Olefination with Sulfonyl Halides and Esters: Scope, Limitations, and Mechanistic Studies of the Hawkins Reaction.

Carbanions of alkanesulfonyl halides and esters react with nonenolizable carbonyl compounds to give olefins. Mechanistic studies reveal that initial aldol-type addition of the carbanions is followed by cyclization-fragmentation to alkenes, and the leaving group on the sulfonyl moiety (RSO2X) controls carbanion stability and rate of the olefin formation.