A Combined Chemical and Enzymatic Strategy for the Construction of Carbohydrate-Containing Antigen Core Units

Glycosidase-mediated coupling of glycal acceptors with galactose donors affords β1,3-linked disaccharides that are versatile intermediates for further chemical and enzymatic manipulation. The utility of these disaccharides is demonstrated by the elaboration of these compounds into the type I and type IV core disaccharides of carbohydrate-containing antigens. Further conversion of the type IV disaccharide to a mucin-type trisaccharide (Galβ1,3(GlcNAcβ1,6)GalNAc) was accomplished with the use of a β1,6-N-acetylglucosaminyltransf erase. This combined use of enzymatic and chemical methodologies allows for the rapid assembly, with high regio- and stereoselectivity, of core oligosaccharides of biologically important glycoconjugates.