A new chiral auxiliary derived from (2S)-phenylglycinol: an access to enantiomerically pure beta-amino acids

A new bicyclic heterocycle 3, which is potentially useful for the synthesis of beta-amino acids, has been obtained from a reaction between (S)-phenylg lycinol and cyanogen bromide followed by a condensation with methyl propiol ate. Conjugate additions of different organocuprate reagents to this chiral Michael acceptor occurred with complete diastereoselectivity. An optically pure beta amino acid was obtained in excellent yield from the masked chira l derivative 4a.