Electrochemical Methylarene Oxidation via Electrolyte Anion Control: Access to ¹⁸ O-Labeled Aromatic Aldehydes

The electrochemical oxidation of methylarenes to aromatic aldehydes has been extensively studied. Nevertheless, strategies capable of efficiently oxidizing both electron-rich and electron-deficient methylarenes remain scarce. Herein, we report a method that utilizes water as the oxygen source, enabling the selective oxidation of both types of methylarenes to aldehydes by modulation of the electrolyte anions. The reaction shows remarkable regioselectivity for polymethyl-substituted arenes, producing only mono-oxidized products. Importantly, ¹⁸O-labeled aldehydes were successfully synthesized via this method with high ¹⁸O incorporation.