Rh-Catalyzed C–H Alkynylation of Indole Derivatives with Silver(I)-Controlled Regiodivergence

We have disclosed silver(I)-induced switching of regioselectivity in rhodium-catalyzed C–H alkynylation of indole derivatives with the help of a pivaloyl directing group by tuning C–H metalation modes. The judicious choice of AgOAc, Ag2O, and Ag2CO3 affords an array of C2-alkynylated indoles, C4-alkynylated indoles, and C2,C4-dialkynylated indoles, respectively. The synthetic utility of the alkyne fragment is demonstrated by derivatization into valuable indole-based compounds.