Asymmetric Hydrogenative Coupling of Indoles with Unsaturated Ketones Enabled by Copper/Ruthenium Relay Catalysis

A relay catalytic system has been developed for the asymmetric hydrogenative coupling of indoles with α,β-unsaturated ketones, affording enantioenriched chiral γ-indole alcohols with broad substrate scope and excellent enantioselectivities (32 examples, up to >99% ee). Mechanistic studies suggest that the relay catalytic system consists of a copper-catalyzed alkylation and ruthenium-catalyzed asymmetric hydrogenation.