Novel Metal Oxide of CuO-ZnO Nanocatalyst Efficiently Catalyzed the Synthesis of 2-Amino-4H-chromenes in Water

Novel metal oxide of CuO-ZnO nanocatalyst was prepared by a coprecipitation method and characterized by x-ray diffusion, Brunauer–Emmett–Teller surface area, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy (EDS) analysis. The catalyst is efficient for the synthesis of 2-amino-4H-chromenes by one-pot condensation of aromatic aldehydes, hydroxynaphthalene derivatives, and malononitrile in water at reflux conditions. Moreover, CuO-ZnO nanocatalyst can be recycled up six times without any significant loss of its catalytic activity.     

Cu@KCC-1-NH-CS2 as a new and highly efficient nanocatalyst for the synthesis of 2-amino-4H-chromene derivatives

In the present work, Cu@KCC-1-NH-CS₂ as a green, efficient, and reusable nano-reactor was designed and used for the one-pot, three-component synthesis of 2-amino-4H-chromene derivatives using the reaction of cyclic 1,3-diketones, arylglyoxals, and malononitrile, under reflux conditions in EtOH. Engineered nanocatalyst characterized using different methods including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), adsorption/desorption analysis (BET), and energy dispersive X-ray spectroscopy (EDS). According to the obtained results, presented protocol for the synthesis of 2-amino-4H-chromenes using Cu@KCC-1-NH-CS₂ gave the desired products in higher yields (89–98%) with short reaction times. Also, under mild reaction conditions this green nanocatalyst indicated recyclable behavior five times with minor reduce in its catalytic activity.     

One-pot,three-component synthesis of polyfunctionalized benzo[h]pyrazolo[3,4-b][1,6]naphthyridine and benzo[g]pyrazolo[3,4-b]quinoline derivatives in the presence of silver nanoparticles (AgNPs)

An efficient and straightforward protocol for one-pot, three-component reaction of aryl glyoxal monohydrates 1a-h , 5-amino-1-aryl-3-methylpyrazoles 2a , b and 4-hydroxyquinoline-2(1H)-one ( 3 ) or 2-hydroxy-1,4-naphthoquinone ( 4 ) using silver nanoparticles (AgNPs) as a high performance nanocatalyst in H₂O/EtOH at 60°C afforded the corresponding polyfunctionalized benzo[h]pyrazolo[3,4-b][1,6]naphthyridines 5a-h and benzo[g]pyrazolo[3,4-b]quinolines 6a-i , respectively. Excellent catalytic activity, high yields, employing green media and green nanocatalyst, cost-effective and simple procedure are some notable advantages of using AgNPs as a noble metal nanocatalyst in this synthetic strategy. The structures of fused heterocycles were confirmed by their Fourier transform infrared, proton nuclear magnetic resonance (¹H-NMR), and ¹³C-NMR spectral data and microanalysis.     

5-Benzyl-1H-tetrazols from the reaction of 1-aryl-5-methyl-1H-tetrazoles with 1,2-dehydrobenzene

A series of 1-aryl-5-benzyl-1H-tetrazoles has been obtained during the reaction of 1-aryl-5-methyl-1H-tetrazoles with 1,2-dehydrobenzene. The mechanism of product formation was investigated.     

Tetrazole compounds. 9. A new approach to tetrazolyl-substituted quinoline derivatives

The acid-catalyzed reaction of 1-aryl-5-(2-dimethylaminovinyl)-1H-tetrazoles 2 with arylamines suitably functionalized in the ortho-position resulted in Z-configurated transamination products which were cyclized to novel 3-tetrazolylquinolines by the action of sodium ethoxide. Thus, on reacting 2 with 2-aminoacetophenone or 2-aminobenzophenone, respectively, the 2-[2-(1-aryl-1H-tetrazol-5-yl)vinyl-amino]aryl ketones 3a-g were obtained, the cyclization of which gave 4-substituted 3-(1-aryl-1H-tetrazol-5-yl)quinolines 4 . In the case of the transamination products 3h-1 , prepared from 2 and methyl anthranilate, the ring closure afforded 3-(1-aryl-1H-tetrazol-5-yl)-1H-quinolin-4-ones 5 . Starting from 2 and anthranilonitrile 4-amino-3-(1-aryl-1H-tetrazol-5-yl)quinolines 10 were obtained via the corresponding intermediates 9 .     

The influence of ultrasonic irradiation on catalytic performance of ZnO nanoparticles toward the synthesis of chiral 1-substituted-1H-tetrazolederivatives from α-amino acid ethyl esters

In this work, a simple and greener protocol for the synthesis of 1-substituted 1H-tetrazole derived from α-amino acid ethyl esters was demonstrated in the presence of zinc oxide nanoparticles (ZnO NPs) under conventional conditions, with heating (at 60 and 80°C and under reflux) compared with ultrasonic. The effect of solvent was investigated to reveal that the solvent system CH₃CN/H₂O was optimum to obtain 1-substituted 1H-tetrazole in high yield. In addition, the effect of irradiation power was studied, which showed that the yield of the reaction was improved at 200 W and the reaction time was shortened to be 30 min. Also, an improvement in the rate of the reaction and the yield of the products was observed when reactions were carried out under sonication conditions in the presence of ZnO NPs compared with conventional methods using various zinc salts as catalysts. The yields of tetrazole compounds 2a–i under sonication were determined (88–96%). Furthermore, the investigated heterogeneous catalytic system was recycled and reused for five runs with significant production of tetrazole 2a as a model target compound in excellent yields at each reaction cycle. In general, the investigated synthetic strategy for the heterocyclization of α-amino acid ethyl ester derivatives to 1-substituted 1H-tetrazoles was in agreement with the green chemistry point of view.     

Synthesis of arylaminotetrazoles by ZnCl2/AlCl3/silica as an efficient heterogeneous catalyst

Abstract  

Arylaminotetrazoles were efficiently synthesized from secondary arylcyanamides by application of ZnCl₂/AlCl₃/silica as a reusable heterogeneous Lewis acid catalyst. 5-Arylamino-1H-tetrazoles can be obtained from arylcyanamides carrying electron-withdrawing substituents on the aryl ring, while with electron-releasing groups 1-aryl-5-amino-1H-tetrazoles will be produced. The former isomer is also produced within longer reaction times (~20 h) even with electron-releasing groups.     

Synthesis,Structure, and Anti-influenza Activity of 2-(Adamantan-1-yl)-5-aryl-1,3,4-oxadiazoles and 2-(Adamantan-1-yl)-5-aryltetrazoles

Two series of new adamantyl derivatives of polynitrogen heterocycles, 2-(adamantan-1-yl)-5-aryl- 1,3,4-oxadiazoles and 2-(adamantan-1-yl)-5-aryl-2H-tetrazoles, have been synthesized, and their structure has been determined by NMR spectroscopy, mass spectrometry, and X-ray analysis. Biological studies in vitro have revealed high inhibitory activity of some of the synthesized 2-(adamantan-1-yl)-5-aryl-2H-tetrazoles against H1N1 influenza A viruses in combination with a relatively low selectivity.     

Selective method for the preparation of isomeric N-alkyl and N-aryl-3(5)-amino-5(3)-hydroxy-1H-pyrazole-1-carboxamides

As part of a program to develop novel mechanism based skeletal muscle relaxants we identified 5-amino-3-hydroxy-1H-pyrazole-1-carboxamide (1) as a potential structural lead. This highly functionalized pyrazole was prepared via a published procedure [1] (Scheme 1, R¹ = R¹ = H), which utilized 3,5-dimethyl-1H-pyrazole-1-carboxamide as an aminocarbonyl transfer reagent, to give with cyanoacethydrazide the semicarbazide intermediate 6 . Base catalyzed cyclization of 6 afforded the initial lead compound. This reaction scheme was extended to the synthesis of additional 4-alkyl- and 4-aryl-5-amino-3-hydroxy-1H-pyrazole-1-carboxamides (Table 1).     

Indium(III)chloride catalyzed synthesis of novel 1H-pyrazolo[1,2-b]phthalazine-5,10-diones and 1H-pyrazolo[1,2-a]pyridazine-5,8-diones under solvent-free condition

An efficient, inexpensive and environmentally friendly synthesis of novel 3-amino-2-benzoyl-1-aryl-1H-pyrazolo[1,2-b]phthalazine-5,10-dione and 3-amino-2-benzoyl-1-aryl-1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives has been developed via one-pot three-component reaction of phthalhydrazide or maleic hydrazide, aldehydes and arylacetonitrile in the presence of catalytic amount of InCl₃ as a Lewis acid catalyst under solvent-free conditions. The most important features of the present protocol are mild reaction conditions, short reaction times, high yields, and a wide range of functional group tolerance.     

Application of novel and reusable Fe3O4@CoII(macrocyclic Schiff base ligand) for multicomponent reactions of highly substituted thiopyridine and 4H-chromene derivatives

In this research study we designed and synthesized Co^II(macrocyclic Schiff base ligand containing 1,4-diazepane) immobilized on Fe₃O₄ nanoparticles as a novel, recyclable, and heterogeneous catalyst. The nanomaterial was fully characterized using various techniques such as Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersiveX-ray spectroscopy, thermogravimetric analysis, vibrating sample magnetometry, differential reflectance spectroscopy, Brunauere–Emmette–Teller method, inductively coupled plasma, and elemental analysis (CHNS). Then, the catalytic performance was successfully investigated in the multicomponent synthesis of 2-amino-4-aryl-6-(phenylsulfanyl)pyridine-3,5-dicarbonitrile and 2-amino-5,10-dioxo-4-aryl-5,10-dihydro-4H-benzo[g]chromene-3-carbonitrile derivatives. Furthermore, the catalyst was isolated using a simple filtration, and recovery of the nanocatalyst was demonstrated five times without any loss of activity.     

2-Amino-4-aryl-6-(ω-carboxyalkyl)-5H-pyrrolo[3,4-d]pyrimidin-7-(6H)ones. Preparation via a one-pot synthesis of 1-(ω-carboxyalkyl)-4-carbethoxy-2,3-dioxopyrrolidines

1-(ω-Carboxyalkyl)-4-carboethoxy-2,3-dioxopyrrolidines were prepared by a one-pot synthesis from β-alanine or γ-aminobutyric acid, ethyl acrylate and diethyl oxalate. In a second one-pot process these products were hydrolyzed, decarboxylated and condensed with aromatic aldehydes under the influence of hydrochloric acid to yield 1-(ω-carboxyalkyl)-4-arylidene-2,3-dioxo-pyrolidines, which yielded 2-amino-4-aryl-6-(ω-carboxyalkyl)-5H-pyrrolo[3,4-d]pyrimidin-7-(6H)-ones upon treatment with guanidine. It was shown that 3,4-dihydro derivatives of certain 2-amino-4-aryl-5H-pyrrolo[3,4-d]pyrimidin-7-(6H)ones, formed initially in the guanidine reaction, readily undergo conversion to 5H-pyrrolo[3,4-d]pyrimidin-7-(6H)ones.     

Novel tris(5-aryl-1H-tetrazol-1-yl)methanes and 2-dichloromethyl-5-aryl-2H-tetrazoles and noncovalent interactions in their crystal structure

A series of tris(5-aryl-1H-tetrazol-1-yl)methanes ( 3a-3g ) and 2-dichloromethyl-5-aryl-2H-tetrazoles ( 4a-4d ) were synthesized by reaction of 5-aryl-NH-tetrazoles with trichloromethane in strong aqueous basic condition. The compounds obtained were fully characterized by means of HRESI-MS, ¹H and ¹³C{¹H} NMR spectroscopies, as well as by single-crystal X-ray diffraction (for 3a , 3b , 4d ). Inspection of the X-ray diffraction data and Hirshfeld surface analysis for tris(5-aryl-1H-tetrazol-1-yl)methanes 3a , b and 2-dichloromethyl-5-aryl-2H-tetrazole 4d showed the presence of noncovalent π-hole•••lone pair and π-hole•••π interactions involving electrophilic tetrazole carbon atom.     

An unexpected formation of pyrazolopyrimidines during the attempted to obtain 5-substituted tetrazoles from carbonitriles

In this Letter, we described the synthesis of new 5-(5-amino-1-aryl-1H-pyrazole-4-yl)-1H-tetrazoles 2a–c from 5-amino-1-aryl-1H-pyrazole-4-carbonitriles 1a–c as well as the unexpected 1H-pyrazolo[3,4-d]pyrimidine derivatives 6a–c from 5-amino-1-aryl-3-methyl-1H-pyrazole-4-carbonitriles 4a–c, instead of 5-(5-amino-1-aryl-3-methyl-1H-pyrazole-4-yl)-1H-tetrazoles 5a–c as desired. In an attempt to obtain these tetrazole derivatives containing the methyl group at C3-position in the pyrazole ring, the amino group in 5-amino-1-(4-methoxyphenyl)-3-methyl-1H-pyrazole-4-carbonitrile 4c was protected by the reaction with sodium hydride and di-tert-butyl-dicarbonate (Boc). The tetrazole derivative 5c was synthesized from the protected compound 7c using analogue methodology to obtain 2a–c and 6a–c.     

Tetrazole compounds. 10. Novel tetrazolylindoles by fischer indolization of substituted tetrazolylacetaldehyde phenylhydrazones

The acid-catalyzed reaction of substituted phenylhydrazines 1 with 1-aryl-5-(2-dimethylaminovinyl)-1H-tetrazoles 2 afforded (1-aryl-1H-tetrazol-5-yl)acetaldehyde phenylhydrazones 3 which on heating in acetic acid/perchloric acid underwent a Fischer indolization to give substituted 3-(1-aryl-1H-tetrazol-5-yl)-indoles 4a-k. Indoles of this type are also formed on subjecting 1 and 2 directly to indolization conditions; thus, starting from phenylhydrazine the tetrazolylindoles 41-s were obtained by a one-pot procedure. Indolization of corresponding N_α-methylphenylhydrazones 5 resulted in 1-methyl-3-(1-aryl-1H-tetrazol-5-yl)indoles 6 .     

Iodine-Catalyzed,Efficient, One-Pot Protocol for the Conversion of Araldehydes into 5-Aryl-1H-tetrazoles

An easy access to various 5-aryl-1H-tetrazoles by a one-pot direct conversion of aldehydes to tetrazoles without the isolation of the intermediate nitriles using commercially available iodine as a catalyst is described. The protocol offers advantages in terms of good yields, mild reaction conditions, short reaction times, and use of readily available environmentally compatible catalyst.     

Fragmentation of 1-aryl-5-(2-dialkylaminovinyl)-1H-tetrazoles upon electron impact

The mass spectrometric behaviour of 1-aryl-5-(2-dialkylaminovinyI)-lH-tetrazoles was studied, especially 1-phenyl-5-(2-dimethylaminovinyl)-l H-tetrazole as a typical example of D- and ¹⁵N-labelled derivatives revealed a rearrangement via a carbodiimide-like intermediate ion.     

Preparation of an efficient catalyst through injection of CuI on modified poly (styrene-co-maleic anhydride) and theoretical investigation of the structural and electronic properties of catalyst

A novel polymer supported [poly (styrene-co-maleic imide) (SMI)]Cu(I) nano-particles was prepared via in situ reaction of 4-amino-5-methyl-4H-1,2,4-triazole-3-thione with [poly (styrene-co-maleic anhydride)] (SMA) along with immobilization of CuI. These nano-particles were fully characterized by using scanning electron microscopy (SEM), energy dispersive spectroscopy analysis, Xray (EDAX), inductively coupled plasma (ICP) analysis, ¹H NMR and FT-IR techniques. Moreover, the structural and electronic features of metal–ligand interactions in the complex model of polymer-supported copper nanocatalyst were assessed using density functional theory calculations. The catalytic activity of these supported Cu(I) nonoparticles was examined in one of the classiest name reaction so–called “click reaction” which is coined K. B Sharpless for the regioselective synthesis of 1,2,3-triazole derivatives using a multicomponent reaction (MCR) involving benzyl halides, sodium azide and terminal alkynes in water as a green solvent. This heterogeneous catalyst showed excellent catalytic activity and was separated by simple filtration and was used at least in five consecutive runs without a significant decrease in its activity.     

Poly(amic acid) salt‐mediated palladium and platinum nanoparticles as highly active and recyclable catalysts for hydrogenation of nitroarenes in water under ambient conditions

Development of highly active and recyclable catalysts for selective hydrogenation of nitroarenes to amines in water at room temperature is always a challenge in chemical industry. This study reports a facile in situ method for synthesis of ultrafine palladium and platinum nanoparticles (NPs) stabilized by poly (amic acid) salt (PAAS) and their potential as catalysts for hydrogenation of nitroarenes with sodium borohydride or molecular hydrogen as reductant in water at room temperature. In the reduction of 4‐nitrophenol to 4‐aminophenol by sodium borohydride, the activity parameters of PdNPs–PAAS and PtNPs–PAAS catalyst is 6.66 × 10³ and 5.58 × 10³ s^?1 M^?1 respectively. In the hydrogenation of diverse nitroarenes under atmospheric hydrogen pressure, PdNPs–PAAS shows high activity but poor selectivity toward desired amines in some cases, while PtNPs–PAAS shows both high activity and high selectivity for selective hydrogenation of nitroarenes to corresponding anilines. The high efficiency of nanocatalyst is due to the quasi‐homogeneous dispersion of metal NPs and synergistic effects between metal NPs and PAAS. In addition, nanocatalyst can be easily recovered with pH‐sensibility of PAAS and reused at least six times without significant loss of catalytic activities.     

Synthesis of 5-cyanopyrazolo[3,4-b]pyridines in the reaction of 5-amino-3-methyl-1-phenylpyrazole with arylidene derivatives of malonodinitrile and ethyl cyanoacetate

This paper describes the synthesis of a new series of 6-amino-4-aryl-5-cyanopyrazolo[3,4-b]pyridines 4 and 4-aryl-5-cyano-6H-pyrazolo[3,4-b]pyridin-6-ones 5 from the reaction of 5-amino-3-methyl-1-phenylpyrazole 1 with arylidene derivatives of malonodinitrile 2 and ethyl cyanoacetate 3 . The structure of the final compounds was determined on the basis of nmr measurements, especially by ¹H, ¹H-, ¹H, ¹³C-COSY, DEPT and X-ray diffraction.