The Impact of Incorporating Piperazine on Biological Activities of Benzazoles

Heterocycles are widely distributed compounds in natural products and are involved in many biological processes. Its uses have been extended to different fields, including industry, medicine, and agriculture sectors. Benzazole is one of the popular heterocycle scaffolds known as a privilege structure which is commonly found in many pharmaceutical agents. Another outstanding scaffold is piperazine that is known as a distinguishable motif in drug design with a wide range of biological activities. One of the fruitful approaches in the drug design is a hybridization of privilege structures in one skeleton which are believed to grant a characteristic feature with improved or more selective biological activities than the two scaffolds. The effect that piperazine imparted while introduced into a benzazole has drawn attention since first used in the nineteenth century. Numerous research has been performed discussing the synthesis and biological activities of benzazoles containing piperazine. In this chapter, we will highlight a general introduction about chemistry and structure of piperazine, and its importance in medicinal chemistry and benzazole as well. Next, several studies will be discussed that highlight the importance of incorporating piperazine in benzazole skeletons, benzimidazole, benzothiazole, and benzoxazole, and biological activity inherited from this combination.