Unexpected formation of a 1,2-diketone from a 1,3-diketone mediated by lanthanides

The first example of the formation of a 1,2-heteroaromatic diketone from a 1,3-diketone by air oxidation mediated by lanthanides is described. The structures of the products are confirmed by X-ray single crystal diffraction and NMR spectroscopy. A possible reaction mechanism is proposed.