Minimally Protected and Stereoselective -Glycosylation of Carboxylic Acid Allows Rapid Access to α-1-- and 2--Acyl Glycosides.

We herein reported a catalytic, minimally protected, and highly α-stereoselective glycosylation protocol using carboxylic acid as an acceptor and glycosyl 8-alkynyl-1-naphthoate as a donor, enabling efficient access to unprotected α-1-- and 2--acyl glycosides. This method demonstrates excellent functional compatibility and scope generality, allowing for the glycosylation of a wide range of complex carboxylic acids. Notably, we successfully synthesized two natural products, α-penta--galloyl-d-glucopyranose and nyctanthesin A, using this protocol. Mechanistic studies highlighted the crucial role of the 1- ester functionality in ensuring chemoselectivity and the important contribution of the 2- functionality in facilitating the reaction.