Catalytic asymmetric aza-Michael-Michael addition cascade: enantioselective synthesis of polysubstituted 4-aminobenzopyrans.

A catalytic asymmetric aza-Michael-Michael addition cascade of anilines to nitroolefin enoates in the presence of chiral bifunctional thiourea catalysts has been disclosed. This reaction provides a mild and efficient approach to polysubstituted chiral 4-aminobenzopyrans bearing three consecutive stereocenters in high yields with excellent stereoselectivities.