Z/E selective synthesis of β,β-disubstituted and (Z)-β- monosubstituted Baylis-Hillman adducts via anionic additions of vinylcuprates to aldehydes

A new method has been developed for the synthesis of achiral β,β- disubstituted and (Z)-β-monosubstituted Baylis-Hillman adducts with excellent Z/E stereospecificity in some cases. The process involves the conjugate additions of R₂CuLi or RMgBr-CuBr-DMS to α,β-acetylenic esters and followed by additions of anionic α-(alkoxycarbonyl)vinyl]copper intermediates to aldehydes. The individual Z- and E- isomers of the resulting β-branched α-(hydroxylalkyl)acrylates can be separated by column chromatography in modest to excellent yield.