Sulphoxide as a Reagent

Methylthiolation of 2-bromoanisole, giving (111), is brought about with dimethyl sulphoxide and NaH at 60—65 °C. 4-Bromoanisole gives a mixture of the corresponding 3- and 4-methylthio-isomers. Mono-halogenonaphthalenes on treatment with dimethyl sulphoxide, Bu OK, and Bu OH at 140 °C give naphthols, t-butyl ethers, and l-methylthio-2- 

The Fe -HgOg-dimethyl sulphoxide system is a source of methyl radicals, but in addition to mono-, di-, and tri-methylated benzoquinones, (112), (113), and isomers of (113) are formed from benzoquinone.  

The sodium salt of the methylsulphinyl carbanion, Me SO CH2 Na+, has simple uses in synthesis, such as converting alcohols into alkoxides, for the synthesis of ethers by alkylation with an alkyl halide, or for synthesis of xanthates by successive treatment with CSa and an alkyl halide. The method is useful for reactions with tertiary alcohols. 

Chen and C.-H, Wang, Bull. Inst. Chem., Acad. Sinica, 1970, 30 (through 

Meurling, K. Sjoberg, and B. Sjoberg, Acta Chem. Scand., 1972, 26, 279. 

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Reactions of Sulphoxides.—The general features of the reactions of sulphoxides can be illustrated by reference to the simplest structural types, without regard for stereochemical details. A minority of the new work published within the period under review falls within this category when the well-defined uses of dimethyl sulphoxide as a reagent are considered separately (p. 50), but interpretation of the reactions of sulphinyl compounds with chirality at sulphur fully in view is the outstanding feature of recent work. 

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