Synthesis of 3‑Acylindoles by Palladium-Catalyzed Acylation of Free (N–H) Indoles with Nitriles

An efficient palladium-catalyzed synthesis of 3-acylindoles using free (N–H) indoles and nitriles has been developed. The acylation reaction proceeded well under the Pd(OAc)₂/2,2′-bipyridine system and with d-(+)-camphorsulfonic acid as the additive. A possible mechanism involving carbopalladation of nitriles and subsequent hydrolysis of ketimines is proposed.