Synthesis of O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-(1→3)-O-β-d-galactopyranosyl-(1→4)-2-acetamido-2-deoxy-d- glucopyranose and two related trisaccharides containing the “lacto-N-biose II” unit

✍ Scribed by Rexford L. Thomas; Rashmi Dubey; Saeed A. Abbas; Khushi L. Matta

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 934 KB
• Volume: 169
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(87)80251-3

✦ Synopsis

Condensation of 3-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D- glucopyranosyl)-2,4,6-tri-O-acetyl-alpha-D-galactopyranosyl bromide (1) with benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-alpha-D-glucopyranoside in boiling benzene and in the presence of mercuric cyanide afforded a trisaccharide that was O-deacetylated to give benzyl O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1----3)-O-beta-D- galactopyranosyl-(1----4)-3,6-di-O-benzyl-2-deoxy-alpha-D-glucopyranosid e, the benzyl groups of which were cleaved by catalytic hydrogenolysis to furnish the title trisaccharide. Alternatively, bromide 1 was allowed to react with 2-acetamido-1,6-anhydro-3-O-benzyl-2-deoxy-beta-D-glucopyranose in 1:1 benzene-nitromethane in the presence of mercuric cyanide, followed by O-deacetylation, column chromatography, and reacetylation to give O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D- glucopyranosyl)-(1----3)-O-(2,4,6-tri-O-acetyl-beta-D-galactopyranosyl)- (1----4)-2-acetamido-1,6-anhydro-3-O-benzyl-2-deoxy-beta-D-glucopyranose . Acetolysis, followed by catalytic hydrogenation and subsequent O-deacetylation furnished the title trisaccharide. A similar condensation of bromide 1 with 4-nitrophenyl 2-acetamido-2-deoxy-4,6-O-(4-methoxybenzylidene)-beta-D-glucopyran oside and 2-nitrophenyl 2-acetamido-2-deoxy-4,6-O-(4-methoxybenzylidene)-alpha-D-galactopy ranoside produced two trisaccharide derivatives, the acetal groups of which were cleaved in hot, 60% aqueous acetic acid, and the resulting diol intermediates O-deacetylated to furnish the desired trisaccharides 4-nitrophenyl O-(2-acetamido-2-deoxy-beta-D- glucopyranosyl)-(1----3)-O-beta-D-galactopyranosyl)-(1----3)-2-acetamido -2- deoxy-beta-D-glucopyranoside and 2-nitrophenyl O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl-(1----3)-O-beta- D-galactopyranosyl-(1----3)-2-acetamido-2-deoxy-beta-D-galactopyranoside .