Studies on the Enantioselective Kinugasa Reaction: Efficient Synthesis of β‐Lactams Catalyzed by N‐PINAP/CuX Complexes

Abstract

AbstractCatalytic enantioselective Kinugasa reactions between acyclic and, for the first time, cyclic nitrones and terminal alkynes are described herein. A catalytic amount of the readily available PINAP/CuX complexes, generated in situ, efficiently catalyzed the Kinugasa reactions, leading to a series of β‐lactams with good enantioselectivities and moderate diastereoselectivities and yields. A broad range of nitrones and terminal alkynes, including the seldom reported alkyl‐substituted alkynes, were tolerated under the reaction conditions. Further investigations proved that the PINAP/CuX catalytic system enabled the synthesis of monobactams on the gram scale (without loss of stereoselectivity and yield) and also both enantiomers by the appropriate choice of readily available atropisomeric N‐PINAP ligands.