Efficient Synthesis and Iodine‐Functionalization of Pyrazoles via KIO3/PhSeSePh System under Acidic Conditions

This manuscript reports a novel method for the direct iodination of the C‐4 pyrazole ring generated in situ by the reaction of 1,1,3,3‐tetramethoxypropane and various hydrazines. In this approach, potassium iodate (KIO3) is used as the iodinating agent and (PhSe)2 is used as catalysts under acidic conditions. This protocol provides a convenient method for the efficient synthesis of 4‐iodo‐1‐aryl‐1H‐pyrazoles, valuable intermediates for several different coupling reactions. We develop a new method for the direct iodination of the C‐4 pyrazole ring generated in situ by the reaction of 1,1,3,3‐tetramethoxypropane and hydrazines. In this approach, potassium iodate is used as the iodinating agent along with diphenyl diselenide under acidic conditions. The method is simple and efficient and allows the synthesis of 4‐iodopyrazoles and other iodinated heterocycles.