The asymmetric vinylogous Mannich reaction of noncyclic dicyanoolefins catalyzed by a bifunctional thiourea–ammonium salt phase transfer catalyst†
Abstract
An efficient enantioselective vinylogous Mannich reaction of N-Boc aminosulfones with noncyclic α,α-dicyanoolefins has been realized using an extraordinary bifunctional thiourea–ammonium salt phase transfer catalyst derived from quinine. A variety of N-Boc aminosulfones and α,α-dicyanoolefins were investigated, and the corresponding products were obtained in excellent yields (up to 99% yield) with excellent enantioselectivities (up to 98% ee). The desired product can be easily converted to a valuable amino ketone.