This disclosure relates to methods for preparing an enantiomerically enriched N-carboxyanhydride of an amino alpha acid of the formula (IIIa) or (IIIb):
from a compound of the formula (IIa) or (IIb), respectively:
wherein R1, R2, and R3 are as defined in the disclosure.
                            这项披露涉及制备
氨基α-酸的对映体富集的N-
羧酸酐的方法,其
化学式为(IIIa)或(IIIb),从相应的化合物的
化学式(IIa)或(IIb)中得到,其中R1、R2和R3如披露中定义的。