O-(6-O-acetyl-2-azide-3,4-di-O-benzyl-2-deoxy-2-α-D-glucopyranosyl)-(1→4)-O-(methyl 2,3-di-O-benzyl-β-D-glucopyranosyluronate)-(1→4)-3,6-di-O-acetyl-2-azido-2-deoxy-α-D-glucopyranosyl trichloroacetimidate