Issue 7, 2006
From the journal:

Organic & Biomolecular Chemistry

Synthesis of oligosaccharides corresponding to Vibrio cholerae O139 polysaccharide structures containing dideoxy sugars and a cyclic phosphate

Dominika Turek,a   Andreas Sundgren,b   Martina Lahmannb  and  Stefan Oscarson*a  

* Corresponding authors

a Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden
E-mail: s.oscarson@organ.su.se
Fax: +46-(0)8-15 49 08
Tel: +46-(0)8-16 2480

b Department of Chemistry, Göteborg University, Gothenburg, Sweden
E-mail: martinal@chem.gu.se
Fax: +46-(0)31-772 3840
Tel: +46-(0)31-772 3066

Abstract

A spacer-equipped tetrasaccharide, p-aminocyclohexylethyl α-L-Colp-(1→2)-β-D-Galp-(1→3)-[α-L-Colp-(1→4)]-β-D-GlcpNAc, containing a 4,6-cyclic phosphate in the galactose residue, has been synthesised. The structure corresponds to a part of the repeating unit of the capsular (and lipo-) polysaccharide of the endemic bacteria Vibrio cholerae type O139 synonym Bengal. The synthetic strategy allows continuous syntheses of the complete O139 hexasaccharide repeating unit as well as of the structurally related repeating unit of serotype O22. Starting from ethyl 2-azido-4,6-O-benzylidene-2-deoxy-1-thio-β-D-glucopyranoside, a thioglycoside tetrasaccharide donor block was constructed through two orthogonal glycosylations with glycosyl bromide donors. First, a properly protected galactose moiety was introduced using silver triflate as promoter and subsequently the two colitose residues, carrying electron-withdrawing protecting groups for stability reasons, under halide-assisted conditions. The tetrasaccharide block was then linked to the spacer in a NIS–TMSOTf-promoted coupling. Transformation of the azido group into an acetamido group using H2S followed by removal of temporary protecting acetyl groups gave a 4′,6′-diol, which was next phosphorylated with methyl dichlorophosphate and deprotected to yield the 4,6-cyclic phosphate tetrasaccharide target structure.

Graphical abstract: Synthesis of oligosaccharides corresponding to Vibrio cholerae O139 polysaccharide structures containing dideoxy sugars and a cyclic phosphate

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Article information

DOI
https://doi.org/10.1039/B518125A
Article type
Paper
Submitted
21 Dec 2005
Accepted
23 Jan 2006
First published
02 Feb 2006

Org. Biomol. Chem., 2006,4, 1236-1241

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Synthesis of oligosaccharides corresponding to Vibrio cholerae O139 polysaccharide structures containing dideoxy sugars and a cyclic phosphate

D. Turek, A. Sundgren, M. Lahmann and S. Oscarson, Org. Biomol. Chem., 2006, 4, 1236 DOI: 10.1039/B518125A

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