title: A building block approach to the synthesis of a family of S-linked α-1,6-oligomannosides.
abstract: The syntheses of α-1,6-S-linked methyl di-, tetra- and hexamannosides are reported. The sulfur linkages are generated through coupling of thiolates (derived from anomeric thioacetates or isothiouronium bromides) with 6-deoxy-6-iodo sugars. Two approaches are detailed that involve [2 + 2 + 2] construction from either the reducing end or the non-reducing end. In constructing from the reducing end, coupling of a disaccharide thioacetate with a 6'-iodo reducing end disaccharide, followed by activation of the resulting tetrasaccharide to a 6'''-iodide, and iterative coupling with the same disaccharide thioacetate afforded the S-linked hexasaccharide, as well as the intermediate di- and tetrasaccharides. On the other hand, construction from the non-reducing end involved coupling of the above disaccharide thioacetate with an anomeric S-trityl protected 6'-iodo disaccharide. The resulting S-trityl tetrasaccharide was converted to a tetrasaccharide thioacetate, which was coupled with the same anomeric S-trityl protected 6'-iodo disaccharide to afford the hexasaccharide, which was elaborated to the methyl thioglycoside. The developed methodology may prove useful for the construction of other S-linked oligosaccharides.
authors.affiliation: School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Tyson
authors.initials: T
authors.lastname: Belz
authors.affiliation: School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address: sjwill@unimelb.edu.au.
authors.forename: Spencer J
authors.initials: SJ
authors.lastname: Williams
mesh_terms: D002240:Carbohydrate Sequence; D006001:Glycoconjugates / Q000737:chemistry*; D007454:Iodides / Q000737:chemistry; D009844:Oligosaccharides / Q000138:chemical synthesis*; D010084:Oxidation-Reduction; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013865:Thioglycosides / Q000737:chemistry*
chemical_list: D006001:Glycoconjugates; D007454:Iodides; D009844:Oligosaccharides; D013438:Sulfhydryl Compounds; D013865:Thioglycosides; C005732:thioacetic acid
keywords: Glycomimetic; Neoglycoconjugates; Oligosaccharides; Protecting groups; Thioglycosides