title: Synthesis of carboxyl-reduced analogues related to the Chlamydia-specific Kdo trisaccharide epitope.
abstract: The disaccharides allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->4)-3-deoxy-a lph a-D- manno-2-octulopyranoside (8), allyl O-(3-deoxy-alpha-D-manno-2-octulopyranosyl)-(2-->8)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosidonate) (24), and allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->8)-3-deoxy-a lph a-D- manno-2-octulopyranoside (35), and the trisaccharides allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->8)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->4)-3-deoxy-a lph a-D-manno-2-octulopyranoside (13) and allyl O-(3-deoxy-alpha-D-manno-2-octulopyranosyl)-(2-->8)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->4)-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosidonate) (30) were prepared. The ketosidic linkages were formed in good yields and high stereoselectivity by BF3 . Et2O-catalyzed reaction of the per-O-acetylated 3-deoxy-alpha-D-manno-2-octulopyranosyl fluoride derivative (16) with 8-O-SiButMe2 derivatives 19 and 21. Coupling reactions using the Kdo monosaccharide bromide derivative 4 or the alpha-(2-->8)-linked Kdo disaccharide bromide derivatives 9 and 26 were performed under Helferich conditions in MeCN or MeNO2, respectively. The disaccharide halides were prepared in good overall yields starting from the readily available allyl beta-glycoside of Kdo. The deprotected oligosaccharides correspond to the genus-specific lipopolysaccharide epitope of Chlamydia and part structures thereof, containing the carboxyl-reduced Kdo-residues at the distal and proximal position of the Kdo trisaccharide epitope, respectively.
authors.affiliation: Institut für Chemie, Universität für Bodenkultur, Wien, Austria.
authors.forename: F W
authors.initials: FW
authors.lastname: D'Souza
authors.forename: P
authors.initials: P
authors.lastname: Kosma
authors.forename: H
authors.initials: H
authors.lastname: Brade
mesh_terms: D002236:Carbohydrate Conformation; D002264:Carboxylic Acids / Q000737:chemistry*; D002689:Chlamydia / Q000276:immunology*; D004187:Disaccharides / Q000138:chemical synthesis* / Q000276:immunology; D000939:Epitopes; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D014312:Trisaccharides / Q000138:chemical synthesis* / Q000276:immunology
chemical_list: D002264:Carboxylic Acids; D004187:Disaccharides; D000939:Epitopes; D011135:Polysaccharides, Bacterial; D014312:Trisaccharides