SYNTHESIS OF O-1 ANTIGEN FRAGMENT OF Klebsiella pneumonia USING GOLD-CATALYSED GLYCOSYLATIONS

Abstract

The O-antigens of Klebsiella pneumonia are present in its cell wall consisting of two polysaccharides: D-galactan I and D-galactan II. Significant studies about D-Galactan I were performed in the literature whereas less amount of research is available about D galactan II. Clinical isolates of K. pneumonia revealed that D-Galactan II was more frequent in diseases such as liver abscess, D-Galactan II is found to be an immunodominant antigen that could be useful as a vaccine candidate. The synthesis of D-Galactan II related chains was not much discussed in the literature. Argunov group in 2019 synthesized a fragment of the D-galactan II as a mixture of cis and trans isomers with an overall yield of 65%. In this premise, we have devised a more convenient approach for the synthesis of Galp-Galp disaccharide building block that can be used to synthesize large chains of D-galactan in a split-couple-split manner by utilising the silver-assisted gold-catalyzed glycosylation reaction.