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In this research, a new heterogeneous catalyst is fabricated through covalent modification of iron-based metal–organic framework with ionic liquid. In more detail, using 2-aminoterephthalic acid and iron (III) chloride hexahydrate, amino-functionalized metal–organic framework has been synthesized and then reacted with 2,4,6-trichloro-1,3,5-triazine and 1,4-diazabicyclo[2.2.2]octane successively to furnish ionic liquid on metal–organic framework. The as-prepared catalyst was characterized by FTIR, TGA, BET, SEM/EDS, XRD and elemental mapping analysis and then employed for catalyzing synthesis of pyrano [2,3‐d]pyrimidines (with yields of 80–100%) from one-pot three-component reaction of aldehydes, barbituric acid and malononitrile in aqueous media. The catalytic test inferred high catalytic activity of the catalyst, superior to that of IL and metal–organic framework. Furthermore, the catalyst could be recovered and recycled for five reaction runs with preserving its morphology.

A 2,2′-Bipyridine-based ionic compound named 2,2′-bipyridinium dihydrogen phosphate was synthesized by addition of phosphoric acid to a solution of 2,2′-Bipyridine in dichloromethane. After the characterization using FT-IR, mass, 1H, 13C and 31P NMR techniques, it was used as a Bronsted dicationic acidic catalyst for the promotion of the synthesis of 2-arylidene malononitrile and 5-arylidene barbituric acid derivatives via Knoevenagel condensation reaction in water. Some of the advantages of this method are the utilization of an easy preparable, cost-effective and eco-friendly organic salt as a catalyst within high rates and yields of the reactions, simple and quick work-up and acceptable reusability of the catalyst.

A simple and efficient method for the synthesis of pyrazolopyranopyrimidines under solvent-free has been developed. The one-pot multicomponent condensation of arylaldehydes with hydrazine hydrate, ethyl acetoacetate and barbituric acid in the vicinity of a mesoporous basic nanomagnetic catalyst, namely DBU immobilized on Fe3O4@nSiO2@mSiO2 was synthesized in remarkably high yields and in short reaction times. Significantly, this catalyst can be easily separated from the reaction media by applying an external magnet, and can be reused for several cycles.

A set of C3N4 samples has been prepared by using melamine, cyanuric acid and barbituric acid as the precursors. The materials were subjected both to physical and chemical characterization and were used as photocatalysts for the selective oxidation of aromatic alcohols in water suspension under UV and visible irradiation. The photoactivity of the materials versus the partial oxidation of four substituted benzyl alcohols was investigated. The type and position of the substituents in the aromatic molecule influenced conversion and selectivity to the corresponding aldehyde. The presence of barbituric and cyanuric acids in the preparation method has changed the graphitic-C3N4 structure, and therefore both the characteristics of the material and the ability of light to activate the surface of the photocatalyst. The most active material prepared in the presence of melamine and cyanuric acid showed a remarkable selectivity towards the aldehyde even under visible irradiation.

We have developed a SnO2/SiO2 catalyzed efficient and rapid protocol for the synthesis of pyrano[2,3-d]pyrimidinone derivatives by the three-component cyclocondensation of aromatic benzaldehydes, malononitrile, and barbituric acid in ethanol at room temperature. Nanocomposite SnO2/SiO2 catalytic materials were synthesized using the sol–gel method. The synthesized catalytic materials were well characterized by using a transmission electron microscope, X-ray diffraction spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, temperature-programmed desorption (NH3-TPD), and Brunauer–Emmett–Teller theory. This protocol has several advantages such as high yield, simple workup procedure, non-toxic, clean, and easy recovery and reusability of the catalytic system. An efficient catalytic system has been developed for the synthesis of pyrano[2,3-d]pyrimidinone derivatives from one-pot three-component cyclocondensation of aromatic benzaldehydes, malononitrile, and barbituric acid in ethanol at room temperature using 15 wt% SnO2/SiO2.

Nano-Fe3O4@SiO2-3,4-dihydroxybenzaldehyde/barbituric acid/phthalhydrazide-FeCl3 (nano-Fe3O4@SiO2-HBP-FeCl3) was prepared and authenticated by usual analytical and spectroscopic techniques. The prepared nano-Fe3O4@SiO2-HBP-FeCl3 was applied to acridinedione and spiroquinazolin-4(3H)-one derivatives under green conditions. In addition, this research offers several advantages such as very easy reaction conditions, simple work-up, excellent yields, high purity of the desired product, short reaction time and one-pot reaction to synthesize Fe3O4@SiO2-HBP-FeCl3. The recycling studies revealed that catalyst could be easily recovered using an external magnet and reused five times without significant loss of its catalytic activity.

An expedient synthesis of spiro-fused heterocycles from multi-component reaction of urea, aryl aldehydes and Meldrum’s or barbituric acid by using polymer gel-entrapped catalyst under aerobic conditions at ambient temperature is reported. The developed protocol is simple, green, atom-economical and includes mild reaction conditions, does not involve tedious workup or purification procedure, avoids hazardous reagents/by-products and results in near-quantitative yields. The polymer gel-entrapped catalyst could be reused seven times without significant change in the catalytic activity.

We report synthesis of triphenyl(propyl-3-hydrogen sulfate)phosphonium bromide ([TPPHSP]Br) as a reusable green Bronsted-acidic ionic liquid catalyst and its application for synthesis of 5-arylidene barbituric acids and pyrano[2,3-d]pyrimidine derivatives by condensation reaction between aromatic aldehydes and barbituric acid or aromatic aldehydes, malononitrile, and barbituric acid in EtOH–H2O in reflux condition with good to excellent yield. The [TPPHSP]Br IL catalyst was characterized by Fourier-transform infrared (FT-IR) spectroscopy, 1H and 13C nuclear magnetic resonance (NMR), and thermogravimetric (TG) analysis and showed good catalytic activity and reusability.

In this study, a novel magnetically recoverable Fe3O4@SiO2-BenzIm-Fc[Cl]/ZnCl2 nano-particle was synthesized using a simple chemical coprecipitation approach. In the FT-IR spectroscopy of nano-particles, related absorption peaks appeared which confirmed the successful synthesis of nano-catalyst. In the EDX spectrum of the nano-catalyst, the expected elements on their regions appeared. The XRD diffusion patterns of nano-catalysts showed the crystalline dispersions of Fe3O4 magnetic nano-particles. According to the FE-SEM and TEM images, the nano-particles have relative mono-dispersity and the average size of nano-particles is around 35 nm. The catalytic activities of the novel magnetic nano-particle were evaluated in the one-pot three-component synthesis of a wide variety of pyran annulated bis-heterocyclic derivatives (38 compounds) under ultrasonic irradiation. A simple, facial and highly efficient ultrasound-assisted method has been introduced for the synthesis of fused bis-heterocyclic pyran derivatives by one-pot, three-component reactions at room temperature. A series of pyrano[3,2-c]chromene derivatives were synthesized using a novel nano-catalyst via the condensation reaction of different aldehydes, malononitrile and 4-hydroxycoumarin. Kojic acid was also used in the three-component reaction for the synthesis of pyrano[3,2-b]pyran derivatives. The method was successful in the synthesis of various pyrano[2,3-d]pyrimidine derivatives. Additionally, new ultrasound-assisted synthesis protocol was used for the synthesis of novel chromeno[2,3-d]pyrimidine derivatives via three-component condensation of aromatic aldehydes, orcinol and barbituric acid. The new catalytic method exhibits some notable advantages such as short reaction times, operational simplicity, green reaction conditions, high yields and easy work-up and purification steps. In addition, the novel magnetic nano-particle could be easily separated by an external magnet and reused for six times without significant loss of its catalytic activity in the reaction.

Two novel types of nanocellulose-based catalyst, viz. nanofibrillated cellulose sulfuric acid (s-NFC) and nanobacterial cellulose sulfuric acid (s-BC), were prepared by a simple method and characterized by Fourier-transform infrared spectroscopy, transmission electron microscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction anlaysis, and nitrogen adsorption measurements. The catalytic activity of these two bio-based solid acid catalysts was examined in a one-pot, four-component coupling reaction of barbituric acid, dimedone, aryl aldehydes, and (hetero)aromatic amines in refluxing ethanol. The results confirmed that s-BC promoted the speed of the mentioned reaction more than s-NFC. The recovery and reusability of the degradable nanostructures showed that they could be used in at least three runs without loss of activity.

A one-pot multi-component reaction of N,N-dimethylbarbituric acid,1,3-cyclohexanedione and 3-bromobenzaldehyde in H2O mediated by diethyl amine as a base affords a new barbituric acid–cyclohexanedione hybrid. The reaction proceeds smoothly, efficiently, and in high yield. The molecular structure of this compound was determined by single-crystal X-ray diffraction crystallography and spectrophotometric analyses. Of the nine possible isomers of the studied compound, the B3LYP/6-31G(d,p) method predicts that form B, in which the two OH groups are involved in significant intramolecular H-bonding interactions with the neighboring carbonyl O atom, is the most stable form in the gas phase. The X-ray structure reveals a different isomer due to intermolecular interactions caused by molecular packing in the crystal, which stabilizes the solid-state structure. Hirshfeld surface analysis of the molecular packing indicates that the H···O interactions are the primary contributor (24.5%) to the intermolecular stabilization in the crystal.

The reactions of aldehydes and barbituric acid at low temperatures in magnetized water, as a green-promoting medium, provides 9-substituted-9H-diuracilopyrans in high-to-excellent yields. This method offers the advantages of short reaction times, simplicity, low costs, high reaction yields, being green, and no need for any organic solvent. Moreover, the influence of magnetized water on the reactivity of the reactants is investigated using molecular dynamics simulations. It is shown that magnetized water has a dramatic impact on the reactivity of the two reactants involved through increase in the strength of the hydrogen bond interactions between them.

An efficient green protocol has been investigated for the synthesis of pyrimido[4,5-b]quinolines derivatives via one-pot three-component condensation of 4-chloro aniline, aromatic aldehyde and barbituric acid using low transition temperature mixtures as new generation and sustainable solvents. The process was accomplished with the use of greener and recyclable reaction media, simple methodology, easy workup procedures and no chromatographic purification with high yield. This new approach is expected to discover some significance in combinatorial synthesis of biologically active scaffolds.

A convenient and new method has been developed for the synthesis of highly substituted dihydro-2H-dipyrimido[1,2-a,4,5-d]pyrimidine-2,4(3H)-dione derivatives by one-pot three-component reactions of barbituric acid, aromatic aldehydes and 2-aminopyrimidine in ethanol under reflux condition without the support of any catalyst. The benefits of this protocol are catalyst-free, clean reaction procedure and providing excellent yields, and the use of ethanol as a solvent, which has been measured to be comparatively environmentally benign.

Molecular diversity for the synthesis of pyran annulated heterocyclic scaffolds has been achieved from the multicomponent reaction of aldehyde, malonitrile and a third participant such as dimedone, barbituric acid and 3-methyl-1H-pyrazol-5(4H)-one. The reactions completed successfully using in situ-developed benzylidenemalononitriles via Knoevenagel reaction catalyzed by aspartic acid as a new efficient organo-catalyst in aqueous ethanol as a green medium at ambient conditions.

An efficient heterogeneous hybrid catalyst was developed by functionalization of halloysite clay nanotubes by γ-aminopropyltriethoxysilane and then immobilization of a Keggin type heteropolyacid, phosphotungstic acid. This hybrid catalyst was characterized by SEM/EDX, FTIR and XRD and its catalytic activity for the synthesis of pyrazolopyranopyrimidine derivatives via four-component domino reaction of barbituric acid, hydrazine hydrate, ethyl acetoacetate and benzaldehyde was investigated. The results indicated that the hybrid system can promote the reaction to afford the desired products in high yields and short reaction times. The superior catalytic activity of this system was confirmed when compared with those reported, previously. Moreover, this novel heterogeneous catalyst was found to be easily separable and recyclable. It was re-used at least three times with negligible loss of activity. Significantly, this protocol can be extended to nonconventional green heating sources such as microwave and ultrasonic irradiations.

Pyrano[2,3-d]pyrimidine derivatives were synthesized via one-pot, three-component condensation reaction of aromatic aldehydes, malononitrile, and barbituric acid in aqueous ethanol catalyzed by Ni2+ supported on hydroxyapatite-core–shell-γ-Fe2O3 nanoparticles (γ-Fe2O3@HAp-Ni2+ NPs) as Lewis acid. The nontoxic nature and easy handling of the catalyst, environmentally friendly and facile work-up procedure, short reaction time, low catalyst loading, and high effectiveness to give products in good to excellent yield are advantages of this approach. Also, γ-Fe2O3@HAp-Ni2+ NPs can be easily recovered and reused for at least six runs.

Succinimidinium N-sulfonic acid hydrogen sulfate ([SuSA-H]HSO4) as a new ionic liquid is prepared and characterized using a variety of techniques, including infrared spectra (FT-IR), 1H and 13C NMR, scanning electron microscopy, a mass spectra method, as well as by Hammett acidity function. The prepared reagent is efficiently able to catalyze the preparation of 5-arylmethylene-pyrimidine-2,4,6-triones via the condensation of aldehydes and barbituric acid. Further studies showed that the condensation of aldehydes with barbituric acid and malononitrile leading to pyrano[2,3-d]pyrimidinone derivatives can also be efficiently promoted in the presence of this reagent. The present methodology offers several advantages, including ease of the preparation and handling of the catalyst, simple and easy work-up, short reaction times, high yields of the products and recyclability of the catalyst.

A novel series of imidazo[1,2-a]pyridinopyrimidine-2,4,6(1H,3H,5H)-triones and thioxopyrimidine-4,6(1H,5H)diones were synthesized via multistep synthesis starting from 2-aminopyridine on cyclisation with phenacyl bromide followed by Vilsmeier–Haack and Knoevenagel condensation reactions. Structures of all the newly synthesized compounds were confirmed by their spectral and analytical studies. All the synthesized compounds were screened for their in vitro antimicrobial activity. Antibacterial activity results revealed that compounds 5f, 5i, and 5j have shown promising activity against S. pyogenes with ZOI ranging from 19 to 20 mm, compound 5g against P. aeruginosa (ZOI 19 mm) and 5f and 5h against S. aureus (ZOI 17, 18 mm) have shown good antibacterial activity. Among barbituric acid and thiobarbituric acid derivatives, thiobarbituric acid derivatives have shown maximum antibacterial activity. None of the compounds were found to be active at 150 µg/mL concentration against tested fungal strains.

1,8-Dioxo-octahydro-xanthenes are easily prepared via the condensation of aldehydes with 1,3-cyclohexadione and/or dimedone using N-sulfonated DABCO as a new and efficient catalyst. This reagent is also efficiently able to catalyze the condensation of aldehydes with barbituric acid leading to 5-arylmethylene-pyrimidine-2,4,6-triones. The structure of the products was characterized by their IR, 1H NMR, and 13C NMR spectroscopy. The present methodology offers several advantages such as ease of preparation and handling of the catalyst, high yields, simple and green procedure, low cost, short reaction times, easy work-up, and preformation of the reaction in the absence of solvent or in water as a green solvent.

Eco-friendly synthesis of pyrano[2,3-d]pyrimidinone derivatives catalyzed by a novel nanocatalyst of ZnO-supported copper oxide in water is reported. The catalyst is synthesized by a co-precipitation method and characterized by BET surface area, XRD, SEM, EDS, and TEM analysis. CuO/ZnO nanocatalyst can promote the yields and reaction times over five runs without significant loss in its efficiency.

An operationally simple, atom-economical, and green procedure has been developed for the synthesis of dihydropyridine derivatives by a simple condensation of barbituric acid, aldehyde, and ammonium acetate in water under catalyst-free conditions. Excellent yields and purity were obtained with only filtration and washing with hot water and ethanol.