Chemical synthesis of the dimeric repeating unit of type Ia group B Streptococcus capsular polysaccharide.

The first chemical synthesis of the dimeric repeating unit of serotype Ia group B Streptococcus capsular polysaccharide was achieved. The on-site elongation and dual glycosylation strategies were utilized to construct two sialotrisaccharide branches based on a hexasaccharide containing adjacent 3,4-di-branched Gal units, which were synthesized via a preactivation-based one-pot glycosylation method.