Dual Brønsted acidic-basic function immobilized on the 3D mesoporous polycalix [4]resorcinarene: As a highly recyclable catalyst for the synthesis of spiro acenaphthylene/indene heterocycles

In this study, a novel dual Brønsted acidic-basic nano-scale porous organic polymer catalyst, PC4RA@SiPr-Pip-BuSO3H, was synthesized through various steps: preparation of a 3D network of polycalix, modification with (3-chloropropyl)-trimethoxysilane, then functionalization of polymer with piperazine and n-butyl sulfonic acid under the provided conditions. The catalyst characterization was performed by FT-IR, TGA, EDS, elemental mapping, PXRD, TEM, and FE-SEM analyses, confirming high chemical stability, activity, recoverability, and excellent covalent anchoring of functional groups. So, the designed catalyst was utilized for preparing spiro-acenaphthylene and amino-spiroindene heterocycles, providing good performance with a high yield of the corresponding products. Accordingly, this catalyst can be used in different organic transformations. Necessary experiments were conducted for the recyclability test of the polymeric catalyst, and the results showed the PC4RA@SiPr-Pip-BuSO3H catalyst can be reused 10 times without any decrease in its activity or quality with excellent stability. The structure of resultant spiro heterocycles was confirmed using 1H NMR, 13C NMR, and FT-IR.

Tungstic acid-functionalized polycalix[4]resorcinarene as a cavity-containing hyper-branched supramolecular and recoverable acidic catalyst in 4H-pyran synthesis

In this study, tungstic acid immobilized on polycalix[4]resorcinarene, PC4RA@SiPr-OWO₃H, as a mesoporous acidic solid catalyst was synthesized and investigated for its catalytic activity. Polycalix[4]resorcinarene was prepared via a reaction between formaldehyde and calix[4]resorcinarene, and then the resulting polycalix[4]resorcinarene was modified using (3-chloropropyl)trimethoxysilane (CPTMS) to obtain polycalix[4]resorcinarene@(CH₂)₃Cl that was finally functionalized with tungstic acid. The designed acidic catalyst was characterized by various methods including FT-IR spectroscopy, energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), elemental mapping analysis and transmission electron microscopy (TEM). The catalyst efficiency was evaluated via the preparation of 4H-pyran derivatives using dimethyl/diethyl acetylenedicarboxylate, malononitrile, and beta-carbonyl compounds, confirmed by FT-IR spectroscopy and ¹H and ¹³C NMR spectroscopy. The synthetic catalyst was introduced as a suitable catalyst with high recycling power in 4H-pyran synthesis.

Synthesis and characterization of thiophene-derived palladium(ii) complex immobilized on FSM-16 and its application in the novel synthesis of 7-(aryl)-7,12-dihydro-6H-indeno[1,2,4]triazolo[1,5-a]pyrimidine-6-one derivatives

The present study aims at synthesizing a palladium complex with a thiophene-carboimine ligand, supported on FSM-16 as a mesoporous silica support. Firstly, the prepared FSM-16 was modified using 3-aminopropyl group. The imine bond was subsequently formed by condensation of FSM-16-propyl amine with thiophene-2-carbaldehyde. Finally, the imine/thiophene-FSM-16 reacted with PdCl₂ to form PdCl₂-imine/thiophene-FSM-16. The structural and physicochemical properties of the prepared nanocomposite were characterized using FT-IR, TEM, XRD, FE-SEM, EDS, BET, and TGA analyses. PdCl₂-imine/thiophene-FSM-16 exhibited efficient catalytic activity in the synthesis of indeno-1,2,4-triazolo[1,5-a]pyrimidine derivatives via a new three-component reaction between indan-1,3-dione, aromatic aldehydes and 3-amino-1H-1,2,4-triazole in water as the green solvent. Significantly, the heterogeneous catalyst can be easily separated from the reaction mixture and reused in another reaction.

Synthesis of novel pyrano[2,3-f]chromene-dione derivatives using phosphoric acid-functionalized silica-coated Fe3O4 nanoparticles as a new reusable solid acid nanocatalyst

In this research, the synthesis of novel indeno[1,2-b]pyrano[2,3-f]chromene-2,12(13H)-dione derivatives in the presence of a newly introduced magnetically recoverable nanosolid acid catalyst is reported. At the first, phosphoric acid-functionalized silica-coated Fe₃O₄ nanoparticles (Fe₃O₄@SiO₂-(CH₂)₃OPO₃H₂) were prepared and well characterized using infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and energy-dispersive X-ray spectroscopy (EDS) techniques. Then, the catalytic activity of the prepared Fe₃O₄@ SiO₂-(CH₂)₃OPO₃H₂ nanocatalyst was investigated for the synthesis of novel indeno[1,2-b]pyrano[2,3-f]chromene-2,12(13H)-dione derivatives via a one-pot and three-component condensation between 5,7-dihydroxy-4-methylcoumarin, indane-1, 3-dione, and various aromatic aldehydes under solvent-free condition. All the products are unknown, and their characterization was performed with the spectral data information obtained from their FT-IR, ¹H and ¹³CNMR, elemental analysis, and their melting points. The reusability study of the introduced nanosolid acid catalyst showed that the catalytic stability is almost completely remained up to five consecutive runs.

Glucose-Decorated Silica-Molybdate Complex: A Novel Catalyst for Facile Synthesis of Pyrano[2,3-d]-Pyrimidine Derivatives

This article describes the preparation and identification of SiO2@Glu/Si(OEt)2(CH2)3N=Mo[Mo5O18] as a new bifunctional acid-base catalyst (both acidic and basic Lewis sites). Aminopropyltriethoxysilane was first reacted with hexamolybdate anions and then treated with glucose to prepare Glu/Si(OEt)2(CH2)3N=Mo[Mo5O18]. Nano-silica was then modified by the prepared glucose/molybdate complex to obtain SiO2@Glu/Si(OEt)2(CH2)3N=Mo[Mo5O18]. The developed catalyst was characterized by FT-IR, EDX, XRD, FE-SEM and TGA analyzes. Its catalytic efficiency was investigated for the preparation of pyrano[2,3-d]pyrimidine derivatives by the reaction between various aldehydes, malononitrile and barbituric acid. The desired products were prepared in the presence of 0.004 g of the prepared catalyst in high to excellent yields.

Efficient and Facile Synthesis of Chromenopyrano[2,3-b] pyridine Derivatives Catalyzed by Sodium Carbonate

In this research, a number of new and known chromenopyrano[2,3-b]pyridine derivatives have been prepared. Initially, according to the reported procedure, pyrano[2,3-c]chromene derivatives were synthesized by the reaction between 4-hydroxycoumarin, aromatic aldehydes and malononitrile using silica sodium carbonate (SSC) as the catalyst. Next, the prepared pyrano[2,3-c]chromenes were reacted by dimethyl acetylenedicarboxylate (DMAD) or cyclohexanone in the presence of sodium carbonate to produce chromenopyrano[2,3-b]pyridine derivatives. The presented protocol avoids the use of expensive catalysts and gives useful potentially bioactive heterocycles in excellent to high yields.

Efficient and Facile Synthesis of Chromenopyrano[2,3-b] pyridine Derivatives Catalyzed by Sodium Carbonate

In this research, a number of new and known chromenopyrano[2,3-b]pyridine derivatives have been prepared. Initially, according to the reported procedure, pyrano[2,3-c]chromene derivatives were synthesized by the reaction between 4-hydroxycoumarin, aromatic aldehydes and malononitrile using silica sodium carbonate (SSC) as the catalyst. Next, the prepared pyrano[2,3-c]chromenes were reacted by dimethyl acetylenedicarboxylate (DMAD) or cyclohexanone in the presence of sodium carbonate to produce chromenopyrano[2,3-b]pyridine derivatives. The presented protocol avoids the use of expensive catalysts and gives useful potentially bioactive heterocycles in excellent to high yields.

Molybdic Acid-Functionalized Nano-Fe3O4@TiO2 as a Novel and Magnetically Separable Catalyst for the Synthesis of Coumarin-Containing Sulfonamide Derivatives

Supported molybdic acid on nano-Fe3O4@TiO2 (Fe3O4@TiO2@(CH2)3OMoO3H) has been successfully prepared, char-acterized and applied as a catalyst for the synthesis of sulfonamide containing coumarin moieties. The prepared Fe3O4nanoparticles by coprecipitation of Fe2+ and Fe3+ ions were treated with tetraethyl orthotitanate to obtain Fe3O4@TiO2. By anchoring 3-chloropropyltriethoxysilan on Fe3O4@TiO2 followed by reacting with molybdic acid, the desired catalyst was produced. The synthesized catalyst was characterized using XRD, SEM, EDS, FT-IR and VSM analysis. Fe3O4@TiO2@(CH2)3OMoO3H was used as a catalyst for the synthesis of sulfonamide containing coumarin moieties via a three-com-ponent reaction of aryl aldehydes, para-toluenesulfonamide and 4-hydroxycoumarin or 5,7-dihydroxy-4-methylcou-marin. The catalyst recovery test showed the catalyst is highly reusable without losing its activity.

A novel protocol for catalyst-free synthesis of fused six-member rings to triazole and pyrazole

Herein, an effectual, quick and novel method is described for the synthesis of new triazolo[1,5-a]pyrimidine, triazolo[5,1-b][1,3] thiazine and pyrazolo[1,5-a]pyrimidine derivatives. This series of fused six-member rings to triazole and pyrazole was prepared via the catalyst-free reaction of dialkyl acetylenedicarboxylates and 3-substituted 1H-1,2,4-triazole or 3-amino-1H-pyrazole-4-carbonitrile. The structures of the prepared products were deduced from their Fourier-transform infrared, elemental analysis and proton and carbon-13 nuclear magnetic resonance spectral data. A novel and green method is described for the synthesis of new triazolo[1,5-a]pyrimidine, triazolo[5,1-b][1,3] thiazine and pyrazolo[1,5-a]pyrimidine derivatives.

Efficient Biomimetic Decarboxylation of Diphenylacetic Acid by [Mn(TPP)X]n-Bu4NIO4 Catalytic Systems: Effect of Anionic Axial Ligands (X-)

Highly efficient decarboxylation of diphenylacetic acid has been performed by tetrabutylammonium periodate in the presence of different [Mn(TPP)X] complexes (X- = anionic axial ligand) in CH2Cl2. In these catalytic systems, diphenylacetic acid was selectively (>97%) converted to benzophenone. The reactivity of manganese porphyrins are markedly influenced by the nature of anionic axial ligands and the efficiency of the catalysts decreases in the order: CN- > OCN- > N3- > SCN- > F- > OAc- ∼ Cl- ∼ Br- ∼ I-∼ ClO4-. Marked improvement in reactivities and selectivities has resulted from addition of imidazole and its derivatives to the reaction mixture. π-Bonding interaction in Mn–X moiety and the possibility of distal hydrogen bonding between imidazole and X- is presented to describe the enhanced catalytic activities observed for Mn(TPP)X (X- = SCN-, N3-, OCN-, CN-). A simple catalytic cycle is also proposed to show the role of X- in the possible intermediates.

Bis (Salicylaldehyde-1, 2-Phenylene Diimine)Mn(III) Chloride (Mn(III)-Salophen) Catalysed Oxidation of Thiols to Symmetrical Disulfides Using Urea Hydrogen Peroxide (UHP) as Mild and Efficient Oxidant

A variety of thiols were oxidised efficiently by a catalytic amount of Mn(III)-salophen 1 in the presence of urea hydrogen peroxide adduct 2 as a convenient and mild oxidant to afford the corresponding disulfides in high yields in quite short reaction times.

A nanocatalyst-assisted protocol to the synthesis of bis(pyrazolyl) methane derivatives bearing aroyl groups by the use of arylglyoxals in the presence of ZnO nanowires as a highly efficient, recyclable, and green catalyst

An efficient, promoted three-component (2+1) catalytic reaction between 3-methyl-1-phenyl-2-pyrazolin-5-one and arylglyoxal derivatives is described by the use of zinc oxide nanowires (ZnO NWs) as a green catalyst. By this achievement, some newly prepared bis(pyrazolyl)methane derivatives containing an aroyl group have been obtained. Starting materials were successfully condensed to obtain target products via three C–C bond formation in the presence of ZnO NWs as an efficient, cost-effective, environmentally friendly, and recyclable nanocatalyst. All synthesized products were obtained with good to excellent yields, and their structures were deduced by FTIR, 1H NMR, and 13C NMR spectroscopies and CHNS elemental analyses. It was shown that ZnO NWs can be separated, recovered after each run, and reused in further cycles (up to six runs) without significant loss of activity.

Tungstic acid-functionalized MCM-41 as a novel mesoporous solid acid catalyst for the one-pot synthesis of new pyrrolo[2,1-a]isoquinolines

Tungstic acid-functionalized MCM-41 (MCM-41–HWO₄) was prepared, characterized and applied as a reusable mesoporous catalyst for the one-pot synthesis of new pyrrolo[2,1-a]isoquinoline derivatives.

Synthesis and characterization of molybdic acid immobilized on modified magnetic nanoparticles as a new and recyclable catalyst for the synthesis of chromeno[4,3-b]chromenes

Synthesis and characterization of molybdic acid immobilized on modified magnetic nanoparticles as a new catalyst is reported.

Preparation and characterization of novel phthalhydrazide-functionalized MCM-41 and its application in the one-pot synthesis of coumarin-fused triazolopyrimidines

Preparation and characterization of novel phthalhydrazide-functionalized MCM-41 and its application in the one-pot synthesis of 4-hydroxycoumarin-fused triazolopyrimidines.

Nano-Fe3O4@SiO2-supported boron sulfonic acid as a novel magnetically heterogeneous catalyst for the synthesis of pyrano coumarins

A novel magnetically heterogeneous catalyst based on the immobilization of boron sulfonic acid onto Fe₃O₄@SiO₂nanoparticles (Fe₃O₄@SiO₂–BSA) is reported. It was characterizedviaFT-IR, XRD, SEM, EDS, and VSM analysis.

Novel synthesis of coumarin-containing secondary benzamide derivatives using tungstate sulfuric acid

A novel one-pot synthesis of coumarin-containing secondary benzamide derivatives is described using tungstate sulfuric acid as a reusable heterogeneous catalyst.

Synthesis and characterization of novel nanosilica molybdic acid and its first catalytic application in the synthesis of new and known pyranocoumarins

Nanosilica molybdic acid as an effective and environmentally safe heterogeneous catalyst has been developed for the synthesis of pyranocoumarins.