Galactosaminogalactan (GAG) is an important cell wall component of Asperillus fumigatus, a common fungal pathogen responsible for invasive mold infection. It is composed of 1,4-linked galactose (Gal), GalN and GalNAc residues that are interconnected through cis-glycosidic linkages and distributed in a random order. The GAG polysaccharide is thought to have potent anti-inflammatory effects. Synthetic fragments of the GAG polymer can serve as powerful tools in various directions. They may serve as synthetic antigens in the generation of potential aspergillosis vaccines and they can be evaluated for their immunomodulatory activity to provide molecules with defined antiinflammatory activity. 4,6-O-di-tert-butylsilylene (DTBS)-directed α-selective galactosylation method, developed by Kiso’s group, is a comprehensive and powerful method for the synthesis of α-galactosyl and galactosaminyl glycans. Here it was applied to synthesize the fragments of GAG polysaccharides through a linear stepwise synthesis strategy.
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