Eco-Friendly Microwave-Assisted Synthesis of Fused Pyrimido[4,5-d] Pyrimidine Derivatives via a Catalyst-Free Hantzsch Multicomponent Reaction

Sustainable green heterocyclic compounds featuring fused bi-, tri-, and tetracyclic systems containing pyrimidine-barbituric acid rings were synthesized via the Hantzsch reaction using a simple and efficient method. The one-pot, three-component reaction involved bis-aldehydes, barbituric acid, and substituted amines, and was carried out under microwave irradiation without the use of a catalyst. The reactions proceeded smoothly, affording the desired products in high yields with straightforward workups. This study emphasizes the importance of green chemistry principles in the synthesis of fused pyrimido[4,5-d]pyrimidine systems, highlighting advantages, such as environmental friendliness, operational simplicity, efficiency, and safety.