One-Pot Synthesis of Functionalized Carbazoles via a CAN-Catalyzed Multicomponent Process Comprising a C–H Activation Step

The microwave-promoted three-component reaction between o-nitrochalcones, primary amines and β-dicarbonyl compounds in the presence of Ce­(IV) ammonium nitrate constitutes the first example of a multicomponent carbazole synthesis. This reaction furnishes highly substituted and functionalized carbazole derivatives via a double annulation process that generates two C–C and two C–N bonds, with water as the only side product. Mechanistically, this transformation has some unusual features that include an intramolecular coupled hydrogenation-dehydrogenation process, the functionalization of a C–H group by direct attack onto a nitrogen function and a CAN-catalyzed reduction via hydride transfer from ethanol. The mechanisms of these reactions were studied with the aid of computational techniques.