Transition metal-free visible light induced intramolecular C–Hal/C–H bond activation leading to cyclization into pyrimido[5′,4′:3,4]pyrrolo[1,2-f ]phenanthridines

An unprecedented transition metal-free visible light-induced autocatalytic intramolecular C–Hal (Hal = Cl, Br, I)/C–H bond activation leading to the formation of a new C–C bond between spatially converged benzene rings has been disclosed. In fact, irradiation of 5,6-diaryl-1H-pyrrolo- [3,4-d ]pyrimidine-2,4-diones with 395 nm LED light at room temperature promotes their cyclization to pyrimido[5′,4′:3,4]- pyrrolo[1,2-f]phenanthridine-12,14(11H,13H)-diones in high yields, with the halogen nature being insignificant.