M. Laronze et al., Oxidative transformation of indole-3-acetonitrile derivatives into the corresponding indole-3-carboxylic acids, EUR J ORG C, (9), 1999, pp. 2285-2291
Indole-3-acetonitriles 1 were transformed into indole-3-carboxylic acids 2
and/or indole-3-carboxaldehydes 3, when treated with tetrabutylammonium flu
oride in the presence of traces of oxygen. This method constitutes a conven
ient preparation of indole-3-carboxylic acids 2.