Synthesis of glycan fragments of glycoproteins using peracetylated N-allyloxycarbonyl-β-D-glucosamine and 1,6-anhydro-β-D-mannopyranose derivatives

Abstract

The disaccharides β-D-GlcNAOC-(1 → 2)-D-Man, β-D-GlcNAOC-(1→ 4)-D-Man, the trisaccharide β-D-GlcNAOC-(1 → 2)-[β-D-GlcNAOC-(1→ 4)]-D-Man, and the tetrasaccharide β-D-GlcNAOC-(1 → 2)-[β-D-GlcNAOC-(1→ 3)]-[β-D-GlcNAOC-(1 → 4)]-D-Man have been synthesized in their peracetylated form, using the Lewis acid catalyzed condensations of 1,3,4,6-tetra-O-acetyl-2-N-allyloxycarbonylamino-2-deoxy-β-D-glucopyranose 1 with properly substituted 1,6-anhydro-β-D-mannopyranose derivatives. The anhydro glycosylation products obtained were then easily transformed into the 4C1 peracetylated derivatives by acetolysis. The N-allyloxycarbonyl groups could be converted into N-acetyl groups in the presence of Pd(0) complexes, followed by reacetylation of the free amino function in high yields. Keywords: N-allyloxycarbonyl, glycosylation, glucosamine, glycan fragments.