Abstract
<jats:p> β-(1→2)-Glucans constitute a relatively rare and substantially underexplored class of polysaccharides. Of particular interest is the macrocyclic β-(1→2)-glucan from Brucella (CβG), which regarded as a promising diagnostic marker of brucellosis. However, the development of CβG-based diagnostic system requires careful consideration of potential interference from short β-(1→2)-linked gluco-oligosaccharides present in various bacterial commensals and pathogens. To address this challenge, we performed the stereoselective synthesis of a representative series of trisaccharide antigens bearing di-β-(1→2)-glucoside motifs. Several strategies for β-selective insertion of the di-β-(1→2)-glucoside block were evaluated, including approaches employing picolylated and silylated donors as well as donors lacking stereodirecting groups at C-2. Optimal results were achieved using nonparticipating thioglycoside donors activated by a FeCl <jats:sub>3</jats:sub> /TCCA promoter system in acetonitrile. The method proved to be widely applicable to a range of monosaccharide acceptors, affording the target trisaccharides with excellent β-selectivity. The applicability of prepared oligosaccharides for profiling carbohydrate specificity of antibodies was demonstrated by large-scale screening of human donor sera. </jats:p>