O 2 -Mediated Te(II)-Redox Catalysis for the Cross-Dehydrogenative Coupling of Indoles.

Very few elements in the periodic system can catalytically activate O 2 , such as in the context of cross-dehydrogenative couplings. The development of O 2 -activating catalysts is essential to enable new and sustainable reactivity concepts to emerge, because these catalysts also often feature specific activating interactions with the target substrates. In this context, the unprecedented Te(II)/Te(III) catalyzed dehydrogenative C3-C2 dimerization of indoles is described herein. The fact that O 2 can be directly utilized as a terminal oxidant in this reaction, as well as the absence of any background reactivity without the redox-active Te catalyst, constitute very important milestones for the fields of cross-dehydrogenative couplings and tellurium catalysis.