Stereocontrolled synthesis of sulfur-linked analogues of the branched tetrasaccharide repeating-unit of the immunostimulant polysaccharide schizophyllan and of its β-(1 → 3)-branched, β-(1 → 6)-linked isomer

✍ Scribed by Marie-Odile Contour-Galcera; Yili Ding; Carmen Ortiz-Mellet; Jacques Defaye

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 497 KB
• Volume: 281
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(95)00334-7

✦ Synopsis

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).