Oxidative Transformation of Indole-3-acetonitrile Derivatives into the Corresponding Indole-3-carboxylic Acids

Indole-3-acetonitriles 1 were transformed into indole-3-carboxylic acids 2 and/or indole-3-carboxaldehydes 3, when treated with tetrabutylammonium fluoride in the presence of traces of oxygen. This method constitutes a convenient preparation of indole-3-carboxylic acids 2.