Oxidatively Induced Selective Carbon-Carbon Bond Formation From Isolated Rhodium(III) Complexes.

This work focuses on oxidatively induced regioselective intramolecular C-C bond formations based on the RhIII complexes synthesized from dirhodium(II) trifluoroacetate with 2-arylpyridines. With the selection of electron-donating groups on the arene rings of 2-arylpyridines, the unusual meta-ortho C-C bond-forming was favored, which led to the formation of meta-substituted 2-arylpyridine homocoupling dimers. On the contrary, the electron-withdrawing groups have tendency to occur conventional ortho-ortho bond-forming, resulting in the formation of new RhIII complexes possessing the intriguing RhIII (TFA)3 fragment. Preliminary mechanistic experiments suggest that the sequential oxidation of RhIII occurred in the reaction.