Construction of chiral quaternary carbon center via catalytic asymmetric aza-Henry reaction with α-substituted nitroacetates

Abstract

The catalytic enantioselective aza-Henry reaction of N-Boc aldimines 2 and 2-nitropropionic acid ethyl ester 3 in mixed solvents were catalyzed by cinchona quaternary ammonium salts to form a new quaternary carbon center. High yields (up to 90%), excellent enantioselectivities (up to 99% ee) and diastereoselectivities ratio (up to 22 : 1) were successfully obtained with mild conditions.