SYNTHESIS OF ENANTIOPURE 2-MALONYLVINYL SULFOXIDES VIA ADDITION-ELIMINATION REACTIONS OF 2-HALOVINYL AND 2-(MESYLOXY)VINYL SULFOXIDES

Enantiomerically pure (E)-2-bromo- and (E)-2-iodovinyl sulfoxides 3a a nd 3b have been prepared in multigram quantities from (E)-1,2-bis(tri- n-butylstannyl)ethene; enantiomerically pure (E)-2-(mesyloxy) vinyl su lfoxide 3c has been synthesized by reaction of the enolate derived fro m condensation of 1-lithiomethyl p-tolyl sulfoxide and DMF with methan esulfonyl chloride. These compounds react with anions derived from die thyl alkylmalonates to produce enantiopure 2-malonylvinyl sulfoxides i n good to excellent yields and with a high degree of stereoselectivity . The transformations proceed through an ''addition-rotation-eliminati on'' sequence, and the stereochemical results reinforce the concept th at nucleophilic additions to vinyl sulfoxides are sterically controlle d and occur predominately syn to the sulfinyl electron lone pair.