Amino-sulphonium Salts

The other main direction of investigation involves the treatment of succinimido- or hydantoinyl-sulphonium salts [e.g. (50) and (51)] with tertiary amines, which affords interesting [2,31- or U,3]-sigmatropically rearranged products e.g. (52)]. The amino-sulphonium salt (51), upon treatment with a carboxylic acid, forms the corresponding carboxy-sulphonium salt as an intermediate, which then reacts with amines to form the acid amides.The synthesis of 9-alkyl- or of 9-phenyl-thioxanthene-iV-(toluene-/7-sulphonyl)sulphimides (53) has been reported. The configuration of (53) has been determined by H n.m.r. 

An intermediate (90) has been identified in the oxidation of a sulphide to a sulphoxide by l-chlorobenzotriazole. This contributes a further example to the growing number of putative quadricovalent sulphur intermediates involved in reactions of divalent sulphur compounds. Reaction of (90) with an alcohol in the presence of AgBp4 gives an alkoxy-sulphonium salt, while a secondary amine similarly gives an amino-... 

Diorgano-sulphiniides and Azasulphonium Salts.—(See also Chapter 1, p. 50.) For efficient -amination of sulphides under very mild conditions O-mesitylene-sulphonylhydroxylamine (MSH) appears to be the reagent of choice. Thus various types of sulphides were converted into a series of novel S -amino-sulphonium mesitylenesulphonates (41) (Scheme 2), the deprotonation of which afforded the more or less stable free sulphimides (44). Reactions of allyi... 

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