title: Stereocontrolled synthesis of sulfur-linked analogues of the branched tetrasaccharide repeating-unit of the immunostimulant polysaccharide schizophyllan and of its beta-(1-->3)-branched, beta-(1-->6)-linked isomer.
abstract: The branched, sulfur-linked tetrasaccharide S-(beta-D-glucopyranosyl)-(1-->3)-S-[(6-S-beta-D-glucopyranosyl)-3,6-dit hio- beta-D-glucopyranosyl]-(1-->3)-S-3-thio-D-glucopyranose (9) has been conveniently prepared by SN2 displacement of the triflate group in 1,2:5,6-di-O-isopropylidene-3-O-trifluoromethylsulfonyl-alpha-D-++ +allofuranose with the sodium salt of 2,4-di-O-acetyl-3,6-di-S-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)- 1,3,6- trithio-beta-D-glucopyranose (5). Conversely, reaction of the sodium salt of 5 with 1,2,3,4-tetra-O-acetyl-6-deoxy-6-iodo-beta-D-glucopyranose afforded the positional isomer S-(beta-D-glucopyranosyl)-(1-->6)-S-[(3-S-beta-D-glucopyranosyl)-3,6-dit hio- beta-D-glucopyranosyl]-(1-->6)-S-6-thio-D-glucopyranose (12).
authors.affiliation: Département de Recherche Fondamentale sur la Matière Condensée/SESAM, Centre d'Etudes de Grenoble, France.
authors.forename: M O
authors.initials: MO
authors.lastname: Contour-Galcera
authors.forename: Y
authors.initials: Y
authors.lastname: Ding
authors.forename: C
authors.initials: C
authors.lastname: Ortiz-Mellet
authors.forename: J
authors.initials: J
authors.lastname: Defaye
mesh_terms: D000276:Adjuvants, Immunologic / Q000138:chemical synthesis / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000138:chemical synthesis / Q000494:pharmacology; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005658:Fungi / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000138:chemical synthesis; D012091:Repetitive Sequences, Nucleic Acid; D012566:Sizofiran / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D013863:Thioglucosides / Q000138:chemical synthesis*
chemical_list: D000276:Adjuvants, Immunologic; D000972:Antineoplastic Agents, Phytogenic; D009844:Oligosaccharides; C098835:S-(glucopyranosyl)(1-3)-S-((6-S-glucopyranosyl)-3,6-dithioglucopyranosyl)(1-3)-S-3-thioglucopyranose; D013863:Thioglucosides; D012566:Sizofiran