Comparative computational study on C-C/C-N/C-Br bond formations in Rh(III)-catalyzed C-H functionalizations: Stepwise versus concerted mechanisms

In this study, based on DFT calculations, we systematically investigated the mechanisms of Rh(III)-catalyzed C-H ortho-functionalizations of arenes. For C-C, C-N, and C-Br bond formations in four reactions, two types of mechanisms, i.e., stepwise pathway and concerted pathway, are compared. Our DFT theoretical modelings indicate that the mechanisms are highly system dependent. For different types of C-C/C-N/C-Br bond formations, either stepwise or concerted pathways can be preferred kinetically. This preference can also be affected by the substrate/reagent, as shown in C-H amidation reactions. The mechanistic variation of the Rh(III)-catalyzed C-H functionalizations revealed in this work demonstrates high complexity of these organic transformations.