Asymmetric synthesis of (R)-α-phenylalkylamines via alkylation of chiral hydrazones by Grignard reagents

Abstract

Chiral hydrazones, obtained by the condensation of (–)-N-aminoephedrine with aryl aldehydes, reacted with Grignard reagents to give chiral hydrazines in almost 100% diastereomeric excess, which were hydrogenolysed to give (R)-α-phenylalkylamines and ephedrine hydrochloride in extremely high enantiomeric excess.