Bifunctional Thiourea–Ammonium Salt Catalysts Derived from Cinchona Alkaloids: Cooperative Phase-Transfer Catalysts in the Enantioselective Aza-Henry Reaction of Ketimines

An efficient enantioselective aza-Henry reaction of aryl α-ketoester-derived ketimines has been realized by using bifunctional thiourea–ammonium salt phase-transfer catalysts, which were derived from quinine. A variety of aryl α-ketoester-derived N-Ts ketimines were investigated, and the corresponding products were obtained in high to excellent yields (up to 99%) with good to high enantioselectivities (up to >99% ee).