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Benzimidazole derivatives have exhibited marvelous utility due to their widespread pharmaceutical features, including anti-fungal, anti-viral, anti-bacterial, anti-cancer, anti-inflammatory, anti-convulsant, analgesic, anti-leishmanial, and so on. On the other hand, benzimidazoles display a fundamental performance in modern catalytic systems, chiefly as ligands for metal-based catalysis and also in the manufacture of some highly useful scaffolds such as N-heterocyclic carbenes. Hence, the design of practical strategies for the construction of the benzimidazole motif is of great importance. Despite the effectiveness of the conventional synthetic methods based on homogeneous catalysis, these protocols mostly encounter serious obstacles, especially from the aspect of the separation of the catalyst from the reaction mixture, as well as, the necessity to use costly catalysts. In this regard, plenty of effort has gone into the preparation of benzimidazoles using heterogeneous catalysts. In this review, we concentrated on discussing the recent achievements in the heterogeneous catalyzed synthesis of functionalized benzimidazole structures, along with crucial mechanistic considerations. We focused on an overview of the latest reusable catalytic methodologies to provide benzimidaloles or 2-substituted/1,2-disubstituted benzimidazole rings thru assorted routes involving condensation, insertion, and cyclization processes. |
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