Glycosylation: The Direct Synthesis of 2-Acetamido-2-Deoxy-Sugar Glycosides
Résumé
Developing methods for the stereoselective synthesis of glycosides, used in the assembly of glycoconjugates or bioactive oligosaccharides, has been essential for making progress in the field of glycosciences. The 2-acetamido-2-deoxy-glycopyranosyl units are the key motifs of these structures and many innovative methods have been elaborated to incorporate these units by stereoselective chemical glycosylation. Most of these methods introduce additional chemical steps to avoid the presence of the acetamide functional group next to the reacting anomeric center. This microreview details the direct but arduous approaches for the synthesis of glycosides in which the NHAc group is present during the glycosylation reaction. Our focus will be on the methods that have appeared in the last two decades.