New Approach to Biologically Active Indolo[2,3-b]quinoxaline Derivatives through Intramolecular Oxidative Cyclodehydrogenation

A convenient synthetic protocol to antiviral agent B-220 and a series of similar indolo[2,3-b]quinoxaline derivatives has been developed. This synthetic approach is based on Buchwald-Hartwig cross-coupling and subsequent annulation by intramolecular oxidative cyclodehydrogenation. For the first time, 6H-indolo[2,3-b]quinoxaline amine derivatives were evaluated for antimycobacterial activity. The moderate bacteriostatic effect against Mycobacterium tuberculosis H(37)Rv was found. A plausible mechanism of antibacterial action was elucidated by the molecular docking.