Exploring the World of Benzimidazole: Synthesis, Reactions, and Diverse Applications—A Comprehensive Review

Abstract

Benzimidazole represents one of the most extensively investigated nitrogen‐containing fused heterocyclic scaffolds owing to its unique structural features, synthetic versatility, and broad spectrum of biological and industrial applications. The presence of a benzene ring fused with an imidazole nucleus imparts remarkable physicochemical and pharmacological properties, making benzimidazole a privileged framework in medicinal chemistry, materials science, catalysis, and supramolecular chemistry. This review critically examines recent advances in the synthesis, reactivity, structure–activity relationships (SAR), and applications of benzimidazole derivatives. Various synthetic approaches, including classical condensation methods, transition‐metal‐catalyzed protocols, multicomponent reactions, microwave‐assisted synthesis, solvent‐free methodologies, and metal‐free organocatalytic routes, are comparatively evaluated with respect to efficiency, substrate scope, mechanistic features, scalability, and sustainability. Particular emphasis is placed on emerging catalytic strategies employing Earth‐abundant metals, recyclable catalysts, and carbon dioxide as a sustainable C1 feedstock. The review further analyzes the influence of N1, C2, and C5/C6 substitutions on biological activity, highlighting key SAR trends governing antimicrobial, anticancer, antiviral, anti‐inflammatory, antioxidant, antidiabetic, and neuroprotective properties. By integrating synthetic methodologies with biological and functional perspectives, this review provides a comprehensive and critical framework for understanding the current state of benzimidazole chemistry and identifies future directions for the development of sustainable and multifunctional benzimidazole‐based systems.