Synthesis of pyranopyrazoles using nano‐Fe‐[phenylsalicylaldiminemethylpyranopyrazole]Cl2 as a new Schiff base complex and catalyst

By the condensation reaction of benzaldehyde with ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of FeCl₂, a pyranopyrazole derivative was prepared which was then reacted with salicylaldehyde to afford nano‐Fe‐[phenylsalicylaldiminemethylpyranopyrazole]Cl₂ (nano‐[Fe‐PSMP]Cl₂). The prepared nano‐Schiff base complex was fully characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, differential thermogravimetry, scanning electron microscopy and UV–visible spectroscopy, and was used as an efficient and catalyst for the preparation of pyranopyrazoles.     

Nano–Mn‐[4‐nitrophenyl‐salicylaldimine‐methyl pyranopyrazole]Cl2 as a new nanostructured Schiff base complex and catalyst for the synthesis of hexahydroquinolines

By the reaction of 4‐nitrobenzaldehyde with ethyl acetoacetate, malononitrile and hydrazine hydrate, pyranopyrazole derivative as an active biological compound was synthsized and then reacted with salicylaldehyde and MnCl₂.4H₂O to afford nano‐Mn‐[4‐nitrophenyl‐salicylaldimine‐methyl pyranopyrazole]Cl₂ (nano‐[Mn‐4NSMP]Cl₂) for the first time. The produced Schiff base complex with nanostructured was fully characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermal gravimetric analysis (TGA), differential thermal gravimetric (DTG) and scanning electron microscope (SEM) and used it as an efficient catalyst for the preparation of hexahydroquinolines.     

Application of 1‐methyl imidazole‐based ionic liquid‐stabilized silica‐coated Fe3O4 as a novel modified magnetic nanocatalyst for the synthesis of pyrano[2,3‐d]pyrimidines

1‐Methyl imidazole‐based ionic liquid‐stabilized silica‐coated Fe₃O₄ magnetic nanoparticles [Fe₃O₄@SiO₂@(CH₂)₃‐1‐methyl imidazole]HSO₄ as a solid acid magnetic nanocatalyst was explored in the synthesis of pyrano[2,3‐d]pyrimidine derivatives. Pyrano[2,3‐d]pyrimidine derivatives were synthesized by a highly efficient three‐component reaction of various benzaldehydes, malononitrile, and barbituric acid. The catalyst was characterized by using various analysis techniques such as Fourier transform infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD), differential scanning calorimetry‐thermogravimetry analysis (DSC‐TGA), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM).     

Fe3O4‐supported Schiff‐base copper (II) complex: A valuable heterogeneous nanocatalyst for one‐pot synthesis of new pyrano[2,3‐b]pyridine‐3‐carboxamide derivatives

A novel Cu (II) Schiff‐base complex immobilized on core‐shell magnetic Fe₃O₄ nanoparticles (Fe₃O₄@SPNC) was successfully designed and synthesized. The structural features of these nanoparticles were studied and confirmed by using various techniques including FT‐IR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy‐dispersive X‐ray spectroscopy (EDS), vibrating sample magnetometer (VSM), X‐Ray diffraction (XRD), wavelength dispersive X‐ray spectroscopy (WDX), and inductively coupled plasma (ICP). These newly synthesized nanoparticles have been used as efficient heterogeneous catalytic system for one‐pot multicomponent synthesis of new pyrano[2,3‐b]pyridine‐3‐carboxamide derivatives. Notably, the catalyst could be easily separated from the reaction mixture by using an external magnet and reused for several successive reaction runs with no significant loss of activity or copper leaching. The present protocol benefits from a hitherto unreported MNPs‐immobilized Cu (II) Schiff‐base complex as an efficient nanocatalyst for the synthesis of newly reported derivatives of pyrano[2,3‐b]pyridine‐3‐carboxamide from one‐pot multicomponent reactions.     

Butane‐1‐sulfonic acid immobilized on magnetic Fe3O4@SiO2 nanoparticles: A novel and heterogeneous catalyst for the one‐pot synthesis of barbituric acid and pyrano[2,3‐d] pyrimidine derivatives in aqueous media

Butane‐1‐sulfonic acid immobilized on magnetic Fe₃O₄@SiO₂ nanoparticles (Fe₃O₄@SiO₂‐Sultone) was easily prepared via direct ring opening of 1,4‐butanesultone with nanomagnetic Fe₃O₄@SiO₂. The prepared reagent was characterized and used for the efficient promotion of the synthesis of barbituric acid and pyrano[2,3‐d] pyrimidine derivatives. All reactions were performed under mild and completely heterogeneous reaction conditions affording products in good to high yields. The catalyst is easily isolated from the reaction mixture by magnetic decantation and can be reused at least eight times without significant loss in activity.     

Efficient atom-economic one-pot multicomponent synthesis of benzylpyrazolyl coumarins and novel pyrano[2,3-c]pyrazoles catalysed by 2-aminoethanesulfonic acid (taurine) as a bio-organic catalyst

The present work describes eco-friendly multicomponent protocol for the synthesis in excellent yields of structurally diverse benzylpyrazolyl coumarin 5 (a–s) involving the reaction of 4-hydroxycoumarin, ethyl acetoacetate, hydrazine hydrate/phenyl hydrazine hydrate and aldehydes, also novel pyrano[2,3-c]pyrazole derivatives 8 (a–k) integrated by isonicotinic acid hydrazide from reaction of aldehyde, ethyl acetoacetate, malononitrile with isoniazid, employing water as a reaction medium and 2-aminoethanesulfonic acid (taurine) as the catalyst. This new methodology endowed the advantages such as short reaction time, recovery of catalysts after catalytic reaction and reusing them without losing their activity and alleviate of operation.     

SO3H‐functionalized nano‐MGO‐D‐NH2: Synthesis,characterization and application for one‐pot synthesis of pyrano[2,3‐d]pyrimidinone and tetrahydrobenzo[b]pyran derivatives in aqueous media

An SO₃H‐functionalized nano‐MGO‐D‐NH₂ catalyst has been prepared by multi‐functionalization of a magnetic graphene oxide (GO) nanohybrid and evaluated in the synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3‐d]pyrimidinone derivatives. The GO/Fe₃O₄ (MGO) hybrid was prepared via an improved Hummers method followed by the covalent attachment of 1,4‐butanesultone with the amino group of the as‐prepared polyamidoamine‐functionalized MGO (MGO‐D‐NH₂) to give double‐functionalized magnetic nanoparticles as the catalyst. The prepared nanoparticles were characterized to confirm their synthesis and to precisely determine their physicochemical properties. In summary, the prepared catalyst showed marked recyclability and catalytic performance in terms of reaction time and yield of products. The results of this study are hoped to aid the development of a new class of heterogeneous catalysts to show high performance and as excellent candidates for industrial applications.     

Catalytic Applications of Nano‐Fe‐[Phenyl‐Salicylaldimine‐Methylpyranopyrazole]Cl2 as a Schiff Base Complex and Nanostructured Catalyst for the Synthesis of Hexahydroquinolines

By the four‐component condensation reaction of benzaldehyde with ethyl acetoacetate, malononitrile, and hydrazine hydrate using FeCl₂, a pyranopyrazole derivative was synthesized and then reacted with salicylaldehyde to give nano‐Fe‐[phenyl‐salicylaldimine‐methylpyranopyrazole]Cl₂ (nano‐[Fe‐PSMP]Cl₂). The prepared nano‐Schiff base complex was successfully used as an efficient catalyst for the synthesis of hexahydroquinolines.     

Zn(ANA)2Cl2 complex as efficient catalyst for the synthesis of dihydropyrano[2,3-c]pyrazoles in aqueous medium via one-pot multicomponent reaction: a green approach

Abstract

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-carbonitrile (4a–l) in a short reaction time (～10?min) in aqueous media at room temperature is described.     

Preparation and characterization of nano-Co-[4-chlorophenyl-salicylaldimine-methyl pyranopyrazole]Cl2 as a new Schiff base complex and catalyst for the solvent-free synthesis of 1-amidoalkyl-2-naphthols

By the reaction of 4-chlorobenzaldehyde with ethyl acetoacetate, malononitrile, and hydrazine hydrate, 6-amino-4-(4-chlorophenyl)-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile was prepared and then reacted with salicylaldehyde and CoCl₂·6H₂O to produce nano-Co-[4-cholorophenyl-salicylaldimine-methylpyranopyrazole]Cl₂ (nano-[Co-4CSMP]Cl₂). The prepared nano-Schiff base complex was reported for the first time and fully characterized by Fourier transform-infrared spectroscopy, thermal gravimetric analysis, differential thermal gravimetric analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and Brunner–Emmett–Teller analyses and applied as an efficient catalyst for the synthesis of some 1-amidoalkyl-2-naphthol derivatives.     

Theophylline as a new and green catalyst for the one-pot synthesis of spiro[benzo[a]pyrano[2,3-c]phenazine] and benzo[a]pyrano[2,3-c]phenazine derivatives under solvent-free conditions

A green, convenient, high yielding and one-pot procedure for the synthesis of novel spiro[benzo[a]pyrano[2,3-c]phenazine] derivatives by domino multi-component condensation reaction between 2-hydroxynaphthalene-1,4-dione, benzene-1,2-diamines, ninhydrine, and malononitrile in the presence of a catalytic amount of 1,3-dimethyl-7H-purine-2,6-dione (theophylline) as an expedient, eco-friendly and reusable solid base catalyst under thermal, microwave irradiation and solvent-free conditions. This procedure has also been applied successfully for the synthesis of benzo[a]pyrano[2,3-c]phenazines.     

A new nano‐Fe3O4‐supported organocatalyst based on 3,4‐dihydroxypyridine: an efficient heterogeneous nanocatalyst for one‐pot synthesis of pyrazolo[3,4‐b]pyridines and pyrano[2,3‐d]pyrimidines

A simple and practical strategy for the synthesis of a novel nano‐Fe₃O₄‐supported organocatalyst system based on 3,4‐dihydroxypyridine (Fe₃O₄/Py) has been developed. The prepared catalyst was characterized using Fourier transform infrared spectroscopy, transmission and scanning electron microscopies, X‐ray diffraction, vibrating sample magnetometry and energy‐dispersive X‐ray analysis. Accordingly, the Fe₃O₄/Py nanoparticles show a superparamagnetic property with a saturation magnetization of 61 emu g^?1, indicating potential application in magnetic separation technology. Our experimental results reveal that the pyridine‐functionalized Fe₃O₄ nanoparticles are an efficient base catalyst for the domino condensation of various aromatic aldehydes, Meldrum's acid and 5‐methylpyrazol‐3‐amine under very mild reaction condition and in the presence of ethanol solvent. Moreover, the synthesized catalyst was used for one‐pot, three‐component condensation of aromatic aldehydes with barbituric acid and malononitrile to produce 7‐amino‐2,4‐dioxo‐5‐phenyl‐2,3,4,5‐tetrahydro‐1H‐pyrano[2,3‐d]pyrimidine‐6‐carbonitriles. All reactions are completed in short times and all products are obtained in good to excellent yields. Also, notably, the catalyst was reused five times without significant degradation in catalytic activity and performance. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of pyrano[2,3‐c]pyrazole derivatives using Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate (Fe3O4@SiO2 nanoparticle‐supported IL) as a novel,green and heterogeneous catalyst

A simple, green and efficient protocol for the one‐pot four‐component synthesis of pyrano[2,3‐c ]pyrazole derivatives produced from reaction between aryl aldehydes, ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of nano magnetic piperidinium benzene‐1,3‐disulfonate was synthesized in water at 60 °C. The Fe₃O₄@SiO₂ nanoparticle‐supported IL was designed and synthesized. The present process offers advantages such as clean reaction, short reaction time, good to excellent yield, easy purification and easy recoverable catalyst.     

Facile Synthesis of Naphtho[2,3‐d]thiazoles,Naphtho[2,3‐e][1,3,4]thiadiazines and Bis(naphtho[2,3‐d]thiazolyl)copper(II) Derivatives from Heteroylthiosemicarbazides

A one step synthesis protocol for the conversion of heteroylthiosemicarbazides and 2,3‐dichloro‐1,4‐naphthoquinone to naphtho[2,3‐d]thiazoles, naphtho[2,3‐e][1,3,4]thiadiazines as well as bis(naphtho[2,3‐d]thiazolyl)copper(II) derivatives is described. The products were conclusively confirmed by single crystal X‐ray analyses. A mechanism for the formation of the products is presented.     

Isatin‐SO3H coated on amino propyl modified magnetic nanoparticles (Fe3O4@APTES@isatin‐SO3H) as a recyclable magnetic nanoparticle for the simple and rapid synthesis of pyrano[2,3‐d] pyrimidines derivatives

Isatin‐SO₃H coated on amino propyl modified magnetic nanoparticles (Fe₃O₄@APTES@isatin‐SO₃H) is found to be a novel, efficient, and reusable magnetic nanocatalyst, and characterized by FT‐IR, SEM, TEM, XRD, EDX, VSM, and TGA analysis. The magnetic nanocatalyst demonstrated outstanding performance in synthesis of pyrano[2,3‐d] pyrimidines derivatives via one‐pot three‐component reaction of various aromatic aldehydes 1, malononitrile 2, and barbituric acid 3 under reflux conditions in mixture of H₂O:EtOH (1:1) as solvent. Easy workup procedure, short reaction time, high yield, simple preparation and easy recovery of the catalyst, mild reaction conditions are some advantages of this work.     

An efficient catalytic method for the synthesis of pyrido[2,3‐d]pyrimidines as biologically drug candidates by using novel magnetic nanoparticles as a reusable catalyst

A convenient method for the synthesis of pyrido[2,3‐d]pyrimidines by using the novel nano‐magnetic silica‐bonded S‐sulfonic acid[Fe₃O₄@SiO₂@(CH₂)₃S–SO₃H] as an efficient and recyclable catalyst under neat conditions is described. The major advantages of the present methodology are high yield, short reaction time, and reusability of the catalyst. Furthermore, the nano‐magnetic silica‐bonded S‐sulfonic acid was fully characterized by using various techniques such as FT‐IR, TG/DTG, DTA, EDX, μXRF, XRD, HRTEM, SEM, SEM elemental mapping, XPS, and N₂ physisorption. The results obtained from this research support the idea of rational design, synthesis, and applications of task‐specific and reusable catalysts for the preparation of various polynitrogenated heterocyclic compounds containing 1,4‐dihydropyridine moieties.     

Multi‐wall carbon nanotube supported Co (II) Schiff base complex: an efficient and highly reusable catalyst for synthesis of 1‐amidoalkyl‐2‐naphthol and tetrahydrobenzo[b]pyran derivatives

An immobilized Co (II) Schiff base complex supported on multi‐wall carbon nanotubes was synthesized and characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy , thermogravimetric analysis and inductively coupled plasma mass spectrometry. It was shown that the supported complex is a facile, eco‐friendly, recyclable, reusable and green catalyst for three‐component condensation of 2‐naphthol and acetamide with various aldehydes for the synthesis of 1‐amidoalkyl‐2‐naphthol derivatives under solvent‐free conditions. Also, in a further study, the catalytic application was studied in the synthesis of tetrahydrobenzo[b ]pyran derivatives via the condensation reaction of malononitrile and dimedone with several aromatic aldehydes. The procedures suggested here for the synthesis of 1‐amidoalkyl‐2‐naphthol and tetrahydrobenzo[b ]pyran derivatives offer several advantages, such as stability, recyclability and eco‐friendliness of the catalyst, simple experimental conditions, short reaction times, high to excellent yields and easy work‐up.     

Synthesis of 4‐((2‐hydroxynaphthalen‐1‐yl)(aryl)methyl)‐5‐methyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐ones using nano‐Zn‐[2‐boromophenyl‐salicylaldimine‐methylpyranopyrazole]Cl2 nanoparticles

Nano‐Zn‐[2‐boromophenyl‐salicylaldimine‐methylpyranopyrazole]Cl₂ (nano‐[Zn‐2BSMP]Cl₂) as a nanoparticle Schiff base complex and a catalyst was introduced for the solvent‐free synthesis of 4‐((2‐hydroxynaphthalen‐1‐yl)(aryl)methyl)‐5‐methyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐ones by the multicomponent condensation reaction of various aromatic aldehydes, β‐naphthol, ethyl acetoacetate, and phenyl hydrazine at room temperature.     

Introduction of organic/inorganic Fe3O4@MCM‐41@Zr‐piperazine magnetite nanocatalyst for the promotion of the synthesis of tetrahydro‐4H‐chromene and pyrano[2,3‐d]pyrimidinone derivatives

Fe₃O₄@MCM‐41@Zr‐MNPs modified with piperazine is easily prepared and characterized using Fourier transform infrared spectroscopy (FT‐IR), X‐ray powder diffraction (XRD), N₂ adsorption–desorption, Transmission electron microscopy (TEM), Energy‐dispersive X‐ray (EDX), Vibrating sample magnetometry (VSM) and Thermogravimetric analysis (TGA) techniques. The characterization results showed that Zr highly dispersed in the tetrahedral environment of silica framework and piperazine is successfully attached to the surface of the nanocatalyst in connection with zirconium. The prepared nanosized reagent (10–30 nm), shows excellent catalytic activity in the synthesis of tetrahydro‐4H‐chromene and pyrano[2,3‐d]pyrimidinone derivatives. All reactions are performed under mild and completely heterogeneous reactions conditions in high yields during short reaction times. On the other hand and due to its superparamagnetic nature the catalyst can be easily separated by the application of an external magnetic field and reused for several times.     

The first urea‐based ionic liquid‐stabilized magnetic nanoparticles: an efficient catalyst for the synthesis of bis(indolyl)methanes and pyrano[2,3‐d]pyrimidinone derivatives

Urea‐based ionic liquid stabilized on silica‐coated Fe₃O₄ magnetic nanoparticles, {Fe₃O₄@SiO₂@(CH₂)₃‐Urea‐SO₃H/HCl}, as an unexceptionable and smooth releasing urea fertilizer in alkali soils was synthesized and fully characterized using Fourier transform infrared, UV–visible and energy‐dispersive X‐ray spectroscopies, X‐ray diffraction, scanning and transmission electron microscopies, atomic force microscopy and thermogravimetric analysis. The nanostructure catalyst as a novel, green and efficient catalyst was applied for the synthesis of bis(indolyl)methane derivatives via the condensation reaction between 2‐methylindole and aldehydes at room temperature under solvent‐free conditions. Also, pyrano[2,3‐d]pyrimidinone derivatives were prepared in the presence of the nanomagnetic urea‐based catalyst by the one‐pot three‐component condensation reaction of 1,3‐dimethylbarbituric acid, aldehydes and malononitrile under solvent‐free conditions at 60 °C. To the best of our knowledge, this is the first report of the synthesis of urea‐based ionic liquid stabilized on silica‐coated Fe₃O₄ magnetic nanoparticles. So the present work can open up a new and promising insight in the course of rational design, synthesis and applications of task‐specific fertilizer‐based nanomagnetic ionic liquids with desirable properties as unexceptionable substances for sustainable processes. Copyright © 2016 John Wiley & Sons, Ltd.