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Abstract: In this work, the immobilized polythiophene on magnetic carbon nanotube (CNT–Fe3O4–PTh) was synthesized and introduced as a novel and recoverable catalytic system. The prepared magnetic heterogeneous nanocatalyst was characterized by FT-IR, TGA, EDX, VSM, XRD, TEM, and FE-SEM. Next, the catalytic efficiency of CNT–Fe3O4–PTh was evaluated through the green synthesis of a variety of dihydropyrimidinone and octahydroquinazolinone through Biginelli reaction between aromatic aldehydes, urea/thiourea, and β-dicarbonyl compounds under solvent-free conditions. The catalyst was magnetically recovered and recycled for five cycles without a discernible loss in its catalytic activity. Simple workup, affordability, short reaction times, mild reaction conditions, and the high yield of products are the interesting features of this project. Graphic abstract: An environmentally benign nanocomposite was prepared using carbon nanotube as an inexpensive, nontoxic, and stable support in the preparation of CNT–Fe3O4–PTh, which was efficiently used as catalyst for the green synthesis of dihydropyrimidinone and octahydroquinazolinone derivatives through Biginelli reaction under solvent-free conditions.[Figure not available: see fulltext.].

Dihydropyrimidinones/thiones (DHPM’s) have been prepared by one-pot condensation of methyl acetoacetate, aldehydes, urea/thiourea in the presence of heteropoly-11-tungsto-1-vanadophosphoric acid, H4[PVW11O40] · 32H2/

A Br?nsted acidic 1-ethyl-1,2,4-triazolium phenylsulfonate has been synthesized and characterized. A catalytic study is performed for 1-ethyl-1,2,4-triazolium phenylsulfonate as acid catalyst for a multicomponent reaction of synthesis of series of 3,4-dih

Abstract: A novel highly efficient magnetically retrievable catalyst was developed by the immobilization of H3PW12O40 (20–60 wt%) on the surface of zirconia-encapsulated Fe3O4 nanoparticles. The prepared HPW supported on nano-Fe3O4@ZrO2 heterogeneous acid catalyst (or n-Fe3O4@ZrO2/HPW) was fully characterized by several physicochemical techniques such as: Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, vibrating sample magnetometry and thermogravimetric analysis. The FT-IR spectroscopic data revealed that H3PW12O40 molecules on the nano-Fe3O4@ZrO2 support existed in the Keggin structure. The acidity of the catalyst was measured by the help of a potentiometric titration with n-butylamine. It was surprising that this very strong solid acid catalyst exhibited an excellent acid strength which was as a result of possessing a higher number of surface active sites compared to its homogeneous analogues. The catalytic activity of the as-prepared novel nano-Fe3O4@ZrO2/HPW was explored through the one-pot three-component synthesis of different 3,4-dihydropyrimidin-2(1H)-ones (i.e. Biginelli reaction) and 1,4-dihydropyridines (i.e. Hantzsh reaction) under solvent free condition. The sample of 40 wt% showed higher acidity and activity in the catalytic transformation. After the reaction, the catalyst/product isolation could be easily achieved with an external magnetic field and the catalyst could be easily recycled for at least five times without any decrease in its high catalytic activity. The excellent recyclability was attributed to the strong interaction between the hydroxyl groups of the nano-Fe3O4@ZrO2 support and the HPW species. Graphical Abstract: [Figure not available: see fulltext.].

The visible-light-mediated aerobic desulfurization and aromatization of Biginelli 3,4-dihydropyrimidine-2(1H)-thiones for a one-step synthesis of 2-unsubstituted pyrimidines was established. The protocol uses molecular oxygen as an inexpensive oxidant, wi

In this work, catalyst composition-activity relationship of supported catalysts in Biginelli and Hantzsch reactions was investigated under mild conditions. Biginelli dihydropyrimidinone/thiones were prepared over Fe-Cu/ZSM-5 as an efficient, convenient, and environmentally benign catalyst under ultrasonic irradiation in aqueous media in very good yields. The Fe-Cu/ZSM-5-catalyzed synthesis of 1,4-dihydropyridines and their aromatization to polysubstituted pyridines and also a new one-pot, two-step, and sequential protocol for the synthesis of pyridine derivatives, employing an aldehyde, ethyl acetoacetate, and ammonium acetate under the same green experimental conditions were illustrated. Three-component condensation in the presence of supported reagent with operational simplicity, inexpensive reagents, short reaction time, high yield of products, and use of non-toxic reagents makes this synthetic protocol an attractive one.

Although glass recycling has been conducted since 1970s, and even though recycled glass waste has been used in the construction of various alternative products, the utilization of glass waste for catalytic applications has not been fully considered until

Four series of heterocyclic compounds 4-dihydropyrimidine-2-thiones 7-12 (series A), N,S-dimethyl-dihydropyrimidines 13-18 (series B), hydrazine derivatives of dihydropyrimidine 19-24 (series C), and tetrazolo dihydropyrimidine derivatives 25-30 (series D

An efficient and green route for the synthesis of dihydropyrimidinones via microwave-assisted Biginelli reaction catalyzed by 3 mol% of heteropolyanion-based ionic liquids under solvent-free conditions has been reported. The practical reaction was found t

Synthesis of three Brnsted acid-based ionic liquids, namely, 1-ethyl-1,2,4-triazolium triflate (1a), 1-propyl-1,2,4-triazolium triflate (1b) and 1-butyl-1,2,4-triazolium triflate (1c), is described. These ionic liquids have been employed as catalysts for

Dihydropyrimidines (DHPM) with a fused tetrazole ring have been synthesized via a smooth and efficient three-step protocol involving N,S-dimethylated and 2-hydrazinyl-dihydropyrimidine intermediates, respectively. The described protocol is applicable to e

A fast and efficient Biginelli synthesis of 3,4-dihydropyrimidin-2-(1H)- ones (or thiones) by the reaction of aromatic aldehydes, β-dicarbonyls, and urea/thiourea using NaHSO4·H2O/ultrasound system is presented. The reactions were ca

Various 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) and their sulfur derivatives were efficiently synthesized by a one-pot cyclocondensation reaction of aromatic and aliphatic aldehydes, β-dicarbonyl compounds and urea (or thiourea) in the presence of sulfur

Five percentage perchloric acid doped silica is successfully used as an efficient mild catalyst for the synthesis of 4-aryl dihydropyrimidine-2(1H)- ones. This method offers significant advantages such as efficiency and mild reaction conditions.

The catalytic activity of Fe3O4 nanoparticles (NPs) in a one-pot three component condensation reaction consisting of an aromatic aldehyde, urea or thiourea, and a β-dicarbonyl under solvent-free conditions was investigated. This reac

The catalytic activity of Fe3O4 nanoparticles (NPs) in a one-pot three component condensation reaction consisting of an aromatic aldehyde, urea or thiourea, and a β-dicarbonyl under solvent-free conditions was investigated. This reac

Multicomponent one-step fusion of a variety of pharmacologically pertinent pyrimidine heterocycles has efficiently been achieved from their respective aldehydes, β-dicarbonyl compounds, and urea/thiourea in the presence of a catalytic amount of tetrachlor

An efficient synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives using samarium chloride as a catalyst from aldehyde, β-keto ester and urea or thiourea in ethanol is described; compared to the classical Biginelli method, this new method has the advant

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