Mechanistic Studies of the Rhodium-Catalyzed Direct C–H Amination Reaction Using Azides as the Nitrogen Source

Direct C-H amination of arenes offers a straightforward route to aniline compounds without necessitating aryl (pseudo)halides as the starting materials. The recent development in this area, in particular in the metal-mediated transformations, is significant with regard to substrate scope and reaction conditions. Described herein are the mechanistic details on the Rh-catalyzed direct C-H amination reaction using organic azides as the amino source. The most important two stages were investigated especially in detail: (i) the formation of metal nitrenoid species and its subsequent insertion into a rhodacycle intermediate, and (ii) the regeneration of catalyst with concomitant release of products. It was revealed that a stepwise pathway involving a key Rh(V)-nitrenoid species that subsequently undergoes amido insertion is favored over a concerted C-N bond formation pathway. DFT calculations …