Use of the stereospecific condensation of,!? carbalkoxysulfones with aldehydes, followed by the stereospecific reduction of the afforded sulfonyl acrylate with sodium dithionite allows us to propose this method as a new way to prepare 2 a,@ unsaturated esters. Steric hindrance seems to be the reason for the selectivity of the reduction and the mechanism was proved, by X-ray of an intermediate, to be a cis Michael addition of HS02-, followed by an anti ...
