Palladium-Catalyzed Direct C–H Glycosylation of Free (<i>N</i>-H) Indole and Tryptophan by Norbornene-Mediated Regioselective C–H Activation

Abstract

We describe the palladium-catalyzed direct C-H glycosylation of free <i>N</i>-H indole or tryptophan for the stereoselective synthesis of 2-glycosylindoles and tryptophan-<i>C</i>-glycosides. This reaction relies on the <i>ortho</i>-directing transient mediator norbornene, which underwent regioselective C-H functionalization at the indole or tryptophan ring, providing high chemoselectivity. This method offers a more straightforward, step-economical, and cost-effective route to construct <i>C</i>-glycosides. The gram-scale amenable building blocks can be further functionalized at C3 and <i>N</i>-H, displaying the robustness of present method.