Synthesis of 5-arylamino-1-arylpyrazoles from 5-aminopyrazoles with arylhalides via CuI catalyzed Ullman coupling reaction

An efficient method for synthesis of 5-arylamino-1-arylpyrazoles was developed by Ullman coupling reaction of 5-aminopyrazoles and arylhalides in the presence of cuprous iodide (CuI) as the catalyst. The corresponding 5-N-arylaminopyrazole products were obtained in good yields (≥65%).