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.