N,N-dialkoxycarbonylamino acids from the sodium hydride-mediated reaction of alkyl chloroformates with mixed anhydrides of N-alkoxycarbonylamino acids.

Abstract

Reaction of mixed anhydride R1OCO-NHCHR2-CO-O-COOR3 for R1 = benzyl and tert-butyl and R3 = methyl, ethyl, benzyl and allyl with sodium hydride and R3OCOCl followed by acid hydrolysis gives modest yields of R1OCO-N(R3OCO)CHR2-COOH. The products are contaminated by parent acid R1OCO-NHCHR2-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 chloroformate.