An Open‐Air Palladium‐Catalyzed Stereoselective O‐Glycosylation of Glycals via in‐situ Generation of gem‐Disubstituted Methanols from p‐Quinone Methides

We devised a palladium-catalyzed α-stereoselective glycosylation that incorporates oxygen via in-situ generation of gem-disubstituted methanols from p-quinone methides to access 2,3-unsaturated gem-diarylmethyl O-glycosides under open-air atmosphere at room temperature. Advantages of this environmentally friendly strategy include the absence of additives and ligands, using water as the green source of oxygen, mildest, operationally simple, exhibiting a wide functional group tolerance, and compatibility with a variety of glycal progenitors in appreciable yields. A mechanistic study has been verified via H₂ ¹⁸ O labeling, which validates that water (moisture) is a sole source of oxygen.