Cost-effective electrosynthesis of a series of edaravones through an electrochemical-assisted domino heteroannulation and paired electrochemical process

Abstract

A series of novel edaravone structures was successfully synthesized through the anodic oxidation of catechols in the presence of edaravone in aqueous solution. The cyclic voltammetric results indicate that a one-pot multi-step sequential reaction occurs between edaravone and the electrochemically derived ortho- and para-benzoquinones affording fused poly-heterocyclic compounds. Using controlled potential coulometry, it has been proved that this catalyst-free, tandem reaction occurs via EC, ECECi, and ECECiCi mechanisms. The paired electrochemical synthesis of compound 5g has been successfully performed in a one-pot process with carbon rods as working electrodes and RVC as counter electrodes in an undivided cell. In addition, the electrosynthesis of edaravone derivatives has been successfully performed in ambient conditions in an undivided cell using an environmentally friendly method with high atom economy. All of the obtained compounds were fully characterized by spectroscopic methods such as FT-IR, 1H NMR, 13C NMR, and MS.