Mild and Selective Ru-Catalyzed Formylation and Fe-Catalyzed Acylation of Free (N—H) Indoles Using Anilines as the Carbonyl Source.

C3-selective formylation and acylation of free (N-H) indoles under mild conditions can be achieved by using Ru- and Fe-catalyzed oxidative coupling of free (N-H) indoles with anilines, respectively. Both processes are operationally simple, compatible with a variety of functional groups and generally provide the desired products in good yields. (13)C-labeling experiments unambiguously established that the carbonylic carbon in the formylation products originated from methyl group of N-methyl aniline.