Exploring the Dual Functions of Distal Acyl Group Direction in Various Nucleophilic Environments.

A universal glycosylation strategy could significantly simplify glycoside synthesis. One approach to achieving this goal is through acyl group direction for the corresponding 1,2-, 1,3-, 1,4-, or 1,6- glycosylation; however, this approach has been challenging for glycosidic bonds that require distal -acyl group direction. We developed an approach in weakly nucleophilic environments for selective 1,4- glycosylation directed by the -4--acyl group. Here, we explored this condition in other distal acyl groups and found that, besides 1,- direction, acyl groups also mediated hydrogen bonding between acyl groups and alcohols. The latter showed a diverse effect and classified the acyl group direction into and categories. Corresponding glycosylation conditions were distinguished as guidance for acyl group direction from either category. Hence, acyl group direction may serve as a general glycosylation strategy.