Enantioselective construction of spirooxindole derivatives through [3+2] annulation catalyzed by a bisthiourea as a multiple-hydrogen-bond donor

Abstract

Anything between ureas? Spiro[isoxazolidine-3,3'-oxindole]s have been constructed by employing methyleneindolinones and nitrones as the starting materials through [3+2] annulation catalyzed by a bisthiourea. Products with three contiguous stereocenters, including one spiroquaternary stereocenter, are obtained in good yields with excellent enantio- and diastereoselectivity. The bisthiourea catalyst acts as a multiple-hydrogen-bond donor to simultaneously activate both substrates.