A Review on Green Synthesis and Biological Activities of Medicinally Important Nitrogen and Oxygen Containing Heterocycles

Recently, the application of green chemistry for the formation of potential bioactive heterocyclic moieties has turned out to be the key area of research for organic chemists due to the growing concern over environmental issues. Therefore, the development of nonhazardous synthetic protocols gained the particular attention of synthetic chemists as a frontier task in the present scenario. Nowadays, microbial infections have been haunting human civilization since prehistoric times, resulting in many deaths worldwide. Cancer is a fatal and dreadful disease without any appropriate cure, thus threatening humanity in both the developing and developed worlds. Therefore, there is a critical requirement for the design and synthesis of new classes of compounds to circumvent these diseases. Heterocycles are unique precursors for the synthesis of various pharmaceuticals and agrochemicals, particularly those possessing N- or O- moieties. The methods to prepare heterocycles are of great importance in synthesizing organic compounds, especially the heterocycles found in natural products. The synthesis of nitrogen and oxygen-containing heterocycles viz. Coumarins, dihydropyrimidinones, imidazoles, isoxazoles, and benzimidazoles represent attractive and demanding work for chemists as these molecules have found extensive applications in several fields, such as materials science, analytical chemistry and most importantly in, medicinal chemistry. In this review paper, we focus on the synthetic strategy to prepare these types of heterocyclic compounds by green methods and discuss their various biological applications.