Noland, W. E.; Brown, C. D.; Bisel, A. M.; Schneerer, A. K.; Tritch, K. J. Acta Crystallogr. Sect. E, 2015, 71, 1414.
The title compound, C23H19NO2S2, was obtained as an unexpected regioisomer from an attempted synthesis of an intermediate for a substituent-effect study on ergot alkaloids. This is the first report of a 1H-indole monothioating at the 2- and 3-positions to give a 3H-indole. In the crystal, the acid H atom is twisted roughly 180° from the typical carboxy conformation and forms centrosymmetric O—H⋯N hydrogen-bonded dimers with the indole N atom of an inversion-related molecule. Together with a weak C—H⋯O hydrogen bond involving the carbonyl O atom, chains are formed along .