N,N-DIALKOXYCARBONYLAMINO ACIDS FROM THE SODIUM HYDRIDE-MEDIATED REACTION OF ALKYL CHLOROFORMATES WITH MIXED ANHYDRIDES OF N-ALKOXYCARBONYLAMINO ACIDS

Reaction of mixed anhydride R(1)OCO-NHCHR(2)-CO-O-COOR(3) for R(1)=ben zyl and tert-butyl and R(3)=methyl, ethyl, benzyl and allyl with sodiu m hydride and R(3)OCOCl followed by acid hydrolysis gives modest yield s of R(1)OCO-N(R(3)OCO)CHR(2)-COOH. The products are contaminated by p arent acid R(1)OCONHCHR(2)-COOH that is not readily removed. About 75% of the acylation originates from intramolecular transfer of the alkyl carbonate moiety; the remainder comes from acylation by the alkyl chl oroformate. (C) Munksgaard 1995.