Nataliya A. Zhukova

Reaction for the synthesis of benzimidazol-2-ones, imidazo[5,4-b]-, and imidazo[4,5-c]pyridin-2-ones via the rearrangement of quinoxalin-2-ones and their aza analogues when exposed to enamines.

A synthetically useful protocol has been developed for the preparation of highly functionalized N-pyrrolylbenzimidazol-2-ones. The reaction of variously substituted 3-aroyl- and 3-alkanoylquinoxalin-2(1H)-ones with commercially available enamines in acetic acid results in a rapid rearrangement and formation of N-pyrrolylbenzimidazol-2-ones in modest to excellent yields. The key step of the rearrangement involves the novel ring contraction of 3-aroyl- and 3-alkanoylquinoxalin-2(1H)-ones with enamines. In this case, the atom of carbon which is displaced from the pyrazine ring of quinoxalin-2(1H)-one becomes the fourth carbon atom of the newly formed pyrrole ring. The method is applicable for the aza analogues of quinoxalin-2(1H)-ones.

Rearrangement of Quinoxalin-2-ones When Exposed to Enamines Generated in Situ from Ketones and Ammonium Acetate: Method for the Synthesis of 1-(Pyrrolyl)benzimidazolones

The reaction of 3-benzoylquinoxalin-2(1H)-ones with enamines (generated in situ from ammonium acetate and the corresponding methylaryl(hetaryl)ketones) proceeds smoothly to give the corresponding substituted 1-(pyrrolyl)benzimidazolone derivatives in moderate yields through the novel rearrangement of 3-benzoylquinoxalin-2(1H)-ones involving a dual cleavage of the C3═N4 and C2-C3 bonds under mild conditions.

Effect of surfactant micelles on solubility and spectral characteristics of 2,2’-bibenzimidazole

The solubilization capacity of surfactants of different types was quantitatively characterized by spectrophotometry toward 2,2’-bibenzimidazole (BBI), whose derivatives possess a wide range of pharmacological activity. 2,2’-Bibenzimidazole solubilized by sodium dodecyl sulfate micelles is characterized by a high molar absorption coefficient (9400 mol−1 L cm−1) at the absorbance maximum (342 nm at pH 4–10), which may serve as a basis for the development of procedures for analytical monitoring of the BBI content in aqueous solutions and biosystems. The ability of surfactants to enhance the solubility of BBI in water and, as a consequence, to increase its bioavailability in the series sodium dodecyl sulfate < cetyltrimethylammonium bromide < Tween-80.

Progress in Quinoxaline Synthesis (Part 1)

Abstract In this two-part review (Part 2 to be published in Progress in Heterocyclic Chemistry , Volume 25), recent advances in the synthesis of quinoxalines are reviewed. Medicinal compounds containing a quinoxaline moiety are also covered. The review covers condensations of 1,2-diaminoarenes, condensations of o -benzoquinone diimines and diimides, syntheses from anilines, syntheses from various other heterocycles, and syntheses from 3,3,6,6-tetrachloro-1,2-cyclohexanedione.

Controlling the release of hydrophobic compounds by a supramolecular amphiphilic assembly

Here, we report a novel approach of using a supramolecular system based on calix[4]resorcinarene and surfactant to facilitate the release of hydrophobic compounds. This finding is an important step towards the development of controlled-release formulations for water-insoluble drugs.

Application of nonionic amphiphiles for increasing solubility in water of alkylated bibenzimidazole derivatives

Solubilization capacity of a number of nonionic micelle-forming compounds toward 2,2´-bibenzimidazole and its alkylated derivatives was determined by spectrophotometry. It was found that as the hydrophilic lipophilic balance of the studied amphiphiles grows, their solubilization effect toward 2,2´-bibenzimidazoles increases and reaches the highest value in the case of pluronic F127. The conversion of bibenzimidazoles to the cationic form induced by lowering the medium pH improves efficiency of the solubilizers.

Fused polycyclic nitrogen-containing heterocycles

The condensation of methyl phenylchloropyruvate with 1-phenyl-3-(2-pyridyl)thiourea and its 3-and 4-picolyl homologs affords the corresponding 4-hydroxythiazolidines, which react with o-phenylenediamine to give one of two possible thiazolo[3,4-a]quinoxalines containing the pyridyl-or picolylimine substituents at position 1. 3a-Hydroxy-3-phenylimino-1-(2-pyridyl)thiazolo[3,4-a]quinoxalin-4-(3H,5H)-one, which is a covalent hydrate of the final product, was isolated as an intermediate in this reaction.

Benzimidazoles and related heterocycles: 11. A novel acid-catalyzed rearrangement in the system 3-benzoylquinoxalin-2(1H)-one-aldehyde-ammonium acetate as a simple and efficient route to 2-(imidazol-4-yl)benzimidazoles

A three-component condensation of 3-benzoylquinoxalin-2(1H)-one with 4-nitrobenzaldehyde and ammonium acetate in AcOH gives 2-[2-(4-nitrophenyl)-5-phenylimidazol-4-yl]benzimidazole via a rearrangement involving the fragment C(2)-C(3)-C(O)Ph of the quinoxaline system and the other two reagents, which supply the fragment -N=C(Ar)-NH- for constructing the imidazole ring. Possible pathways of this reaction are discussed.

Recent Advances in the Synthesis of Benzimidazol-2-ones via Rearrangements

Abstract This chapter covers recent progress in the synthesis of benzimidazol-2-ones (1,3-dihydro-2H-benzimidazol-2-ones) via rearrangements of various heterocyclic systems such as benzodiazepin(di)ones, quinoxalin(on)es, tetrazolones, condensed and spiro compounds with a benzimidazole system, and anthranilic acid and its derivatives. The chapter also shows how benzimidazol-2-ones are useful intermediates for the synthesis of more complex organic molecules.

New method for the synthesis of 2-substituted benzimidazole-5(6)-carboxylic acids

A new method is proposed for the synthesis of 2-substituted benzimidazole-5(6)-carboxylic acids. The acid-catalyzed rearrangement of 2(3)-aroyl-3(2)-oxo-3,4(1,2)-dihydroquinoxaline-6-carboxylic acids was shown to proceed with the formation of 2-(3-arylquinoxalin-2-yl)-1H-benzimidazole-5(6)-carboxylic acids. NMR studies of the rearrangement reaction product, 2-(3-phenylquinoxalin-2-yl)-1Hbenzimidazole-6-carboxylic acid, indicated that it existed as a mixture of two tautomeric forms due to benzimidazole tautomerism under the NMR conditions. The carboxyl group of the synthesized benzimidazoles was used for the preparation of new derivatives.