Green synthesis of Cu/zirconium silicate nanocomposite by using Rubia tinctorum leaf extract and its application in the preparation of N‐benzyl‐N‐arylcyanamides

A simple and convenient protocol was established for the synthesis of the N‐benzyl‐N‐arylcyanamides through N‐benzylation of a wide variety of arylcyanamides using copper nanoparticles immobilized on natural zirconium silicate as a novel and green heterogeneous catalyst. In this study, we showed a novel, cost efficient, convenient and simple method for green synthesis of Cu/zirconium silicate nanocomposite by using Rubia tinctorum leaf extract as capping and reducing agent. The structure of the novel catalyst was successfully characterized using a number of micro/spectroscopic techniques such as XRD, FESEM, BET, EDS, TEM, FT‐IR and elemental mapping. TEM micrographs of obtaining biocatalyst revealed mostly spherical particles with an average diameter of about 15–25 nm on the surface of natural support. The prepared catalyst was used in the N‐benzylation of a variety of arylcyanamides with benzyl bromide and showed high activity and stability for the efficient synthesis of N‐benzylarylcyanamides in good yields. Remarkably, the catalyst can be easily recovered from the reaction medium and reused up to five runs without losing its catalytic activity.     

Biosynthesis of Pd/MnO2 nanocomposite using Solanum melongena plant extract and its application for the one‐pot synthesis of 5‐substituted 1H‐tetrazoles from aryl halides

In this work, for the first time, Solanum melongena plant extract was used for the green synthesis of Pd/MnO₂ nanocomposite via reduction osf Pd(II) ions to Pd(0) and their immobilization on the surface of manganese dioxide (MnO₂) nanoparticles (NPs) as an effective support. The synthesized nanocomposite were characterized by various analytical techniques such as Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy dispersive X‐ray spectroscopy (EDS) and UV–Vis spectroscopy. The catalytic activity of Pd/MnO₂ nanocomposite was used as a heterogeneous catalyst for the one‐pot synthesis of 5‐substituted 1H‐tetrazoles from aryl halides containing various electron‐donating or electron‐withdrawing groups in the presence of K ₄ [Fe (CN) ₆ ] as non‐toxic cyanide source and sodium azide. The products were obtained in good yields via a simple methodology and easy work‐up. The nanocatalyst can be recycled and reused several times with no remarkable loss of activity.     

Facile Chan‐Lam coupling using ferrocene tethered N‐heterocyclic carbene‐copper complex anchored on graphene

Ferrocene tethered N‐heterocyclic carbene‐copper complex anchored on graphene ([GrFemImi]NHC@Cu complex) has been synthesized by covalent grafting of ferrocenyl ionic liquid in the matrix of graphene followed by metallation with copper (I) iodide. The [GrFemImi]NHC@Cu complex has been characterized by fourier transform infrared (FT‐IR), fourier transform Raman (FT‐Raman), CP‐MAS ¹³C NMR spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), energy dispersive X‐ray (EDX) analysis, X‐ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area analysis and X‐ray diffractometer (XRD) analysis. This novel complex served as a robust heterogeneous catalyst for the synthesis of bioactive N‐aryl sulfonamides from variety of aryl boronic acids and sulfonyl azides in ethanol by Chan‐Lam coupling. Recyclability experiments were executed successfully for six consecutive runs.     

One‐pot green synthesis of Cu/bone nanocomposite and its catalytic activity in the synthesis of 1‐substituted 1H‐1,2,3,4‐tetrazoles and reduction of hazardous pollutants

In this work, a simple and green method is reported for the biosynthesis of Cu/bone nanocomposite using Cordyline fruticosa extract as a stabilizer and reductant. Animal bone was used as a natural support to prevent the accumulation of Cu nanoparticles. The catalytic activity of Cu/bone nanocomposite was assessed in the synthesis of 1‐substituted 1H‐1,2,3,4‐tetrazoles and reduction of various organic dyes, including 4‐nitrophenol (4‐NP), nigrosin (NS), congo red (CR) and methylene blue (MB). The best catalytic performance in the synthesis of 1‐substituted tetrazoles was achieved using 0.05 g of Cu/bone nanocomposite at 120°C. In addition, under optimal conditions, the absorption bands corresponding to 4‐NP, CR, NS and MB completely disappeared after about 6 min, 3 min, 50 s and 7 s, respectively. The biosynthesis protocol used in the preparation of Cu/bone nanocomposite offers a very attractive area for further research.     

Dendrimer‐encapsulated Cu(Π) nanoparticles immobilized on superparamagnetic Fe3O4@SiO2 nanoparticles as a novel recyclable catalyst for N‐arylation of nitrogen heterocycles and green synthesis of 5‐substituted 1H‐tetrazoles

In this study, dendrimer‐encapsulated Cu(Π) nanoparticles immobilized on superparamagnetic Fe₃O₄@SiO₂ nanoparticles were prepared via a multistep‐synthesis. Then, the synthesized composite was fully characterized by various techniques such as fourier transform infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD), dynamic light scattering (DLS), UV‐vis spectroscopy, energy dispersive X‐ray analysis (EDX), thermogravimetric analysis (TGA) and vibration sample magnetometer (VSM). From the information gained by FE‐SEM and TEM studies it can be inferred that the particles are mostly spherical in shape and have an average size of 50 nm. Also, the amount of Cu is determined to be 0.51 mmol/g in the catalyst by inductively coupled plasma (ICP) analyzer. This magnetic nano‐compound has been successfully applied as a highly efficient, magnetically recoverable and stable catalyst for N‐arylation of nitrogen heterocycles with aryl halides (I, Br) and arylboronic acids without using external ligands or additives. The catalyst was also employed in a one‐pot, three‐component reaction for the efficient and green synthesis of 5‐substituted 1H‐tetrazoles using various aldehydes, hydroxylamine hydrochloride and sodium azide in water. The magnetic catalyst can be easily separated by an external magnet bar and is recycled seven times without significant loss of its activity.     

Synthesis,crystal structures,spectral FT‐IR,NMR and UV–Vis investigations and Hirshfeld surface analysis of two new 2‐hydroxyethyl‐substituted N‐heterocyclic carbene precursors

This study discusses the synthesis of two new 2‐hydroxyethyl substituted N‐heterocyclic carbene (NHC) precursors. The NHC precursors were prepared from 1‐(alkyl/aryl)benzimidazole and alkyl halides. They were characterized using ¹H NMR, ¹³C NMR, FT‐IR, UV–Vis spectroscopy, and elemental analysis techniques. Molecular and crystal structures of 1 and 2 were determined using the single‐crystal X‐ray diffraction method. Crystal structure of the compounds features NHC precursors and chloride anions. Additionally in 2 , the asymmetric unit has a water molecule, which forms a tetrameric chloride‐hydrate assembly with the chloride anion. The chloride anions play an important role in the stabilization of crystal structures to form a two‐dimensional supramolecular architecture. The 3D Hirshfeld surface and the associated 2D fingerprint plots were also drawn to gain insights into the behavior of the interactions in the compounds.     

Direct C—H Bond Activation of Benzoxazole and Benzothiazole with Aryl Bromides Catalyzed by Palladium(II)‐N‐heterocyclic Carbene Complexes

Herein, we report that a series of novel palladium(II)‐NHC complexes (NHC=N‐heterocyclic carbene) were synthesized. The structures of all novel complexes were characterized by ¹H NMR, ¹³C NMR, FT‐IR spectroscopy and elemental analysis techniques. These palladium(II)‐NHC complexes were tested as efficient catalysts in the direct C—H bond activation of benzoxazole and benzothiazole with aryl bromides in the presence of 1 mol% catalyst loading at 150 °C for 4 h. Under the given conditions, various aryl bromides were successfully applied as the arylating reagents to achieve the 2‐arylbenzoxazoles and 2‐arylbenzothiazoles in acceptable to high yields.     

Novel N‐Alkylbenzimidazole‐Ruthenium (II) complexes: Synthesis and catalytic activity of N‐alkylating reaction under solvent‐free medium

In this article, direct N‐alkylation reactions of amines with alcohols derivatives have been investigated. For this purpose, a new series ruthenium (II) complexes bearing N‐coordinated benzimidazole complexes with have been synthesized and fully characterized by elemental analysis, FT‐IR, ¹H NMR and, ¹³C NMR spectroscopies. Additionally, the structures of the complexes 2b and 2c have been confirmed by X‐ray crystallography. Although the N‐alkylating reaction is usually performed in toluene, the catalytic study of complexes 2a‐d has carried out no additional solvent and alcohol acted both as solvent and reactant of alkylating by using a little excess of alcohols. Surprisingly, conversion and selectivity of amine product for alkylation reaction have been seen high in medium solvent‐free relative to in toluene.     

Cu–N‐heterocyclic carbene‐catalysed synthesis of 2‐aryl‐3‐(arylethynyl)quinoxalines from one‐pot tandem coupling of o‐phenylenediamines and terminal alkynes

A series of new benzimidazolium chlorides bearing N,N′‐benzyl, 2,4,6‐trimethylbenzyl and 2,4,6‐triisopropylbenzyl substituents have been designed and synthesized from various o‐phenylenediamines. Subsequently, corresponding Cu‐based N‐heterocyclic carbenes (NHCs) were generated in situ in the reaction medium which represents a new application of NHCs exploiting distinct catalytic property towards intermolecular cyclization reaction cascade for the synthesis of 2‐aryl‐3‐(arylethynyl)quinoxalines from o‐phenylenediamines and terminal alkynes. The outcome of the cyclization reaction product depends upon the N,N′‐substituents present on the benzimidazolium chlorides.     

Convenient synthesis of poly(γ‐benzyl‐L‐glutamate) from activated urethane derivatives of γ‐benzyl‐L‐glutamate

A series of activated urethane‐type derivatives of γ‐benzyl‐L ‐glutamate were synthesized, and their potential as monomers for polypeptide synthesis was investigated. The derivatives of the focus of this work were a series of N‐aryloxycarbonyl‐γ‐benzyl‐L ‐glutamate 1 , of which aryl groups were phenyl, 4‐chlorophenyl, and 4‐nitrophenyl. These urethanes 1 were reactive in polar solvents such as dimethylsulfoxide, N,N‐dimethylformamide (DMF), and N,N‐dimethylacetamide (DMAc), and were efficiently converted into poly(γ‐benzyl‐L ‐glutamate) (poly(BLG)) under mild conditions; at 60 °C without addition of any catalyst. Among the three urethanes, that having 4‐nitrophenoxycarbonyl group 1c was the most reactive to give poly(BLG) efficiently, as was expected from the highly electron deficient nature of the nitrophenoxycarbonyl group. On the other hand, the urethane 1a having phenoxycarbonyl group was also efficiently converted into poly(BLG), in spite of the intrinsically less electrophilicity of the phenoxycarbonyl group. In addition, the successful formation of poly(BLG) by the reaction of 1a favored its diluted concentration (0.1 M) much more than 2.0 M, the optimum initial concentration for 1c . ¹H NMR spectroscopic analyses of the reactions in situ revealed that the predominant pathway from 1 to poly(BLG) involved the intramolecular cyclization of 1 into the corresponding N‐carboxyanhydride, with release of phenol and its successive ring‐opening polymerization with release of carbon dioxide. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2649–2657, 2008     

Synthesis and characterization of macroinitiator‐amino terminated PEG and poly(γ‐benzyl‐L‐glutamate)‐PEO‐poly(γ‐benzyl‐L‐glutamate) triblock copolymer

Macroinitiator‐amino terminated poly(ethylene glycol) (PEG) (NH₂‐PEO‐NH₂) was prepared by converting both terminal hydroxyl groups of PEG to more reactive primary amino groups. The synthetic route involved reactions of chloridize, phthalimide and finally hydrazinolysis. Furthermore, poly(γ‐benzyl‐L ‐glutamate)‐poly(ethylene oxide)‐poly(γ‐benzyl‐L ‐glutamate) (PBLG‐PEO‐PBLG) triblock copolymer was synthesized by polymerization of γ‐benzyl‐L ‐glutamate N‐carboxyanhydride (Bz‐L‐GluNCA) using NH₂‐PEO‐NH₂ as macroinitiator. The resultant NH₂‐PEO‐NH₂ and triblock copolymer were characterized by FT‐IR, ¹H‐NMR and gel permeation chromatography (GPC) techniques. The results demonstrated that the degree of amination of the NH₂‐PEO‐NH₂ could be up to 1.95. The molecular weight of the PBLG‐PEO‐PBLG triblock copolymer could be adjusted easily by controlling the molar ratio of Bz‐L ‐Glu NCA to the macroinitiator NH₂‐PEO‐NH₂. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis and antioxidant activities of novel N‐aryl (and N‐alkyl) γ‐ and δ‐imino esters and ketimines

Novel N‐aryl (and N‐alkyl) γ‐ and δ‐imino esters 2a–g ( 3a–g ) and N‐aryl (and N‐alkyl) ketimines 2h–j ( 3h–j ) were synthesized in high yields (80–99%) from their corresponding γ‐ and δ‐keto esters and ketones in this study. The structures of the synthesized compounds were clarified by Fourier transform infrared (FT‐IR), NMR (¹H and ¹³C), mass spectrometry, and elemental analyses. Isomerizations [E/Z] were also determined by their ¹H NMR spectra. The free‐radical scavenging activity of imines was evaluated using the 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) method. The relationships between the structure and antioxidant activity of these compounds are discussed. Among these compounds, 2a–c (at the concentration 1000 μg/mL) exhibit high antioxidant activity similar to those of the standards (butylated hydroxyanisole [ BHA], butylated hydroxytoluene [ BHT], and ascorbic acid).     

Synthesis and biological activity of novel N‐tert‐butyl‐N,N′‐substitutedbenzoylhydrazines containing 2‐methyl‐3‐(triphenylgermanyl)propoxycarbonyl

In a search for new insect growth regulators with unusual biological properties and different activity spectrum, we thought that the preservation of the bioactive unit and the introduction of 2‐methyl‐3‐(triphenylgermanyl)propoxycarbonyl in N‐tert‐butyl‐N,N′‐dibenzoylhydrazine would enhance their larvicidal activities to a significant degree. Therefore, we designed and synthesized N′‐tert‐butyl‐N′‐[2‐methyl‐3‐(triphenylgermanyl)propoxycarbonyl]‐N‐benzoylhydrazine and analogs by two procedures. These novel compounds were characterized by elemental analyses, IR, and ¹H NMR. At the same time, N‐tert‐butyl‐N‐substitutedbenzoylhydrazines were prepared by a new method, and some reactions involved were studied. The preliminary results indicate that some compounds have inhibitory effects against plant pathogenetic bacteria such as early blight of tomato. Copyright © 2002 John Wiley & Sons, Ltd.     

Ultrasound‐Assisted Synthesis of 6‐Methyl‐1,2,3,4‐tetrahydro‐N‐aryl‐2‐oxo/thio‐4‐arylpyrimidine‐5‐carboxamides Catalyzed by Uranyl Nitrate Hexahydrate

An efficient and simple method developed for the synthesis of 6‐methyl‐1,2,3,4‐tetrahydro‐N‐aryl‐2‐oxo/thio‐4‐arylpyrimidine‐5‐carboxamide derivatives ( 4a‐o ) using UO₂(NO₃)₂.6H₂O catalyst under conventional and ultrasonic conditions. The ultrasound irradiation synthesis had shown several advantages such as milder conditions, shorter reaction times and higher yields. The structures of all the newly synthesized compounds have been confirmed by FT‐IR, ¹H NMR, ¹³C NMR and mass spectra.     

高选择性N-单甲基化芳香胺的合成

本文报道了一种高效专一性合成N-单甲基芳胺的方法。芳胺先与醋酐反应生成乙酰胺,再与碘甲烷在氢化钠作用下反应生成相应的N-甲基乙酰芳胺。在乙二醇中用酸水解高产率得到相应的N-单甲基芳胺。并将该方法用于药物中间体的合成。     

A New Route to N‐Aryl 2‐Alkenamides,N‐Allyl N‐Aryl 2‐Alkenamides,and N‐Aryl α,β‐Unsaturated γ‐Lactams from N‐Aryl 3‐(Phenylsulfonyl)propanamides

A series of N‐aryl 2‐alkenamides were produced efficiently by treating N‐aryl 3‐(phenylsulfonyl)‐propanamides with potassium tert‐butoxide in THF at 0°C. With out isolation, it was further treated with an additional equivalent of potassium tert‐butoxide and allyl bromide to give N‐allyl N‐aryl 2‐alkenamides in one pot in good yields. Followed by a ring‐closing metathesis reaction, these N‐allyl N‐aryl 2‐alkenamides were respectively converted into corresponding N‐aryl α,β‐unsaturated γ‐lactams in moderate yields.     

New Approach to N‐substituted‐1,2,3,6‐tetrahydro‐pyridine‐4‐carbaldehyde,a Precursor for Synthesizing Aricept®, Isoguvacine,and Deethylibophyllidine

A new route towards the synthesis of N‐substituted‐4‐formylpiperidine using N‐benzyl or tryptaminyl‐sulfonylacetamide and α,β‐unsaturated ester as starting materials is described. Formal synthesis of Aricept^®, deethylibophyllidine, and isoguvacine, which have potential biological activities, were synthesized via this strategy.     

Synthesis and characterization of a novel organic–inorganic hybrid salt and its application as a highly effectual Brønsted–Lewis acidic catalyst for the production of N,N′‐alkylidene bisamides

In this research, a novel organic–inorganic hybrid salt, namely, N¹,N¹,N²,N²‐tetramethyl‐N¹,N²‐bis(sulfo)ethane‐1,2‐diaminium tetrachloroferrate ([TMBSED][FeCl₄]₂) was prepared and characterized by Fourier‐transform infrared spectroscopy (FT‐IR), energy‐dispersive X‐ray spectroscopy (EDX), elemental mapping, field emission scanning electron microscopy (FE‐SEM), X‐ray diffraction (XRD), thermal gravimetric (TG), differential thermal gravimetric (DTG), and vibrating‐sample magnetometry (VSM) analyses. Catalytic activity of the hybrid salt was tested for the synthesis of N,N′‐alkylidene bisamides through the reaction of benzamide (2 eq.) and aromatic aldehydes (1 eq.) under solvent‐free conditions in which the products were obtained in high yields and short reaction times. The catalyst was superior to many of the reported catalysts in terms of two or more of these factors: the reaction medium and temperature, yield, time, and turnover frequency (TOF). [TMBSED][FeCl₄]₂ is a Brønsted–Lewis acidic catalyst; there are two SO₃H groups (as Brønsted acidic sites) and two tetrachloroferrate anions (as Lewis acidic sites) in its structure. Highly effectiveness of the catalyst for the synthesis of N,N′‐alkylidene bisamides can be attributed to synergy of the Brønsted and Lewis acids and also possessing two sites of each acid.     

Application of the Fe3O4@1,10‐phenanthroline‐5,6‐diol@Mn nano‐catalyst for the green synthesis of tetrazoles and its biological performance

The Fe₃O₄ magnetic particles were modified with 1,10‐phenanthroline‐5,6‐diol (Phen) and the related Mn complex (Fe₃O₄@Phen@Mn) synthesized as a heterogeneous catalyst to be used for the one‐pot three‐component synthesis of various tetrazoles. The catalysts were characterized by several methods, such as the elemental analysis, FT‐IR, X‐ray powder diffraction, dispersive X‐ray spectroscopy, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, thermogravimetric‐differential thermal analysis, vibrating sample magnetometer and X‐ray photoelectron spectroscopy. In addition, the antioxidant and antibacterial activities of the catalyst and its Phen ligand were in vitro screened with 2,2‐diphenyl‐1‐picrylhydrazyl by free radical scavenging methods. Results showed that the synthesized compounds possess strong antioxidant activity (IC50; 0.172  ±  0.005 mg ml^?1) as well as a good antibacterial potential in comparison to standards.     

Morphology and Electrical Conductivity of Poly(N‐vinylcarbazole)/Carbon Nanotubes Nanocomposite Synthesized by Solid State Polymerization

This communication describes the morphology and DC conductivity of poly(N‐vinylcarbazole) (PNVC)/multi‐walled carbon nanotubes (MWCNTs) nanocomposite. The nanocomposite has been synthesized by solid state in situ polymerization of N‐vinylcarbazole (NVC) monomer in the presence of MWCNTs at an elevated temperature. Fourier transform infrared (FT‐IR) spectroscopy studies reveal the ability of MWCNTs to promote the in situ polymerization of the NVC monomer. Field‐emission scanning electron microscopy (FE‐SEM) observations show the homogeneous wrapping of MWCNTs' outer surface by PNVC polymer. Transmission electron microscopy (TEM) images and Raman spectroscopy results support the SEM observations. Thermogravimetric analyses reveal a significant improvement of thermal stability of the nanocomposite sample in the higher temperature region. The resulting nanocomposite material exhibits a dramatic improvement of the DC conductivity inherent to the PNVC. For example, the DC conductivity increases from ≈5.9 × 10⁻¹³ S · cm⁻¹ for PNVC to ≈12 S · cm⁻¹ for the nanocomposite, an increase of about 10¹³ in the electrical conductivity.