Synthesis of a glycotripeptide and a glycosomatostatin containing the 3-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-L-serine residue

3-O-(2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosyl)-N- (tert-butyloxycarbonyl)-L-serine was synthesized and condensed by the solid-phase procedure to give the sequence Gly-beta-D-GlcpNAc-(1 leads to 3)-Ser]-Ala-OH and beta-D-GlcpNAc-(1 leads to 3)-Ser-13-somatostatin. The synthetic glycopeptides appeared homogeneous on t.l.c. and l.c. examination and showed the correct amino acid composition and 2-amino-2-deoxy-D-glucose content. The structure of Gly-beta-D-GlcpNAc-(1 leads to 3)-Ser]-Ala-OH was further confirmed by mass spectrometry of the N-acetyl permethyl derivative, and by n.m.r. spectroscopy.