Preferred C2−H Activation of Quinoline N‐Oxides Catalyzed by Palladium Acetate: DFT Study on the Plausible Mechanism and Regioselectivity

A density functional theory study on the multi‐path and multi‐step C−H activation of quinoline N‐oxides catalyzed by the dimeric complex Pd 2 (OAc) 4 has been carried out to fully address the strong preference for C2−H activation observed experimentally. The plausible C−H activation mechanism was identified as the undirected mechanism rather than the coordination‐directed mechanism, because the former has lower free‐energy barriers than the latter. The kinetic and thermodynamic parameters of different C−H activation reactions have been calculated and compared. The preference for C2−H activation over C8−H activation should be a result of the kinetic discrimination, while that over the remaining C−H activation processes could be attributed to the thermodynamic spontaneity.