Diastereoselective conjugate addition reactions of chiral organocuprates provide β-functionalized ketones in high yield and diastereoselectivity. A disadvantage of these reactions is the requirement of a full equivalent of enantiopure starting material.
More recently, catalytic enantioselective methods have been developed based on the copper(I)-catalyzed conjugate addition of Grignard reactions to enones. The proposed mechanism involves transmetalation from the Grignard reagent to copper, conjugate addition, and rate-determining reductive elimination (see the analogous upper pathway in equation (2)).