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).     

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.     

MCM‐41‐SO3H as a nanoreactor for the one‐pot,solvent‐free synthesis of 1,8‐dioxo‐9‐aryl decahydroacridines

One‐pot four‐component synthesis of 1,8‐dioxo‐9‐aryl decahydroacridines in solvent‐free condition was efficiently performed in the presence of MCM‐41‐SO₃H as a nanocatalyst and nanoreactor in good yields. The method provides several advantages such as low cost, operational and experimental simplicity, high yields, and short reaction times. J. Heterocyclic Chem., (2012).     

Silica‐supported perchloric acid as a recyclable catalyst for efficient trimethylsilyl cyanide addition to aldehydes

HClO₄? SiO₂ (0.6 mol%) acts as a highly effective catalyst for cyanation of various aldehydes to the corresponding O‐trimethylsilyl cyanohydrins, in high yields and short reaction times. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of 2‐Aryl‐1‐arylmethyl‐1H‐1,3‐benzimidazole Derivatives Using Silica‐bonded Propyl‐S‐sulfonic Acid as Recyclable Solid Acid Catalyst

A highly selective synthesis of 2‐aryl‐1‐arylmethyl‐1H‐1,3‐benzimidazoles from the reaction of o‐phenylenediamine and aromatic aldehydes in the presence of silica‐bonded propyl‐S‐sulfonic acid (SBSSA) at 80°C in water in good to excellent yields was developed.     

Novel CuFe2O4@SiO2‐OP2O5H magnetic nanoparticles: Preparation,characterization and first catalytic application to the synthesis of 1,8‐dioxo‐octahydroxanthenes

New functionalized magnetic core–shell nanoparticles, CuFe₂O₄@SiO₂‐OP₂O₅H, were prepared by grafting of phosphorus pentoxide on CuFe₂O₄@SiO₂ nanoparticles and characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray analysis, inductively coupled plasma optical emission spectrometry and vibrating sample magnetometry. The catalytic activity of CuFe₂O₄@SiO₂‐OP₂O₅H as a novel catalyst was evaluated in the synthesis of 1,8‐dioxo‐octahydroxanthenes under solvent‐free conditions. The results showed that the catalyst has high activity and the desired products are obtained in high yields within short reaction times. The catalyst is readily recovered using magnetic decantation and can be used at least four times without noticeable deterioration in catalytic activity.     

Phospho sulfonic acid as an efficient and recyclable solid acid catalyst for the solvent-free preparation of acylals

Phospho sulfonic acid (PSA) acts as a highly effective and reusable catalyst for the chemo-selective protection of aldehydes with acetic anhydride under solvent-free conditions. The desirable features of this new catalytic methodology include its sustainability, effectiveness in the absence of solvent, a facile work-up procedure, and economic viability. PSA is fully characterized by Fourier transform infrared spectroscopy, wide-angle X-ray scattering analysis, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The catalyst can be reused several times without significant loss of activity. In addition, no chromatographic separations are needed to obtain the desired products.     

Sulfonic acid functionalized silica as an efficient heterogeneous recyclable catalyst for one‐pot synthesis of 2‐substituted benziimidazoles

An efficient one‐pot synthesis of 2‐substituted benzimidazoles from o‐phenylenediamine and aldehydes in the presence of sulfonic acid functionalized silica at room temperature is reported.     

Kaolin: A recyclable catalyst for the synthesis of 1,5‐benzodiazepines

2,3‐Dihydro‐1H‐1,5‐benzodiazepines are synthesized by the condensation of o‐phenylenediamine and various ketones in the presence of kaolin as a recyclable catalyst in dichloroethane. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:215–217, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20354     

Nanocrystalline TiO2, via green combustion synthesis,as an efficient and reusable catalyst for the preparation of 1,8‐dioxooctahydroxanthenes and 1,8‐dioxodecahydroacridines

Nanocrystalline TiO₂ is synthesized using a green combustion method and used as a recyclable catalyst for the one‐pot multicomponent synthesis of 1,8‐dioxodecahydroacridines and 1,8‐dioxooctahydroxanthenes, under solvent‐free conditions. This method is mild, environmentally friendly, inexpensive and highly effective for obtaining good to excellent yields of the products. Copyright © 2015 John Wiley & Sons, Ltd.     

ZrOCl2·8H2O: a highly efficient catalyst for the synthesis of 1,8‐dioxo‐octahydroxanthene derivatives under solvent‐free conditions

ZrOCl₂·8H₂O has been found to be an efficient catalyst for the synthesis of 1,8‐dioxo‐octahydroxanthenes from aldehydes and 5,5‐dimethylcyclohexane‐1,3‐dione under solvent‐free conditions. Copyright © 2009 John Wiley & Sons, Ltd.     

Molybdate sulfonic acid: preparation, characterization, and application as an effective and reusable catalyst for octahydroxanthene-1,8-dione synthesis

Molybdate sulfonic acid (MSA) as a highly efficient catalyst was synthesized and employed for the synthesis of octahydroxanthene-1,8-dione derivatives. MSA efficiently catalyzed condensation of a wide range of aryl aldehydes and cyclohexane-1,3-diones to obtain octahydroxanthene-1,8-diones. It was characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), and FT-IR spectroscopy. This catalyst can be recovered and reused several times in other reactions maintaining its high activity. This novel and green method is very cheap and has many advantages such as excellent yields, the use of recoverable and eco-friendly catalysts, and a simple work-up procedure.     

Iron‐containing ionic liquid as an efficient and recyclable catalyst for the synthesis of C3‐substituted indole derivatives

A facile and efficient protocol for the synthesis of C3‐substituted indole derivatives has been developed under mild condition. The iron‐containing ionic liquid, 1‐(2‐hydroxyethyl)‐1,4‐diazabicyclo[2.2.2] octanylium tetrachloroferrate ([Dabco‐C₂OH][FeCl₄]) as a recyclable catalyst has been successfully used in the synthesis of trisindolines, bis(3‐indolyl) methanes and β‐indolyl alcohols for the first time. The products of trisindolines and bis(3‐indolyl) methanes are easily separated and purified without chromatographic technique. The catalyst was recycled six times without significant activity loss.     

Hydrogen‐bonded molecular ladders in S‐(4‐nitrophenyl)thioglycolic acid

Molecules of the title compound, [(4‐nitro­phenyl)­sulfanyl]­acetic acid, C₈H₇NO₄S, are linked by paired O—H?O hydrogen bonds [H?O 1.81 Å, O?O 2.6456 (15) Å and O—H?O 178°] into centrosymmetric dimers containing an R(8) motif. A single C—H?O hydrogen bond having a nitro O atom as acceptor [H?O 2.47 Å, 3.3018 (19) Å and C—H?O 147°] links the dimers into a molecular ladder, and neighbouring ladders are weakly linked into sheets by aromatic π–π‐stacking interactions.     

Carbon-based nanocatalyst: An efficient and recyclable heterogeneous catalyst for one-pot synthesis of gem-bisamides,hexahydroacridine-1,8-diones and 1,8-dioxo-octahydroxanthenes

Journal of the Iranian Chemical Society - In this abstract, we discuss the progress related to sulfonated carbon-based materials in various acid-catalyzed organic transformations which are then...     

Silica-bonded S-sulfonic acid a recyclable catalyst for the synthesis of coumarins

Silica-bonded S-sulfonic acid(SBSSA) was prepared by the reaction of 3-mercaptopropylsilica(MPS) and chlorosulfonic acid in chloroform.This solid acid has been employed as a recyclable catalyst for the synthesis of coumarins from phenols andβ-ketoesters at 80℃under solvent-free conditions.     

Synthesis and application of silica phenyl sulfonic acid as a solid acid heterogeneous catalyst for one‐pot synthesis of 2‐aryl‐1‐arylmethyl‐1H‐1,3‐benzimidazoles and bis(indolyl)methanes in water

Silica phenyl sulfonic acid (SPSA) was prepared and effectively used in the one‐pot synthesis of 2‐aryl‐1‐arylmethyl‐1H‐1,3‐benzimidazoles from o‐phenylenediamine with aldehydes in water in the presence of tetrabutyl ammonium bromide with good to high yield. Also, SPSA was used as a catalyst for the synthesis of bis(indolyl)methanes in water. J. Heterocyclic Chem., (2011).     

Cobalt manganese oxide nanoparticles as recyclable catalyst for efficient synthesis of 2‐aryl‐1‐arylmethyl‐1H‐1,3‐benzimidazoles under solvent‐free conditions

Cobalt manganese oxide nanocatalyst was synthesized and it was found that it is a highly efficient green catalyst for the synthesis of 2‐aryl‐1‐arylmethyl‐1H‐1,3‐benzimidazoles under solvent‐free conditions. The marked advantages of this method are the simple experimental procedures, shorter reaction times, high yields of product, reusable and non‐toxic catalyst and solvent‐free conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

KIT-6-anchored sulfonic acid groups as a heterogeneous solid acid catalyst for the synthesis of aryl tetrazoles

In the current study, a simple, environmentally benign and cost-effective method is presented for the preparation of 5-substituted-1H-aryltetrazoles. To this goal, mesoporous KIT-6 silica anchored with sulfonic acid (–SO₃H) groups via post-grafting modification was synthesized using the sol–gel method and characterized by XRD, TGA, FTIR, BET, TEM and SEM techniques. For the preparation of tetrazole derivatives, the effect of various parameters such as catalyst amount, aryl nitrile:azide ratio, temperature and reaction time was tested. The hybrid organic/inorganic catalyst could be recovered easily through a simple filtration and reused multiple times without significant loss in activity.     

Silica-bonded S-sulfonic acid as a recyclable catalyst for chemoselective synthesis of 1,1-diacetates

A simple and efficient procedure for the preparation of silica-bonded S-sulfonic acid (SBSSA) by reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acid in chloroform is described. This solid acid is employed as a recyclable catalyst for the synthesis of 1,1-diacetates from aromatic aldehydes and acetic anhydride under mild and solvent-free conditions at room temperature.