Acetylated methyl glucopyranuronate trichloroacetimidate as a glycosyl donor for efficient synthesis of disaccharides

Allyl (methyl 2,3,4-tri-O-acetyl-β-d-glucopyranosyl uronate)-(1→3)-4,6-O-benzylidene-2-deoxy-2-phthalimido-β-d-glucopyranoside (4) and benzyl (methyl 2,3,4-tri-O-acetyl-β-d-glucopyranosyl uronate)-(1→3)-4,6-O-benzylidene-2-deoxy-2-phthalimido-β-d-glucopyranoside (5) have been efficiently synthesized by coupling allyl 4,6-O-benzylidene-2-deoxy-2-phthalimido-β-d-glucopyranoside (2) or benzyl 4,6-O-benzylidene-2-deoxy-2-phthalimido-β-d-glucopyranoside (3) with methyl (2,3,4-tri-O-acetyl-1-O-trichloroacetimidoyl)-α-d-glucopyranuronate (1), respectively, using trimethylsilyl triflate as promoter.