DFT Study on the Mechanism of Palladium(0)-Catalyzed Reaction of Aryl Iodides, Norbornene, and Di-tert-butyldiaziridinone

The reaction mechanism of palladium(0)-catalyzed reaction of aryl iodides, norbornene, and di-tert-butyldiaziridinone has been studied theoretically. Two reaction mechanisms were calculated. The reaction mechanism involving Cs2CO3 combination first followed by alkene insertion is calculated to be preferred to the one in which alkene insertion occurs first followed by Cs2CO3 combination. The calculations suggest that the reaction proceeds via C–I bond oxidative addition, CsI·CsCO3 cluster anion formation, alkene insertion, C–H bond activation, N–N bond oxidative addition, and two successive C­(sp2)–N bond-forming, and C­(sp3)–N bond-forming reductive elimination steps. The N–N bond oxidative addition involves the rate-determining transition state with a free energy barrier of 29.4 kcal/mol. The role of base Cs2CO3 played during CsI·CsCO3 cluster anion formation and N–N bond oxidative addition process has been discussed according to the formation of relatively strong Pd–O bond. The role of base K2CO3 has been calculated and compared with Cs2CO3.