4.3. General procedure for the synthesis of 3,4-
dihydropyrimidin-2-(1H)-ones under microwave irradiation
method (method B)
A mixture of aldehyde (1.0 mmol), ethyl acetoacetate
(1.0 mmol), urea (1.5 mmol), and nano-g-Fe2O3eSO3H was placed
in a microwave reaction vial. The LG microwave oven MG 555f was
programmed to 250 W at 60 C. The progress of the reaction was
monitored by TLC. After completion of the reaction, ethyl acetate
(5 mL) was added and the catalyst was separated by applying an
external magnet. The solvent was evaporated and the residue was