Metal-Free Synthesis of Acyl Glycosides and Application to Oligosaccharide Synthesis.

Oligosaccharides are involved in numerous biological processes. Achieving optimal anomeric selectivity and regioselectivity remains challenging. Herein, we present a method for the oxidative glycosylation of thioglycosides with hypervalent iodine reagents derived from carboxylic acid to form C-O bonds. The reaction of thioglycosides with various hypervalent iodine carboxylates afforded acyl O-glycosyl compounds. These acyl O-glycosyl compounds could react with thioglycoside acceptors to produce disaccharides; trisaccharides and tetrasaccharides could be synthesized by repeating this method.