Synthesis of Indolo[3,2-b] carbazoles via an Anomeric-Based Oxidation Process: A Combined Experimental and Computational Strategy

Indolo[3,2-b] carbazole is a molecule of great biological significance, as it is formed in vivo after consumption of cruciferous vegetables. The reaction of 1H-indole and various aldehydes in the presence of a catalytic amount of N, 2-dibromo-6-chloro-3,4-dihydro-2H-benzo[e][1,2,4] thiadiazine-7-sulfonamide 1,1-dioxide as an efficient and homogeneous catalyst in acetonitrile at 50 degrees C produces 6,12-disubstituted 5,7-dihydroindolo[2,3-b] carbazole with an in good to excellent yield. The presented technique offers a fast and robust method, by the use of inexpensive commercially available starting materials toward 6,12disubstituted 5,7-dihydroindolo[2,3-b] carbazole. A new anomeric-based oxidation was kept in mind for the final step of the indolo[2,3-b] carbazoles synthesis. The suggested anomeric-based oxidation mechanism was supported by experimental and theoretical evidences.