Synthesis of Benzofuran-2-One Derivatives and Evaluation of Their Antioxidant Capacity by Comparing DPPH Assay and Cyclic Voltammetry

Abstract

The present work aimed to synthesise promising antioxidant compounds as a valuable alternative to the currently expensive and easily degradable molecules that are employed as stabilizers in industrial preparation. Taking into account our experience concerning domino Friedel-Crafts/lactonization reactions, we successfully improved and extended the previously reported methodology toward the synthesis of 3,3-disubstituted-3<i>H</i>-benzofuran-2-one derivatives <b>9</b>-<b>20</b> starting from polyphenols <b>1</b>-<b>6</b> as substrates and either diethylketomalonate (<b>7</b>) or 3,3,3-trifluoromethyl pyruvate (<b>8</b>) as electrophilic counterpart. The antioxidant capacity of the most stable compounds (<b>9</b>-<b>11</b> and <b>15</b>-<b>20</b>) was evaluated by both DPPH assay and Cyclic Voltammetry analyses performed in alcoholic media (methanol) as well as in aprotic solvent (acetonitrile). By comparing the recorded experimental data, a remarkable activity can be attributed to few of the tested lactones.