Fig. 1

Glycosyl cation structures. Schematic representation of possible glycosyl cation structures of glycosylating agents containing a C2-participating group. After cleavage of the leaving group, the carbocation can adopt three hypothetical structures, which differ substantially in the interaction of the acetyl group with the anomeric carbon. The type of interaction affects the exact conformation of the ring pucker, which influences the kinetics of the subsequent nucleophilic attack and, as a result, the stereochemical outcome