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

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 ß-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.

(2E,6E)-2,6-Bis(2,6-dichloro-benzyl-idene)-cyclo-hexa-none.

The title compound, C(20)H(14)Cl(4)O, was prepared by the reaction of 2,6-dichloro-benzaldehyde and cyclo-hexa-none. In the mol-ecule, the central cyclo-hexa-none ring adopts an envelope conformation, while the terminal benzene rings make a dihedral angle of 57.87 (9)°.

Ultrasound promoted rapid and green synthesis of 1,8-dioxo-octahydroxanthenes derivatives using nanosized MCM-41-SO(3)H as a nanoreactor, nanocatalyst in aqueous media.

An efficient and green procedure has been developed for the synthesis of 1,8-dioxo-octahydroxanthenes derivatives. The reaction was carried out in water under ultrasound irradiation, using nanosized MCM-41-SO(3)H. In this method, several types of aromatic aldehyde, containing electron-withdrawing groups as well as electron-donating groups, were rapidly converted to the corresponding 1,8-dioxo-octahydroxanthenes in good to excellent yields. This novel synthetic method is especially favored because it provides a synergy of the nanosized MCM-41-SO(3)H and ultrasound irradiation which offers the advantages of high yields, short reaction times, simplicity and easy workup compared to the conventional methods reported in the literature.

Ultrasound-promoted greener synthesis of aryl-14-H-dibenzo[a,j]xanthenes catalyzed by NH4H2PO4/SiO2 in water.

Silica supported ammonium dihydrogen phosphate (NH(4)H(2)PO(4)/SiO(2)) is found to be a recyclable heterogeneous catalyst for a rapid and efficient synthesis of various aryl-14-H-dibenzo[a,j]xanthenes with excellent yields using ultrasonic irradiation. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction times and milder conditions.