摘要:
A general procedure for the synthesis of enantiopure beta-substituted, beta-amino acids is presented. Alkylation of the sodium enolates derived from chiral N-acyloxazolidinone imides 2 (R = Me, i-Pr, t-Bu, Ph, Bn) with tert-butyl bromoacetate afforded the 2-substituted succinate derivatives 3 in good yields (82-89%) and with high selectivity (greater than or equal to 93:7). Following hydrolysis, Curtius rearrangement of the resulting carboxylic acid provided the enantiopure benzyloxycarbonyl (Cbz)-protected beta-amino esters 6 in good yields (74-79%).