LAUSR

Abstract The functioning, Pot, Atom, and Step Economic (PASE) green chemistry proposition has been approached for the synthesis of pyrimido[4,5-d]pyrimidines by the multicomponent reaction (MCR) of barbituric acid, guanidine, and aldehyde derivatives using water solvent and iodine catalyst through ultrasound and microwave irradiation methods. Reaction optimization was performed by varying solvents, reaction time, the concentration of catalyst, and reaction methods. Microwave irradiation approach using water solvent and iodine catalyst (8 mol%) with 5 min led to offer the highest yield. EWG substituted compound 4 g (4-NO2, guanidine) [87% (U.S.), 93% (M.W.)] was found to be the highest yielded compound in this study. The greenness of the reaction was estimated by calculating some green chemistry metrics. The metrics approved the proposed protocol as an ideal, green, and sustainable approach. GRAPHICAL ABSTRACT