Organocatalytic Asymmetric Michael Addition of Rhodanines to Azadienes for Assembling of Sulfur-containing Tetrasubstituted Carbon Stereocenters

The squaramide catalyzed enantioselective Michael addition of rhodanines to 2-arylidene-N-tosylbenzofuran-3(2H)-imines has been established, which enables the formation of benzofurans bearing both rhodanine and sulfur-containing tetrasubstituted stereocenter structural motif in good to high yields with good to excellent enantio- and diastereoselectivities.