I-Amino 1-deoxy derivatives of unprotected O-beta-D-galactopyranosyl-(1 --> 3)-2-acetamido-2-deoxy-beta-D-glucopyranose,
2-acetamido-2-deoxy-D-galactose, D-galactose, lactose, D-fucose, D-mannose, and 2-deoxy-D-arabino-hexose
were prepared and acylated with N-fluorenylmethoxycarbonylaspartic acid alpha-tert-butyl
ester. The anomeric configuration of the N-glycosyl bond (including that of the mannose
derivative) in each of the purified compounds was shown to be beta. The probable stability
of the N-glycosyl and glycosidic bonds during the conditions of solid-phase peptide
synthesis was investigated by treatment of the glycosylated asparagine derivatives
with different concentrations of trifluoroacetic acid. Based on their stability, we
found that Fmoc-Asn(sugar)-OH derivatives are excellent candidates for automated synthesis
of biologically active glycopeptides.
