Synthesis of the N-carboxy-α-amino acid anhydrides of several O-acetylated serine glycosides

Abstract

The O-acetylated O-(β-glycopyranosyl)- l-serine derivatives of d-galactose, lactose, cellobiose, 2-acetamido-2-deoxy- and 2-deoxy-2-dodecamido- d-glucose, and O-acetylated O-(α- l-rhamnopyranosyl)- l-serine were synthesized by KoenigsKnorr condensation of the corresponding acetobromo sugars with N-benzyloxycarbonyl- l-serine benzyl ester, followed by hydrogenolysis of the benzyloxycarbonyl and benzyl ester groups. Treatment of the O-acetylated serine glycosides with phosgene gave the corresponding N-carboxy-α-amino acid anhydrides or Leuchs' anhydrides which are useful reagents to link sugars to linear and branched synthetic polypeptide antigens. The free serine glycosides were obtained by treatment of the O-acetylated derivatives with methanolic ammonia.