Synthesis of blood-group substances. Part 8. A synthesis of the branched trisaccharide 2-acetamido-2-deoxy-4-O-(α-L-fucopyranosyl)-3-O-(β-D-galactopyranosyl)-D-glucopyranose

Abstract

Reaction of 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide with benzyl 2-acetamido-4-O-allyl-6-O-benzyl-2-deoxy-α-D-glucopyranoside provided crystalline benzyl 2-acetamido-3-O-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-4-O-allyl-6-O-benzyl-2-deoxy-α-D-glucopyranoside in 87% yield. Deallylation followed by condensation with 1-O-(N-methyl) acetimidyl-2,3,4-tri-O-benzyl-β-L-fucopyranose provided the crystalline derivative (13). The title trisaccharide was obtained after O-deacetylation followed by catalytic hydrogenolysis. Preparations of 2-acetamido-2-deoxy-3-O-(β-D-galactopyranosyl)-D-glucopyranose and 2-acetamido-2-deoxy-4-O-(α-L-fucopyranosyl)-D-glucopyranose are reported.