Efficient One‐Pot Synthesis of Bis(4‐hydroxycoumarin)methanes in the Presence of Sulfonic Acid Functionalized Nanoporous Silica (SBA‐Pr‐SO3H)

An efficient and simple method for the synthesis of bis(4‐hydroxycoumarin)methanes has been achieved through a one‐pot condensation of aryl aldehydes and 4‐hydroxycoumarin in the presence of nanoporous solid acid catalyst of SBA‐Pr‐SO₃H with pore size of 6 nm. Excellent yields, short reaction times, reusability of the catalyst and simple workup are advantages of this synthetic procedure.     

Silica‐bonded S‐sulfonic Acid as a Recyclable Catalyst for Synthesis of 2,3‐Dihydroquinazolin‐4(1H)‐ones

2,3‐Dihydroquinazolin‐4(1H)‐one derivatives were synthesized via a one‐pot, three component reaction of isatoic anhydride and an aromatic aldehyde with ammonium acetate or primary amine catalyzed by silica‐bonded S‐sulfonic acid in ethanol at 80°C. The reaction work‐up is simple and the catalyst is easily separated from the products by filtration. The heterogeneous catalyst was recycled for ten runs upon the condensation reaction of isatoic anhydride and 4‐chlorobenzaldehyde with ammonium acetate without losing its catalytic activity.     

Copper‐supported β‐cyclodextrin‐functionalized magnetic nanoparticles: Efficient multifunctional catalyst for one‐pot ‘green’ synthesis of 1,2,3‐triazolylquinazolinone derivatives

The green synthesis of 2‐(4‐((1‐phenyl‐1H‐1,2,3‐triazol‐4‐yl)oxy)phenyl)quinazolin‐4(3H)‐one derivatives is reported. The catalyst for this synthesis is copper‐supported β‐cyclodextrin‐functionalized magnetic silica–iron oxide nanoparticles ([Cu@BCD@SiO₂@SPION]). [Cu@BCD@SiO₂@SPION] simultaneously catalyses ‘click’ reaction, oxidation of C? N bond and multicomponent reaction. The desired 1,2,3‐triazolylquinazolinone product is easily obtained in water at room temperature under mild reaction conditions. Another advantage of the catalyst is its reusability. It can simply be isolated using an external magnet and reused in reactions with no significant decrease in catalyst efficiency. Transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometry and Fourier transform infrared spectroscopy are used for exact characterization of the [Cu@BCD@SiO₂@SPION] catalyst.     

Synthesis and characterization of bromine source supported on magnetic Fe3O4 nanoparticles: A new,versatile and efficient magnetically separable catalyst for organic synthesis

Tribenzylammonium tribromide supported onto magnetic nanoparticles (Br₃‐TBA‐Fe₃O₄) as a bromine source was successfully synthesized and characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and vibrating sample magnetometry. The synthesized catalyst is shown to be a versatile and highly efficient heterogeneous catalyst for the Knoevenagel condensation and synthesis of 2,3‐dihydroquinazolin‐4(1H )‐one and polyhydroquinoline derivatives. To the best of the authors' knowledge, this is the first report of the use of a bromine source immobilized on Fe₃O₄ nanoparticles as a magnetically separable catalyst for these reactions. The nanosolid catalyst can be magnetically recovered and reused readily several times without significant loss in catalytic efficiency.     

Direct Mechanocatalysis: Palladium as Milling Media and Catalyst in the Mechanochemical Suzuki Polymerization

The milling ball is the catalyst. We introduce a palladium‐catalyzed reaction inside a ball mill, which makes catalyst powders, ligands, and solvents obsolete. We present a facile and highly sustainable synthesis concept for palladium‐catalyzed C?C coupling reactions, exemplarily showcased for the Suzuki polymerization of 4‐bromo or 4‐iodophenylboronic acid giving poly(para‐phenylene). Surprisingly, we observe one of the highest degrees of polymerization (199) reported so far.     

Regioselective Synthesis of Thiopyrano[3,2‐c][1]benzothiopyran‐5(2H)‐one and Thieno[3,2‐c][1]benzothiopyran‐4(2H)‐one

4‐Mercaptothiocoumarin was alkylated with different propargylic and allylic halides under phase‐transfer‐catalyzed conditions in the presence of tetrabutylammonium bromide (TBAB) or benzyl triethylammonium chloride (BTEAC) catalyst in dichloromethane–aqueous NaOH solution (1%) at room temperature. These 4‐thiopropynyl and thioallyl thiocoumarins were then refluxed in chlorobenzene and quinoline to give thiopyrano[3,2‐c][1]benzothiopyran‐5(2H)‐one and thiopyrano[3,2‐c][1]benzothiopyran‐4‐one respectively.     

Synthesis of Bis‐Thiazolidinones Using Chitosan‐attached Nano‐CuFe2O4 as an Efficient and Retrievable Heterogeneous Catalyst

The preparation of bis‐thiazolidinones has been achieved by a one‐pot condensation reaction of araldehydes, ethylenediamine, and 2‐mercaptoacetic acid in the presence of nano‐CuFe₂O₄@chitosan under reflux conditions in toluene. The catalyst was characterized by powder X‐ray diffraction (XRD), scanning electronic microscopy (SEM), vibrating sample magnetometer (VSM) measurements, thermal gravimetric analysis (TGA), and FT‐IR spectroscopy. This method provides several advantages including excellent yields, wide range of products, reusability of the catalyst, and a low amount of the catalyst.     

Copper(I) complex of 1,3‐DimethylBarbituric acid modified SBA‐15 and its catalytic role for the synthesis of 2,3‐Dihydroquinazolin‐4(1H)‐ones and Imidazoles

An efficient one‐pot method for synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones and tri/tetra substituted‐1H‐imidazoles has been accomplished in the presence of catalytic amounts of Cu(I)‐1,3‐dimethylbarbituric acid modified SBA‐15 as heterogeneous catalyst with good to excellent yields. The catalyst is reusable and can be applied several times without any decrease in product yield. The synthesized catalyst was characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), energy dispersive X‐ray spectroscopy (EDS), thermal gravimetric analysis (TGA), N₂ adsorption/desorption isotherms (BET), Fourier transform infrared spectroscopy (FT‐IR) and atomic absorption spectroscopy (AAS).     

Fe_3O_4纳米粒子作为高效、可重复使用催化剂用于无溶剂条件下合成9,9-二甲基-9,10-二氢-8H-苯并[α]占吨11(12H)-酮（英文）

A simple and efficient method for the synthesis of 9,9‐dimethyl‐9,10‐dihydro‐8H‐benzo‐[α]xanthen‐11(12)‐one derivatives (DDBXs) was developed by the condensation reaction of various substituted aryl aldehydes with 2‐naphthol and dimedone using Fe3O4 magnetic nanoparticles (MNPs) as a heterogeneous catalyst under solvent‐free conditions at 90–110 °C.The experimental procedure is very simple,the products are formed in high yields and the catalyst is easily separated by applying an external magnetic field.     

Solar Photocatalytic Degradation of 4‐Chlorophenol in Kaolinite Catalysts

This research applies semiconductor photocatalysts, which are formed by metal ion exchange on the surface of kaolinite catalyst with cations, to the study of photocatalytic degradation of 4‐chlorophenol. The analysis results of catalyst properties shows that, after sintering at 400 °C, kaolinite catalyst has a particle size of between 10–100 nm indicating the nano level of synthesized catalysts. Under the same condition, kaolinite‐Ag/Zn catalyst works better in degradation efficiency than single kaolinite‐Ag and kaolinite‐Zn catalysts. Kaolinite‐Zn catalyst declines in degradation efficacy after 150 minutes and performs poorer than the other three types of kaolinite catalysts. In the experiments of different amounts of catalysts, when the concentration exceeds 0.1 wt%, utilization of light energy and degradation efficiency will be reduced due to shielding effect. When at different pH values, the higher the pH value, the more OH‐will be released and that is beneficial for reaction with substances and the increase of reaction rate. Finally multivariate analysis proves that there is one determining factor that influences the photocatalytic degradation of 4‐chlorophenol in kaolinite catalysts, named as “the factor with intermediates competition degree,” the one affecting the 4‐CP degradation at different weight percentages that is referred to as the “shielding effect factor.”     

An Efficient One‐Pot Synthesis of 7,7‐Dimethyl‐2‐(2‐oxo‐2H‐chromen‐3‐yl)‐4‐aryl‐7,8‐dihydroquinolin‐5(6H)‐one Derivatives Using Chitosan–SO3H as Biodegradable Organocatalyst

Chitosan sulfonic acid (CS–SO₃H), a biodegradable green catalyst, was found to be an impressive system for one‐pot four‐component reaction of different aromatic aldehydes, 3‐acetylcoumarin, dimedone, and ammonium acetate leading to 7,7‐dimethyl‐2‐(2‐oxo‐2H‐chromen‐3‐yl)‐4‐aryl‐7,8‐dihydroquinolin‐5(6H)‐one under solvent‐free condition. This methodology produces diverse superiorities such as operational simplicity, short reaction time, and high yield. Further, the catalyst can be reused for four times without any noticeable decrease in the catalytic activity.     

One-pot Three-component Synthesis of 3,4-Dihydroquinazolin- 4-one Derivatives under Aqueous Medium or Solvent-free Conditions

3,4-Dihydroquinazolin-4-one derivatives were synthesized in moderate to high yields by one-pot condensation of anthranilic acid, amines, and formic acid or orthoester without catalyst under aqueous medium or solvent-free conditions.     

Microwave Promoted and Improved Thermal Synthesis of Spiro[Indole‐Pyranobenzopyrans] and Spiro[Indole‐Pyranoimidazoles]

Spiro[indole‐pyranoimidazoles] ( 5 ) and spiro[indole‐pyranobenzopyrans] ( 6 ) are readily synthesized in one step in 86–92 and 91–97% yields by the Michael condensation of 3‐dicyanomethylene‐2H‐indol‐2‐ones ( 2 ) with 1‐phenyl‐2‐thiohydantoin ( 3 ) and 4‐hydroxy‐2H‐1‐benzopyran‐2‐one ( 4 ), respectively, without using any catalyst under different reaction conditions (conventional heating and microwave irradiation using (a) polar solvents (b) neutral alumina/silica gel as inorganic solid support in solvent free conditions). 2 was synthesized in situ by the Knoevenagel condensation of indole‐2,3‐dione ( 1 ) and malononitrile in the absence of any catalyst. 100% conversion was observed in most cases on TLC which also showed the formation of a single product. The comparison between the various methods is established.     

Ammonium metavanadate as an efficient catalyst for the synthesis of 2,4,5‐triaryl‐1H‐imidazoles

Ammonium metavanadate (NH₄VO₃) is an inexpensive, efficient and mild catalyst for the synthesis of 2,4,5‐triaryl‐1H‐imidazole from the one‐pot three‐component condensation of benzil/benzoin, an aldehyde and ammonium acetate in excellent yield. This method has the advantages of good yield, green catalyst, simple procedure, much faster reactions. J. Heterocyclic Chem., (2011).     

Ultrasound Promoted and Ionic Liquid Catalyzed Cyclocondensation Reaction for the Synthesis of 4(3H)-Quinazolinones

4(3H)‐Quinazolinones were synthesized in high yields by one‐pot three‐component condensation of anthranilic acid, carboxylic acid and aniline in the presence of ionic liquid such as 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate (BMImBF₄) as catalyst under solvent free and neutral conditions.     

Piece by Piece—Electrochemical Synthesis of Individual Nanoparticles and their Performance in ORR Electrocatalysis

The impact of individual HAuCl₄ nanoreactors is measured electrochemically, which provides operando insights and precise control over the modification of electrodes with functional nanoparticles of well‐defined size. Uniformly sized micelles are loaded with a dissolved metal salt. These solution‐phase precursor entities are then reduced electrochemically—one by one—to form nanoparticles (NPs). The charge transferred during the reduction of each micelle is measured individually and allows operando sizing of each of the formed nanoparticles. Thus, particles of known number and sizes can be deposited homogenously even on nonplanar electrodes. This is demonstrated for the decoration of cylindrical carbon fibre electrodes with 25±7 nm sized Au particles from HAuCl₄‐filled micelles. These Au NP‐decorated electrodes show great catalyst performance for ORR (oxygen reduction reaction) already at low catalyst loadings. Hence, collisions of individual precursor‐filled nanocontainers are presented as a new route to nanoparticle‐modified electrodes with high catalyst utilization.     

Eco‐friendly synthesis of 1,8‐dioxo‐octahydroxanthenes catalyzed by ionic liquid in aqueous media

A biodegradable functionalized ionic liquid 3‐(N,N‐dimethyldodecylammonium)propanesulfonic acid hydrogen sulfate ([DDPA][HSO₄]) was prepared and used as a Brønsted acid–surfactant‐combined catalyst for the eco‐friendly one‐pot synthesis of 1,8‐dioxo‐octahydroxanthenes at 100°C in water. Under these conditions, the reaction of various aromatic aldehydes with dimedone generated 1,8‐dioxo‐octahydroxanthenes in good yields with a simple postreaction procedure. The products could simply be separated from the catalyst/water system, and the catalyst could be reused at least six times without noticeably decreasing the catalytic activity. J. Heterocyclic Chem., (2011).     

Ultrasound‐Promoted Catalyst‐Free Synthesis of 2,2′‐(1,4‐Phenylene)bis[1‐acetyl‐1,2‐dihydro‐4H‐3,1‐benzoxazin‐4‐one] Derivatives

A convenient approach to 2,2′‐(1,4‐phenylene)bis[1‐acetyl‐1,2‐dihydro‐4H‐3,1‐benzoxazin‐4‐one] derivatives 4 was explored employing the one‐pot condensation of anthranilic acids (=2‐aminobenzoic acids) 1 with terephthalaldehyde (=benzene‐1,4‐dicarboxaldehyde; 2 ) under ultrasound‐irradiation conditions (Scheme 1). The reactions proceeded smoothly in the presence of excess Ac₂O in the absence of any other catalyst and solvent to afford the respective products in high yields.     

Polymer‐supported pyridinium catalysts for synthesis of cyclic carbonate by reaction of carbon dioxide and oxirane

Polymer‐supported pyridinium salts, prepared by quaternarization of crosslinked poly(4‐vinylpyridine) with alkyl halides, effectively catalyze the reaction of carbon dioxide (1 atm) and glycidyl phenyl ether (GPE) to afford the corresponding five‐membered cyclic carbonate (4‐phenoxymethyl‐1,3‐dioxolan‐2‐one). Poly(4‐vinylpyridine) quarternarized with alkyl bromides show high catalytic activities, and the reaction of carbon dioxide (1 atm) and GPE at 100 °C affords 4‐phenoxymethyl‐1,3‐dioxolan‐2‐one quantitatively in 6 h. The rate constant in the reaction of GPE and carbon dioxide in N‐methyl pyrrolidinone using poly(4‐vinylpyridine) quarternarized with n‐butyl bromide (k_obs = 102 min^?1) is almost comparable with those for homogeneous catalysts with good activities (e.g., LiI), and the rate of the reaction obeys the first‐order kinetics. A used catalyst may be recovered by centrifugation, and the recycled catalyst also promotes the reaction of GPE and carbon dioxide. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5673–5678, 2007     

(C5H6N4O)(C5H5N4O)3(C5H4N4O)[Bi2Cl11]Cl2 as a simple and efficient catalyst in Biginelli reaction

A highly efficient and facile procedure for the one‐pot three‐component synthesis of 3,4‐dihydropyrimidin‐2‐(1H )ones/thiones from the one‐pot condensation of aldehyde, β‐dicarbonyl compound and urea/thiourea was developed. The methodology is applicable to a wide range of substrates with high yield in the presence of (C₅H₆N₄O)(C₅H₅N₄O)₃(C₅H₄N₄O)[Bi₂Cl₁₁]Cl₂. The complex is an air‐stable, environmentally friendly and recoverable catalyst and can efficiently catalyze the Biginelli reaction. The catalyst has high catalytic efficiency with low catalyst loading, and can be recycled ten times with only a small loss of activity.