Dynamic Kinetic Asymmetric Reductive Amination: Synthesis of Chiral Primary β-Amino Lactams

Abstract

A highly efficient ruthenium-catalyzed asymmetric reductive amination (ARA) of racemic β-keto lactams with molecular hydrogen and ammonium salts is disclosed for the synthesis of enantiomerically pure primary amino lactams through dynamic kinetic resolution (DKR). By this approach, a range of syn primary β-amino lactams were obtained in high yields with high chemo-, enantio-, and diastereoselectivity (up to 98 % yield, 99 % ee, >20:1 d.r., syn products). The utility of the products has been demonstrated by rapid access to a key synthetic intermediate towards biologically active drug molecules. Meanwhile, mechanistic studies and control experiments indicate that the reaction may proceed through the hydrogenation of an iminium intermediate.

Keywords: asymmetric catalysis; asymmetric hydrogenation; chiral lactams; primary amines; reductive amination.