One-Step Synthesis of 7-Bromobenzo[ c ]chromeno[4,3,2- gh ]phenanthridines through a Sequential Bromination/Cyclization/Aromatization Reaction Using N -Bromosuccinimide (NBS).

Herein, metal- and oxidant-free synthesis of 7-bromobenzo[ c ]chromeno[4,3,2- gh ]phenanthridines is reported using N -bromosuccinimide. Sequential regioselective bromination, intramolecular ring cyclization, and aromatization reactions occur in a single step through a successive radical-catalyzed pathway. The mechanistic pathway for the cyclization is supported by a DFT study. Selective bromination in the fully aromatic skeleton is accomplished without involving additional aromatic electrophilic ring bromination. As a synthetic application, the Suzuki coupling reaction of compound 5a with boronic acid is reported to get compound 8a . Aggregation-induced emission of one of the synthesized compounds ( 5h ) is also investigated in THF/hexane solvent along with concentration-dependent emission spectroscopy.