Recent advances in the synthetic transformation of benzimidazole scaffolds as privileged pharmacophores for cancer chemotherapy (2020–present)

Benzimidazole is a fused heterocycle of benzene and imidazole rings. It has attracted marked attention as a privileged pharmacophore with a wide spectrum of biological activities-bioactivities among which anticancer therapeutic potential is most studied. This review presents synthetic approaches in structural diversity comprehensively approved clinically used drugs by the FDA patents and benzimidazole-based hybrid therapeutics advancements with special consideration of their potential as anticancer agents. The compiled research in this article revealed that many benzimidazole derivatives even hybrids with triazole quinoline hydrazine oxazole coumarin moieties etc. execute topoisomerase inhibitory tubulin disruptive DNA intercalating fragmenting apoptosis inducing varied biological mechanisms. Several conventional and green synthetic methods involving ultrasonic-and-microwave-assisted synthesis, one-pot reactions, multicomponent reactions (MCRs), and click reactions are described emphasized on optimized yields and compound structural variability. The addition of electron-withdrawing groups (EWGs), electron-donating groups (EDGs), metal complexes, and scaffold-linking approaches have possibly enhanced their anticancer activity. Strikingly, FDA-approved benzimidazole drugs and clinical candidates exhibited potential chemotherapeutic anticancer activity, bioavailability, and molecular selectivity. A detailed structure–activity relationship (SAR) emphasizes the role of the benzimidazole nucleus in discovering anticancer agents and provides future direction toward structure-guided rational design for developing next-generation therapeutic agents containing the versatile benzimidazole nucleus.