Mechanistic Insights into Nickel-Catalyzed Hydroheteroarylation of Vinylarenes

초록

The mechanisms of nickel-catalyzed hydroheteroarylation of vinylarenes were studied by use of computational techniques. Optimized structures for all of the stationary points in the gas phase were investigated using the density functional theory (BP86) method. The SDD pseudopotential, along with its associated basis set, was used to describe the nickel centers, while the 6-31G* basis set was used for the main group atoms C, O, N, and H. Two distinct possible pathways in the title reaction were evaluated, involving the conventional oxidative addition and the new direct addition, respectively. Furthermore, in each pathway, two types of reaction processes were explored, which leads to 1,1-diarylethane as product and 1,2-diarylethane as product, respectively. Our calculated results indicate that the newly found addition mechanism is more favorable than the conventional oxidative addition due to the strong steric hindrance. The reaction pathway leading to 1,1-diarylethane as product has the higher possibility to occur, with the energy barrier being lower by ca. 9kcal/mol compared with that forming to 1,2-diarylethane as product, which is in good agreement with the experimental observation.