Enantioselective Cyanosilylation of ,-Dialkoxy Ketones by Using Phosphine-Thiourea Dual-Reagent Catalysis

The first highly enantioselective cyanosilylation of ,-dialkoxy ketones enabled by a dual-reagent catalysis has been developed. With the combination of a chiral bifunctional phosphine-thiourea and methyl acrylate, the key organophosphorus zwitterion intermediate was generated in situ as a novel Lewis base, which catalyzed the enantioselective cyanosilylation reaction in excellent yields (up to 99%) with good-to-excellent enantioselectivities (up to 94% ee).