Enantioselective addition of dialkylzinc to aromatic aldimines mediated by camphor-derived chiral β-amino alcohols

Abstract

The enantioselective addition of diethylzinc or dimethylzinc to N-(diphenylphosphinoyl)imines mediated by 1 or 2 could be achieved in high yields (70-97%) and enantioselectivities (85-98% ee). The catalytic loading of 1 or 2a could be reduced to 10 mol% for methylation or ethylation of imines in high yields and enantioselectivities (79-96%) when the reaction was conducted in the presence of 1.8 equiv of methanol. N-Monosubstituted amino alcohols induced higher enantioselectivity than their N,N-disubstituted congener in our catalytic system.