SYNTHESIS OF THE TETRASACCHARIDE O-α-L-FUCOPYRANOSYL-(1->2)-3)>-O-β-D-GALACTOPYRANOSYL-(1->4)-2-ACETAMIDO-2-DEOXY-D-GLUCOPYRANOSE, THE ANTIGENIC DETERMINANT OF HUMAN BLOOD-GROUP B (TYPE 2)

Article abstract of DOI:10.1016/S0008-6215(00)80391-2

Treatment of benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-4-O-β-D-galactopyranosyl-α-D-glucopyranoside with benzaldehyde in the presence of zinc chloride, followed by regioselective benzoylation (N-benzoylimidazole in dichloromethane) provided crystalline benzyl 2-acetamido-4-O-(3-O-benzoyl-4,6-O-benzylidene-β-D-galactopyranosyl)-3,6-di-O-benzyl-2-deoxy-α-D-glucopyranoside.Condensation of this disaccharide with 2,3,4-tri-O-benzyl-1-O-(N-methylacetimidyl)-β-L-fucopyranose in nitromethane in the presence of p-toluenesulfonic acid and molecular sieves 4 Angstroem gave benzyl O-(2,3,4,-tri-O-benzyl-α-L-fucopyranosyl)-(1->2)-O-(3-O-benzyl-4,6-O-benzylidene-β-D-galactopyranosyl)-(1->4)-2-acetamido-3,6-di-O-benzyl-2-deoxy-α-D-glucopyranoside.Debenzoylation, followed by condensation with 2,3,4,6-tetra-O-benzyl-1-O-(N-methylacetimidyl)-β-D-galactopyranose under the same conditions provided a tetrasaccharide derivative that was catalytically hydrogenolyzed into the title compound.