Shigellosis is an endemic diarrheal disease caused by Gram negative bacteria named
Shigella. The most exposed polysaccharides of Shigella sonnei display a zwitterionic disaccharide repeating unit (AB) made of two rare amino sugars:
[4)-α-l-AltpNAcA-(1→3)-β-d-FucpNAc4N-(1→]. An original synthesis of a ready-for-oligomerization AB disaccharide is
reported. The targeted orthogonally protected disaccharide was synthesized from l-glucose and tetra-O-acetyl-β-d-glucosamine. The challenging introduction of the 4B-azido group masking the amino moiety of the AAT residue was performed at the disaccharide
stage by a two-step procedure (triflation followed by nucleophilic displacement with
NaN3). A post-glycosylation oxidation strategy was employed to access the altruronate
moiety.
Key words
amino sugars - glycosylation - oligosaccharide synthesis - shigellosis - vaccine
