A highly efficient and improved synthetic methodology for the preparation of dihydropyrimidinone derivatives using β-dicarbonyl compounds, urea/thiourea and aromatic aldehydes using Fe3O4–MWCNT as a nanocatalyst under ultrasound irradiation is reported. The present method has promising features for the reaction such as the very short reaction time, excellent product yields, simple work-up procedure and operational simplicity. The advantages of this novel protocol as compared to other synthetic methods are clean conversion, the amount of catalyst, high catalytic activity and ease of recovery from the reaction mixture using an external magnet, and reuse several times without significant losses in performance.
