title: Synthesis and n.m.r. analysis of branched trisaccharide and pentasaccharide haptens of the beta-hemolytic streptococci group A and the preparation of synthetic antigens.
abstract: The synthesis of branched trisaccharide and pentasaccharide portions of the cell-wall polysaccharide of the beta-hemolytic Streptococci Group A is described. The key dissaccharide acceptors, allyl or 8-(methoxycarbonyl)ocytol 3-O-(3,4,6-tri-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl)-4-O -benzyl - alpha-L-rhamnopyranoside, in conjunction with a selectively blocked alpha-L-rhamnopyranosyl chloride under Koenigs-Knorr conditions, afforded the branched trisaccharides in 81 and 62% yield, respectively. Analogously, glycosylation of the 8-(methoxycarbonyl)octyl disaccharide with a protected beta-D-GlcpNAc-(1----3)-alpha-L-Rhap-(1----3)-alpha-L-Rhap chloride gave the pentasaccharide in 43% yield. The key disaccharide acceptors were obtained, in turn, from the allyl or 8-(methoxycarbonyl)octyl rhamnoside acceptors and 3,4,6-tri-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl chloride under Koenigs-Knorr conditions. The latter glycosyl donor has not been described previously. Removal of the protecting groups afforded the trisaccharide haptens as their 1-propyl and 8-(methoxycarbonyl)octyl glycosides and the pentasaccharide as its 8-(methoxycarbonyl)octyl glycoside. The compounds have been subjected to detailed analysis by two-dimensional n.m.r. methods. Preparation of the synthetic antigens followed coupling of the 8-(methoxycarbonyl)octyl glycosides to bovine serum albumin via the acyl azide intermediates.
authors.affiliation: Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada.
authors.forename: B M
authors.initials: BM
authors.lastname: Pinto
authors.forename: K B
authors.initials: KB
authors.lastname: Reimer
authors.forename: A
authors.initials: A
authors.lastname: Tixidre
mesh_terms: D002240:Carbohydrate Sequence; D006241:Haptens / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000138:chemical synthesis / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000138:chemical synthesis*; D013297:Streptococcus pyogenes / Q000276:immunology*; D014312:Trisaccharides / Q000138:chemical synthesis / Q000276:immunology
chemical_list: D006241:Haptens; D009844:Oligosaccharides; D011135:Polysaccharides, Bacterial; D014312:Trisaccharides