N-Tosyl-(S)-Prolyl Chloride in Kinetic Resolution of Racemic Heterocyclic Amines

The kinetic resolution of racemic heterocyclic amines via acylation with N-tosyl-(S)-prolyl chloride was systematically investigated. It was established that racemic mixtures of aromatic amines could be resolved with high efficiency, while the acylation of 2and 3-methylpiperidines occurred with low diastereoselectivity. A method for the preparation of enantiomerically pure (3R)-7,8-difluoro-3-methyl3,4-dihydro-2H-[1,4]benzoxazine was developed.