Synthesis of a Disaccharide Glycosyl Donor for Use in the Assembly of Oligosaccharides Structurally Related to the Repeating Unit of the Main Chain of Rickettsia typhi O-Polysaccharide

Starting from (2-methyl-5-tert-butylphenyl)-2,3-di-O-benzyl-1-thio-β-d-glucopyranoside and phenyl-2-azido-3,4-di-O-acetyl-2-deoxy-1-seleno-α-l-fucopyranoside the (2-methyl-5-tert-butylphenyl)-4-O-(2-azido-3,4-di-O-acetyl-2-deoxy-α-l-fucopyranosyl)-2,3-di-O-benzyl-1-thio-β-d-glucopyranoside was synthesized, which is planned for the use in the assembly of oligosaccharides structurally related to the repeating unit of the R. typhi O-polysaccharide. During this work, the conditions for selective activation selenoglycoside in the glycosylation reaction were selected. It was also shown that the use of MeOTf as a promoter afford chemoselective activation of selenoglycoside in the presence of thioglycoside.