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The review discusses the use of the Dimroth rearrangement in the synthesis of condensed pyrimidines which are key structural fragments of antiviral agents. The main attention is given to publications over the past 10 years. The bibliography includes 107 references.

A novel and efficient protocol for the synthesis of diversely substituted 2,2′-bibenzimidazoles from the reaction of 3-cyanoquinoxalin-2(1H)-ones with 1,2-diaminobenzenes has been developed, which ...

A facile approach to a range of substituted 7-(benzimidazol-2-yl)thioxolumazines [7-(benzimidazol-2-yl)-2-thioxo-2,3-dihydropteridin-4(1H)-ones] and 7-(benzimidazol-2-yl)lumazines [7-(benzimidazol-2-yl)pteridine-2,4(1H,3H)-diones] is described. These new biheterocyclic systems are obtained via H2SO4-catalyzed rearrangement of quinoxalin-2-ones in the presence of 5,6-diamino-2-mercapto- and 2,5,6-triaminopyrimidin-4-ols. Thus, benzimidazole and pteridine rings are constructed in one synthetic step. A plausible ANRORC (addition of nucleophile, ring opening and ring closure)-type reaction mechanism is proposed. Applying the rearrangement to the aza-analogue of 3-benzoylquinoxalin-2(1H)-one—i.e., 3-benzoylpyrido[2,3-b]pyrazin-2(1H)-one—with 5,6-diamino-2-mercaptopyrimidin-4-ol makes it possible to synthesize inaccessible 7-(1H-imidazo[4,5-b]pyridin-2-yl)-6-phenyl-2-thioxo-2,3-dihydropteridin-4(1H)-one. 7-(Benzimidazol-2-yl)-6-(2-fluorophenyl)-2-thioxo-2,3-dihydropteridin-4(1H)-ones undergoes intramolecular nu...

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.

A novel and efficient protocol for the synthesis of diversely substituted 2,2'-bibenzimidazoles from the reaction of 3-cyanoquinoxalin-2(1

Interaction of quinoxalin-2(1H)-one-3-carbaldoximes with 1,2-benzenediamine derivatives in AcOH or n-BuOH at reflux in the presence of sulfuric acid as catalyst was found to give 3-(benzimidazol-2-yl)quinoxalin-2(1H)-ones and 2-(benzimidazol-2-yl)quinoxalines in relatively good yields, which formed as a result of the Weidenhagen reaction and Mamedov rearrangement, respectively. The reaction in AcOH afforded 2-(benzimidazol-2-yl)quinoxalines in preference to the 3-(benzimidazol-2-yl)quinoxalin-2(1H)-ones, while the reverse result was obtained in n-BuOH. The synthetic utility of this strategy was illustrated by the concise, one-pot synthesis of 3-(3H-imidazo[4,5-b]pyridin-2-yl)quinoxalin-2(1H)-ones.

A facile approach to a range of substituted 7-(benzimidazol-2-yl)thioxolumazines [7-(benzimidazol-2-yl)-2-thioxo-2,3-dihydropteridin-4(1 H)-ones] and 7-(benzimidazol-2-yl)lumazines [7-(benzimidazol-2-yl)pteridine-2,4(1 H,3 H)-diones] is described. These new biheterocyclic systems are obtained via H

The rearrangement process includes a novel ring contraction as the key step to produce various benzimidazole structures bearing a pyrrole part at one of the nitrogens.

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.