title: Synthesis of a novel asparagine-linked heptasaccharide structure via p-methoxybenzyl-assisted beta-mannosylation.
abstract: Synthesis of a core heptasaccharide asparagine N4-[alpha-D-mannopyranosyl-(1 --> 6)-[(alpha-D-mannopyranosyl)-(1 --> 3)]-[(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 --> 2)]-(beta-D-mannopyranosyl)-(1 --> 4)-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 --> 4)-[(alpha-L-fucopyranosyl)-(1 --> 6)]-2-acetamido-2-deoxy-beta-D-glucopyranosyl]-L-asparagine (1a) found from CHO glycosylation mutant cell LEC 14 is described. The structure of 1a is highly novel in terms of the presence of an extra GlcNAc residue linked to the 2-position of beta-linked mannose. The synthesis was performed using p-methoxybenzyl-assisted intramolecular aglycon delivery as the key transformation. 4,6-O-TIDPS-protected thiomannoside methyl 2-O-p-methoxybenzyl-4,6-O-(1,1,3,3-tetraisopropyl)disiloxanylid ene-3-O-trimethylsilyl-1-thio-alpha-D-mannopyranoside was adopted for this particular purpose, which afforded beta-mannoside p-methoxyphenyl 2,3-O-(p-methoxybenzylidene)-4,6-O-(1,1,3,3-tetraisopropyl)+ ++disiloxanylidene-beta-D-mannopyranosyl-(1 --> 4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranoside stereoselectively in 75% yield.
authors.affiliation: Institute of Physical and Chemical Research (RIKEN) and CREST, Japan Science and Technology Corporation, Saitama.
authors.forename: Y
authors.initials: Y
authors.lastname: Ohnishi
authors.forename: H
authors.initials: H
authors.lastname: Ando
authors.forename: T
authors.initials: T
authors.lastname: Kawai
authors.forename: Y
authors.initials: Y
authors.lastname: Nakahara
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
mesh_terms: D000818:Animals; D001216:Asparagine / Q000737:chemistry*; D016466:CHO Cells; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006224:Cricetinae; D009682:Magnetic Resonance Spectroscopy; D008358:Mannose / Q000737:chemistry*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: C420662:Man-Man-A-D-Glu-Man-A-D-Glu-Fuc-A-D-Glu-Asn; D009844:Oligosaccharides; D001216:Asparagine; D008358:Mannose