Rh(III)-Catalyzed C–H Activation/Intramolecular Cyclization: Access to N‑Acyl-2,3-dihydro‑1H‑carbazol-4(9H)‑ones from Cyclic 2‑Diazo-1,3-diketones and N‑Arylamides

A Rh­(III)-catalyzed C–H activation/cyclization cascade reaction is described. The reaction involves cyclic 2-diazo-1,3-diketones and N-arylamides, and it proceeds via an intermolecular C–C bond formation and subsequent intramolecular C–N bond formation. A variety of N-acyl-2,3-dihydro-1H-carbazol-4­(9H)-ones were obtained under mild conditions in good to excellent yields (65–90%). Key features of this strategy include high-efficiency, operational simplicity, scalability, and broad functional-group tolerance. In addition, H₂O and N₂ are the only byproducts. Carbazole derivatives with free NH groups can be easily obtained through N-deprotection reactions.