Keto-sulphides

Matsuda, and Y. Kishida, Chem. andPharm. Bull. (Japan), 1971,19,2207. 

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In this approach the keto aldehyde (96) was subjected to Michael addition with p-keto sulphide to obtain the adduct (103) in quantitative yield. These adducts differ in configuration only at C-ll or at sulfur... 

Desulphurization of / -keto-sulphides by tris(dimethylamino)phosphine is thought to proceed via a phosphonium salt intermediate, e.g. (52), which can collapse to give a variety of products depending upon the substrate used and the reaction conditions. ... 

Tris(dimethylamino)phosphine desulphurizes / -keto-sulphides (60) to give ketones and enol ethers as major products a mechanism involving initial... 

Lithium or copper enolates, generated in situ by conjugate reduction of afi-unsaturated ketones, may be trapped by MeSSMe, PhSSPh, or PhSCl to give the /S-ketosulphide. /3-Keto-sulphides and -selenides are available on chloral-alumina oxidation of the corresponding /3-hydroxy compounds. The latter compounds may be prepared by alumina-promoted epoxide ring opening by thiols and selenols (Scheme 16). ... 

Diacids.—Cyclic /3-keto-sulphides, which are easily prepared from the parent ketone, can be oxidized to the acetates (7), which on further oxidation with alkaline hydrogen peroxide undergo ring opening to aw-diacids (Scheme 4). Similar treatment of linear carboxylic acid esters, but using iodine in methanol in the final step, leads to a a-keto-ester ketals (8). 

Thioacetals have been converted into -keto-sulphides by reaction... 

Preparation.—In addition to a number of reactions of thiols, discussed in the preceding section, a variety of other routes have been explored for the preparation of sulphides. U.v. irradiation of thiolesters gives mixtures (CHa CO SPh gives PhSH, PhSMe, o- and p-AcPhSH, and disulphides as major products), while addition of an alkyl halide to a thiolester in the presence of strong base (LiH, PhgCLi, etc.) provides a one-step route. A novel /3-keto-sulphide synthesis from a 1,2-diketone is illustrated by the conversion of (29) into (30). ° Alternative routes to jS-keto-sulphides often... 

Keto-sulphides.—The activated methylene group in Ph CO-CHaSMe undergoes typical substitution reactions, e.g. hydrazone formation with a diazonium cation (58). Phenacyl sulphides give the corresponding ketone... 

Books published recently include several that are wholly devoted to organosulphur compoundsand others " in which specific chapters are relevant to the coverage in this chapter. Reviews have appeared that deal with applications of organosulphur compounds in synthesis " (including uses of yff-keto-sulphides, vinyl sulphones, and vinyl sulphides ) and the synthesis of organosulphur compounds,sulphenyl compounds, indolethiols, allenic sulphides and sulphenamides, organosilyl sulphides, selenides, and tellurides, optically active... 

Miller and D. R. McKean, Tetrahedron Lett., 1979, 1003 [cyclobutanones - y-keto-sulphides with PhSH, ZnClj, and HCl] R. W. Gray and A. S. Dreiding, J. Indian Chem. Soc., 1978,55,1224 [Cl substitution accompanied by dehydrochlorination and dehydrobromination by PhS, leading to 2-(phenylthio)-3,7-dehydrotropone] B. C. Musial and M. E. Peach, Phosphorus Suffitr, 1977, 3,41 ... 

Functional Groups.—Kinetic studies of dehydrochlorination reactions in the gas phase reveal participation of neighbouring groups in aliphatic 2-chloroethyl sulphides. Physical studies indicate interactions of functional groups in /ff-keto-sulphides and in the corresponding nitriles. A more unusual example of participation by sulphur is the enhanced rate of reduction by 1 of y-(methylthio)alkyl methyl sulphoxides. ... 

A small number of papers that cover mechanistic aspects deal with the factors that stabilize the developing carbonium ion in the hydrolysis of 0,S-thioacetaIs. An electron-transfer, mild reduction system (iron polyphthalocyanine) has been shown to reduce benzil dithioacetal to the / -keto-sulphide [PhCOCPh(SPh)2 PhCOCHPhSPh]. Homolysis of dithioacetals on heating with BuKDOBu in PhCI followed by a 1,2-shift of an alkylthio-group leads to l,2-bis-(alkylthio)alkyl compounds/ ... 

Trimethylsilyl alkenyl ethers (511), prepared by reaction of the corresponding ketones with trimethylsilyl chloride in DMF, react with polyhalo-geno-compounds in boiling DMF-chlorobenzene in the presence of cuprous chloride to give halogeno-ajJ-unsaturated ketones (512). The ethers (511) also react with phenylsulphenyl chloride to give / -keto-sulphides (513) and with di- and tri-chloroacetyl chlorides to give 1,3-diketones (514). ... 

As keto-sulphides are useful synthetic intermediates, a new method of preparation is welcome. The reaction involves treatment of a-thiocarbanions with pentacarbonyliron followed by work-up with methyl iodide (Scheme 45). ... 

Stable thiet cations (64) reportedly were isolated by treatment of certain /3-keto-sulphides with phosphorus oxychloride. Addition of sodium hydride... 

The photochemical synthesis of a thiepin 1,1-dioxide from a 4/f-thiopyran-4-one 1,1-dioxide has been reported earlier (see Vol. 3, p. 528). The j8-keto-sulphides (13) and (14) underwent photochemical rearrangement, involving a 1,3-sulphur shift, which yielded complex 2,3,4,5-tetrahydrothiepin-3-one derivatives. ... 

Alkylation of thiols is represented by their reaction with O-alkyl NN-di-cyclohexylureas at 100—110 and -keto sulphide synthesis using CF3-... 

S Ag"" and a-bromoketones an alternative route to -keto-sulphides employs an aldehyde and LiCH(SPh)2, and treatment of the adduct with MeLi. Sulphur ylides are now shown to be capable of acting as C—S transfer agents, in addition to their well-known ability to alkylate through carbon. Among five products from cyclopropenium cations and are a 3-methylthio-cyclobutene and a 3-methylthiomethyl-cyclopropene. The use of Bunte salts in sulphide synthesis is illustrated by the synthesis of 1- of 2-naphthyl sulphides from the naphthols with sodium benzylthiosul-phate. ... 

Substitution reactions of simple sulphenyl chlorides with features of additional interest include 1,3-dithiolan formation by reaction of 1,2-disulphenyl chlorides at a methylene group o to —CHO formation of cK-chloro- -keto-sulphides from sulphenyl chlorides and adducts of phosphines with 1,2-dicarbonyl compounds free-radical substitution of saturated alkanes by C6CI5SCI and synthesis of aa-dinitroalkyl sulphides by treatment of gem-dinitroalkanes with sulphenyl chlorides in the presence of base. ... 

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