Nitric acid-catalyzed aerobic oxidation of benzylic sp3 CH bonds of isochromans, xanthenes and 9-fluorenone under additive-free conditions

HNO3 was demonstrated to be an effective catalyst for aerobic oxidation of benzylic sp3 CH bonds under additive-free conditions. A series of isochromans, xanthenes and fluorenes underwent this transformation to give the targeted products in low to high yields under the catalysis of HNO3, which provided an effective method for the synthesis of the synthetically and biologically valued isochromanones, xanthones and 9-fluorenones.122