A proline-catalyzed asymmetric Robinson annulation reaction

A single-step enantioselective synthesis of the Wieland-Miescher ketone (5) is presented. We show that L-proline as well as a number of other chiral amines can act as catalysts of both steps of the Robinson annulation reaction. Other chiral amines are identified as catalysts of Michael and aldol addition reactions. (C) 2000 Elsevier Science Ltd. All rights reserved.