Nitrosonium Ion Catalyzed Oxidative Bromination of Arenes

A nitrosonium catalyzed bromination of electron-rich arenes has been developed, using bromide salts as bromine sources, oxygen gas as a terminal oxidant and Bronsted acids (sulfuric acid, TFA or HBr). This arene bromination process is free of transition metals, proceeding in acetic acid and under mild temperatures (25-50 degrees C) to give brominated arenes with good to excellent yields. Our mechanistic studies indicated that this oxidative bromination of arenes reaction is catalyzed by nitrosnium ion (NO+), without the involvement of Br2 or Br+. The kinetic isotope effect of this reaction was measured using pentadeuteriophenyl phenyl ether (kH/kD=1.1). image