Most efforts toward the improvement of automated synthesis of oligosaccharides focused on how to perform iterative processes most efficiently in automated fashion. The synthesis of oligosaccharides with 1,2-trans- glycosidic linkages has been routinely carried out using C2 participating protecting groups. The generation of 1,2-cis- glycosidic linkages is still the greatest challenge for automated oligosaccharide synthesis. Herein, we present efficient 1,2-cis glycosidic bond formations with various galactose and glucose building blocks that utilize remote participating group effects in automated solid-phase synthesis. 4-O-Acetyl of galactose, and 6-O-acetyl of glucose are most effective to induce a-glycosidic bond formation. 3-O-acetyl works as a secondary effector. The optimized building blocks were employed in the synthesis a-Gal containing oligosaccharides such as pentasaccharide a-Gal epitope, -iso-Globo-series, and Globo-series. Furthermore, tetra, and penta a-glucans containing multiple 1,2-cis glycosidic linkages were synthesized using the automated synthesizer. These results encouraged us to synthesize glycan structures of high complexity containing a-glucosidic as well as a-galactosidic linkages. The most immunogenic carbohydrate antigens out of seven frame-shifted epitopes from two Streptococcus pneumonia antigens were identified on a microarray. We built up the efficient fundament using automated synthetic system, and the optimized building blocks to map the most antigenic carbohydrate epitope en route to a synthetic carbohydrate vaccine.

?Installation of multiple 1,2-cis glycosidic bonds by automated synthesis

248th National Meeting (2014)

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