Addition reactions of lithium ester enolates, α-lithionitriles, and sodium amides to dimethyl(vinyl)sulphonium salts

Abstract

Reactions of dimethyl(vinyl)sulphonium salts (1) with some lithium ester enolates and α-lithionitriles (2) give cyclopropanes (3). However, when the α-carbon atoms of the lithium salt are tertiary [compounds (4)] butene derivatives (5) are formed. With α-lithiopropio- and α-lithiobutyro-nitriles (8), moreover, pyrrolines (11) are obtained. Sodium N-methylacetamide adds to dimethylstyrylsulphonium perchlorate (1a) to yield N-methyl-N-(1-phenylvinyl)acetamide (16).