Recent Advances in Synthetic Strategies of Benzimidazole and its Analogs: A Review

Abstract: It has been established on the basis of reported research that benzimidazoles and their analogs are active scaffolds. Benzimidazole is a benzofused imidazole compound that is present in several marketed molecules with a wide range of uses that established its importance in pharmaceutical sectors and industry. Drugs with a benzimidazole nucleus have unique structural characteristics and an electron-rich environment that allows them to attach to a variety of physiologically significant sites and produce a variety of actions. The development of benzimidazole heterocyclic molecules as antihistaminic (H1-receptor antagonist, for example, bilastine; 5-HT3 antagonist, for example, leri-setron); antimicrobial (antibiotic, for example, ridinilazole); antiulcer (proton pump inhibitor (PPI), for example, ilaprazole); antihypertensive (calcium channel blocker, for example, mibefradil); and drugs used to treat cancer include those that are antiparasitic (specifically anthelmintic, such as fubendazole), antipsychotic (D2 receptor antagonist, such as clopimozide), analgesic (opioid analgesic, such as clonitazene), and phosphodiesterase inhibitor (PDE3 inhibitor, such as adibendan). Due to its broad applications, scientists are continuously enthralled by benzimidazoles and their derivatives to study their chemistry. Several synthesis strategies can prepare benzimidazole or its derivatives and the focus will always be on new, greener, and more economical ways for its synthesis. Among all methods, catalytic cyclization, catalytic coupling, and catalytic reactions are the most used approaches for the synthesis of benzimidazoles and their analogs. The present review entitled various synthetic approaches for synthesizing benzimidazole from 2009 to 2021 and its derivatives, which will be very useful to researchers for developing benzimidazole moieties.