A Green and Efficient Synthesis Method of Benzo[c]cinnolines: Electrochemical Reduction of 2,2’‐Dinitrobiphenyl in the Presence of CO2

Abstract

AbstractBenzo[c]cinnolines are an essential framework material in medicinal chemistry owing to its promising anti‐cancer and antioxidant activity, and good pharmacological properties. Accordingly, benzo[c]cinnolines are synthesized through electrochemical reduction of 2,2’‐dinitrobiphenyl (DNBP) in aprotic solvents with CO2. Cyclic voltammetry (CV), cyclic voltabsorptometry (CVA), derivative cyclic voltabsorptometry (DCVA) techniques, and in‐situ FT‐IR spectroelectrochemistry are used to investigate the mechanism of electrochemical reduction of DNBP in the presence of CO2. It is a reversible 2‐electron‐transfer reaction in an aprotic solution of DMSO in the absence of CO2, while it turned into a completely irreversible 8‐electron process in the presence of CO2. Benzo[c]cinnolines were finally obtained by potentiostatic electrolysis with conversion rate of 99 %, indicating the high selectivity of this reaction. Above all, DNBP can be electrochemically reduced into BC in the presence of CO2, providing a theoretical and practical path for electrochemical synthesis of bioactive benzo[c]cinnolines (BC).