A Highly Efficient and Green Synthesis of Pyrimido-Fused Benzophenazines via Microwave-Assisted and H3PW12O40@Nano-ZnO Catalyzed a Sequential One-Pot Cyclization in Aqueous Medium

Abstract

A rapid, efficient, and environmentally benign procedure for the synthesis of novel heteroaryl-substititued dihydrobenzo[a]pyrimido[5′,4′:5,6]pyrido[2,3-c]phenazines has been developed via condensation/Knoevenagel/Michael/heterocyclization reactions of 2-hydroxynaphthalene-1,4-dione, o-phenylenediamine, aromatic aldehydes, and 6-amino-1,3-dimethyluracil in the presence of H3PW12O40@nano-ZnO as a recyclable heterogeneous catalyst in aqueous medium under microwave irradiation. This sequential green process with main aspects such as: operational simplicity, high yields, low cost, easy handling, eco-friendly and reusability of the catalyst, absence of any tedious workup, or purification and avoidance of hazardous or toxic reagents/catalysts/solvents opens an effective and convenient way to pyrimido-functionalized benzophenazine systems, which are promising compounds for different biomedical applications.