Metal‐ and Solvent‐Free Synthesis of Maleimide Fused Carbazoles from (Indol‐3‐Yl)cyclohexanones and Maleimides

Abstract A metal‐ and solvent‐free strategy for the preparation of maleimide‐fused carbazoles has been developed. This protocol started from 2‐(indol‐3‐yl)cyclohexanones and maleimides, providing various maleimide‐fused carbazoles in 45–90% yields. The present approach was catalyzed by trimethylsulfoxonium iodide and involved a cascade of oxidation, [4+2] annulation, and dehydrogenative aromatization. Moreover, these maleimide‐fused carbazole products could be further transformed into other polycyclic aromatic hydrocarbons. magnified image