Facile One-Pot Synthesis of Novel 6-Monosubstituted 5,11-Dihydroindolo[3,2-b]carbazoles and Preparation of Different Derivatives

The synthesis of novel 6-monosubstituted 5,11-dihydroindolo[3,2-b]carbazoles was accomplished by a three-stage one-pot procedure involving condensation of indole and an aldehyde ­affording 3,3ʹ-bis(indolyl)methanes, followed by isomerization to the 2,3ʹ-analogues and acid-catalyzed intramolecular reaction with triethyl orthoformate to give the corresponding 6monosubstituted indolo[3,2-b]carbazoles in good overall yield. Different substitution patterns, such as N-alkylation, N-arylation, formylation and bromination, were successfully introduced, leading to the formation of novel substituted 5,11-dihydroindolo[3,2b]carbazole derivatives.