A Critical Analysis of the Modern Synthetic Procedures Used to Produce Benzimidazole Candidates

Background: Benzimidazole is a remarkable heterocyclic chemical compound in which the phenyl ring is fused with the imidazole ring at positions 4 and 5. Benzimidazole derivatives have lots of medicinal activity in the pharmaceutical industry. Therefore, the synthesis of benzimidazole derivatives is challenging in this scientific field. Methods: In benzimidazole synthesis, simple nucleophilic substitution and condensation reactions involving carbonyl compounds and o-phenylenediamine have been used in previous times. Currently, green chemistry aspects such as solvent-free conditions, metal-free conditions, or using nanoparticle catalysts in various ways involving condensation, and cyclization are the methods of the new era. Results: Green chemistry methods are used widely in various chemical reactions, such as it was observed that the use of solvent-free conditions, metal-free conditions, or using nanoparticle catalysts molecules is a more efficient way to synthesize benzimidazole derivative. Conclusion: In this review, benzimidazole scaffold syntheses that have only recently been described in the literature through the end of 2021 are covered. Monosubstituted benzimidazoles (MSBs) and disubstituted-benzimidazoles (DSBs) are the primary targets of our research currently. Different ways have been found to make functionalized derivatives of benzimidazole, which are shown in this review as a powerful scaffold.