Ylide rearrangement in adducts from allenic sulphonium salts and malonic esters

Abstract

Addition of malonic esters to allenic sulphonium salts gives products derived from subsequent reactions of the initial adducts by two pathways which involve ylide rearrangement; structural factors which determine the pathways are defined. MUCH recent work on unsaturated sulphonium salts has been concerned with ylide rearrangement and with synthetic application of addition reactions. We now report the diverse rearrangement pathways which follow nucleophilic addition of malonates to allenic sulphonium salts.