An environmentally friendly electrochemical method for synthesis of pyrazole derivatives

Electrochemical oxidation of catechol and some of 3-substituted catechols (1a–c) has been studied in the presence of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (3) as the nucleophile at various pH values in aqueous solution using cyclic voltammetric and controlled-potential coulometric methods. The results revealed that the products derived from catechols (1a–c) participate in Michael addition reactions with 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (3) via an ECEC mechanism, converts it to form the corresponding pyrazole derivatives (8a–c). The electrosynthesis of these products was carried out at the surface of carbon electrode in an undivided cell under controlled-potential conditions which is an environmentally friendly method.