A highly efficient one-pot multicomponent synthesis of 3,4-dihydropyrimidin-2-(1H)-ones/thiones catalyzed by strontium pyroarsenate nano-plates

Unveiling the choline chloride-thiourea (1 : 1) DES as a greener medium and reagent for pyrimidinethione synthesis from α,β-unsaturated carbonyl compounds

Widespread studies on developing greener organic chemistry techniques were prompted by growing concerns about the health and environmental issues brought on by the effects of organic compounds. Since solvents and catalysts are necessary for many organic reactions, greener solvents and catalysts could remedy this problem. 3,4-Dihydropyrimidine-2(1H)-thiones (DHPMs) are an essential class of biomolecules. Several methods for synthesizing DHPMs have been reported. Nevertheless, most of these methods were linked to one or more disadvantages, such as laborious catalyst production, use of expensive catalysts, and severe reaction conditions like longer reaction times, higher temperatures and strong base, and reduced yields. Therefore, a simple, effective, and environmentally friendly protocol for the synthesis of 4,6-diaryl-3,4-dihydropyrimidine-2(1H)-thiones from α,β-unsaturated carbonyl compounds using the biodegradable, cheap, and easily accessible choline chloride : thiourea (CC : TU) 1 : 1 room temperature deep eutectic solvent (DES) is reported. The pyrimidinethione products were obtained from structurally and electronically diverse α,β-unsaturated carbonyl compounds in good to excellent (45-99%) yields under the optimized reaction conditions. The CC : TU (1 : 1) DES was used for the first time in a synthetic protocol, and it was found to be an augmenting medium and a reactant for the reaction. Hopefully, this paper will open doors to developing new DESs for synthesis. It will also encourage scientists to explore using CC : TU (1 : 1) as a solvent and reactant for several organic transformations involving thiourea.

Magnetic BiFeO3 nanoparticles: a robust and efficient nanocatalyst for the green one-pot three-component synthesis of highly substituted 3,4-dihydropyrimidine-2(1H)-one/thione derivatives

In this research, magnetic bismuth ferrite nanoparticles (BFO MNPs) were prepared through a convenient method and characterized. The structure and morphological characteristics of the prepared nanomaterial were confirmed through analyses using Fourier-transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), elemental mapping, powder X-ray diffraction (XRD), N2 adsorption-desorption isotherms and vibrating sample magnetometry (VSM) techniques. The obtained magnetic BFO nanomaterial was investigated, as a heterogeneous Lewis acid, in three component synthesis of 3,4-dihydropyrimidin-2 (1H)-ones/thiones (DHPMs/DHPMTs). It was found that the BFO MNPs exhibit remarkable efficacy in the synthesis of various DHPMs as well as their thione analogues. It is noteworthy that this research features low catalyst loading, good to excellent yields, environmentally friendly conditions, short reaction time, simple and straightforward work-up, and the reusability of the catalyst, distinguishing it from other recently reported protocols. Additionally, the structure of the DHPMs/DHPMTs was confirmed through 1H NMR, FTIR, and melting point analyses. This environmentally-benign methodology demonstrates the potential of the catalyst for more sustainable and efficient practices in green chemistry.

l-Asparagine-EDTA-amide silica-coated MNPs: a highly efficient and nano-ordered multifunctional core-shell organocatalyst for green synthesis of 3,4-dihydropyrimidin-2(1H)-one compounds

In this study, new l-asparagine grafted on 3-aminopropyl-modified Fe3O4@SiO2 core-shell magnetic nanoparticles using the EDTA linker (Fe3O4@SiO2-APTS-EDTA-asparagine) was prepared and its structures properly confirmed using different spectroscopic, microscopic and magnetic methods or techniques including FT-IR, EDX, XRD, FESEM, TEM, TGA and VSM. The Fe3O4@SiO2-APTS-EDTA-asparagine core-shell nanomaterial was found, as a highly efficient multifunctional and recoverable organocatalyst, to promote the efficient synthesis of a wide range of biologically-active 3,4-dihydropyrimidin-2(1H)-one derivatives under solvent-free conditions. It was proved that Fe3O4@SiO2-APTS-EDTA-asparagine MNPs, as a catalyst having excellent thermal and magnetic stability, specific morphology and acidic sites with appropriate geometry, can activate the Biginelli reaction components. Moreover, the environmental-friendliness and nontoxic nature of the catalyst, cost effectiveness, low catalyst loading, easy separation of the catalyst from the reaction mixture and short reaction time are some of the remarkable advantages of this green protocol.

A facile hydrothermal synthesis of high-efficient NiO nanocatalyst for preparation of 3,4-dihydropyrimidin-2(1H)-ones

The present work introduces a one-step and facile hydrothermal procedure as a green process for the first time to synthesize nickel(II) oxide (NiO) nanoparticles. The as-prepared nanomaterials were used as high efficient, low toxic and cost catalyst for the synthesis of some organic compounds. Ni(NO₃)₂ and some natural extract were used as a surfactant for the first time to synthesis NiO nanomaterials. A high synthesis yield (91%) was obtained for S₂. Rietveld analysis affirmed the cubic crystal system of the obtained NiO nanocatalyst. The morphology studies were carried out with the FESEM method and the images revealed a change from non-homogenous to homogenous spherical particles when the Barberryas was used instead of orange blossom surfactant. Besides, the images revealed that the particle size distribution was in the range of 20 to 60 nm. The synthesized catalysts were used for the first time in Biginelli multicomponent reactions (MCRs) for the preparation of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) under the present facile reaction conditions. High yield (97%) of the final product was achieved at the optimum condensation reaction conditions (Catalyst: 60 mg; temperature: 90 °C and time: 90 min) when ethyl acetoacetate/methyl acetoacetate (1 mmol), benzaldehyde (1 mmol) and urea (1.2 mmol) were used. A kinetic study affirmed pseudo-first-order model for Biginelli reactions followed the pseudo-first-order model.