Enantioselective Aza‐Henry Reaction of Imines Bearing a Benzothiazole Moiety Catalyzed by a Cinchona ‐Based Squaramide

An efficient enantioselective aza‐Henry reaction of nitroalkanes to imines bearing a benzothiazole moiety catalyzed by a Cinchona ‐based squaramide has been developed. In the reaction of imines, the corresponding products were obtained in good to excellent yields (up to 99%) with excellent enantioselectivities (up to >99% ee ) for most of the aromatic substituted imines. The imines with electron‐withdrawing groups gave better yields than those bearing electron‐donating groups in the aza‐Henry reaction. Moreover, a one‐pot three‐component enantioselective aza‐Henry reaction using 2‐aminobenzothiazoles, aldehydes, and nitromethane was also developed. Moderate to good yields and high enantioselectivities were obtained in the one‐pot cases (up to 98% ee ).