Cancer is one of the deadliest diseases in many developed and developing countries. Continuous efforts are required for designing better therapeutic agents for the treatment of cancer with more efficacy, selectivity, and less toxicity. The fused heterocyclic ring system has been identified by several researchers as a privileged structure that can be used as the basis for drug discovery in medicinal chemistry. The hetero-aromatic bicyclic ring system acts as a pharmacophore in a wide range of drugs with therapeutic potential. According to studies in the literature, various substituted benzimidazoles have distinct pharmacological profiles with multi-targeting ability, making them an important anchor for the production of novel therapeutic agents against complex cancers, including breast cancer, skin cancer, and blood cancer. In this article, we have discussed various synthetic methods for the synthesis of anti-cancer benzimidazoles and their derivatives in different solvent conditions, substrates, and various catalysts, mainly those which are eco-friendly and economical. We also focused on various derivatives those are under clinical trials containing benzimidazole moiety.

Benzothiazole is a heterocyclic compound that contains a benzene ring fused with a five-member 1,3-thiazole ring. Several types of research have established its potential as an antimicrobial agent, anticancer agent, anti-epileptic agent, antiviral agent, etc. Nowadays, various effective drugs utilize the hybridization of two or more pharmacophores in a single-molecule for synergizing its pharmacological action or to interact with more than one target or to reduce the side effects associated with it. In this article, various strategies for the synthesis of different pharmacologically active hybrid compounds containing benzothiazole with different substituents are highlighted. Apart from presenting the synthesis strategies, the article also highlights various pharmacological actions and molecular interactions with different biological molecules of the potential drugs containing benzothiazole.