Synthesis of the trisaccharide outer core fragment of Burkholderia cepacia pv. vietnamiensis lipooligosaccharide

The synthesis of β-Gal-(1→3)-α-GalNAc-(1→3)-β-GalNAc allyl trisaccharide as the outer core fragment of Burkholderia cepacia pv. vietnamiensis lipooligosaccharide was accomplished through a concise, optimized, multi-step synthesis, having as key steps three glycosylations, that were in-depth studied performing them under several conditions. The target trisaccharide was designed with an allyl aglycone in order to open a future access to the conjugation with an immunogenic protein en route to the development of a synthetic neoglycoconjugate vaccine against this Burkholderia pathogen.

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► Outer core fragment of Burkholderia cepacia pv. vietnamiensis lipooligosaccharide.
► Synthesis of trisaccharide composed of galactose and N-acetyl-galactosamine.
► Allyl aglycone on the target for future conjugation with immunogenic protein.
► Stereoselective α- or β-glycosylations with 2-azido-4,6-benzylidene-GalN donors.
► 1,2-Orthoester formation avoided in glycosylation with 2-methoxycarbonyl-Gal donor.