Facile Access to 1 H ‐Indazoles through Iodobenzene‐Catalyzed C–H Amination under Mild, Transition‐Metal‐Free Conditions

The transition‐metal‐ and halogen‐free synthesis of N ‐aryl‐substituted 1 H ‐indazole and derivatives was accomplished on the basis of the iodobenzene‐catalyzed intramolecular C–H amination of hydrazones under mild conditions. Reactions of hydrazones derived from ketones and hydrazines with a catalytic amount of iodobenzene in the presence of Oxone as an oxidant in trifluoroacetic acid took place to afford 1 H ‐indazoles in moderate to good yields. A plausible reaction mechanism was described on the basis of the control experiments.