Alkenyl Glycosyl Donors as Versatile Tools for Carbohydrate Synthesis

This review highlights the development and applications of alkenyl glycosyl donors, a class of glycosyl donors featuring alkenyl leaving groups at the anomeric position. Beginning with the discovery of n-pentenyl glycosides (NPGs) and n-pentenyl esters (NPEs), the field has expanded to include diverse ether, ester, ortoester, thioether, and sulfone type donors. These donors exhibit versatile reactivity and can be activated through various mechanisms, including halogen-mediated, acid-promoted or catalyzed, and photoredox pathways. Their compatibility with synthetic strategies such as armed/disarmed, latent/active, orthogonal, and automated glycan assembly has significantly advanced the synthesis of complex carbohydrates.