Enantioselective Construction of Vicinal Sulfur-functionalized Quaternary and Tertiary Stereocenters via Organocatalytic Michael Addition of 5H-Thiazol-4-ones to 1-Azadienes

An organocatalytic enantioselective Michael addition of 5H-thiazol-4-ones to 1-azadienes has been developed. In the presence of chiral phosphoric acid, a series of optically active benzofuran derivatives featured by vicinal sulfur-containing quaternary and tertiary stereocenters were obtained in high yields (71-99%) with high stereoselectivities (70-96%eeand 8 : 1-20 : 1 d.r.).