Trifluoroacetic acid-mediated selective oxidation of arylamines to nitroarenes via in situ formed peroxytrifluoroacetic acid.

The importance of selectively oxidizing an amine into a value-added nitro compound is well-recognized in organic synthesis. However, the lack of control over selectivity and the complex synthesis of costly catalysts significantly hinder the industrial application of these reactions. In this work, an environmentally friendly approach was developed for the selective oxidization of arylamines to nitroarenes. This method used 30% peroxide as the oxidant and trifluoroacetic acid (TFA) as both the solvent and reactant and in situ formed peroxytrifluoroacetic acid without the addition of any metals or additives. This reaction exhibited excellent oxidative selectivity and a broad substrate scope. Various electron-rich and/or electron-deficient arylamines, diamino aromatics and drug molecules were selectively and effectively oxidized to the corresponding nitro compounds in high yields (up to 100%). Mechanism studies show that the reaction proceeds via a nitrosobenzene intermediate pathway.