Silver trifluoromethanesulfonate as a new efficient catalyst for glycosylation reactions using 2-alkoxy-glyco-[2,1-d]-2-oxazoline glycosyl donors, contributing to the suppression of side reactions of intermolecular aglycon transfer and polymerization of oxazoline derivatives of sugars

The use of silver trifluoromethanesulfonate as a catalyst for glycoside synthesis using 2-(2,2,2-trichloroethoxy)-2-oxazoline glycosyl donors with d-gluco and d-galacto configuration has been studied. Silver trifluoromethanesulfonate allows the glycosylation reaction to be carried out under very mild conditions in a neutral medium, similar to the sym-collidinium trifluoromethanesulfonate previously used for this purpose. However, compared to sym-collidinium trifluoromethanesulfonate, silver trifluoromethanesulfonate provides better yields of target products and helps to suppress unwanted side reactions such as intermolecular aglycon transfer and polymerization of oxazoline derivatives of sugars. It has been found that the best results of oligosaccharide synthesis are obtained with an equimolar ratio between the glycosyl donor and the catalyst.

2-Alkoxy-glyco-[2,1-d]-2-oxazolines; 2-Amino-2-deoxy sugars; Intermolecular aglycon transfer; Oligosaccharide synthesis; Polymerization of 2-alkoxy-2-oxazoline derivatives; Silver trifluoromethanesulfonate.