The Method For Construction Of 2-deoxy-2-amino-α-glucosidic Bonds And Its Application In The Synthesis Of Trisaccharide O-antigen Of Proteus Vulgaris TG103

The construction of 2-deoxy-2-amino-α-glucosidic bond is a challenging work,and it is of great significance in the synthesis of biological polysaccharides.We developed a new method of glycosylation,in which α-stereoselective construction of1,2-cis glycosidic bonds was achieved via conformation-restrained 2-nitroglycal donor and organic thiourea catalyst.This method has the advantages of simple operation,high reaction efficiency,good universality of substrate and stereoselectivity,and has application value in the synthesis of biological polysaccharide molecules.Proteus mirabilis and Proteus vulgaris are zoonotic pathogens of great public health significance.Because of their antibiotic resistance,it is urgent to develop vaccines against these pathogens.Lipopolysaccharide is the main surface antigen of Proteus and an important virulence factor.The common O-antigen of Proteus mirabilis OE and Proteus vulgaris TG103 containing trisaccharide repeating units{→6)-α-D-Glcp NAc-(1→3)-β-D-Galp-(1→3)-α-D-Galp NAc-(1→}.Two 1,2-cis-α-glycosidic bonds in the trisaccharide repeating unit were constructed by use of newly developed method.And the fully protected trisaccharide repeating unit was successful synthesized for the first time.