Theoretical studies on the mechanism of Pd-catalyzed regioselective C-H alkylation of indole with MesICHCFOTf.

The reaction mechanism of Pd-catalyzed regioselective C-H alkylation of indole with MesICHCFOTf has been investigated by the density functional theory calculations. The reaction mechanism mainly contains four steps: C-H activation, oxidative addition, reductive elimination, and ligands substitution. From our calculations, we find that the C-H activation step was realized by the acetate anion (OAc) assisted concerted metalation deprotonation (CMD) process and the transition state of C-H activation process is a square planar configuration. Moreover, the calculation results suggest that the regioselectivity of C-H bond alkylation of indole with MesICHCFOTf can be ascribed to the different stability of the CMD transition states in C-H activation step and the relative stabilities of deprotonated intermediates.