Electrochemical oxidation of substituted catechols in the presence of pyrazol-5-ones: characterization of products and reaction mechanism

The electrochemical oxidation of substituted catechol derivatives has been investigated in the presence of pyrazol-5-ones as C-H acid nucleophiles by using constant current technique in acetate buffer solution. The results indicate that different reaction mechanisms are involved and not only 1,4-Michael adducts but also 1,6-Michael adducts are formed, depending on the nature of the starting catechols and the nucleophiles, as well as the reaction conditions.

1,4-addition or 1,6-addition of pyrazol-5-ones to electrochemically-generated o-benzoquinones? The nature of the starting catechols plays a predominant role!