3-Oxo 3H-indole from dioxygen copper-catalyzed oxidation of indole: One-flask synthesis of 2-dialkylamino 3-oxo 3H-indoles.

Cu(I)Cl-catalyzed oxidation of indole 1 by dioxygen in anhydrous acetonitrile leads to highly reactive 3- oxo 3H- indole 2, which provides directly 2- dialkylamino 3- oxo 3H- indoles 3 in presence of dialkylamines. Amidines 3, previously difficult to prepare, are potentially useful synthons in the field of heterocyclic chemistry.