C-H amination is a straightforward method to synthesize nitrogen-containing organic compounds. Electrochemical oxidation serves as a powerful method to functionalize C-H bonds of aromatic compounds. However, it often suffers from overoxidation when the product is easily oxidized compared to the starting material. Therefore, electrooxidative C-H amination of aromatic compounds has been difficult so far. To solve the problem, we have developed a new approach to the electrochemical intermolecular C-H amination of aromatic compounds via N-arylpyridinium ions, which can be converted to aromatic primary amines by a subsequent chemical reaction.

In this paper we report that the method can also be applied to the intramolecular C-H amination of aromatic compounds to give nitrogen-containing heteroaromatics. Benzoxazoles and benzothiazoles were successfully synthesized from phenols and thiophenols, respectively. The intermediacy of the electrooxidatively inactive cationic intermediates which avoid overoxidation is responsible for the success of the transformation.