Concise synthesis of di- and trisaccharides related to the O-antigens from Shigella flexneri serotypes 6 and 6a, based on late stage mono-O-acetylation and/or site-selective oxidation - Institut Pasteur Accéder directement au contenu
Article Dans Une Revue Tetrahedron Année : 2013

Concise synthesis of di- and trisaccharides related to the O-antigens from Shigella flexneri serotypes 6 and 6a, based on late stage mono-O-acetylation and/or site-selective oxidation

Résumé

Shigella flexneri serotypes 6 and 6a are closely related bacteria causing shigellosis in humans. Their O-antigens are {→4)-β-d-GalpA-(1→3)-β-d-GalpNAc-(1→2)-[3Ac/4Ac]-α-l-Rhap-(1→2)-α-l-Rhap-(1→}n acidic polysaccharides ({ABAcCD}n), which only differ in the degree of O-acetylation. A concise synthesis of two disaccharides (BC, BAcC) and four trisaccharides, representing portions and/or analogs of the O-antigens, is described. A protected intermediate compatible with late stage 3C-O-acetylation, and/or galactosyl (A°) to galacturonic acid (A) conversion, was designed and assembled from trichloroacetimidate and thioglycoside donors tuned for high yielding glycosylation and excellent stereocontrol. The galacturonic moiety was efficiently introduced from galactose using a TEMPO/NaOCl/NaClO2-based oxidation protocol optimized for full compatibility with sensitive moieties, such as allyl ethers and acetates. Final Pd/C-mediated deprotection provided the targets, including the propyl glycoside ABAcC, its non O-acetylated counterpart ABC, and the non acidic analogs A°BAcC and A°BC. The BC and ABC oligosaccharides are also portions of the O-antigen from Escherichia coli O147, which causes diarrhea in pigs.

Domaines

Chimie organique

Dates et versions

pasteur-02043363 , version 1 (20-02-2019)

Identifiants

Citer

Pierre Chassagne, Laurent Raibaut, Catherine Guerreiro, Laurence A Mulard. Concise synthesis of di- and trisaccharides related to the O-antigens from Shigella flexneri serotypes 6 and 6a, based on late stage mono-O-acetylation and/or site-selective oxidation. Tetrahedron, 2013, 69 (48), pp.10337-10350. ⟨10.1016/j.tet.2013.10.011⟩. ⟨pasteur-02043363⟩
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