Diastereoselectivity of conjugate addition to γ-alkyl-α,β-unsaturated esters; stereocontrol with the aid of organocopper reagents

Abstract

The conjugate addition of organo-cuprate and -copper reagents to the trans-ester (1) produced the anti-isomer (4a) predominantly, while addition of cuprates to the cis-esters (2 and 3) gave the syn-isomer (5) preferentially, and addition of organocopper compounds to (2) and (3) afforded the anti-isomer (4) predominantly; this change indicates the importance of reagent type in controlling 1,2-asymmetric induction during conjugate addition.