4-Alkyl-4-thieno[2',3':4,5]pyrrolo[2,3-]quinoxaline Derivatives as New Heterocyclic Analogues of Indolo[2,3-]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-thieno[2',3':4,5]pyrrolo[2,3-]quinoxaline derivatives. For the first time, these polycyclic compounds were evaluated for antimycobacterial activity, including extensively drug-resistant strains. A reasonable bacteriostatic effect against HRv was demonstrated.

Reaction of Pyrrolobenzothiazines with Schiff Bases and Carbodiimides: Approach to Angular 6/5/5/5-Tetracyclic Spiroheterocycles.

1-Pyrrole-2,3-diones, fused at []-side with a heterocycle, are suitable platforms for the synthesis of various angular polycyclic alkaloid-like spiroheterocycles. Recently discovered sulfur-containing []-fused 1-pyrrole-2,3-diones (aroylpyrrolobenzothiazinetriones) tend to exhibit unusual reactivity. Based on these peculiar representatives of []-fused 1-pyrrole-2,3-diones, we have developed an approach to an unprecedented 6/5/5/5-tetracyclic alkaloid-like spiroheterocyclic system of benzo[]pyrrolo[3',4':2,3]pyrrolo[2,1-]thiazole via their reaction with Schiff bases and carbodiimides.

Approach to Pyrido[2,1-][1,3]benzothiazol-1-ones via In Situ Generation of Acyl(1,3-benzothiazol-2-yl)ketenes by Thermolysis of Pyrrolo[2,1-][1,4]benzothiazine-1,2,4-triones.

Acyl(imidoyl)ketenes are highly reactive heterocumulenes that enable diversity-oriented synthesis of various drug-like heterocycles. Such ketenes, bearing heterocyclic substituents, afford angularly fused pyridin-2(1)-ones in their [4+2]-cyclodimerization reactions. We have utilized this property for the development of a new synthetic approach to pharmaceutically interesting pyrido[2,1-][1,3]benzothiazol-1-ones via the [4+2]-cyclodimerization of acyl(1,3-benzothiazol-2-yl)ketenes generated in situ.

Nucleophile-induced ring contraction in pyrrolo[2,1-][1,4]benzothiazines: access to pyrrolo[2,1-][1,3]benzothiazoles.

Pyrrolo[2,1-][1,3]benzothiazoles are an important class of fused sulfur and nitrogen-containing heterocycles intensively studied in medicinal chemistry and pharmacology. In the present paper, a new synthetic approach to pyrrolobenzothiazoles is developed based on 1,4-thiazine ring contraction in 3-aroylpyrrolo[2,1-][1,4]benzothiazine-1,2,4-triones under the action of nucleophiles. The proposed approach works well with alkanols, benzylamine, and arylamines.

Amination of 5-Spiro-Substituted 3-Hydroxy-1,5-dihydro-2-pyrrol-2-ones.

The 3-hydroxy-1,5-dihydro-2-pyrrol-2-one motif is a valuable scaffold in drug discovery. The replacement of the 3-oxy fragment in 3-hydroxy-1,5-dihydro-2-pyrrol-2-ones-based compounds with a 3-amino one (3-amino analogs of 3-hydroxy-1,5-dihydro-2-pyrrol-2-ones, 3-amino-1,5-dihydro-2-pyrrol-2-ones) can play a crucial role in their biological effect. Thus, approaches to 3-amino-1,5-dihydro-2-pyrrol-2-ones are of significant interest.