4-Alkyl-4<i>H</i>-thieno[2',3':4,5]pyrrolo[2,3-<i>b</i>]quinoxaline Derivatives as New Heterocyclic Analogues of Indolo[2,3-<i>b</i>]quinoxalines: Synthesis and Antitubercular Activity

The synthetic approach based on a sequence of Buchwald-Hartwig cross-coupling and annulation through intramolecular oxidative cyclodehydrogenation has been used for the construction of novel 4-alkyl-4 H -thieno[2',3':4,5]pyrrolo[2,3- b ]quinoxaline derivatives. For the first time, these polycyclic compounds were evaluated for antimycobacterial activity, including extensively drug-resistant strains. A reasonable bacteriostatic effect against Mycobacterium tuberculosis H 37 Rv was demonstrated. A plausible mechanism for antimycobacterial activity of heterocyclic analogues of indolo[2,3- b ]quinoxalines has been advanced on the basis of their molecular docking data.