N-Sulfonic acid poly(4-vinylpyridinium) chloride as a highly effcient and reusable catalyst for the Biginelli reaction简

A mild, simple and efficient procedure for the preparation of 3,4-dihydropyrimidin-2（1H）-ones and -thiones is described using N-sulfonic acid poly（4-vinylpyridinium） chloride （NSPVPC） as a heterogeneous and efficient catalyst under solvent-free conditions. Simple methodologies, easy work-up procedure, easy preparation of the catalyst, excellent yields and very short reaction times are among the other advantages of this work. Further, the catalyst can be reused and recovered for several times without significant decrease in its activity.     

Nano-Fe3O4@silica sulfuric acid as a reusable and magnetically separable potent solid acid catalyst in Biginelli-type reaction for the one-pot multicomponent synthesis of fused dihydropyrimidine derivatives: A greener NOSE and SFRC approach

An efficient, highly product selective, eco-friendly, one-pot multicomponent synthesis of dihydropyrimidine derivatives via Biginelli reaction has been described. The reaction was developed by greener nanoparticle-catalyzed organic synthesis enhancement (NOSE) chemistry and solvent free reaction condition (SFRC) approaches, which helped us in making the procedure greener. The reaction went smoothly with a diverse range of aromatic, aliphatic, hetero-aromatic aldehydes, different amine sources, as well as various β-dicarbonyl compounds, showing the flexibility of this methodology. Magnetically separable nano-Fe₃O₄@SiO₂@SO₃H, which acts as a potent solid acid catalyst, was characterized by FT-IR, SEM, EDX and TEM, VSM, and TGA analyses. The catalyst was recycled from the reaction mixture easily by an external magnet and reused in five more consecutive runs without much decrease in catalytic activity. Its catalytic efficiency was compared to other nano and bulk solid acid catalyst in order to ascertain the best combination for the conversion.     

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.     

Valence state of active elements on the surface of a multicomponent catalyst under the action of reaction medium

A method to study the valence state of Fe, Cu and Ni on the surface of a multicomponent catalyst by X-ray photoelectron spectroscopy (XPS) under reduction and action of reaction medium is proposed.     

Cellulose sulfuric acid as a bio-supported and recyclable solid acid catalyst for the one-pot synthesis of 2,4,5-triarylimidazoles under microwave irradiation

Abstract

A simple, rapid, and highly efficient method has been attempted for the three-component condensation of benzil/benzoin, aldehydes, and ammonium acetate under microwave irradiation in the presence of a catalytic amount of bio-supported cellulose sulfuric acid under solvent-free conditions to afford the 2,4,5-triarylimidazole derivatives. The catalyst is easily prepared, inexpensive, separated simply by filtration, gives excellent yield of products with shorter reaction times, and is recyclable several times.     

Change in carbon content on the surface of a multicomponent catalyst during its reduction, oxidation and due to action of the reaction medium

The change in the carbon content on the surface of Fe, Cu, Ni containing catalysts has been studied by X-ray Photoelectron Spectroscopy (XPS) under different treatments. It has been concluded that the superficial carbon content affects the content of an active element,e.g. copper, on the catalyst surface.     

Heterogenized tungsten complex: an efficient and high yielding catalyst for the synthesis of structurally diverse tetra substituted pyrrole derivatives via four-component assembly

An efficient, high yielding, and expeditious method has been developed for the synthesis of diversity oriented pyrrole derivatives via a four component, one-pot cyclocondensation reaction of amines, aldehydes, α-methylene ketones, and nitroalkanes using silica supported tungstic acid as a heterogeneous catalyst for the first time. The scope of the domino reaction is successfully explored toward synthesis of highly aryl-substituted pyrroles. The reaction was conveniently promoted by silica supported tungstic acid and the catalyst could be recovered easily after the reaction and reused without any loss of its catalytic activity. The advantageous features of this methodology are high atom-economy, operational simplicity, shorter reaction time, convergence, and facile automation.     

A convenient and efficient one-pot method for the synthesis of novel acridine-calix[4]arene derivatives as new DNA binding agents via multicomponent reaction

A new approach is applied for the synthesis of novel acridine-calix[4]arene derivatives via a multicomponent reaction. These compounds have been characterised by ¹H NMR, ¹³C NMR and HR-MS. Our binding studies between acridine-functionalised calix[4]arenes and calf thymus DNA (CT-DNA) via fluorescence titration show that these compounds have a good affinity to CT-DNA.     

Synthesis and characterization of sulfonated-mercaptopropanoic acid coated Fe3O4 nanoparticles as a novel acid magnetic catalyst for Biginelli reaction

In this paper, Fe₃O₄ nanoparticles were coated with 3-mercaptopropanoic acid (MPA) through a simple in-situ method and subsequently oxidized by H₂O₂/H₂SO₄ to obtain a novel acid magnetic catalyst (Fe₃O₄/SMPA). This catalyst exhibited high catalytic activity in the one-pot synthesis of different 3,4-dihydropyrimidin-2(1H)-ones under mild and solvent-free conditions, along with excellent level of reusability.     

Synthesis of a biphenyl-based axially chiral amino acid as a highly efficient catalyst for the direct asymmetric aldol reaction

A biphenyl-based axially chiral amino acid (S)-2 has been designed and synthesized. The new amino acid (S)-2 has been found to be a more efficient catalyst than (S)-1 in the direct asymmetric aldol reaction of acetone with aldehydes. For instance, the use of only 0.1 mol % of (S)-2 was sufficient to complete the reaction between acetone and 4-nitrobenzaldehyde, giving the corresponding aldol adduct in good yield with an excellent enantioselectivity.     

固体铁系超强酸的制备及催化水杨酸异丙酯的合成

报道固体铁系超强酸作为酯化催化剂，并研究了用此催化剂催化合成水杨酸异 丙酯，实验结果表明：水杨酸与异丙醇的投料比n酸：n醇＝1：6，催化剂的用量占 反应物总投料质量的6％，反应时间为4h,得产物水杨酸异丙酯，其产率达到94．5 ％，同时对催化剂的催化性能进行了讨论。     

MCM-41-anchored sulfonic acid (MCM-41-SO3H): An efficient heterogeneous catalyst for green organic synthesis

MCM-41-anchored sulfonic acid (MCM-41-SO₃H) used as a solid acid catalyst has been reported in recent years for various synthetic protocols. The superior advantage of MCM-41-SO₃H is that it can be recovered and reused several times without loss of its efficiency. In this tutorial review, we attempt to give an overview of the use of MCM-41-SO₃H as a solid and heterogeneous catalyst in the synthesis of various organic compounds that have industrial and pharmaceutical applications.     

Crosslinked poly(ethylene oxide) modified with tetraalkylammonium salts as phase transfer catalyst

Radiation crosslinked poly(ethylene oxide)s (PEO) modified with two tetraalkylammonium salts: allyldimethyldodecylammonium bromide and ethylmethacrylate dimethyldodecylammonium bromide were prepared. They have been characterized by elemental analysis, IR, ¹H-NMR spectra, and DSC measurements. Their activity as phase transfer catalysts (PTC) in the model displacement reaction of 1-bromooctane with aqueous sodium cyanide were studied. The reaction kinetics were followed under pseudo-first-order conditions. Small amounts of onium salt inserted into the PEO network gave rise to a five time increase in the rate constant. The recovered catalysts could be re-used without loss of activity. © 1995 John Wiley & Sons, Inc.     

N-磺酸基聚(4-乙烯吡啶)硫酸氢铵作为新型、高效、可重复使用的固体酸催化剂用于无溶剂条件下酰化反应(英文)

N-Sulfonic acid poly(4-vinylpyridinum) hydrogen sulfate has been developed as a recyclable solid acid catalyst for the acetylation of alcohols, phenols, thiols, and amines, as well as the 1,1- diacetylation of aldehydes under solvent-free conditions at room temperature. The acetylated products were formed in good to excellent yields over short reaction times, and the catalyst could be readily recovered by filtration and used several times without any discernible loss in activity. The hydrogen sulfate anion of the catalytic system was found to play a critical role in enhancing the reaction time and yield of the acetylation reaction.     

A new protocol for Biginelli (or like) reaction under solvent-free grinding method using Fe (NO3)3.9H2O as catalyst

Abstract

A new protocol for Biginelli (or like) reaction has been developed under solvent-free grinding method using catalytic amount of hydrated ferric nitrate or clayfen. The advantage of this novel protocol lies in the avoidance of organic solvent, high yield, energy efficiency, variation of substrates, and use of inexpensive catalyst. The recycling of catalyst is also possible with clayfen for more than three times. Furthermore, the catalytic activity of ferric nitrate retains its efficiency in methanol and acetone as reaction medium.     

Phosphated tungstate: An efficient new solid phosphoric acid catalyst for the synthesis of heterocyclic nitrones

Phosphated tungstate as a new, reusable and efficient solid phosphoric acid catalyst was synthesized and used to promote the reaction of diaminoglyoxime with various aromatic aldehydes. The prepared phosphated tungstate was characterized using various techniques including X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy and thermal analysis. A wide variety of heterocyclic nitrones were obtained under mild reaction conditions and in high yields by using the prepared catalyst.     

Silica sulfuric acid (SSA) as a solid acid heterogeneous catalyst for one-pot synthesis of substituted pyrroles under solvent-free conditions at room temperature

A variety of N-substituted pyrroles have been synthesized by reacting γ-diketones with amines, diamines or triamine in the presence of silica sulfuric acid (SSA) at room temperature under solvent-free conditions. The experiment protocol features simple operations, and the products are isolated in high to excellent yields (70-98%).     

One-pot synthesis of dihydropyrimidones using silica-supported heteropoly acid as an efficient and reusable catalyst: Improved protocol conditions for the Biginelli reaction

An efficient synthesis of 3,4-dihydropyrimidinones or thiones (DHPMs) is described, using silica-supported heteropoly acid H₃PW₁₂O₄₀/SiO₂ (PW/SiO₂) for the first time as the catalyst from an aldehyde, β-keto ester and urea or thiourea in acetonitrile. Compared to the classical Biginelli reaction conditions, this method consistently has the advantage of excellent yields, mild reaction conditions, ease of workup, survival of different functional groups, and short reaction times.