CuSO4-Catalyzed Tandem C(sp3)–H Insertion Cyclization of Toluenes with Isonitriles to Form Indoles

A CuSO4-catalyzed tandem benzylic C–H insertion cyclization of toluene derivatives and isonitriles is described. The naturally abundant salt CuSO4serves as a low-cost ligand-free redox catalyst. This reaction provides a practical modular synthesis of N-aryl indoles from isonitriles.