A general method for the synthesis of enantiomerically pure beta-substituted, beta-amino acids through alpha-substituted succinic acid derivatives

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