Synergistic Glycosylation as Key to the Chemical Synthesis of an Outer Core Octasaccharide of Helicobacter pylori

Helicobacter pylori, a widespread gastric bacterial pathogen that infects 90 % of the population in developing countries, causes chronic gastritis, peptic ulcers and gastric cancer. Battling H. pylori infection is a serious challenge due to the increased resistance to antibiotics and the lack of vaccines. The lipopolysaccharide covering the H. pylori cell‐surface outer membrane is an attractive target for the development of a glycoconjugate vaccine. Here, we report a [3+5] convergent synthesis of an outer core octasaccharide of H. pylori employing just three orthogonally protected building blocks. A synergistic glycosylation strategy enables the creation of five pivotal 1,2‐cis‐α‐glucosidic bonds consist of four types of linkages using just three monomers. This strategy can be expanded to many 1,2‐cis‐α‐gluoside‐containing oligosaccharides both in solution and solid phase. Constructing glycans of the stomach: H. pylori is a bacterial pathogen that infects more than half of the world's population. A synergistic glycosylation strategy was developed to construct the lipopolysaccharide of the pathogen as a first step towards developing a glycoconjugate vaccine.