A building block approach to the synthesis of a family of S-linked α-1, 6-oligomannosides. (24th June 2016)

• Record Type: Journal Article
• Authors: Belz, Tyson; Williams, Spencer J.
• Is Part Of: Carbohydrate research. Volume 429(2016)
• Page Start: 38
• Page End: 47
• Publication Date: 2016-06-24
• Subjects: Thioglycosides -- Protecting groups -- Glycomimetic -- Neoglycoconjugates -- Oligosaccharides; Carbohydrates -- Periodicals; Chemistry, Organic -- Periodicals; Biochemistry -- Periodicals; Carbohydrates -- Periodicals; Chimie organique -- Périodiques; Glucides -- Périodiques; Biochemistry; Carbohydrates; Chemistry, Organic; Periodicals; Electronic journals; 507.78
• DOI: 10.1016/j.carres.2016.04.015
• Languages: English
• ISSNs: 0008-6215

Abstract

Highlights: A family of S-linked α-1, 6-oligomannosides up to hexasaccharides were synthesized. Compounds were assembled from preformed sulfur-containing mannose building blocks. The thioglycoside linkages formed by coupling of anomeric thiolates with 6-iodo sugars. Reducing-end and non-reducing end extensions were investigated. Graphical abstract: 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.