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.
Enantioselective Conjugate Silyl Additions to α,β-Unsaturated Aldehydes Catalyzed by Combination of Transition Metal and Chiral Amine Catalysts
SANTORO, STEFANO;
2011
Abstract
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.