Stereocontrol in asymmetric S(E)' reactions of γ-substituted α,β-unsaturated aldehydes.

Asymmetric SE' reactions of (E)- and (Z)-γ-substituted-α,β-unsaturated aldehydes have been studied for the stereocontrolled preparation of nonracemic alcohols. Mild exchange reactions of allylic stannanes provide access to chiral 1,3-bis(tolylsulfonyl)-4,5-diphenyl-1,3-diaza-2-borolidines. These reagents display reactivity with the γ-substituted α,β-unsaturated aldehydes, which is characterized by matched and mismatched elements of stereocontrol.