Enantioselective Conjugate Silyl Additions to α,β‐Unsaturated Aldehydes Catalyzed by Combination of Transition Metal and Chiral Amine Catalysts

We report that transition metal‐catalyzed nucleophilic activation can be combined with chiral amine‐catalyzed iminium activation as exemplified by the unprecedented enantioselective conjugate addition of a dimethylsilanyl group to α,β‐unsaturated aldehydes. These reactions proceed with excellent 1,4‐selectivity to afford the corresponding β‐silyl aldehyde products 3 in high yields and up to 97:3 er using inexpensive bench stable copper salts and simple chiral amine catalysts. The reaction can also generate a quaternary stereocenter with good enantioselectivity. Density functional calculations are performed to elucidate the reaction mechanism and the origin of enantioselectivity.