Synthesis of Phenanthridine Derivatives by Oxidative Cyclization of 2-Isocyanobiphenyls with Boronic Acids

Chatani et al. have reported the synthesis of phenanthridine derivatives by oxidative cyclization of 2-isocyanobiphenyls with boronic acids. According to their results, the reaction of 2-isocyanobiphenyls with boronic acids in the presence of Mn(acac)₃ gives phenanthridine derivatives in high yields under relatively mild conditions. They have proposed that this reaction proceeds by the intramolecular homolytic aromatic substitution (HAS) via an imidoyl radical intermediate.