Asymmetric One-Pot Conjugate Addition of Grignard Reagents to alpha,beta-Unsaturated Compounds Followed by Reaction with Carbenium Ions

摘要

Asymmetric catalytic multistep reactions enable the formation of structurally complex compounds from simple starting materials. Enantioselective Cu-catalyzed 1,4-additions of Grignard reagents to Michael acceptors form reactive chiral enolates. We show here that these chiral enolates react in a one-pot fashion with naked carbenium ions, such as tropylium, 1,3-benzodithiolium, and dianisylmethylium ions. The corresponding products were obtained in good yields, with enantioselectivities up to 96% ee and high diastereomeric purities.