Carboxylate-Assisted Iridium (III)-Catalyzed C(sp2)–H Amidation of 2‑Aroylimidazoles With Dioxazolones

The Ir­(III)-catalyzed ortho C–H amidation of 2-aroylimidazoles with 3-aryldioxazolones as an amidating reagent is reported. The method provides a broad substrate scope with wide functional group compatibility. Mechanistic studies indicate that C–H bond cleavage is reversible and appears not to be the rate-determining step. The presence of an electron-donating group in the 2-aroylimidazoles and an electron-withdrawing group in the 3-aryldioxazoles significantly accelerates the reaction, suggesting that nitrene insertion is the rate-determining step.