Synthesis,characterization, and catalytic application of Fe3O4‐Si‐[CH2]3‐N=CH‐aryl for the efficient synthesis of novel poly‐substituted pyridines

Fe₃O₄ magnetic nanoparticles (MNPs) were functionalized by aminopropylsilane and reacted with aromatic aldehyde, and Fe₃O₄‐Si‐[CH₂]₃‐N=CH‐Aryl and Fe₃O₄‐Si‐(CH₂)₃‐NH‐CH₂‐Aryl MNPs were prepared as novel magnetic nanocatalysts. Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), and scanning and transmission electron microscopy (SEM and TEM) were used to identify the MNPs. The catalytic activity of the MNPs was evaluated in the one‐pot synthesis of some novel poly‐substituted pyridine derivatives.     

(3‐Oxo‐[1,2,4]triazolidin‐1‐yl)bis (butane‐1‐sulfonic acid) functionalized magnetic γ‐Fe2O3 nanoparticles: A novel and heterogeneous nanocatalyst for one‐pot and efficient four‐component synthesis of novel spiro[indeno[1,2‐b]quinoxaline derivatives

The efficient synthesis of novel spiro[indeno[1,2‐b]quinoxaline derivatives via the four‐component condensation of amines, ninhydrin, isatoic anhydride, and о‐phenylenediamine derivatives catalyzed by ( 3‐oxo‐[1,2,4]triazolidin‐1‐yl)bis (butane‐1‐sulfonic acid) supported on γ‐Fe₂O₃ as novel heterogenous magnetic nanocatalyst was described. The novel nanocatalyst was characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), vibrating sample magnetometry (VSM), Field Emission Scanning Electron Microscopy (FE‐SEM), and thermal analysis (TGA‐DTG). The nanoparticles covered by (3‐oxo‐[1,2,4]triazolidin‐1‐yl)bis (butane‐1‐sulfonic acid) showed enhanced catalytic performance in the preparation of spiro[indeno[1,2‐b]quinoxaline derivatives in excellent yields. Moreover, this method showed several advantages such as mild conditions, high yields, easy work‐up, and being environmentally friendly. The catalyst can be easily separated from the reaction mixture by an external magnet, recycled, and reused several times without a noticeable decrease in catalytic activity.     

Fe3O4@MCM-48-SO3H:An efficient magnetically separable nanocatalyst for the synthesis of benzo[f]chromeno[2,3-d]pyrimidinones

Sulfonic acid groups were grafted onto three different types of synthesized magnetic nanoparticles, namely Fe3O4, Fe3O4@SiO2, and Fe3O4@MCM‐48. The sulfonic acid‐functionalized nanoparticles were evalu...     

Fe3O4@MCM-48–SO3H:合成苯并[f]色烯并[2,3-d]嘧啶酮的高效、可磁性分离纳米催化剂（英文）

Sulfonic acid groups were grafted onto three different types of synthesized magnetic nanoparticles, namely Fe3O4, Fe3O4@SiO2, and Fe3O4@MCM‐48. The sulfonic acid‐functionalized nanoparticles were evaluated as catalysts for the synthesis of 5‐aryl‐1H‐benzo[f]chromeno[2,3‐d]pyrimidine‐2,4(3H,5H)‐dione derivatives in terms of activity and recyclability. Their catalytic activities were compared with that of the homogeneous acid catalyst 1‐methylimidazolium hydrogen sulfate ([HMIm][HSO4]). The activity of Fe3O4@MCM‐48–SO3H was comparable to those of the other heter‐ogeneous and homogeneous catalysts.     

A New Four‐Component Reaction for the Synthesis of Spiro[4H‐indeno[1,2‐b]pyridine‐4,3′‐[3H]indoles]

A new four‐component synthesis of spiro[4H‐indeno[1,2‐b]pyridine‐4,3′‐[3H]indoles] and spiro[acenaphthylene‐1(2H),4′‐[4H‐indeno[1,2‐b]pyridines] by the reaction of indane‐1,3‐dione, 1,3‐dicarbonyl compounds, isatins (=1H‐indole‐2,3‐diones) or acenaphthylene‐1,2‐dione, and AcONH₄ in refluxing toluene in the presence of a catalytic amount of pyridine is reported.     

Application of [Fe3O4@SiO2@(CH2)3Py]HSO4− as heterogeneous and recyclable nanocatalyst for synthesis of polyhydroquinoline derivatives

Four‐component condensation reaction of aromatic aldehydes, dimedone, ethyl acetoacetate and ammonium acetate in the presence of a catalytic amount of ionic liquid on silica‐coated Fe₃O₄ nanoparticles as a heterogeneous, recyclable and very efficient catalyst provided the corresponding polyhydroquinoline derivatives in good to excellent yields in ethanol under reflux condition. The [Fe₃O₄@SiO₂@(CH₂)₃Py]HSO₄^? catalyst was characterized using various techniques such as scanning electron microscopy, powder X‐ray diffraction, thermogravimetric analysis, vibrating sample magnetometry and Fourier transform infrared spectroscopy. Furthermore, the recovery and reuse of the catalyst were demonstrated seven times without detectable loss in activity.     

Thiourea dioxide‐grafted γ‐Fe2O3/HAp magnetic nanoparticles: Efficient,green and reusable nanocatalyst for synthesis of pyranopyridine derivatives

A novel t hiourea dioxide‐functionalized hydroxyapatite‐encapsulated hybrid core‐shell γ‐Fe₂O₃@HAp‐TUD nanoparticles (MNPs) were prepared and characterized by FT‐IR, EDX, SEM, XRD, TGA and VSM analytical methods. The catalytic activity of these MNPs was evaluated through one‐pot three‐component reactions between various substituted aldehydes, malononitrile and 3‐cyano‐6‐hydroxy‐4‐methyl‐pyridin‐2(1H )‐one to afford the corresponding pyrano[2,3‐b]pyridines in high yields under mild and solvent‐free conditions. The catalyst can be easily recycled in a magnetic field and reused in five consecutive runs without significant decrease of its catalytic activity.     

γ‐Fe2O3@Cu3Al‐LDH‐TUD as a new Amphoteric,Highly Efficient and Recyclable Heterogeneous Catalyst for the Solvent‐free Synthesis of Dihydropyrano[3,2‐c]pyrazoles and dihydropyrano[3,2‐c]chromens

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 established by FT‐IR, EDX, SEM, XRD, and hystogram of particle size analytical methods. The results obtained from these analytical methods confirmed the successful immobilization of the thiourea dioxide onto the magnetic support. The synthesized magnetic nanoparticles (MNPs) exhibited high catalytic activity in one‐pot three‐component reactions under mild and solvent‐free conditions for the synthesis of diverse ranges of dihydropyrano[3,2‐c]pyrazoles and dihydropyrano[3,2‐c]chromens. All the reactions proceeded smoothly to furnish the respective products in excellent yields. Simple isolation of the products, avoidance of harmful organic solvents, versatility of the catalyst and its easy magnetic separation and reusability with no significant loss of activity are the main advantages of the present method.     

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.     

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.     

Fe3O4@SiO2@sulfated boric acid as superparamagnetic and recyclable nanocatalyst‐assisted,one‐pot,pseudo four‐component synthesis of 5‐amino‐2‐aryl‐3H‐chromeno[4,3,2‐de][1,6]naphthyridine‐4‐carbonitrile derivatives

The catalytic performance of the superparamagnetic nanocatalyst Fe₃O₄@SiO₂@Sulfated boric acid as a green, recyclable, and acidic solid catalyst in the synthesis of chromeno[4,3,2‐de][1,6]naphthyridine derivatives has been studied. Chromeno[4,3,2‐de][1,6]naphthyridine derivatives via a pseudo four‐component reaction from aromatic aldehydes (1 mmol), malononitrile (2 mmol), and 2′‐hydroxyacetophenone in the presence of Fe₃O₄@SiO₂@Sulfated boric acid (0.004 g) as a nanocatalyst in 3 mL of water as a green solvent at 80°C has been synthesized. The advantages of this method are higher product yields in shorter reaction times, easy recyclability and reusability of the catalyst, and easy work‐up procedures. The nanocatalyst was reused at least six times. The nanocatalyst retained its stability in the reaction, and after reusability, it was separated easily from the reaction by an external magnet.     

Synthesis,Characterization and Reactions of 4‐Hydrazino‐2‐methylpyrimidino[4′5′:4,5]thiazolo[3,2‐a]benzimidazole

4‐Hydrazino‐2‐methylpyrimidino[4′,5′:4,5]thiazolo[3,2‐a]benzimidazole ( 4 ) was obtained from hydrazinolysis of the 4‐chloro derivative 3 with hydrazine hydrate. The hydrazino derivative 4 was further cyclized to the corresponding pyrazole 5 , pyrazolone 6 and 5‐methyl‐1,2,4‐triazolo[1″,5″:3′,4′]pyrimidino[5′,6′:5,4]‐thiazolo[3,2‐a]benzimidazole ( 9 ) and 5‐methy‐1,2,4‐triazolo[4″,3″:3′,4′]pyrimidino[5′,6′:5,4]thiazolo‐[3,2‐a]benzimidazole ( 10 ), respectively. The triazolo derivative 10 was isomerized to the triazolo derivative 9 under a variety of reaction conditions.     

Enantioselective synthesis of 3‐amino‐1‐aryl‐1H‐benzo[f]chromene‐2‐carbonitrile derivatives by Fe3O4@PS‐arginine as an efficient chiral magnetic nanocatalyst

A novel chiral magnetic nanocatalyst was prepared by the surface modification of Fe₃O₄ magnetic nanoparticles (MNPs) with a chloropropylsilane and further by arginine to form Fe₃O₄@propylsilan‐arginine (Fe₃O₄@PS‐Arg). After the structural confirmation of Fe₃O₄@PS‐Arg synthesized MNPs by Fourier transform‐infrared, X‐ray diffraction, field emission‐scanning electron microscopy, transmission electron microscopy, vibrating‐sample magnetometry and thermogravimetric analyses, their catalytic activity was evaluated for one‐pot enantioselective synthesis of 3‐amino‐1‐aryl‐1H‐benzo[f]chromene‐2‐carbonitrile derivatives. The results showed that in the presence of 0.07 g Fe₃O₄@PS‐Arg nanocatalyst and ethanol as solvent, the best reaction yield (96%) was obtained in the least time (5 min). Easy operation, reusability and stability, short reaction time, high reaction yields and good enantioselectivity are the major advantages of the newly synthesized nanocatalyst. Also, this study provides a novel strategy for further research and investigation on the synthesis of new reusable enantioselective catalysts and chiral compounds.     

A Novel,One‐Pot Four‐Component Route to 2′‐Thioxo‐2′,3′‐dihydrospiro[indole‐3,6′‐[1,3]thiazin]‐2‐one Derivatives

An efficient route to 2′,3′‐dihydro‐2′‐thioxospiro[indole‐3,6′‐[1,3]thiazin]‐2(1H)‐one derivatives is described. It involves the reaction of isatine, 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ⁵‐phosphanylidene)ethan‐1‐one, and different amines in the presence of CS₂ in dry MeOH at reflux (Scheme 1). The alkyl carbamodithioate, which results from the addition of the amine to CS₂, is added to the α,β‐unsaturated ketone, resulting from the reaction between 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ⁵‐phosphanylidene)ethan‐1‐one and isatine, to produce the 3′‐alkyl‐2′,3′‐dihydro‐4′‐phenyl‐2′‐thioxospiro[indole‐3,6′‐[1,3]thiazin]‐2(1H)‐one derivatives in excellent yields (Scheme 2). Their structures were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses.     

Synthesis,characterization and catalytic performance of core‐shell structure magnetic Fe3O4/P(GMA‐EGDMA)‐NH2/HPG‐COOH‐Pd catalyst

A strategy has been developed for the synthesis, characterization and catalysis of magnetic Fe₃O₄/P(GMA‐EGDMA)‐NH₂/HPG‐COOH‐Pd core‐shell structure supported catalyst. The P(GMA‐EGDMA) polymer layer was coated on the surface of hollow magnetic Fe₃O₄ microspheres through the effect of KH570. The core‐shell magnetic Fe₃O₄/P(GMA‐EGDMA) modified by ‐NH₂ could be grafted with HPG. Then, the hyperbranched glycidyl (HPG) with terminal ‐OH were modified by ‐COOH and adsorbed Pd nanoparticles. The hyperbranched polymer layer not only protected the Fe₃O₄ magnetic core from acid–base substrate corrosion, but also provided a number of functional groups as binding sites for Pd nanoparticles. The prepared catalyst was characterized by UV–vis, TEM, SEM, FTIR, TGA, ICP‐OES, BET, XRD, DLS and VSM. The catalytic tests showed that the magnetic Fe₃O₄/P(GMA‐EGDMA)‐NH₂/HPG‐COOH‐Pd catalyst had excellent catalytic performance and retained 86% catalytic efficiency after 8 consecutive cycles.     

Ionic Liquid as an Efficient Promoting Medium for Synthesis of Bis‐Pyrazolo[3,4‐b:4′,3′‐e]Pyridines

The preparation of a series of bis‐pyrazolo[3,4‐b:4′,3′‐e]pyridines by the reaction of 5‐aminopyrazole with aldehydes in ionic liquid [bmim]Br is described. This new method has the advantages of easier work‐up, milder reaction conditions, high yields and environmental friendliness compared with other methods.     

Covalent bonding of magnetic Fe3O4 nanoparticles to aminopropyl‐functionalized magnesium phyllosilicate clay: Synthesis and cytotoxic potential investigation

Stable water dispersion of Fe₃O₄ magnetic nanoparticles (NPs) were successfully synthesized by using 3‐glycidoxypropyltrimethoxysilane (GPTMS) and Mg‐phyllo (organo) silicate known as aminoclay (AC) containing pendant amino groups with the approximate composition (R₈Si₈Mg₆O₁₆(OH)₄, R = CH₂CH₂CH₂NH₂). The Fe₃O₄‐GPTMS magnetic NPs with an epoxy functional group are suitable for forming a covalent bond with the amine group of aminoclay in an epoxy ring opening reaction. Appropriate Fe₃O₄‐GPTMS‐aminoclay (FG‐AC) magnetic composite are promising carriers for the targeting and delivery of platinum‐based anticancer drugs. Analysis of the cytotoxicity of the nanostructures on a K562 leukemia cell line using a colorimetery assay shows that both the FG‐AC and cis‐platin/FG‐AC magnetic composite were biocompatible. The nanostructures characterizations were investigated by Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy and energy dispersive analysis of X‐ray techniques. Magnetic measurement revealed that the saturated magnetization of the FG‐AC nanocomposite reached 7.6 emu/g and showed the characteristics of magnetism.     

Efficient Synthesis of Spiro[furan‐3,3′‐indoline] Derivatives via Reactions of Pyridinium Salts with Isatinylidene Acetoacetates

An efficient synthetic procedure for the functionalized spiro[furan‐3,3′‐indoline] derivatives was successfully developed by domino reactions of N‐phenacylpyridinium bromides or N‐ethoxycarbonylmethylenepyridinium bromide with isatinylidene acetoacetate in the presence of triethylamine in ethanol at room temperature. The mechanism included sequential Michael addition of the in situ generated pyridinium ylide and intramolecular substitution of enolate.     

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.     

Fe3O4–cysteamine hydrochloride magnetic nanoparticles: New,efficient and recoverable nanocatalyst for Knoevenagel condensation reaction

Fe₃O₄ magnetic nanoparticles (MNPs) were obtained using a reduction–precipitation method. These MNPs were modified with cysteamine hydrochloride. This catalyst was characterized using a number of physicochemical measurements. The Fe₃O₄–cysteamine MNPs, as an efficient and heterogeneous catalyst, were successfully used for Knoevenagel condensation under mild conditions. The activity of this nanomagnetic catalyst in the Knoevenagel condensation of aromatic aldehydes and malononitrile is described. Easy preparation of the catalyst, easy work‐up procedure, excellent yields and short reaction times are some of the advantages.