A Michael Addition and Peterson Olefination Sequence Using 1-Silylethenyl Sulfides and Sulfoxide

Abstract
Reaction of organolithiums with a 1-(trimethylsilyl)ethenyl sulfide produces 1,2-bis(trimethylsilyl)cyclopropanes, while use of 1-silylethenyl sulfides bearing a bulkier silyl moiety results in exclusive formation of the corresponding Michael adduct anions which are then quenched with aldehydes to give vinyl sulfides. On the contrary, a 1-(trimethylsilyl)ethenyl sulfoxide undergoes smooth Michael addition with a variety of organo-metallics and the resulting carbanion intermediates can be quenched with aldehydes to produce vinyl sulfoxides. Scope and limitations of these sequential reactions are discussed.