Green synthesis of pyrimido‐isoquinolines and pyrimido‐quinoline using ZnO nanorods as an efficient catalyst: Study of antioxidant activity

In this paper, we report the synthesis of pyrimido[2,1‐a] isoquinoline and pyrimido[1,2‐a]quinoline derivatives in high yields from the reaction of isoquinoline or quinoline, activated acetylenic compounds, and amides in the presence of ZnO nanorods (ZnO‐NRs) as catalyst under solvent‐free conditions at room temperature. ZnO‐NRs show good improvement in the yield of the product and significant reusability. Also, the antioxidant activities of the some of the newly synthesized compounds were carried out by 1,1‐diphenyl‐2‐picrylhydrazyl (PDDH) radical trapping and ferric ion reducing potential tests and compared with those of the synthetic antioxidants 2‐tert‐butylhydroquinone (TBHQ) and butylated hydroxytoluene (BHT). These compounds do not show good DPPH radical scavenging but display good ferric ion reducing power.     

An efficient one-pot three-component synthesis and antimicrobial evaluation of tetra substituted thiophene derivatives

A convenient one-pot three-component method for the preparation of tetra-substituted thiophene derivatives has been developed. Reaction of acetyl acetone 1, phenyl isothiocynate 2 and 2-chloromethyl derivatives 3a–3c in the presence of potassium carbonate afforded the target compounds, namely ethyl2-(4-acetyl-3-methyl-5-(phenylamino)thiophen-2-yl)-2-oxoacetate derivatives 4a–4e, ethyl 3-(4-acetyl-3-methyl-5-(phenylamino)thiophen-2-yl)-3-oxopropanoate derivatives 4f–4i, di((4-acetyl-3-methyl-5-phenylamino)thiophen-2-yl)ketone derivatives 4j–4n in reasonable overall yields. The synthesized compounds were screened for antimicrobial activity. The detailed synthesis, spectroscopic data and antimicrobial activities of synthesized compounds were reported.     

ZnO nanorods as an efficient catalyst for the synthesis of imidazo[1,2-a]azines and diazines

Abstract  

ZnO nanorods were synthesized using a novel and solvent-free procedure and their catalytic activity in the preparation of imidazo[1,2-a]azines and diazines was studied. The effects of the amount of catalyst and its reusability were investigated to optimize the reaction conditions. The ZnO nanorods exhibited higher catalytic activity than that of bulk ZnO.     

HPA decorated Halloysite Nanoclay: An efficient catalyst for the green synthesis of Spirooxindole derivatives

A novel heterogeneous catalyst, HPA@HNTs‐IMI‐SO₃H, was designed and synthesized based on functionalization of halloysite nanotubes with ionic liquid and subsequent incorporation of heteropolyacid. The structure of the catalyst was studied and confirmed by using SEM/EDX, FTIR, XRD, ICP‐AES, TGA, DTGA and BET. Moreover, the catalytic activity of HPA@HNTs‐IMI‐SO₃H was investigated for promoting ultrasonic‐assisted three‐component reaction of isatines, malononitrile or cyanoacetic esters and 1,3‐dicarbonyl compounds to afford corresponding spirooxindole in high yields and short reaction time. The reusability of the catalyst was also studied. Notably, the catalyst could be recovered and reused for three reaction runs. However, reusing for fourth reaction runs led to the decrease of the catalytic activity. Considering leaching test results, that observation was attributed to the leaching of heteropolyacids, which can be induced by ultrasonic irradiation.     

ZnO nanoparticles: a green efficient catalyst for the room temperature synthesis of biologically active 2-aryl-1,3-benzothiazole and 1,3-benzoxazole derivatives

A facile synthetic protocol for the synthesis of 2-aryl-1,3-benzothiazoles and 1,3-benzoxazoles has been demonstrated using ZnO nanoparticles as a mild and efficient heterogeneous catalyst. The reactions using ZnO nanoparticles were very fast (<8 min) and provided excellent yields (>90%) of the products. The catalyst was recycled and reused up to eight times without significant loss of catalytic activity. The potential application of 2-(4-hydroxyphenyl)-1,3-benzothiazole as new acid–base indicator has also been demonstrated in this Letter.     

Lithium bromide as an efficient,green, and inexpensive catalyst for the synthesis of quinoxaline derivatives at room temperature

Abstract

An efficient, simple, and green procedure for the synthesis of quinoxaline derivatives is described. The condensation of 1,2-diamines with 1,2-diketones using lithium bromide (LiBr) in H₂O/EtOH as a green reaction media at room temperature affords the title compounds in high to excellent yields and in short reaction times.     

Synthesis of imidazole derivatives: Ester and hydrazide compounds with antioxidant activity using ionic liquid as an efficient catalyst

The pyrrolidinium hydrogen sulfate (PHS) was used as an excellent ionic liquid catalyst for the preparation of many imidazoles moiety, which have biologically application via one-pot multicomponent reaction. Imidazoles were afforded through the reaction of equimolar from 1,2-diphenylethane-1,2-dione, ammonium acetate, different aromatic aldehydes, and ethyl glycinate hydrochloride. This method has the advantages of giving excellent yield, shortened reaction times, and ease of establishment. Moreover, the yielded of imidazoles components can be purified and crystallized by a nonchromatographic technique, and the catalyst can be reused. These entire novel synthesized components have been identified by spectral data: IR, NMR and mass spectra. These compounds have an in vivo antioxidant activity on experimental animals (rats).     

Catalyst-free green synthesis and study of antioxidant activity of new pyrazole derivatives

In this research, a novel procedure for the synthesis of pyrazole derivatives in excellent yields was studied using catalyst-free multicomponent reaction of isoquinoline, activated acetylenic compounds, alkyl bromides, triphenylphosphine and hydrazine in water under ultrasonic irradiation at room temperature. The advantages of this procedure than to reported methods are short time of reaction, high yields of product, easy separation of product, clean mixture of reaction and green media for performing reaction. In addition, because of having pyrazole and isoquinoline core in the synthesized compounds, in this research, antioxidant activity of some synthesized compounds was investigated.     

Copper-polymer nanocomposite: An efficient catalyst for green Huisgen click synthesis

A new method for Huisgen [3+2] cycloaddition synthesis of 1,4- and 1,4,5-substituted-1H-1,2,3-triazoles was reported. The reaction was catalyzed by the product of thermolysis of copper (II) poly-5-vinyltetrazolate. Heterogeneous catalyst includes copper nanoparticles which supported on polymeric matrix. It presents recovered and recycled catalyst and the catalyzed reaction proceeds in aerobic conditions at room temperature in aqueous media.     

Carboxymethyl cellulose as a green and biodegradable catalyst for the solvent-free synthesis of benzimidazoloquinazolinone derivatives

Carboxymethyl cellulose (CMC) was used as an efficient, and environmentally friendly catalyst for the solvent-free three-component synthesis of quinazolinone derivatives by condensation of 2-aminobenzimidazole, dimedone or 1,3-cyclohexanedione, and different aldehydes. The catalyst was recovered easily, and reused without significant loss of its activity. Solvent-free and mild reaction conditions, nontoxic-, biodegradable-, and inexpensive catalyst, environmentally benign method, and high to excellent yields are some important features of this protocol.     

Green synthesis of Fe3O4/ZnO magnetic core-shell nanoparticles by Petasites hybridus rhizome water extract and their application for the synthesis of pyran derivatives: Investigation of antioxidant and antimicrobial activity

In this research, Fe₃O₄/ZnO magnetic core-shell nanoparticles (Fe₃O₄/ZnO MCNPs) were synthesized through a green method using Petasites hybridus rhizome water extract as a reducing and stabilizing agent. The morphology and size of the Fe₃O₄/ZnO MCNPs was identified by X-ray diffraction, scanning electron microscopy, and Energy-dispersive X-ray spectroscopy (EDX) analysis. The catalytic activity of the Fe₃O₄/ZnO MCNPs was evaluated in the efficient and green preparation of pyran derivatives in excellent yield using three-component reactions of dimedone, aldehydes, and malononitrile in ethanol at room temperature. The ability of some synthesized compounds to scavenge the 2,2-diphenyl-1-picrylhydrazyl radical was measured and the results proved this observation. Moreover, the antimicrobial activity of some synthesized compounds was proved by employing the disk diffusion test on Gram-positive and Gram-negative bacteria. The results for the disk diffusion test showed that compounds ( 4c, 4d, 4f and 4g ) prevented bacterial growth.     

Citric acid:An efficient and green catalyst for rapid one pot synthesis of quinoxaline derivatives at room temperature

The condensation of o-phenylenediamines with 1,2-dicarbonyl compounds in the presence of citric acid afforded the corresponding quinoxaline derivatives in higher yields at room temperature in ethanol,and most of the reactions were completed in less than 1 min.     

Sulfamic acid as efficient and reusable catalytic system for the synthesis of pyrrole,furan, and thiophene derivatives

Sulfamic acid has been utilized for the first time as an efficient and reusable catalytic system for the synthesis of heteroaromatics such as pyrrole, furan, and thiophene derivatives from 1,4‐diketones. This new procedure offers significant improvements in the reaction rates and yields in a shorter reaction time and a lower reaction temperature contrasted with the reported results. The recovered catalyst can be reused for subsequent runs with only a gradual decrease in activity. The most important feature is that the reaction process is homogeneous whereas the separation process is heterogeneous, which is often seen in other catalysts, and so it is a good character for technical application. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:144–148, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20389     

NBS as an efficient catalyst for the synthesis of 1,5-benzodiazepine derivatives under mild conditions

Various biologically important 1,5-benzodiazepine derivatives were efficiently synthesized in excellent yields using catalytic amounts of NBS (10 mol %). This inexpensive, nontoxic, and readily available catalyst efficiently catalyzes the condensation of several aromatic as well as aliphatic ketones with substituted o-phenylenediamines.     

Ionic liquid promoted green synthesis of new pyridazino benzazepine derivatives: Evaluation of antioxidant activity

In this research, we investigated preparation of pyridazino benzazepine derivatives in high yields via the domino and one-pot reaction of isatoic anhydride, N-methylimidazole, alkyl bromides, activated acetylenic compounds, and hydrazine in ionic liquid as green media at 80°C. Also, antioxidation property of some prepared pyridazino benzazepines due to having pyridazin and benzazepine core is investigated by employing of trapping diphenyl-picrylhydrazine radical and ability of ferric reduction experiment. Our procedure has a few benefits relative to reported method such as good rate of reaction, product with high efficiency, and simple separation of product from mixture of reaction.     

Nanoporous aluminosilicate catalyst with 3D cage-type porous structure as an efficient catalyst for the synthesis of benzimidazole derivatives

Herein we demonstrate for the first time, the synthesis of benzimidazoles through the coupling of aldehydes with o-phenylenediamine by using highly acidic nanoporous aluminosilicate with 3D structure and cage-type pores as the catalyst. The catalyst resulted in excellent yields in short reaction times presumably due to its high acidity, large pore diameter, high surface area, and cage-type 3D porous structure.     

Protic pyridinium ionic liquid: As an efficient,green and environmentally friendly catalyst for the one-pot synthesis of amidoalkyl naphthol derivatives

A green and efficient synthesis of amidoalkyl naphthol derivatives via the three-component reaction between aryl aldehyde, 2-naphthol and amide derivatives using 2-methylpyridinium trifluoromethanesulfonate ([2-MPyH]OTf) as a catalyst (5 mol%) is described. This method provides several advantages over alternative procedures such as low cost, under thermal solvent-free green procedure, simple procedure and direct isolation of the products in high yields.     

SPIONs as a nanomagnetic catalyst for the synthesis and anti-microbial activity of 2-aminothiazoles derivatives

A series of aminothiazole derivatives have been synthesized by using ultrasmall superparamagnetic iron oxide nanoparticles (SPIONs) nanomagnetic catalysis, which were prepared by reducing the Fe(II) and Fe(III) precursors using aqueous ammonia then characterized by the XRD, FTIR, SEM, and TEM. The 2-aminothiazole derivatives were obtained by coupling 2-aminothiazole diazonium salt with active methylene compounds then cyclization with hydrazine hydrate to afford pyrazolyl derivatives. The one-pot reaction of 2-aminothiazole with an aromatic aldehydes in the presence of Fe₃O₄ NPs to give Schiff bases derivatives. An efficient protocol is developed proudest yields and reduction reaction time and easy separation. Therefore, all synthesized compounds were evaluated for anti-microbial activity.