Electron-withdrawing groups carbopalladation

However, the reaction of substrates having a strong electron-withdrawing substituent such as nitro group can occur effectively (e. g., Eq. 43) [91,92]. Thus, another mechanism involving intramolecular aromatic C-H activation would also participate in the reaction. Other possibilities including carbopalladation have also been considered [91]. Therefore, it is likely that the mechanism is not unity and several pathways occur depending on the employed substrates, catalysts, and reaction conditions. 

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