NEW METHOD FOR THE SYNTHESIS OF 2-SUBSTITUTED BENZIMIDAZOLE-5(6)-CARBOXYLIC ACIDS
DOI:
https://doi.org/10.1007/4076Keywords:
4-aminobenzoic acid derivatives, benzimidazole-5(6)-carboxylic acids, 2, 5'-bibenzimidazoles, 2-oxo-3, 4-dihydroquinoxaline-6-carboxylic acids, o-phenylenediamine, Mamedov rearrangement.Abstract
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-2yl)-1H-benzimidazole-5(6)-carboxylic acids. NMR studies of the rearrangement reaction product, 2-(3-phenylquinoxalin-2-yl)-1H-benzimidazole-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.
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Published
2017-11-07
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Original Papers