Reaction of sulphimides with electrophilic acetylenes
Abstract
Stable sulphonium imidoylides (2) have been isolated from the reaction of N-aryl-SS-dimethylsulphimides (1) with electrophilic acetylenes at room temperature. Similar ylides (2) are also formed from SS-dimethyl-N-phthalimidosulphimide. The ylides (2a, c, and e) give the pyrroles (3) when heated with a further mol. equiv. of dimethyl acetylenedicarboxylate or dibenzoylacetylene. The ylide (2c) reacts with other electrophiles, including hydrogen chloride, iodomethane, benzoyl chloride, and cyanogen bromide; these reactions (Scheme 5) involve electrophilic attack at the nitrogen atom of the ylide followed by nucleophilic attack at sulphur or at an S-methyl group.