Three component reactions: An efficient and green synthesis of 3,4-dihydropyrimidin-2-(1H)-ones and thiones using silica gel-supported l-pyrrolidine-2-carboxylic acid-4-hydrogen sulfate

Retracted Article: Boric acid in magnetized water: clean and powerful media for synthesis of 3,4-dihydropyrimidin-2(1H)-ones

Water was magnetized via an external magnetic field and employed, for the first time, as a solvent in green preparation of 3,4-dihydropyrimidin-2(1H)-ones by the one-pot three-component condensation reaction using boric acid as a catalyst. Shorter reaction times, higher yields, and cleaner reaction profiles were some advantages of using magnetic water.

1, 1'-Sulfinyldiethylammonium Bis (Hydrogen Sulfate) as a Recyclable Dicationic Ionic Liquid Catalyst for the Efficient Solvent-free Synthesis of 3, 4-Dihydropyrimidin-2(1H)-ones via Biginelli Reaction

OBJECTIVE

A facile and efficient method for synthesis of 3, 4-dihydropyrimidin-2(1H)-ones via Biginelli reaction catalyzed by a novel dicationic Brönsted acidic ionic liquid, [(EtNH2)2SO][HSO4]2, has been successfully developed.

MATERIALS AND METHODS

3, 4-Dihydropyrimidin-2(1H)-ones were synthesized through one-pot condensation of aromatic aldehydes, ethyl acetoacetate, and urea under solvent-free conditions using [(EtNH2)2SO][HSO4]2 as a novel catalyst. The progress of the reaction was monitored by thin-layer chromatography (ethyl acetate / n-hexane = 1 / 5). The products have been characterized by IR, 1H NMR, 13C NMR, and also by their melting points.

RESULTS

In this research, a library of dihydropyrimidinone derivatives was synthesized via Biginelli reaction under solvent-free conditions at 120oC using [(EtNH2)2SO][HSO4]2 as a catalyst. Various aromatic aldehydes, as well as heteroaromatic aldehydes, were employed, affording good to high yields of the corresponding products and illustrating the substrate generality of the present method. In addition, the prepared dicationic Brönsted acidic ionic liquid can be easily recovered and reused.

CONCLUSION

1, 1'-Sulfinyldiethylammonium bis (hydrogen sulfate), as a novel dicationic ionic liquid, can act as a highly efficient catalyst for the synthesis of 3, 4-dihydropyrimidin-2(1H)-ones under solvent-free conditions.

Recent developments in the synthesis and applications of dihydropyrimidin-2(1H)-ones and thiones

Dihydropyrimidin-2(1H)-ones/thiones (DHPMs) are important heterocyclic compounds owing to their excellent biological activities and have been widely utilized in pharmaceutical applications. Recently, numerous DHPM derivatives have been prepared. This review covers the synthesis of DHPMs and improved procedures for the preparation of DHPMs from 1995 to 2016.

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 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.

Polymer-supported benzimidazolium based ionic liquid: an efficient and reusable Brønsted acid catalyst for Biginelli reaction

A polymer-supported benzimidazolium based ionic liquid (PSBIL) was synthesized by reaction of poly(vinylbenzyl chloride) and benzimidazole followed by ring opening of 1,4-butane sultone and acidification with sulphuric acid.

Immobilization of phosphomolybdic acid nanoparticles on imidazole functionalized Fe3O4@SiO2: a novel and reusable nanocatalyst for one-pot synthesis of Biginelli-type 3,4-dihydro-pyrimidine-2-(1H)-ones/thiones under solvent-free conditions

Fe₃O₄@SiO₂-imid-PMAⁿ: a novel and reusable nanocatalysts.

Bi-SO3H Functionalized Ionic Liquid Based on DABCO: New and Efficient Catalyst for Facile Synthesis of Dihydropyrimidinones

A simple and efficient method for the one-pot Biginelli condensation reaction of aldehydes,β-dicarbonyl compounds, and urea or thiourea employing [DABCO](SO3H)2Cl2as a novel ionic liquid catalyst is described.