Diastereoselectivity of conjugate addition to γ-alkoxy-α,β-unsaturated esters via organocopper–Lewis acids and related reagents. Importance of the double bond geometry in controlling the selectivity

Abstract

The Lewis acid mediated addition of organocopper reagents to the trans-ester (7a) produced the anti-isomer (8a) predominantly, while addition to the cis-derivative (7b) gave the syn-isomer (9a) preferentially, and addition of organometallic compounds to the diester (7c) also afforded the syn-isomer (9b) predominantly; this change in diastereoselectivity indicates the importance of the double bond geometry in controlling the 1,2-asymmetric induction of γ-alkoxy-α,β-unsaturated carbonyl compounds.