A Rapid and Efficient Synthesis of a Trisaccharide Sequence Related to the Core Structure of the Asparagine-linked Type Glycoproteins by Using a Chitobiose Derivative as a Key Starting Material
Allyl 2-acetamido-3-O-benzyl-4-O-(2-acetamido-3-O-benzyl-4,6-O-benzylidene-2-deoxy-β-D-glucopyranosyl)-2-deoxy-β-D-glucopyranoside (5) was efficiently prepared from chitobiose octaacetate in high yield. Coupling of 5 with 2,3,4-tri-O-benzyl-α-L-fucopyranosyl bromide by the halide ion-catalyzed glycosidation reaction afforded the protected trisaccharide intermediate in 58% yield. Deallylation followed by catalytic hydrogenolysis gave 2-acetamido-4-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-2-deoxy-6-O-(α-L-fucopyranosyl)-D-glucopyranose.