Synthesis of Benzo[a]carbazoles and Dibenzo[c,g]carbazoles via Sequential Gold Catalysis and Photomediated Cyclization

Herein, we report a reaction protocol for the construction of benzo[a]carbazole and dibenzo[c,g]carbazole frameworks. The detailed gold catalytic reaction conditions developed for the challenging intermolecular carbon nucleophilic addition to internal alkynes are realized, giving the desired alkyne hydroarylation products in good yields. The resulting trisubstituted alkenes are able to undergo photomediated cyclization, furnishing the desired carbazole molecules with excellent yields and high efficiency.