Palladium-Catalyzed Direct C-H Glycosylation of Free (-H) Indole and Tryptophan by Norbornene-Mediated Regioselective C-H Activation.

We describe the palladium-catalyzed direct C-H glycosylation of free -H indole or tryptophan for the stereoselective synthesis of 2-glycosylindoles and tryptophan--glycosides. This reaction relies on the -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 -glycosides. The gram-scale amenable building blocks can be further functionalized at C3 and -H, displaying the robustness of present method.