Modular Synthesis of Carbazole-Based Conjugated Molecules through a One-Pot Annulation/Dehydrogenation Sequence

An efficient one-pot indole-to-carbazole strategy with cyclohexanones as the aryl source is described. This cascade carbazole formation is enabled by the NH4I-catalyzed annulation of indoles, cyclohexanones, and alkenes and subsequent dehydrogenative aromatization. The present work provides a modular synthesis of arylcarbazoles, benzocarbazoles, and naphthocarbazoles with excellent regioselectivity and broad functional group tolerance. More than 40 benzo-fused carbazoles were synthesized, and the UV-vis absorption and photoluminescent spectra of some products were measured to study their photophysical properties.