Electrochemical Study of Catechol Derivatives in the Presence of β-diketones: Synthesis of Benzofuran Derivatives

Abstract

The electrochemical oxidation of 4-(1,3-dithiolan-2-yl)benzene-1,2-diol was studied in the presence and absence of acetylacetone (2a), dimedone (2b) and 4-hydroxycoumarin (2c) as nucleophiles in aqueous solution by means of cyclic voltammetry and controlled-potential coulometry. The results indicate that these nucleophiles participate in Michael addition reaction with the oxidized form of catechol derivatives, and then convert it to the corresponding new benzofuran derivatives. The electrochemical synthesis of compounds has been successfully performed at a carbon rod electrode and in two-compartment cell. The observed homogeneous rate constants (kobs) of the reaction of oxidized form of catechol derivatives with 2a-c as nucleophiles were estimated by comparing the experimental cyclic voltammograms with the digital simulated results. The calculated kobs was found to vary in the order 4-hydroxycoumarin (2c) < dimedone (2b) < acetylacetone (2a).