Visible Light‐Induced Cyanomethyl Radical Triggered Cascade Cyclization of Phenyl‐Linked 1,6‐Enynes with a‐Halogenated Acetonitriles

Abstract Photo‐promoted cyanomethyl radical procedures for the preparation of 2,3‐dihydro‐1 H ‐indenes and 2,8‐dihydrocyclopenta[ a ]indenes from phenyl‐linked 1,6‐enynes with α ‐halogenated acetonitriles are reported. The iodocyanomethylation/cyclization is performed via an atom‐transfer radical addition (ATRA) strategy under photocatalyst‐ and oxidant‐free conditions. In particular, the photoinduced cyanomethylative cascade bicyclization is carried out under the fac ‐Ir(ppy) 3 /Na 2 CO 3 catalystic symtem and visible light irradiation. These methods offer a one‐step and atom‐economical access to diverse cyano‐group containing five‐membered rings with broad substrate scope and high selectivity. A plausible reaction mechanism is also proposed.