Mechanistic understanding of Rh-catalyzed N-sulfonylaldimine insertion into aryl C–H bonds

A detailed investigation is presented to understand the catalytic pathway of our recently reported Rh(III)-catalyzed N-tosylaldimine insertion into aryl C–H bonds. Herein, the key intermediates were isolated and determined by X-ray crystallography of their single crystals. The kinetic characterization of each factor in this catalytic reaction was conducted. The studies indicate that N-tosyl aldimine insertion into the C–Rh bonds rather than C–H bond activation or protonolysis is the rate-determining step. These mechanistic insights have significant implications for the development of a more efficient catalytic reaction system to realize the addition of C–H bonds to normal aldehydes and ketones, to achieve sp3 C–H bond activation, and to implement asymmetric catalysis in the near future.