A Theoretical Study on Pd-catalyzed, Friedel-Crafts Intermolecular Acylation: Does Generated In Situ Aroyl Triflate Act as A Reactive Electrophile to Functionalize C–H Bond of Arenes?

The mechanism of Pd-catalyzed, Friedel-Crafts intermolecular acylation of arenes to ketones was comprehensively investigated by using DFT calculations. The calculated results revealed that this transformation was composed of several key steps: C–I bond oxidative addition, CO insertion, reductive elimination and C–H bond functionalization. Of these steps, the last was found to be the rate–determining step, and it occurred much more easily with strongly electrophilic aroyl triflate compared to other resultant counterparts. In addition, our calculation provides a rationale for experimental findings that simple Pd salts exhibit superior catalytic abilities compared to phosphine-ligated Pd catalysts.