Minimally Protected and Stereoselective <i>O</i>-Glycosylation of Carboxylic Acid Allows Rapid Access to α-1-<i>O</i>- and 2-<i>O</i>-Acyl Glycosides
Bangxing Hao, Rongxia Li, Panpan Wang, Yingjie Wang, Xiaolong Li, Peng Xu, Qian Zhang, Xinhao Zhu, Xiaojuan Zhang, Yugen Zhu
Abstract
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- O - and 2- O -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- O -galloyl- d -glucopyranose and nyctanthesin A, using this protocol. Mechanistic studies highlighted the crucial role of the 1- O ester functionality in ensuring chemoselectivity and the important contribution of the 2- O functionality in facilitating the reaction.