title: The chemical synthesis of O-alpha-L-fucopyranosyl-(1 goes to 2)-O-beta-D-galactopyranosyl-(1 goes to 3)-O-[alpha-L-fucopyranosyl-(1 goes to 4)]-2-acetamido-2-deoxy-D-glucopyranose, the Lewis b blood-group antigenic determinant.
abstract: An approach has been developed for the rapid synthesis of benzyl 2-acetamido-2-deoxy-3-O-beta-D-galactopyranosyl-beta-D-glucopyranoside (5). Disaccharide 5 was per(trimethylsilyl)ated, to provide the fully protected trimethylsilyl (Me3Si) derivative which, on treatment with pyridine-acetic anhydride-acetic acid for 2 days, gave the disaccharide derivative having O-acetyl groups selectively at the primary positions and Me3Si groups at the secondary positions. The latter groups were readily cleaved by treatment with aqueous acetic acid in methanol, to afford benzyl 2-acetamido-6-O-acetyl-3-O-(6-O-acetyl-beta-D-galactopyranosyl)-2-deoxy-beta-D- glucopyranoside, which, is isopropylidenation, gave the desired, key intermediate 9, having two hydroxyl groups free. Condensation of 9 with 2,3,4-tri-O-benzyl-alpha-L-fucopyranosyl bromide, under catalysis by halide ion, afforded the tetrasaccharide derivative, from which the title tetrasaccharide was obtained by systematic removal of the protecting groups. The structure of the final product, and of various other intermediates, was established by 1H- and 13C-n.m.r. spectroscopy.
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D000939:Epitopes; D006801:Humans; D007983:Lewis Blood Group Antigens / Q000276:immunology*; D009682:Magnetic Resonance Spectroscopy; D009844:Oligosaccharides / Q000138:chemical synthesis*
chemical_list: D000939:Epitopes; D007983:Lewis Blood Group Antigens; D009844:Oligosaccharides; C033206:O-alpha fucopyranosyl-(1-2)-O-beta-galactopyranosyl-(1-3)-O-(alpha-fucopyranosyl)-(1-4)-2-acetamido-2-deoxy-glucopyranose