title: A concise synthesis of 3-fluoro-5-thio-xylo- and glucopyranoses, useful precursors towards their corresponding pyranonucleoside derivatives.
abstract: The chemical synthesis of 1,2,4-tri-O-acetyl-3-deoxy-3-fluoro-5-thio-D-xylopyranose, 1,2,4,6-tetra-O-acetyl-3-deoxy-3-fluoro-5-thio-alpha-D-glucopyranose and their corresponding nucleosides of thymine is described. Treatment of 3-fluoro-5-S-acetyl-5-thio-D-xylofuranose, obtained by hydrolysis of the isopropylidene group of 3-fluoro-1,2-O-isopropylidene-5-S-acetyl-5-thio-D-xylofuranose, with methanolic ammonia and direct acetylation, led to triacetylated 3-deoxy-3-fluoro-5-thio-D-xylopyranose. Condensation of acetylated 3-fluoro-5-thio-D-xylopyranose with silylated thymine afforded the corresponding nucleoside. Selective benzoylation and direct methanesulfonylation of 3-fluoro-1,2-O-isopropylidene-alpha-D-glucofuranose gave the 6-O-benzoyl-5-O-methylsulfonyl derivative, which on treatment with sodium methoxide afforded the 5,6-anhydro derivative. Treatment of the latter with thiourea, followed by acetolysis, gave the 3-fluoro-5-S-acetyl-6-O-acetyl-1,2-O-isopropylidene-5-thio-alpha-D-glucofuranose. 3-fluoro-5-S-acetyl-6-O-acetyl-5-thio-D-glucofuranose, obtained after hydrolysis of 5-thiofuranose isopropylidene, was treated with ammonia in methanol and directly acetylated, giving tetraacetylated 3-deoxy-3-fluoro-5-thio-alpha-D-glucopyranose. Condensation of the latter with silylated thymine afforded the desired 3-deoxy-3-fluoro-5-thio-beta-D-glucopyranonucleoside analogue.
authors.affiliation: Department of Biochemistry and Biotechnology, Laboratory of Organic Chemistry, University of Thessaly, 26 Ploutonos Str., GR-41221 Larissa, Greece.
authors.forename: Evangelia
authors.initials: E
authors.lastname: Tsoukala
authors.forename: Stella
authors.initials: S
authors.lastname: Manta
authors.forename: Niki
authors.initials: N
authors.lastname: Tzioumaki
authors.forename: George
authors.initials: G
authors.lastname: Agelis
authors.forename: Dimitri
authors.initials: D
authors.lastname: Komiotis
mesh_terms: D015394:Molecular Structure; D011714:Pyrans / Q000737:chemistry*; D054330:Thiosugars / Q000138:chemical synthesis*; D013936:Thymidine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D011714:Pyrans; D054330:Thiosugars; D013936:Thymidine