Cascade Michael−Aldol Reactions Promoted by Hydrogen Bonding Mediated Catalysis

Highly enantio- and diastereoselective tandem Michael−aldol reactions, efficiently catalyzed by a cinchona alkaloid thiourea via synergistic noncovalent hydrogen-bonding activation of both the Michael donor and acceptor, have been developed. The process affords a powerful means for the construction of versatile chiral thiochromanes with the formation of three stereogenic centers in a one-pot synthesis from simple achiral compounds.