Enantioselective Vinylogous Michael Addition of α,α-Dicyanoolefins to Azadienes Catalyzed by an L-Tert-Leucine-Derived Squaramide Catalyst

A highly enantioselective vinylogous Michael addition reaction of azadienes with α,α-dicyanoolefins, catalyzed by a squaramide catalyst derived from L-tert-leucine, has been developed. A variety of azadienes and α,α-dicyanoolefins were investigated, and the corresponding products were obtained in high yields (up to 99%) with excellent enantioselectivity (up to 98% ee). Notably, these enantioenriched products could be readily converted to functionalized arylthiophene derivatives, a class of compounds with significant potential for pharmaceutical applications.