Fe3O4@SiO2@Propyl–ANDSA: as a new catalyst for one-pot synthesis of 4H-chromene

Research on Chemical Intermediates - This work describes a new method for a one-pot multicomponent condensation of a variety of aldehydes with dimedone and malononitrile in water, providing a...     

β-Cyclodextrin as a supramolecular catalyst for the synthesis of 2Hindazolo[2,1-b]phthalazine-trione derivatives in water and their antimicrobial activities

An efficient and green method has been developed for the synthesis of 2H-indazolo[2,1-b]phthalazinetriones derivatives by employing 15 mol%β-cyclodextrinvia a one-pot multicomponent reaction of aldehyde,dimedone,hydrazine hydrate with succinic anhydride/phthalic anhydride in water at 80 ℃ for first time.The catalyst could be recovered and reused for four consecutive cycles without appreciable loss in catalytic activity and evaluated for in vitro antimicrobial activity against different Gram-positive and Gram-negative bacterial strains.The outcome of the screening study showed that compound 6d,6f and7 n exhibited excellent activity against E.coil.Whereas,compound 6f and 6h exhibited excellent activity against P.aeurginosa,and compound 6c,and 6e displayed again excellent activity against Staphylococcus aureus whereas compound 7o shows excellent activity against S.aureus and B.subtilis when compared with Ampicillin(standard control).The results indicated that maximum compounds are moderately effective against bacterial growth and their effectiveness is highest against standard drugs.     

Fe3O4@SiO2–NH2 core-shell nanocomposite as an efficient and green catalyst for the multi-component synthesis of highly substituted chromeno[2,3-b]pyridines in aqueous ethanol media

ABSTRACT

An efficient and green approach for synthesizing chromeno[2,3-b]pyridine derivatives through one-pot three-component reactions of salicylaldehydes, thiols, and malononitrile has been developed by Fe₃O₄@SiO₂–NH₂ nanocatalyst in aqueous ethanol media under re?ux conditions. The present procedure provides several advantages such as environmentally benign, straightforward, excellent yields, short reaction times, cost-effective, good recyclability, little catalyst loading, and facile catalyst separation for the preparation of chromeno[2,3-b]pyridines as important privileged medicinal scaffold. In addition, aminopropyl-coated Fe₃O₄@SiO₂ nanoparticles were fully characterized by scanning electron microscopy, X-ray diffraction, energy dispersive analysis of X-ray, vibrating sample magnetometer, and FT-IR analysis.     

Stannous oxalate as a novel catalyst for the synthesis of polytrimethylene terephthalate

Stannous oxalate was prepared efficiently and characterized by XRD and FT-IR. It exhibited higher catalytic activity and had profitable effect than tetrabutyl titanate and stannous octoate for the synthesis of polytrimethylene terephthalate (PTT) via esterification-route. Over this catalyst, the degree of esterification of pure terephthalic acid was up to 94.4% at 260°C after 1.5 h, while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PTT polyester, polymerized at 260°C, 60 Pa for 2 h, was 0.8950 dL/g and 15 mol/t, respectively. Stannous oxalate was a promising catalyst for the synthesis of PTT polyester.     

Synthesis and characterization of silica-coated Fe3O4 nanoparticle@silylpropyl triethylammonium polyoxometalate as an organic–inorganic hybrid heterogeneous catalyst for the one-pot synthesis of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones

In this study, silica-coated Fe₃O₄ nanoparticle@silylpropyl triethylammonium polyoxometalate catalyst was fabricated and characterized using atomic absorption, inductively coupled plasma optical emission spectrometry, elemental analysis, thermogravimetric analysis, Fourier-transform infrared, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and vibrating sample magnetometry analyses. The activity of this catalyst was examined in the synthesis of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones. The bonding of the polyoxometalate to the surface of the nanoparticles exhibited excellent catalytic activity in this synthesis. Besides, the catalyst showed good reusability and recovery from the reaction mixture. Tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones were synthesized in high yields in the presence of inexpensive supported solid acid catalysts under classical heating conditions.     

One-pot synthesis of 2H-indazolo[2,1-b]phthalazine-triones via nano γ-Al2O3/BF3/Fe3O4 as an efficient catalyst and theoretical DFT study on them

Experimental and computational studies were carried out for the synthesis of 2H-indazolo[2,1-b]phthalazine-triones using γ-Al₂O₃/BF₃/Fe₃O₄ as a nanocatalyst in optimized and solvent-free conditions. The most significant features of the existing protocol are easy preparation of the catalyst, short reaction times, environmentally benign, and milder reaction conditions. The analysis data were reported using the experimental results of this investigation, such as: H-NMR, FT-IR (Fourier-transform infrared spectroscopy), X-ray diffraction, vibrating-sample magnetometer, Thermal gravimetric analysis (TG-DTG), nitrogen adsorption isotherm, Field Emission Scanning Electron Microscopy, and Transmission electron microscopy images of nanocatalyst. In this study, 2H-indazolo[2,1-b]phthalazine-triones have also been theoretically investigated using DFT-B3LYP/6-31G method. Also, some of the physical chemistry properties have examined for conformers of products, which there was good agreement between the computational results and obtained experimental for the products.     

Preparation and characterization of Fe3O4@Cu-β-CD as a hybrid magnetic catalyst for the synthesis of dihydropyrano[2,3-c]pyrazoles in H2O

Research on Chemical Intermediates - Fe3O4@Cu-β-CD is a hybrid composite with high catalytic activity. Easy separation with an external magnet and recyclability are the advantages of this...     

Fe3O4@SiO2@ADMPT/H6P2W18O62: a novel Wells–Dawson heteropolyacid-based magnetic inorganic–organic nanohybrid material as potent Lewis acid catalyst for the efficient synthesis of 1,4-dihydopyridines

A novel Wells–Dawson heteropolyacid-based magnetic Inorganic–organic nanohybrid, Fe₃O₄@SiO₂@ADMPT/H₆P₂W₁₈O₆₂, was fabricated and used as a green, efficient, eco-friendly, and highly recyclable catalyst for the one-pot and multi-component synthesis of 1,4-Dihydopyridine (1,4-DHP) derivatives from the reaction of various aromatic aldehydes with ethyl acetoacetate and ammonium acetate with good to excellent yields and in a short span of time. The nanohybrid catalyst was prepared by the chemical anchoring of Wells–Dawson heteropolyacid H₆P₂W₁₈O₆₂ onto the surface of functionalized Fe₃O₄ nanoparticles with 2,4-bis(3,5-dimethylpyrazol)-triazine (ADMPT) linker. These nanocatalysts were identified by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and vibrating sample magnetometer (VSM). This protocol is developed as a safe, cost-effective and convenient alternate method for the synthesis of 1,4-DHP derivatives utilizing an eco-friendly, and a highly reusable catalyst.     

Synthesis and characterization of Fe3O4@SiO2–polymer-imid–Pd magnetic porous nanospheres and their application as a novel recyclable catalyst for Sonogashira–Hagihara coupling reactions

We demonstrate herein the modification of magnetic nanoparticles and their use as a magnetic nanocatalyst in direct coupling reactions of aryl halides with terminal alkynes. Magnetite particles were prepared by simple co-precipitation method in aqueous medium, and then Fe₃O₄@ SiO₂ nanosphere was synthesized by using nano-Fe₃O₄ as the core, TEOS as the silica source and PVA as the surfactant. Fe₃O₄@SiO₂ was coated with polymeric N-heterocyclic carbene/Pd. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, thermogravimetric analysis, vibration sample magnetometer and N₂ adsorption–desorption isotherm analysis. Poly (N-vinyl imidazole) functionalized Fe₃O₄@SiO₂ nanoparticle was found to be an efficient nanocatalyst in Sonogashira–Hagihara cross-coupling reactions. The nanocatalyst can be easily recovered by a magnetic field and reused for six runs without appreciable loss of its catalytic activity.     

Preparation and characterization of MNPs–PhSO3H as a heterogeneous catalyst for the synthesis of benzo[b]pyran and pyrano[3,2-c]chromenes

Research on Chemical Intermediates - In this study, an efficient and novel procedure has been reported for loading sulfanilic acid on the surface of magnetite Fe3O4 nanoparticles using...     

Post‐synthetic modification of IR-MOF‐3 as acidic-basic heterogeneous catalyst for one-pot synthesis of pyrimido[4,5-b]quinolones

Research on Chemical Intermediates - In this study, a modified IR-MOF-3 via a multi-step post-synthesis modification, namely IR-MOF-3-ILOAc-Fe(acac)3, was prepared as an ion-pair heterogeneous...     

New applications of phosphoric acid supported on alumina (H3PO4–Al2O3) as a reusable heterogeneous catalyst for preparation of 2,3-dihydroquinazoline-4(1H)-ones, 2H-indazolo[2,1-b]phthalazinetriones,and benzo[4,5]imidazo[1,2-a]pyrimidines

An eco-friendly procedure for synthesis of 2,3-dihydroquinazoline-4(1H)-one, 2H-indazolo[2,1-b]phthalazinetrione, and benzo[4,5]imidazo[1,2-a]pyrimidine derivatives by three-component reaction, with phosphoric acid supported on alumina as catalyst, is described. Noticeable features of the method are that it is solvent-free, work-up is easy, yields are excellent, and the catalyst is reusable.     

Synthesis of benzo[b]xanthene-triones and tetrahydrochromeno[2,3-b]xanthene tetraones via three- or pseudo–five-component reactions using Fe3O4@SiO2/PEtOx as a novel,magnetically recyclable,and eco-friendly nanocatalyst

In this study, poly(2-ethyl-2-oxazoline) (PEtOx) immobilized on Fe₃O₄ nanoparticles (Fe₃O₄@SiO₂/PEtOx) has been constructed as a new, heterogeneous, efficient, and recyclable nanocatalyst. The prepared nanocatalyst was characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) analysis, and vibrating-sample magnetometer (VSM) techniques. Nanocatalyst was employed to synthesize benzo[b]xanthene-triones and tetrahydrochromeno[2,3-b]xanthene tetraones via one-pot three- or pseudo–five-component reaction between 2-hydroxy-1,4-naphthoquinone or 2,5-dihydroxy-1,4-benzoquinone, aldehyde, and dimedone or 1,3-cyclohexanedione under reflux condition in ethanol. The catalyst could be easily separated and recycled several times without considerable loss of activity. Clean methodology, easy work-up, mild reaction condition, short reaction time with good-to-excellent yields, and simple preparation of the catalyst are some advantages of the presented work.     

CoFe2O4–SiO2–SO3H nanocomposite as a magnetically recoverable catalyst for oxidative bromination of alkynes

A hybrid catalyst has been prepared by incorporating sulfonic acid onto cobalt ferrite magnetic nanoparticles. The catalyst was successfully applied for rapid (20?min) synthesis of α,α-dibromoketones directly from alkynes and NBS. The reaction works well in the presence of 10?wt% of the catalyst at room temperature to produce the desired products in high yield. The catalyst could be recovered using an external magnet and reused without appreciable change in activity.     

Synthesis of bioactive magnetic nanoparticles spiro[indoline-3,4′-[1,3]dithiine]@Ni (NO3)2 supported on Fe3O4@SiO2@CPS as reusable nanocatalyst for the synthesis of functionalized 3,4-dihydro-2H-pyran

New bioactive magnetic nanoparticles of spiro[indoline-3,4′-[1,3]dithiine]@Ni (NO₃)₂ supported on Fe₃O₄@SiO₂@CPS were synthesized in five steps. The structure of synthesized magnetic nanoparticles was identified by using Energy-Dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Thermal Gravimetric Analysis (TGA), Infrared spectroscopy (FT-IR), Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), Vibrating Sample Magnetometer (VSM) and Brunauer Emmett Teller (BET) surface analysis. Antimicrobial activity of the synthesized magnetic nanoparticles based on MIC (Minimum Inhibitory Concentration) and MBC (Minimum Bactericidal Concentration) and MFC (Minimum Fungicidal Concentration) values were also examined. Furthermore, the synthesized magnetic nanoparticles exhibited appropriate catalytic properties in the synthesis of the 3,4-dihydro-2H- pyran derivatives.     

An efficient synthesis of novel chromeno[3’, 4’：5, 6]pyrano[2, 3-b]indole derivatives

An efficient two-step method was described for the synthesis of chromeno[3',4':5,6]pyrano[2,3-b]indole derivatives. The three-component reaction of 4-hydroxycoumarin, variously substituted benzaldehydes and indolin-2-one was promoted by P2O5 in refluxing ethanol to give trimolecular adducts, which were then cyclized in 1,2-dichloroethane under reflux using POCl3.     

A pot-economical and green synthesis of novel (benzo[d]imidazo[2,1-b]thiazol-3-yl)-2H-chromen-2-one in ethanol–PEG-600 under catalyst-free conditions

A catalyst-free, environmentally benign, and simple one-pot multi-component protocol has been developed for the efficient synthesis of novel (benzo[d]imidazo[2,1-b]thiazol-3-yl)-2H-chromen-2-one derivatives in excellent yields using ethanol-PEG-600. This novel and green protocol have the advantages of shorter reaction times, high conversions, and follow the group-assisted-purification (GAP) chemistry process, which can avoid traditional purifications, chromatography and recrystallization. This is the first report for the synthesis of benzo[d]imidazo[2,1-b]thiazol-3-yl)-2H-chromen-2-one.     

Fe3O4@SiO2-polymer-imid-Pd magnetic porous nanosphere as magnetically separable catalyst for Mizoroki–Heck and Suzuki–Miyaura coupling reactions

The activity of palladium nanoparticles supported on poly (N-vinylpyrrolidone) grafted Fe₃O₄@SiO₂ was investigated in the cross-coupling reactions. We have applied this catalyst under low loading of the supported palladium nanoparticles for the coupling of aryl halides with alkenes (Mizoroki–Heck reaction) and organoboronic acids (Suzuki–Miyaura reaction) in the absence of phosphorous ligands. Short reaction times and excellent yields of the products express the effectiveness of this catalyst. The nanocatalyst can be separated from the reaction mixture by applying a permanent magnet externally and can be reused for six times without appreciable change in catalytic activity. Also, the amount of leaching of Pd nanoparticles has been determined by ICP analysis and results showed low leaching of the metal into solution from the supported catalyst.