Chiral derivative 3 was shown to be a precursor of alpha and beta -substituted beta -amino acids as well as alpha,beta -disubstituted beta -amino acids. The key steps of the procedure are a diastereoselective alkylation of synthon 3 by organocuprates reagents and a diastereoselective alkylation of the: alkylated adduct. (C) 2000 Elsevier Science Ltd. All rights reserved.
A New Chiral Auxiliary Derived from (2<i>S</i>)-Phenylglycinol: an Access to Enantiomerically Pure β-Amino Acids
A new bicyclic heterocycle 3, which is potentially useful for the synthesis of β-amino acids, has been obtained from a reaction between (S)-phenylglycinol and cyanogen bromide followed by a condensation with methyl propiolate. Conjugate additions of different organocuprate reagents to this chiral Michael acceptor occurred with complete diastereoselectivity. An optically pure β amino acid was obtained in excellent yield from the masked chiral derivative 4a.