An efficient one-pot solvent-free synthesis and photophysical properties of 9-aryl/alkyl-octahydroxanthene-1,8-diones

A facile and efficient protocol for the synthesis of 9-aryl/alkyl-3,3,6,6-tetramethyl-1,2,3,4,5,6,7,8-octahydroxanthene-1,8-diones has been developed by one-pot reaction of dimedone with aldehydes in the presence of InCl₃ or P₂O₅ under solvent-free conditions. The optical behaviors of the xanthenediones have been investigated by UV-vis and fluorescence spectroscopy. The present approach offers the advantages of simple methodology, clean and mild reaction, high atom-economy, short reaction time, low environmental impact, wide substrate scope, high yield, and excellent purity.     

An expedient and straightforward solvent-free synthesis of 1,8-dioxo-octahydroxanthenes using eco-friendly aluminized polyborate catalyst

The present work deals with a catalytic application of aluminized polyborate as a mild solid acid catalyst for multicomponent synthesis of 1,8-dioxo-octahydroxanthenes under solvent-free condition at 100°C-110°C. It involves selective domino Knoevenagel-Michael reaction of 1 mole of aromatic aldehyde with 2 moles dimedone. The aluminized polyborate is simply synthesized by using boric acid and aluminum trichloride and characterized by FT-IR, XRD, SEM and EDAX techniques. The mild Lewis acidity, crystalline solid nature, stability and recyclability are significant features of the catalyst. The solvent-free condition, clean reaction profile, inexpensive and non-toxic catalyst, operational simplicity, good to excellent product yields, reduced reaction time and applicability to wide range of substrate are crucial features of this protocol.     

An efficient heterogeneous iron oxide nanoparticle catalyst for the synthesis of 9-substituted xanthene-1,8-dione

Research on Chemical Intermediates - An efficient and simple method for the synthesis of xanthene derivatives by using iron oxide nanoparticles (NPs) as a catalyst has been investigated. Synthesis...     

Calcined oyster shell nanoparticles (COS NPs): a new,efficient and reusable catalyst for one-pot rapid preparation of 1,8-dioxo-octahydroxanthenes under solvent-free conditions

Research on Chemical Intermediates - Calcined oyster shell nanoparticles (COS NPs) as a novel heterogeneous nanocatalyst were prepared and fully characterized by X-ray fluorescence analysis,...     

A novel bioglycerol-based recyclable carbon catalyst for an efficient one-pot synthesis of highly substituted imidazoles

The new bioglycerol-based carbon catalyst acts as an efficient, readily available, and reusable catalyst for the synthesis of 2,4,5-trisubstituted imidazoles/1,2,4,5-tetrasubstituted imidazoles, when aromatic aldehyde, ammonium acetate/amine, and 1,2-diketone are reacted in acetonitrile.     

A simple and efficient one-pot synthesis of β-acetamido carbonyl compounds using sulfated zirconia as a heterogeneous recyclable catalyst

Sulfated zirconia has been employed as an efficient recyclable catalyst for the preparation of various β-acetamidoketones or esters at room temperature. The process involves the one-pot multicomponent reactions of aromatic aldehydes, enolizable ketones or β-ketoesters and acetonitrile in the presence of acetyl chloride.     

Nano-sulfated zirconia as an efficient, recyclable and environmentally benign catalyst for one-pot three component synthesis of amidoalkyl naphthols

One pot synthesis of amidoalkyl naphthols by reaction of aromatic aldehydes,2-naphthol and amide/urea using nano-sulfated zirconia as a catalyst is reported.The reaction was carried out under solvent-free conditions.The method gave good yields of amidoalkyl naphthols in short reaction time.The catalyst is recycled for five consecutive times without loss of activity.     

Neat synthesis of octahydroxanthene-1,8-diones,catalyzed by silicotungstic acid as an efficient reusable inorganic catalyst

In this article, the first use of silicotungstic acid (H₄SiW₁₂O₄₀) as a catalyst for the synthesis of octahydroxanthene-1,8-diones by the reaction of 5,5-dimethylcyclohexane-1,3-dione (dimedone) with various aldehydes under thermal solvent-free conditions is described. The obtained results showed that the catalyst has a high catalytic activity, and the desired products were obtained in high yields. Moreover, the catalyst was found to be reusable, and a considerable catalytic activity still could be achieved after the fifth run. Easy work-up and avoidance of using harmful organic solvents are the other advantages of this simple procedure.     

Highly efficient recyclable heterogeneous palladium catalyst for C-C coupling, amination and cyanation reactions

An inexpensive, air-moisture stable and reusable PS-Pd(II)-anthra complex was synthesized by reacting chloro-methylated polystyrene with anthranilic acid to get polymer anchored ligand which was then reacted with PdCl₂ to get polymer anchored complex. This complex was characterized by different spectroscopic and elemental analyses. The activity of the Pd-complex as catalyst was tested for the Suzuki, Heck, Sonogashira cross-coupling and also for amination and cyanation reactions under various conditions. The catalyst exhibits high catalytic activities for the coupling of various aryl halides with organoboronic acid, alkene, alkyne and amine along with the cyanation of aryl halides providing excellent yields of desired product. Further, the catalyst can be easily recovered quantitatively by simple filtration and reused up to five times without sufficient loss of its catalytic activity.     

Molecular iodine: An efficient catalyst for the one-pot synthesis of primary 1-aminophosphonates

A new and convenient procedure has been developed for the one-pot synthesis of different types of primary 1- aminophosphonates from aldehydes/ketones, HMDS and diethyl phosphite using I₂ as an inexpensive, non-toxic, non-metallic and readily available catalyst. These reactions proceeded under solvent-free conditions and produced the desired products in high yields.     

Aluminatesulfonic acid: Novel and recyclable nanocatalyst for efficient synthesis of aminoalkyl naphthols and amidoalkyl naphthols

In this study, an efficient, mild, and eco-friendly procedure is developed for the preparation of 1-amidoalkyl-2-naphthols and Betti bases from one-pot three-component condensation of aldehydes, 2-naphthol, and nitrogen sources (amides for amidoalkyl naphthols and amine for Betti bases) in the presence of aluminatesulfonic acid nanoparticles (ASA NPs) as recoverable catalyst under solvent-free conditions. ASA NPs were prepared by a simple reaction of net chlorosulfonic acid and sodium aluminate in high purity. ASA NPs were characterized by Fourier transform IR, X-ray powder diffraction, transmission electron microscopy, energy-dispersive X-ray, thermal gravimetric analysis, and UV diffusion/reflectance techniques. On the basis of the thermal gravimetric analysis and some activation parameters evaluated from decomposition thermal steps using Coats–Redfern model, the catalyst showed high thermal stability. High yields, short reaction time, easy workup, inexpensive, and reusability of the catalyst are advantages of this method.     

A simple and efficient one-pot synthesis of 1,4-dihydropyridines using heterogeneous catalyst under solvent-free conditions

One-pot condensation of β-dicarbonyl compounds with aldehydes and ammonium acetate in the presence of HClO₄–SiO₂ at 80 °C under solvent-free conditions with good to excellent yields. The catalyst is easily prepared, stable, reusable and efficiently used under reaction conditions.     

Silica gel / NaHSO4: An efficient and recyclable heterogeneous catalyst for high yield synthesis of 1,5‐benzodiazepine derivatives under microwave irradiation

Silica gel supported sodium hydrogen sulfate catalyzes efficiently the condensation of o‐phenylenediamines with ketones under microwaves in solvent free conditions to afford the corresponding 1,5‐benzodiazepine derivatives in high yields. Compared to conventional reaction conditions, this new approach consistently has the advantage of excellent yields (90‐98%) and short reaction times of 0.50 – 1.00 min.     

Ligandless heterogeneous palladium: an efficient and recyclable catalyst for Suzuki‐type cross‐coupling reaction

A mild and efficient ligand‐free Suzuki‐type cross‐coupling reaction of benzoyl chlorides and arylboronic acids catalyzed by heterogeneous Pd/C was developed. Benzoyl chlorides undergo cross‐coupling with electronically diverse arylboronic acids to give biaryl ketones in excellent yield, under aqueous media and optimum temperature. The application of 3 mol% of 10 wt% Pd/C to the cross‐coupling delivers utmost efficiency, and could be reused up to many consecutive cycles without any loss in activity. This method proceeds under aqueous media and a recyclable catalytic system, offering an environmentally benign alternative to the existing protocols. Copyright © 2014 John Wiley & Sons, Ltd.     

CuO nanoparticles: An efficient and recyclable nanocatalyst for the rapid and green synthesis of 3,4-dihydropyrano[c]chromenes

Copper oxide nanoparticles showed excellent catalytic activity through three-component condensation reaction of aldehydes, malononitrile, and 4-hydroxycoumarin for the synthesis of 3,4-dihyropyrano[c]chromenes in water medium in excellent yields and very short reaction times.     

An efficient synthesis of 2-benzoxepines from Morita-Baylis-Hillman adducts using heterogeneous recyclable catalysts

2-Benzoxepines have efficiently been synthesized from Morita-Baylis-Hillman adducts, alkyl 3-aryl-3-hydroxy-2-methylenepropanoates by treatment with HCHO catalyzed by silica supported perchloric acid (HClO4.SiO2) or Amberlyst-15 in CH2Cl2 under reflux for a short period of time (1.5-2.5 h). The catalyst can be recovered and recycled. The antibacterial properties of the new 2-benzoxepines were studied but no activity was found.