Catalytic enantioselective conjugate addition of diethylzinc to chalcones using chiral amino alcohol–nickel complexes

A series of chiral β-amino alcohols derived from (S)-leucine, valine, and phenylalanine were examined as chiral ligand in nickel-catalyzed conjugate addition of diethylzinc to chalcones. The (S)-valine-derived amino alcohol possessing a piperidine ring and two flexible phenethyl groups was found to be an efficient ligand to catalyze the conjugate addition with high enantioselectivity (up to 92% ee).