Electrochemical study of catechol and some 3-substituted catechols in the presence of 4-hydroxy coumarin: Application to the electro-organic synthesis of new coumestan derivatives

Electrochemical oxidation of catechol (1d), 3-methylcatechol (1a), 5-methoxycatechol (1b) and 2,3-dihydroxybenzoic acid (Ic) in the presence of 4-hydroxycoumarin as nucleophile in aqueous solution has been studied using cyclic voltammetry and controlled-potential coulometry. The results indicate that (1a-1d) participating in a 1,4 (Michael) addition reaction convert to coumestan derivatives (5a-5d). The electrochemical synthesis of 5a-5d has been successfully performed in an undivided cell in good yield and purity.