Ultrasound promoted one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones using dendrimer-attached phosphotungstic acid nanoparticles immobilized on nanosilica

[Display omitted] •3,4-Dihydropyrimidin-2(1H)-ones catalyzed by Dendrimer-PWAn.•A convenient sonochemical method is described for the preparation of 3,4-dihydropyrimidin-2(1H)-ones.•Good to excellent yields were achieved within shorter reaction time.•High catalytic activity and reusability of nanocatalyst were observed. A highly efficient and improved synthetic methodology for the preparation of 3,4-dihydropyrimidin-2(1H)-ones and thiones in the Biginelli reaction by condensation of β-dicarbonyl compounds, urea/thiourea and aromatic aldehydes using Dendrimer-PWAn as a nanocatalyst under ultrasonic irradiation is reported. Compared with classical Biginelli reaction conditions, this new method has the advantage of easy reaction condition, short reaction time, excellent yields, recyclable green catalyst, reduced environmental impacts and absence of any tedious workup or purification. The catalyst can be easily recovered by filtration and reused for eight consecutive reaction cycles without significant loss of activity. Also, SEM and DLS images of the catalyst after reaction cycle were investigated.