Synthesis of a Pentasaccharide Fragment Related to the Inner Core Region of Rhizobial and Agrobacterial Lipopolysaccharides.

ABSTRACT: The pentasaccharide fragment ?-d-Man-(1 ? 5)-[?-d-Kdo-(2 ? 4)-]?-d-Kdo-(2 ? 6)-?-d-GlcNAc-(1 ? 6)-?-d-GlcNAc equipped with a 3-aminopropyl spacer moiety was prepared by a sequential assembly of monosaccharide building blocks. The glucosamine disaccharide-as a backbone surrogate of the bacterial lipid A region-was synthesized using an 1,3-oxazoline donor, which was followed by coupling with an isopropylidene-protected Kdo-fluoride donor to afford a protected tetrasaccharide intermediate. Eventually, an orthogonally protected manno-configured trichloroacetimidate donor was used to achieve the sterically demanding glycosylation of the 5-OH group of Kdo in good yield. The resulting pentasaccharide is suitably protected for further chain elongation at positions 3, 4, and 6 of the terminal mannose. Global deprotection afforded the target pentasaccharide to be used for the conversion into neoglycoconjugates and "clickable" ligands.

SUBMITTER: Trattnig N 

PROVIDER: S-EPMC5715290 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature