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Abstract: A simple, green, and efficient protocol has been developed for the synthesis of biologically active 1,4dihydropyrano[2,3c]pyrazole derivatives via one-pot four-component reaction of various substituted benzaldehydes, hydrazine hydrate or phenylh

In this study, the Zn (II)-Schiff base covalently anchored onto the surface of CaO@SiO2 nanoparticles. The structure of this hybrid nanomaterial (CaO@SiO2-NH2-Sal-Zn) was characterized using the analytical techniques such

A convenient and eco-friendly, one-pot synthetic protocol for pharmaceutically important pyran-based heterocyclic compounds is repeated herein. The reactions were carried out at room temperature in a water–ethanol solvent mixture under direct irradiation

In this work, a new, green and beneficial nanomagnetic catalyst was easily fabricated using sulfuric acid as an acidic group on Fe3O4 nanoparticles coated with tris (hydroxymethyl) aminomethane (THAM). The synthesized catalyst was characterized by FT-IR, TGA/DTG, XRD, TEM, EDS, VSM, and SEM analyses. Next, its catalytic activity was studied for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives. This catalyst has advantages such as high catalytic activity, non-toxicity, easy separation from the reaction mixture using an external magnet and reuses for several times without significantly reducing in its catalytic activity.

In this research, the main emphasis has been focused on the preparation of a novel Fe3O4-supported propane-1-sulfonic acid-grafted graphene oxide quantum dots (Fe3O4@GOQD-O-(propane-1-sulfonic acid)) that it was

An external base-free, efficient, cost-effective, and environmentally benign protocol has been developed for the one-pot multicomponent synthesis of highly functionalized pyranopyrazoles and benzochromenes using water extract of Agave americana (century p

The application of yttrium iron garnet (YIG) superparamagnetic nanoparticles as a new recyclable and highly efficient heterogeneous magnetic catalyst for one-pot synthesis of pyrano[2,3-c]pyrazole derivatives under solvent-free conditions, as well as etherification and esterification reactions are described. The advantages of the proposed method include the lack of organic solvents, clean reaction, rapid removal of the catalyst, short reaction times, excellent yields, and recyclability of the catalyst.

Abstract: Fe3O4-magnetized N-pyridin-4-amine-functionalized graphene oxide [Fe3O4@GO-N-(pyridin-4-amine)] was readily prepared via a three-step procedure. The synthesized nanofilms were characterized by scanning

In this work, an efficient and straight procedure has been described for one-pot three-component synthesis of pyranopyrazole derivatives in the presence of a new cobalt Schiff-base complex immobilized on silica-coated Fe3O4 nanoparti

Three facile and efficient routes for one-pot, cobalt (II) nitrate hexahydrate catalyzed multi-component synthesis of 2-amino-3-cyanopyridine and pyranopyrazole derivatives have been developed. The present protocols offer the products in good yields from the simple and readily available starting materials. The other salient features of these protocols are operational simplicity, easy isolation of product without the need of column chromatographic purification, and the use of cobalt (II) nitrate hexahydrate as an efficient catalyst.

A recoverable molybdenum Schiff-base complex immobilized on silica-coated Fe3O4 nanoparticles was prepared and characterized. This superparamagntic nanocatalyst, which is separable using an external magnet, can be used as an efficien

We have developed a simple, straightforward and highly efficient multi-component one-pot synthesis of 2-amino-3-cyano-4H-pyrans and pyran-annulated heterocyclic compounds. Zn(L-proline)2 has been utilized as a mild and efficient Lewis acid cata

SBA/hydrotalcite/heteropolyacid nanocomposite is synthesized via a novel procedure in which the as-prepared heteropolyacid-loaded SBA-15 was impregnated with calcined hydrotalcite. The ternary hybrid system was characterized by using SEM/EDS, XRD, BET, TP

The amino acid ionic liquid tetrabutylammonium asparaginate (TBAAsp) was immobilized on titanomagnetite (Fe3?xTixO4) nanoparticles in a facile one-pot process using an organosilane compound (TMSP) as spacer. The modified F

A series of pyrimidine annulated dihydropyrano[2, 3-c]pyrazole derivatives were synthesized and screened for their antimicrobial activity. The precursor, dihydropyrano[2, 3-c]pyrazole was synthesised under catalyst free condition using PEG-400 as reaction

Sodium fluoride was identified as an efficient catalyst for the preparation of series of dihydropyrano [2,3-c]pyrazoles (4a–l) by the three-component condensation of 3-Methyl-1-phenyl-2-pyrazoline-5-one (1), aromatic aldehydes (2) and malononitrile (3) in

Thiourea dioxide was immobilized on γ-Fe2O3@Cu3Al-LDH magnetic nanoparticles to prepare the γ-Fe2O3@Cu3Al-LDH-TUD MNPs. The structure and properties of these magnetic nanoparticles were est

A new magnetic nanocatalyst based on the immobilization of tungstic acid onto 3-chloropropyl-grafted TiO2-coated Fe3O4 nanoparticles (Fe3O4@TiO2@(CH2)3OWO3H

The first example of recyclable Zn(ANA)2Cl2 catalyzed tandem one-pot three-component protocol reaction between aromatic aldehydes, malononitrile, and phenylmethylpyrazolone to furnish 4-substituted-1,4-dihydropyrano[2,3-c]pyrazole-5-

A three-component process for the one-pot synthesis of 6-amino-4-aryl-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazoles by the reaction of aldehydes, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one, and malononitrile in the presence of FSM-16-SO3/s

This report provides a description of an efficient and simple procedure for the synthesis of pyrano[2, 3-c]pyrazole derivatives via a one-pot three-component reaction of arylmethylidene malononitrile, ethylacetoacetate and phenylhydrazine in the presence of amino-functionalized SBA-15 as a highly effective heterogeneous solid basic catalyst under solvent-free conditions. The remarkable advantages are the simplicity of the experimental procedures, high yields, short reaction times, and reusability of the catalyst.

The invention provides a method for preparing a pyrano[2, 3-c]pyridine derivative through catalysis of a basic ionic liquid, and belongs to the technical field of organic synthesis. The molar ratio of aromatic aldehyde, ethyl acetoacetate or ethyl benzoyl

Optimization of a green approach to the synthesis of pyrano[2,3-c]pyrazoles based on the one-pot, four-component condensation via a domino Knoevenagel/Michael/cyclization sequence was investigated. This method involved the evaluation of the activity of se

{Fe3O4@SiO2@(CH2)3-thiourea dioxide-SO3H/HCl}, a newly reported nanomagnetic core–shell supported solid acid catalyst, was successfully employed in the preparation of 4,4′-(arylmethylene)bi

This report describes a new and convenient procedure for heterogenization of L-proline organocatalyst, which is based on non-covalent immobilization of L-proline on the surface of anion-exchange resin amberlite IRA900OH (AmbIRA900OH) as an efficient, chea

Chromenes, the oxygen-containing heterocyclic compounds, have a “special” place in biologically active natural products and in synthetic chemistry and in the fields of medicinal, agrochemical, cosmetic, and pigment industries. In this work, piperidine was used as a base catalyst for the convenient synthesis of 1,4-dihydropyrano[2,3-c]pyrazole, 5,10-dihydro-4H-benzo[g]chromene, and pyrazolo[1,2-a] [1,2,4]triazole derivatives at ambient temperature. This methodology has several advantages including the use of easily accessible and inexpensive catalysts, short reaction times, high yields, convenient work-up, and not needing column chromatography.

Ag/TiO2 nano thin films was found to be efficient and green heterogeneous catalyst for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives via a one-pot three-component reaction between 3-methyl-1H-pyrazol-5(4H)-one or 3-methyl-1(phenyl)-

In this work, a wide range of novel pyrazolo[4′,3′:5,6]pyrano[2,3-b]quinolin-5-amines were synthesized as tacrine analogs. At first, reaction of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one, aromatic aldehydes, and malononitrile gave 6-amino-4-aryl-3-methyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles. Then, reaction of the latter compounds with cyclohexanone led to the formation of the title compounds. Also, they were evaluated for their in vitro acetylcholinesterase and butyrylcholinesterase inhibitory activities. Interestingly, most of them showed good inhibitory activity comparing with rivastigmine as the reference drug.

A robust intramolecular cyclopropanation reaction was first performed on pyranopyrazole and pyranopyrimidine-dione derivatives to obtain spirocyclopropylpyrazolones and barbiturates, using iodosylbenzene (PhIO) or the combination of iodobenzene diacetate (PIDA)/molecular iodine (I2), under mild reaction conditions. Syntheses of functionally and stereochemically diversified, novel spiropyrazolone fused 2-iminothiophene and spiropyrazolone fused pyrroline scaffolds were also demonstrated via Lewis acid catalyzed highly diastereoselective (3 + 2) cycloaddition reactions of the synthesized spiro-cyclopropyl pyrazolones with phenyl isothiocyanate and benzonitrile, respectively.

An efficient and recyclable homogeneous catalyst is developed using commercially cheap L-proline and melamine for the synthesis of chromenes and spirochromenes (spirooxindoles) via multicomponent reactions at room temperature. Systematic studies were conducted in order to achieve desired reactivity and recyclability of the catalyst using various α-amino acids and aromatic amines as donor-acceptor pairs. Among the screened combinations, L-proline and melamine (3:1 ratio; 3 mol% on total weight) was found to be best catalyst to give the desired products with excellent yields (up to 99%) in very short times (1–15 min) at room temperature in DMSO as solvent. The catalyst was recovered by adding EtOAc and reused up to 5 cycles without losing the catalytic activity.

A one-pot, four-component reaction of ethyl acetoacetate, hydrazine hydrate, aldehydes, and malononitrile was discussed using Lewis acid catalyst morpholine triflate (MorT) to afford a series of dihydropyrano[2,3-c]pyrazoles, which were generally catalyze

Imidazole-based ionic liquid-stabilized on silica coated Fe3O4 magnetic nano particles [nano-Fe3O4SiO2(CH2)3-Imidazole-SO3H]Cl as a novel heterogeneous acidic catalyst

In this work, titanomagnetite nanoparticles (Fe3-xTixO4) have been used as a novel suppport for the synthesis of a magnetic acidic catalyst. These nanoparticles were functionalized with sulfonic acid groups to prepare the

A green and efficient approach for synthesis of some new 4H-pyran derivatives is reported, catalyzed by green recyclable poly(4-vinylpyridine)-supported copper iodide nanoparticle catalyst in water. This procedure has many advantages such as operational s

Silica-coated magnetic NiFe2O4 nanoparticle-supported Preyssler heteropolyacid (H14[NaP5W30O110]) catalyzed efficiently the synthesis of highly substituted pyran derivatives under ultrasoni

A powerful, magnetic, supported, acid catalyst, NiFe2O4@SiO2-H3PW12O40, was prepared by chemical support of Keggin (H3PW12O40) heteropolyacid (HPA) on silica-coated NiFe2O4 magnetic nanoparticles. XRD, TEM, SEM, VSM, and FTIR confirmed that the keggin HPA is well dispersed on the surface of silica-coated NiFe2O4 magnetic nanoparticles. The magnetically recoverable catalyst could be easily recycled at least six times without significant loss of catalytic activity. After full characterization, its catalytic activity was investigated in the synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-c]pyrazole derivatives. Graphical Abstract: (1) Novel silica-coated magnetic NiFe2O4 nanoparticles-supported H3PW12O40 was fabricated and characterized. (2) Recyclability of the catalyst. (3) Avoiding use of corrosive acid catalysts. (4) Green chemistry.

A green and recoverable nano-structured diphosphate (Na2CaP2O7) was synthesized and fully characterized using FT-IR spectra, X-ray diffraction patterns (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray

Increased expression of efflux transport proteins confers the Multi Drug Resistant (MDR) phenotype to drug resistant bacteria, which can be mitigated by efflux pump inhibitors (EPI). EPI's have the dual advantage of restoring efficacy of antibiotics and retarding the evolution of drug resistant mutants. In this study, 17 heterocyclic derivatives synthesized by a polyethylenimine (PEI) catalyzed one-pot protocol were evaluated for their EPI potential. Based on in silico studies and in vitro studies, 5 benzochromene (BC) based compounds (among 17 heterocyclic derivatives), were observed to significantly potentiate the effect of ciprofloxacin (CPX) and displayed a best modulation factor of 32, against the NorA overexpressed mutant SA-1199B. Toxicity analyses using the zebrafish model showed that, from all the benzochromene compounds evaluated, BC9 exhibited low toxicity. BC9 inhibited the NorA efflux pump at a minimum effective concentration (MEC) of 2 mg ml1 (4.03 mM) and even at subinhibitory concentrations, and it was effective in reversing the CPX MIC of both the ATCC strain and a clinical isolate of MRSA by 128 and 4 fold respectively. Our results show that benzochromene derivative BC9 is a highly specific NorA inhibitor that can be employed to mitigate MDR strains of S. aureus that overexpress the NorA efflux pump.

Highly stable, super-paramagnetic nanoparticle supported L-proline catalyst (nano-FDP) which shows extra-ordinary catalytic activity was synthesized for the first time from economical and easily available starting materials. Characterization of the synthe

Catalytic applications of 1-methylimidazolium trinitromethanide {[HMIM]C(NO2)3}as the first nano ionic liquid (NIL) was studied. The described NIL was efficiently tested in the synthesis of 5-amino-pyrazole-4-carbonitrile derivatives

A facile one-pot multicomponent protocol for the synthesis of bio-active pyrano[2,3-c]pyrazole and benzylpyrazolyl coumarin derivatives has been demonstrated using ZrO2 nanoparticles as a catalyst at room temperature. The reactions are very fas

A novel, biochemical, and eco-friendly method has been developed for the synthesis of Ag nanoparticles using an aqueous leaf extract of readily accessible Cinnamomum tamala as reducing and stabilizing agents. These Ag nanoparticles were used to catalyze t

A simple and efficient procedure for the synthesis of 1,4-dihydropyrano[2,3-c]pyrazole derivatives has been developed by a one-pot three-component reaction of various aldehydes with malononitrile and 3-methyl-1-phenyl-2-pyrazoline-5-one in the presence of

N,2-Dibromo-6-chloro-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine-7-sulfonamide 1,1-dioxide (DCDBTSD) as a highly efficient and homogeneous catalyst was successfully applied for the synthesis of 4H-pyran, pyranopyrazole and pyrazolo[1,2-b]phthalazine derivat

The reaction between aromatic aldehydes, malononitrile and 3-methyl-1-phenyl-2-pyrazoline-5-one catalysed by silica supported perchloric acid nanoparticles (HClO4-sio2 nanoparticles) in solvent H2O under reflux provided a

Abstract An efficient and convenient synthesis of 1,4-dihydropyrano[2,3-c]pyrazole derivatives is described, using the electrogenerated anion of ethanol as the base in the presence of sodium bromide as an supporting electrolyte in a one-pot, three compone

Sulfonated polypyrrole nanospheres and polypyrrole N-functionalized acetic acid were synthesized. The catalytic efficiency of the prepared solid acid catalysts for the synthesis of 4Hpyrano[2,3-c]pyrazoles derivatives was evaluated and compared. The resul

Tin sulfide nanoparticles (SnS-NPs) were prepared in aqueous solution at room temperature on the surface of activated carbon (AC) and were investigated using field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-r

THE 3-Methyl-1-phenyl-1H-pyrazol-5(4H)-one (1) was used to synthesis pyran,and pyridine derivatives through its multicomponent reactions with aromatic aldehydes and cyanomethylene reagents. The synthesized products were evaluated for their cytotoxicity ag

A simple, efficient, and environmentally benign route was developed for the preparation of 2-amino-3-cyano-4-aryl-7,7-dimethyl-5,6,7,8-tetrahydrobenzo[b]pyrans and 6-amino-5-cyano-4-aryl-1,4-dihydropyrano[2,3-c]pyrazoles from the condensation of various aldehydes, malononitrile, and 1,3-dicarbonyl compounds (1,3-cyclohexanedione or 5,5-dimethyl-1,3-cyclohexanedione) or 3-methyl-1-phenyl-2-pyrazoline-5-one, using NH4H2PO4/Al2O3 with good yields. The use of easily available catalyst, shorter reaction times, better yields, the simplicity of the reaction, the heterogeneous system, and the easy work up are the advantages of the present method. Characterization of the catalyst was performed by FT-IR spectroscopy, X-ray diffraction (XRD) techniques, thermal analysis (TG/DTG) and Transmission electron microscopy (TEM).