Direct C2 Acylation of Free (N-H) Indoles Enabled by Pd(II)/Norbornene Cooperative Catalysis.

We report a regioselective C2 acylation of free (N-H) indoles enabled by Pd(II)/norbornene (NBE) cooperative catalysis. This protocol circumvents the pre-installation and removal of N-directing groups, enabling direct C2-H acylation under mild, open-air conditions. Utilizing acid anhydrides as acylating agents, the reaction shows good functional group tolerance and provides a highly step-economical platform to biologically relevant 2-acylindoles, as demonstrated by the streamlined, single-step synthesis of a platelet-derived growth factor receptor (PDGFR) kinase inhibitor.