A highly convergent synthesis of a complex oligosaccharide derived from group B type III Streptococcus

An efficient synthesis of a heptasaccharide derived from group B type III Streptococcus carrying an artificial spacer (1) is described. Rapid assembly of a protected heptasaccharide (16a) is accomplished from readily available building blocks 2-5 without a single protecting group manipulation between glycosylation steps. The synthetic strategy may be applied to the assembly of other branched complex oligosaccharides. The deprotected heptasaccharide 1 was coupled to a poly[N-(acryloyloxy)succinimide, and the resulting material will be used for the development of an ELISA assay to detect antibodies against GBS, type III in pregnant women.