ABSTRACT: In this work, one-pot electrochemical cyclization nitration of (E)-3-(3,4-dihydroxyphenyl)acrylic acid (3,4-DHPA) and electronitration of two polyphenol derivatives (rutin and quercetin) have been performed via intermolecular and normal Michael-type addition processes in divided cell and constantcurrent coulometry mode. In the first step, the electrochemical behavior of (E)-3-(3,4-dihydroxyphenyl)acrylic acid (3,4-DHPA), quercetin (QE), and rutin (RUT) has been carried out in the absence and presence of sodium nitrite as a nucleophile in a water (acetate buffer, c = 0.2 M, pH = 5.0)/ethanol mixture (70:30, v/v) at the glassy carbon electrode. On the voltammetric timescale, decreasing of reduction peaks represented the remarkable reactivity of the oxidized form of the desired compounds and NaNO2 in the Michael-type addition reaction (EC mechanism). Mechanistically, 3,4-DHPA is deprotonated in pH = 5.0, and after the oxidation process (−2e−, −2H+), the resulting COO− reacted with the o-benzoquinone ring via the intermolecular Michael-type addition reaction. Further anodic oxidation followed by the 1,6-addition reaction and aromatization results in the formation of the coumarin adduct. Finally, the in vitro biological assessment (antibacterial activity) of the synthesized compounds was performed against different bacterial ATCC strains such as Escherichia coli, Bacillus cereus ATCC 14759, Staphylococcus aureus ATCC 29213, E. coli ATCC 25922, and Salmonella enteritidis ATTC 13076. Also, molecular docking of nitro compounds was carried out via calculating a variety of interactions between receptors (PDB ID: 4ESF, 6BFZ, 6V3Z, 1JIJ) and relevant compounds.
