Metal-Free Synthesis of 5-Trifluoromethyl-1,2,4-Triazoles from Iodine-Mediated Annulation of Trifluoroacetimidoyl Chlorides and Hydrazones

A metal-free approach for the synthesis of 5-trifluoromethyl-1,2,4-triazoles from trifluoroacetimidoyl chlorides and hydrazones has been achieved under aerobic oxidative conditions. The reaction proceeds through a cascade base-promoted intermolecular C-N bond formation and iodine-mediated intramolecular C-N bond oxidative coupling sequence. The protocol features broad substrate scope and can be scaled up to gram scale.