The mechanisms of rhodium-catalyzed coupling reaction of ketoxime and 1,3-enynes were investigated by employing the density functional theory (DFT) calculations. Different 1,3-enynes would lead to different annulation products. Reaction A undergoes five sequential steps (C-H activation, 1,3-enyne migratory insertion, 1,4-Rh migration, cyclization, and deprotonation) to lead to [4 + 1] annulation product. Whereas, due to the electronic effect, the process generating [4 + 2] product in reaction A is restricted. In contrast, the electron-withdrawing group of N(Me)2 group in 1,3-enyne would bring about the [4 + 2] annulation product in reaction B. Our calculated results indicate that no [4 + 1] annulation product could be obtained in reaction C, in agreement with the experimental observation that the cis-allyl hydrogen in 1,3-enyne is crucial for the [4 + 1] annulation reaction.
The mechanisms of C−C activation of 1-Benzylcyclopropan-1-ol to produce 1,6-diketone have been investigated by density functional theory (DFT) calculations. The catalyst [Cp*RhCl2]2 and additive Ag2CO3 play an important role in controlling the selectivity. By employing [Cp*RhCl2]2 as catalyst and Ag2CO3 as additive, the product is 1,6-diketone, whereas the β-hydride elimination product could not be obtained. The product would become monoketone in the absence of [Cp*RhCl2]2. In addition, the combination of catalyst [Cp*RhCl2]2 and additive AgOAc would also lead to monoketone. The observed selectivity could be attributed to the electronic effect.