35-4]  · C2H6ClO3PS  · Oxodimethoxyphosphoranesulfenyl Chloride  · (MW 176.57) (2; R1 = R2 = OEt)

[1186-08-9]  · C4H10ClO3PS  · Oxodimethoxyphosphoranesulfenyl Chloride  · (MW 204.63) (3; R1 = R2 = O-i-Pr)

[55655-36-2]  · C6H14ClO3PS  · Oxodimethoxyphosphoranesulfenyl Chloride  · (MW 232.69)

(reacts as a pseudohalogen;1 adds across alkenes and alkynes with little regioselectivity;2-5 can thiophosphorylate aldehydes and ketones a to the carbonyl6)

Physical Data: (1) bp 50 °C/0.06 mmHg. (2) bp 50 °C/0.2 mmHg. (3) bp 86 °C/2 mmHg.

Solubility: sol CH2Cl2, CCl4, benzene, diethyl ether, THF.

Form Supplied in: yellow liquids; not commercially available.

Preparative Methods: prepared from a variety of different precursors using the procedures shown in eq 1.1

Handling, Storage, and Precautions: stability is in the order: phosphoro, (R1O)2P- > phosphono, (R1O)R2P- > phosphino, R1R2P-. Phosphoryl derivatives are quite stable and may be distilled under vacuum. They decompose upon storage, even at low temperatures, and are often prepared and used in situ. Phosphono derivatives lose sulfur on heating and phosphino derivatives lose sulfur at 20 °C and are only moderately stable at 0 °C.

Additions to Alkenes.

The addition of phosphoranesulfenyl chlorides to alkenes is not as regioselective as similar additions of methanesulfenyl chloride or other alkyl- and arylsulfenyl chlorides where anti-Markovnikov products tend to predominate.2 This is due to the fact that additions of phosphoranesulfenyl chlorides proceed by an AdE2 mechanism which does not necessarily involve a thiiranium ion intermediate, in contrast to those of C-sulfenyl chlorides.3,7 The electron-withdrawing property of the phosphorus impairs the bridging ability of the sulfur atom sufficiently to make the intermediate possess more carbonium ion character, with the chloride counterion more closely associated with the sulfur atom.2,8 Also, the oxygen atom attached to phosphorus may contribute to stabilization of cationic intermediates (eq 2).3

The additional regiochemical dependence of these additions on the steric and electronic effects of the alkene and phosphorus substituents can contribute to the low regioselectivity of these reactions (eqs 3 and 4).3,4

Addition to Alkynes.

The substantial amount of cis product produced in the addition of phosphoranesulfenyl chlorides to alkynyl compounds is evidence for an unsymmetrical reaction intermediate in which an appreciable amount of positive charge is localized on one carbon atom (eq 5).5

Addition to Allylsilanes and Allylstannanes.

Reaction of phosphoranesulfenyl chlorides with allylsilanes and allylstannanes is similar, with both giving the products of an SE2 mechanism (although this mechanistic pathway has not been proven).5 In the case of allylsilanes, however, other products are also formed (eq 6).

Reaction with Aldehydes and Ketones.

Aldehydes and ketones may be thiophosphorylated a to the carbonyl by reaction of silyl enol ethers with phosphoranesulfenyl chlorides (eq 7).6

Reaction with Acetylide Anions.

The preparation of S-ethynyl esters of thiophosphoric acids occurs in moderate yield by the reaction of phosphoranesulfenyl chlorides with Ethynylmagnesium Bromide (eq 8).9

Reaction with a-Diazo Ketones.

Reaction of phosphoranesulfenyl chlorides with a-diazo ketones may be performed in CH2Cl2 or ether at -15 °C, or in benzene at 6 °C. Since these reaction conditions preclude the formation of a carbene intermediate, the reaction is thought to proceed via a diazonium cation to give a-chloro-substituted esters of thiophosphoric acid (eq 9).10

1. (a) Capozzi, G.; Modena, G.; Pasquato, L. In The Chemistry of Sulphenic Acids and their Derivatives; Patai, S., Ed.; Wiley: New York, 1990; p 403. (b) Kuehle, E. The Chemistry of Sulphenic Acids; Theime: Stuttgart, 1973.
2. Mueller, W. H.; Rubin, R. M.; Butler, P. E. JOC 1966, 31, 3537.
3. Kutyrev, G. A.; Sadykova, L. A.; Cherkasov, R. A. JGU 1991, 61, 1821.
4. Kutyrev, G. A.; Vinokurov, A. I.; Ishmaeva, E. A.; Shakirov, I. K.; Shagidullin, R. R.; Cherkasov, R. A.; Pudovik, A. N. JGU 1979, 49, 458.
5. Kutyrev, G. A.; Kapura, A. A.; Cherkasov, R. A.; Pudovik, A. N. JGU 1985, 55, 1919.
6. Dybowski, P.; Skowronska, A. S 1990, 609.
7. (a) Kutyrev, G. A.; Vinokurov, A. I.; Cherkasov, R. A.; Pudovik, A. N. DOK 1979, 245, 306. (b) Kutyrev, G. A.; Vinokurov, A. I.; Istomina, B. I.; Cherkasov, R. A.; Pudovik, A. N. IZV 1981, 51, 837.
8. Mueller, W. H. AG(E) 1969, 8, 482.
9. Godovikov, N. N.; Vikhreva, L. A.; Babsheva K. K.; Sherstobitov, O. E.; Balashova, E. K.; Kugusheva, L. I.; Rozengart, V. I.; Brestkin, A. P.; Kabachnik, M. I. IZV 1983, 1453.
10. (a) Khaskin, B. A.; Makhaeva, G. F.; Torgasheva, N. A.; Ishmuratov, A. S.; Yankovskaya, V. L.; Fetisov, V. I.; Malygin, V. V.; Martynov, I. V. IZV 1989, 2508. (b) Khaskin, B. A.; Ishmuratov, A. S.; Torgasheva, N. A. JGU 1991, 61, 993.

Helen M. Organ

Merck Research Laboratories, Rahway, NJ, USA

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