Mild regioselective iodination of pyrazoles using <Emphasis Type="Italic">n</Emphasis>-butyltriphenylphosphonium peroxodisulfate

A practical, efficient and inexpensive method of synthesis of iodopyrazoles by the reaction of pyrazoles with iodine using n-butyltriphenylphosphonium peroxodisulfate as an oxidant at room temperature is reported. The use of n-butyltriphenylphosphonium peroxodisulfate is feasible due to its easy preparation and handling, high stability and activity.