- Accelerated Hantzsch electrospray synthesis with temporal control of reaction intermediates
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Complex chemical reactions can occur in electrosprayed droplets on the millisecond time scale. The Hantzsch synthesis of 1,4-dihydropyridines was studied in this way using on-line mass spectral analysis to optimize conditions and characterize the product
- Bain, Ryan M.,Pulliam, Christopher J.,Cooks, R. Graham
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- A highly efficient magnetic solid acid nanocatalyst for the synthesis of new bulky heterocyclic compounds
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Fe3O4 nanoparticles were prepared and coated with 3-aminopropyltriethoxysilane (APTES). The formed amine-surfaced Fe3O4@APTES NPs were further chemically modified with maleic anhydride (MAH) to generate Fe3O4@APTES·MAH NPs. This catalyst was characterized by FT-IR, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), energy dispersive X-ray analyzer (EDAX), vibrating sample magnetometry (VSM) and the dynamic light scattering (DLS) measurement technique. The catalyst showed high thermal stability and good reusability. Some new bulky heterocyclic compounds such as bis(2,4,5-triarylimidazole), bis(1,4-dihydropyridine), bis(1,8-dioxooctahydroxanthene) and bis(1,8-dioxo-decahydroacridine) derivatives were synthesized using 4,4′-(alkylazanediyl)dibenzaldehyde as substrate and Fe3O4@APTES or Fe3O4@APTES·MAH as catalyst. The high purity products were isolated and the catalyst was easily separated with a simple work-up with magnetic field and was recycled several times without noticeable loss of reactivity under the described reaction conditions.
- Nasr-Esfahani, Masoud,Rafiee, Zahra,Montazerozohori, Morteza,Kashi, Hassan
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- An efficient and solvent-free one-pot synthesis of 1,4-dihydropyridines under microwave irradiation
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An efficient synthesis of 1,4-dihydropyridines using lanthanum oxide as a catalyst from aldehydes, β-ketoester and ammonium acetate without solvent under the irradiation of microwave is described. Compared with the classical Hantzsch reaction, this new me
- Kuraitheerthakumaran,Pazhamalai,Gopalakrishnan
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- The SBA-15/SO3H nanoreactor as a highly efficient and reusable catalyst for diketene-based, four-component synthesis of polyhydroquinolines and dihydropyridines under neat conditions
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An efficient diketene ring-opening synthesis of polyhydroquinoline derivatives using SBA-15 sulfonic acid modified mesoporous substrates a green and reusable catalyst in a single-pot four-component coupling reaction of diketene, alcohol, enamine, and alde
- Rostamnia, Sadegh,Pourhassan, Fatemeh
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- The multicomponent Hantzsch reaction: Comprehensive mass spectrometry monitoring using charge-tagged reagents
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A novel strategy for the ESI-MS monitoring of reaction solutions involving the alternate use of permanently charge-tagged reagents has been used for comprehensive mass spectrometry monitoring of the multicomponent Hantzsch 1,4-dihydropyridine reaction. By placing a charge tag on either, or both, of the two key reactants, ion suppression effects for ESI were eliminated or minimized, and comprehensive detection of charge-tagged intermediates was achieved. The strategy allowed the trapping and characterization of the important intermediates in the mechanism for 1,4-dihydropyridine formation.
- Santos, Vanessa G.,Godoi, Marla N.,Regiani, Thaís,Gama, Fernando H. S.,Coelho, Mirela B.,De Souza, Rodrigo O. M. A.,Eberlin, Marcos N.,Garden, Simon J.
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- Diketene-based neat four-component synthesis of the dihydropyrimidinones and dihydropyridine backbones using silica sulfuric acid (SSA)
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Heterocyclic skeleton building blocks to afford dihydropyrimidinones and dihydropyridines based on neat adducts of diketene, alcohols and aldehydes via silica sulfuric acid (SSA) catalyzed ring opening of diketene in four-component Biginelli-type and Hant
- Rostamnia, Sadegh,Lamei, Kamran
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- Photoinduced umpolung addition of carbonyl compounds with α,β-unsaturated esters enables the polysubstituted γ-lactone formation
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We herein report the photoinduced intermolecular umpolung addition of aromatic ketones/aldehydes with α,β-unsaturated esters via ketyl radical intermediates. Following an intramolecular transesterification, a variety of γ-lactone derivatives are readily accessed. Mechanistic investigations demonstrate the significant role of Hantzsch ester, which serves both as the electron and proton donor. This journal is
- Gu, Jia-Yi,Zhang, Wei,Jackson, Seth R.,He, Yan-Hong,Guan, Zhi
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- SnCl4-functionalized nano-Fe3O4 encapsulated-silica particles as a novel heterogeneous solid acid for the synthesis of 1,4-dihydropyridine derivatives
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A novel type of green heterogeneous solid acid was prepared by the immobilization of SnCl4 on the surface of Fe3O4@SiO2 (Fe3O4@SiO2-SnCl4) and characterized by Fourier
- Bamoniri, Abdolhamid,Fouladgar, Sara
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- Research on heterocyclic compounds. XLIII. Synthetic studies on 1,4-dihydropyridine derivatives
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In order to obtain N-benzyl-3,5-dicarbethoxy-2,6-dimethyl-4-phenyl-1,4-dihydropyridine 1 as a lead compound of pharmacological interest, the classical Hantzsch synthetic method and the modified Collie procedure were used. However, only a very low yield of
- Rimoli, Maria Grazia,Avallone, Lucia,Zanarone, Serena,Abignente, Enrico,Mangoni, Alfonso
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- N-Propyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride-SBA-15 (SBA-DABCO) as basic mesoporous catalyst for the synthesis of 1,4-dihydropyridine hetrocyclic compounds
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Regarding the green chemistry's goals, the development of mesoporous silica materials as attractive candidates in the search for supporting of catalysts is currently a subject of increasing interest. Therefore, in the present research n-propyl-4-aza-1-azo
- Kiasat, Ali Reza,Davarpanah, Jamal
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- Unprecedented synthesis of hantzsch 1,4-dihydropyridines under biginelli reaction conditions
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Hantzsch 1,4-dihydropyridines are synthesized in high yields by a one-pot cyclocondensation of aldehyde, β-ketoester, and urea on the surface of silica gel under microwave irradiation in solvent-free conditions.
- Yadav,Subba Reddy,Reddy
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- Silica (NPs) supported Fe (III) as a reusable heterogeneous catalyst for the one-pot synthesis of 1, 4-dihydropyridines under mild conditions
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A cheap and recyclable silica (NPs) supported Fe (III) was prepared as heterogeneous catalyst for the synthesis of various substituted 1,4-dihydropyridines via condensation of aldehydes with ethyl acetoacetate and ammonium acetate in ethanol. The products
- Safaei-Ghomi, Javad,Ziarati, Abolfazl,Zahedi, Safura
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- Halloysite Nanotubes Functionalized Sulfonic Acid: Synthesis, Spectroscopic Characterization, Computational Studies and Application for the Synthesis of 1,4-Dihydropyridines
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In this study, naturally occurring clay halloysite has been used to synthesize novel halloysite functionalized sulfonic acid in two steps, i.e. functionalization followed by oxidation, and its catalytic activity has been estimated for one-pot synthesis of
- Gupta, Princy,Prakash, Nayan,Ramawat, Yogeshwar,Rajput, Palvi,Fayaz, Amir,Roy, Tapta Kanchan
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- g-C3N4@Ce-MOF Z-scheme heterojunction photocatalyzed cascade aerobic oxidative functionalization of styrene
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A special composite of the cerium-based metal-organic framework (Ce-UiO-66) modified with graphitic carbon nitride nanosheets (g-C3N4) has been synthesized. In order to make a comparison, a series of composites comprising g-C3N4and Ce-MOF were synthesized as well. Their structural features were investigated using Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), sorption of nitrogen (BET and BJH), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), X-ray fluorescence spectroscopy (XRF) and diffuse reflectance UV-Vis spectroscopy (UV-Vis DRS) and electron spin resonance (ESR) techniques. According to the obtained results, it was found that nanosheets of mesoporous g-C3N4act as linkers between the cerium sites, playing a critical role in the formation of composites. In fact, the embedded g-C3N4nanoparticles in the Ce-MOF cause a new kind of meso-porosity. Moreover, the coordination of nitrogen atoms in the graphitic carbon nitride structure to cerium atoms of the crystal brings about substantial changes in the optical properties, increasing the photoreactivity. On the other hand, since there is a physical contact between Ce-UiO-66 and g-C3N4in the composite, the unaltered pore volume and optical properties lead to the formation of a physical mixture rather than a composite. The g-C3N4@Ce-MOF as a photocatalyst was employed in photocatalytic aerobic oxidative Hantzsch pyridine synthesis of styrene and indicated high performance under visible light. The stability and reusability of g-C3N4@Ce-MOF were also examined and showed high efficiency up to the 5th run. Besides, the PXRD and FT-IR analyses taken from the retrieved g-C3N4@Ce-MOF nanocomposite confirmed the catalyst stability after the completion of the cascade aerobic oxidative reaction. Despite the photocatalytic performance, the synergistic effect of open metal sites in the MOF as Lewis acid and nitrogen in g-C3N4have greatly improved the efficiency of the catalyst. Moreover, the study of the reaction mechanism using ESR indicates the positive effect of composite formation on the performance of the photocatalytic aerobic oxidation reaction by the superoxide radical (O2˙—), as a selective oxidant species.
- Karimia, Meghdad,Sadeghia, Samira,Gavinehroudi, Reza Ghahremani,Mohebali, Haleh,Mahjoub, Alireza,Heydari, Akbar
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p. 6671 - 6681
(2021/04/22)
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- Boosting the catalytic performance of manganese (III)-porphyrin complex MnTSPP for facile one-pot green synthesis of 1,4-dihydropyridine derivatives under mild conditions
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In this study, the metal complex (5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin manganese (III) chloride; denoted as MnTSPP) represents a promising efficient and reusable heterogeneous solid catalyst for facile and highly efficient one-pot synthesis of 1,4 dihydropyridine derivatives via three-component condensation reaction of aromatic aldehyde, ethyl acetoacetate, and ammonium acetate under green and mild reaction conditions. The simple operation, short reaction time (15 min), and the high efficiency (99%) are the special advantage of this protocol. Furthermore, the green aspects of this synthetic protocol were more studied by examination of the reusability of MnTSPP for four consecutive cycles without a significant loss of catalytic activity. Remarkably, the new synthesis presented advantages in terms of safety, commercially available catalyst, simplicity, stability, mild conditions, short reaction time, and excellent yields, using a mixture of H2O and C2H5OH environmental-friendly solvent, operationally facile, wide tolerance of starting materials, and excellent recoverable of the catalyst.
- Ali El-Remaily, Mahmoud Abd El Aleem Ali,Hamad, Hesham A.,Soliman, Ahmed M. M.,Elhady, Omar M.
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- Synthesis, characterization and cytotoxicity evaluation of a novel magnetic nanocomposite with iron oxide deposited on cellulose nanofibers with nickel (Fe3O4@NFC@ONSM-Ni)
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A heterogeneous, magnetically recoverable nanocomposite, Fe3O4@NFC@ONSM-Ni(ii) was prepared by immobilization of a novel Ni(ii) Schiff base complex on Fe3O4@NFC nanoparticles followed by treatment with melamine. This trinuclear catalyst has been characterized using several analytical techniques including FT-IR, TEM, Fe-SEM, EDX, DLS, ICP, TGA, VSM, and XRD. It was used as an efficient catalyst for one-pot solvent-free synthesis of 1,4-dihydropyridine and poly-hydro quinoline derivatives through Hantzsch reaction. This catalyst showed remarkable advantage over previously reported catalysts due to suitable conditions, short reaction time, high efficiency and lower catalyst load and timely recovery of the magnetic catalyst. Moreover, the effects of Fe3O4@NFC@ONSM-Ni(ii) nanoparticles on thein vitroproliferation of human leukemia cell line (k562) and human breast cancer cells (MDA-MB-231) were investigated. The results of MTT and Hochest assays suggested that the nanoparticles could effectively inhibit the proliferation of these cancer cells in a time- and concentration-dependent manner.
- Ghamari Kargar, Pouya,Noorian, Maryam,Chamani, Elham,Bagherzade, Ghodsieh,Kiani, Zahra
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p. 17413 - 17430
(2021/05/25)
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- Urea as an ammonia surrogate in the hantzsch’s synthesis of polyhydro-quinolines / 1,4-dihydropyridines under green reaction conditions
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Synthesis of polyhydroquinolines via Hantzsch’s multicomponent reaction (MCR) involves the use of a hygroscopic and moderately toxic ammonium salt as one of the key reactants. In our effort, we have found urea as an effective ammonia surrogate when the MC
- Anna, Venkateswara Rao,Dhananjaya, G.,Mahesh Kumar, P.,Narayana Murthy, V.,Pal, Manojit,Pulla Reddy, S.,Raghunadh, Akula
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supporting information
p. 226 - 232
(2021/03/19)
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- Dual solvent-catalyst role of deep eutectic solvents in Hantzsch dihydropyridine synthesis
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Deep eutectic solvents are a class of new generation green solvents formed from two or more components, which furnish a new homogeneous liquid phase with lower melting point than the individual components. Here, for the first time, dual role of DES as cat
- Shaibuna,Sreekumar
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supporting information
p. 1742 - 1753
(2021/04/09)
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- Sulfonamide-functionalized covalent organic framework (COF-SO3H): an efficient heterogeneous acidic catalyst for the one-pot preparation of polyhydroquinoline and 1,4-dihydropyridine derivatives
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Herein, we report the sulfonamide-functionalized covalent organic framework (COF-SO3H) prepared from melamine and terephthalaldehyde and subsequent sulfonation, as an acidic porous catalyst for the one-pot preparation of polyhydroquinoline and
- Farsi, Razieh,Mohammadi, Mohammad Kazem,Saghanezhad, Seyyed Jafar
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p. 1161 - 1179
(2020/11/18)
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- Synthesis and characterization of bis-triazolyl-pyridine derivatives as noncanonical dna-interacting compounds
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Besides the well-known double-helical conformation, DNA is capable of folding into various noncanonical arrangements, such as G-quadruplexes (G4s) and i-motifs (iMs), whose occurrence in gene promoters, replication origins, and telomeres highlights the br
- Amato, Jussara,Biroccio, Annamaria,Brancaccio, Diego,Carotenuto, Alfonso,De Tito, Stefano,Di Porzio, Anna,Galli, Ubaldina,Iaccarino, Nunzia,Iachettini, Sara,Marzano, Simona,Pagano, Bruno,Randazzo, Antonio,Santoro, Federica,Tron, Gian Cesare,Zizza, Pasquale
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- USY-zeolite catalyzed synthesis of 1,4-dihydropyridines under microwave irradiation: structure and recycling of the catalyst
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The Hantzsch three-component reaction is the best-known multicomponent reaction, affording dihydropyridines which have been employed therapeutically and also as visible‐light photoredox catalysts. In this work we report the application of an ultra-stable
- Alponti, Leonardo H.R.,Picinini, Monize,Urquieta-Gonzalez, Ernesto A.,Corrêa, Arlene G.
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- Trinuclear cis-dioxidomolybdenum(VI) complexes of compartmental C3 symmetric ligands: Synthesis, characterization, DFT study and catalytic application for hydropyridines (Hps) via the Hantzsch reaction
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Trinuclear cis-dioxidomolybdenum(VI) complexes of the type [{MoVIO2(MeOH)}3L1-7] (1–7) have been synthesized using tris(H2ONO) donor ligands [H6L1-7 (I–VII)] assembled from benzene-1,3,5-tricarbohydrazide (bthz) and the corresponding salicylaldehyde (sal). All the ligands and the complexes were characterized by numerous techniques, such as FT-IR, UV–visible, NMR (1H and 13C) spectroscopy, electrochemical study, elemental analysis, thermogravimetric study and single crystal X-ray diffraction of the ligand III and complexes 1 and 5. In the presence of H2O2 as an oxidant, these complexes show excellent catalytic potential towards the one-pot three-components [ethyl acetoacetate, benzaldehyde (or its derivatives) and ammonium acetate] dynamic covalent assembly in the Hantzsch reaction. Under solvent free conditions, as high as 98% conversion along with 100% selectivity towards diethyl 2,6-dimethyl-4-phenyl-1,4-dihydropyridine-3,5-dicarboxylate (1,4-DHP) has been achieved in 1 h. Although solvents do not improve the conversion, they do influence the selectivity of the products. With the elapse of time, the conversion of dihydropyridine to the diethyl 2,6-dimethyl-4-phenylpyridine-3,5-dicarboxylate derivative occurs and completes in ca. 10 h with a distinct color change, showing the importance of the catalysts. Efforts have been made to provide suitable reaction pathways for the catalytic reaction based on spectroscopic and density functional theory studies.
- Avecilla, Fernando,Gupta, Puneet,Maurya, Mannar R.,Tomar, Reshu
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supporting information
(2020/06/08)
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- Green synthesis and characterization of novel Mn-MOFs with catalytic and antibacterial potentials
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This study focused on the synthesis of a new manganese-based metal-organic framework and the investigation of its application aspects. A Mn-MOF nanostructure, namely UoB-4, was prepared using a Schiff base organic linker (H2bbda: 4,4′-[benzene-
- Aryanejad, Sima,Bagherzade, Ghodsieh,Moudi, Maryam
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p. 1508 - 1516
(2020/02/06)
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- Ferric Sulfasalazine Sulfa Drug Complex Supported on Cobalt Ferrite Cellulose; Evaluation of Its Activity in MCRs
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Abstract: The green and nano catalyst was simply prepared through the reaction of ferric sulfasalazine with nanomaterial CoFe2O4-cellulose as a magnetic biopolymer surface. This novel heterogeneous organometallic catalyst was charact
- Rostamizadeh, Shahnaz,Daneshfar, Zahra,Khazaei, Ali
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p. 2091 - 2114
(2020/01/31)
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- Efficient one-pot synthetic methods for the preparation of 3,4-dihydropyrimidinones and 1,4-dihydropyridine derivatives using BNPs?SiO2(CH2)3NHSO3H as a ligand and metal free acidic heterogeneous nano-catalyst
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Heterocyclic compounds with biological and pharmacological activates like 3,4-dihydropyrimidin-2-(1H)-ones and 1,4-dihydropyridines have attracted great interest. Boehmite nanoparticles functionalized with silylpropyl sulfamic acid (BNPs?SiO2(C
- Bahrami, Kiumars,Khodamorady, Minoo,Sohrabnezhad, Samira
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- Green synthesis of benzimidazoloquinazolines and 1,4-dihydropyridines using magnetic cyanoguanidine-modified chitosan as an efficient heterogeneous nanocatalyst under various conditions
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Abstract: In the present study, we demonstrated the synthesis of magnetic cyanoguanidine-modified chitosan (MCGC) as an efficient and green retrievable heterogeneous nanocatalyst for one-pot three-component synthesis of benzimidazoloquinazolines (from 2-aminobenzimidazole, aromatic aldehydes, and dimedone) and 1,4-dihydropyridines (via Hantzsch-type condensation of ethyl acetoacetate, aromatic aldehydes, and ammonium acetate) under the ultrasonic irradiation and reflux conditions. The structure of the catalyst was fully confirmed using Fourier transform infrared spectroscopy, vibrating sample magnetometer, field emission scanning electron microscopy, energy dispersive spectroscopy, and thermogravimetric analysis. Increased amount of amino groups that are generated by modifying the surface of chitosan with cyanoguanidine as well as presence of hydroxyl groups determined the catalytic activity of MCGC. Furthermore, as experimental results confirmed, the ultrasonic-promoted reactions gave the better results in terms of reaction time, yield, and purity of isolated products. Cost effectiveness, mild conditions, low catalyst loading, convenient work-up, and ecofriendly solvent are some of the remarkable advantages of this protocol.
- Javanmiri, Kaveh,Karimian, Ramin
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p. 199 - 212
(2020/01/31)
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- [Fesipmim]Cl as highly efficient and reusable catalyst for solventless synthesis of dihydropyridine derivatives through Hantzsch reaction
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Abstract: In the present investigation, magnetic ferrite nanoparticles (ferrite NPs) were synthesized and coated with silica (ferrite?SiO2NPs) by using the sol-gel method. After that, silica propylmethylimidazolium chloride ionic liquid [Sipmim]Cl was prepared and linked with the above-prepared ferrite?SiO2NPs to synthesize ferrite silica propylmethylimidazolium chloride [Fesipmim]Cl catalyst. The formation of [Fesipmim]Cl catalyst was confirmed by Fourier-transform infrared (FT-IR) spectroscopy analysis. X-ray diffraction (XRD) analysis confirmed the structure of ferrite NPs and ferrite?SiO2 NPs. Transmission electron microscopy (TEM) evidenced the successful formation of ferrite NPs and ferrite?SiO2 NPs. Scanning electron microscopy (SEM) results revealed the change in morphology of ferrite NPs, ferrite?SiO2NPs and [Fesipmim]Cl. The magnetic properties of [Fesipmim]Cl catalyst were measured by vibrating sample magnetometer (VSM). The efficiency of the [Fesipmim]Cl catalyst was checked by using it for the synthesis of different derivatives of dihydropyridine through Hantzsch reaction via a three-component coupling reaction of substituted benzaldehydes, ethyl/ methyl acetoacetate and ammonium acetate. The formation and structures of all the synthesized compounds were confirmed by FT-IR, 1HNMR, 13C NMR spectral analyses. The reusability of the catalyst [Fesipmim]Cl was checked up to seven cycles and found to have excellent activity up to five cycles. Graphic abstract: [Figure not available: see fulltext.].
- Agrwal, Akansha,Kasana, Virendra
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- CoFe2O4@SiO2-NH2-CoII NPs catalyzed Hantzsch reaction as an efficient, reusable catalyst for the facile, green, one-pot synthesis of novel functionalized 1,4-dihydropyridine derivatives
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A magnetically heterogeneous CoFe2O4@SiO2-NH2-CoII nanoparticle was synthesized by the immobilization of Co (II) complex onto CoFe2O4@SiO2 nanoparticles, and the heterogeneous magnetic nanocatalyst was characterized by XRD, TEM, TGA, EDX, and FT-IR techniques. Then, the green and reusable method was introduced for a multicomponent synthesis of 1,4-dihydropyridine derivatives via Hantszch reaction. The synthesis of 1,4-dihydropyridine derivatives was proceeded by the reaction of aldehyde, ethyl acetoacetate, and ammonium acetate in the presence of this magnetic nanocatalyst in EtOH/Water (1:1). Simple work-up, short reaction times, excellent yields (60–96percent) as well as green solvent are some advantages of this novel approach, and the corresponding products were purified with no need for chromatographic separation.
- Allahresani, Ali,Mohammadpour Sangani, Mehri,Nasseri, Mohammad Ali
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- Metal free biomimetic deaminative direct C-C coupling of unprotected primary amines with active methylene compounds
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An unprecedented direct C-C coupling reaction of unprotected primary amines with active methylene compounds is reported. The reaction involves a biomimetic deamination of amines which was achieved under conditions free of metallic reagents and strong oxidizing agents. A wide range of primary amines was reacted with different active methylene compounds to provide structurally diverse trisubstituted alkenes and dihydropyridines. A kinetic study revealed an activation barrier of 10.1 kcal mol-1 for the conversion of a key intermediate of the reaction.
- Ghosh, Santanu,Jana, Chandan K.
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supporting information
p. 10153 - 10157
(2019/12/26)
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- A highly selective H/D exchange reaction of 1,4-dihydropyridines
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Herein, we report a simple, economical, and effective acid-mediated method for the in situ deuteration of Hantzsch esters and their 4-substituted derivatives, including some drugs that constitute important calcium channel blockers which are effective for
- Wang, Kaiqian,Chen, Xiaoping,Peng, Xiao,Wang, Ping,Liang, Feng
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supporting information
p. 3845 - 3852
(2019/04/26)
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- MIL-101-SO3H metal-organic framework as a Br?nsted acid catalyst in Hantzsch reaction: An efficient and sustainable methodology for one-pot synthesis of 1,4-dihydropyridine
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A straightforward and efficient methodology for the one-pot multicomponent synthesis of 1,4-dihydropyridine has been developed using MIL-101-SO3H metal-organic framework as a solid Br?nsted acid. The presence of the uniformly distributed Br?nsted acidic sulfonic acid sites throughout the framework and the high stability bestow the catalyst with excellent reactivity towards the synthesis of 1,4-dihydropyridine under simple reaction conditions using renewable ethanol as the solvent. The present methodology tolerates various functional groups and allows the synthesis of 1,4-dihydropyridine derivatives in good to excellent yields through Hantzsch reaction. The developed methodology proceeds under mild conditions, avoids corrosive reagents and special reaction conditions, and is amenable to gram scale synthesis. The sustainable nature of the catalyst was proved by the easy recovery and the reusability of the catalyst, as it was reused several times without loss in activity, which was confirmed from the FTIR, PXRD and SEM analyses of the reused catalyst.
- Devarajan, Nainamalai,Suresh, Palaniswamy
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p. 6806 - 6814
(2019/05/10)
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- The First Recyclable, Nanocrystalline CdS Thin Film Mediated Eco-benign Synthesis Of Hantzsch 1, 4 Dihyropyridines, 1, 8-Dioxodecahydroacridine and Polyhydroquinolines derivatives
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In the present study, we report a recyclable, nanocrystalline CdS thin film mediated efficient one-pot, three component synthesis of Hantzsch 1, 4 Dihydropyridine in good yields. The catalyst is also effective for the efficient synthesis of Polyhydroquinoline and 1, 8-dioxodecahydroacridine derivatives in good to excellent yields. The CdS thin film catalyst was prepared by chemical bath deposition (CBD) technique. The cadmium sulphide thin film was characterized by powder XRD and FT-IR studies. The average crystallite size (D) was calculated from powder XRD by using Scherrer formula and SEM analysis. The elemental composition of the CdS thin film was established by EDS analysis. The effect of temperature, substituent's, catalyst loading and mole ratio on the reaction was also studied. All the products were thoroughly characterized by 1H-NMR, 13C-NMR, FT-IR, Mass spectral and CHN analysis. A plausible mechanism for the CdS thin film catalyzed synthesis of 1, 4 DHP's is proposed. The heterogeneous catalyst could be easily recovered from the reaction mixture and successively reused at least five times without loss of activity.
- Lavanya,Venkatapathy,Magesh,Perumal,Sathishkumar,Amudha
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- Preparation method and application of novel ionic beta-naphthol aldehyde Schiff base zirconium complex
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The invention belongs to the technical field of catalytic organic synthesis, and particularly relates to a preparation method and application of a novel ionic beta-naphthol aldehyde Schiff base zirconium complex. Zirconium atoms are coordinated with a beta-naphthol aldehyde Schiff base ligand and water molecules, and two perfluoroalkyl (aryl) sulfonic acid groups are combined with central atom zirconium through covalent bonds and ionic bonds respectively. The preparation method comprises the following steps: dissolving beta-naphthol aldehyde Schiff base zirconium dichloride in a solvent, adding a silver salt under the protection of N2, reacting the mixture for 1-4 hours in a dark place at room temperature, performing filtration, adding n-hexane into filtrate until layering, putting the solution into a refrigerator, and freezing the solution for 24 hours to separate out the beta-naphthol aldehyde Schiff base zirconium complex. The beta-naphthol aldehyde Schiff base zirconium complex hashigh air stability and strong Lewis acidity, and can efficiently catalyze the Hantzsch reaction of aldehyde, beta-ketoester and ammonium acetate to synthesize 1,4-dihydropyridine derivatives.
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Paragraph 0041-0043; 0072-0082
(2019/12/02)
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- The efficient synthesis of Hantzsch 1,4-dihydropyridines via metal-free oxidative C–C coupling by HBr and DMSO
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A novel and efficient synthesis of Hantzsch 1,4-dihydropyridines through metal-free oxidative C–C coupling process was described. The reaction between benzylic alcohols, 1,3-dicarbonyl compounds and ammonium hydroxide in the presence of HBr in DMSO at 75 °C led to afford 1,4-dihydropyridine in excellent yields. This protocol introduces the use of benzyl alcohols instead of aldehydes as a new modification of the Hantzsch reaction.
- Rezaei, Narjes,Ranjbar, Parviz Rashidi
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p. 4102 - 4106
(2018/10/20)
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- Preparation and characterization of doped Sr.2Co.8Fe12O19 hexaferrite: An efficient heterogeneous catalyst for one pot synthesis of 1,4-dyhydropyridine derivatives
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A clean and efficient method has been developed for the synthesis of 1,4-dihydropyridine derivatives using aromatic aldehyde, ethyl acetoacetate, and ammonium acetate using cobalt doped strontium hexaferrite under microwave irradiation conditions. This pr
- Aswar,Ladole
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p. 1525 - 1530
(2020/06/27)
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- Facile template-free route to fabricate core–shell Fe3O4@PANI-SO3H urchin-like nanoparticles as reusable catalyst for Hantzsch reaction: change morphology upon sulfonation
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Abstract: This paper describes a novel and effective approach to fabricate the core–shell Fe3O4@PANI-SO3H urchin-like morphology in a self-assembly method as nano-magnetic solid acid catalyst. The Fe3O4@PANI microspheres were synthesized via an in situ surface polymerization of aniline monomer in an acidic condition, using ammonium persulfate as the oxidant. It was found that upon sulfonation of polyaniline (PANI), the morphology changes to morphology similar to urchin confirming the transmission electron microscopy and field emission scanning electron microscopy results. The as-prepared solid acid catalyst was also carefully analyzed by energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis and vibrating sample magnetometry. This new magnetic core–shell material was shown to have high catalytic performance for one–pot synthesis of 1,4-dihydropyridine derivatives. In addition, the catalyst can be easily separated using an external magnet. Recyclability and reusability for several runs, facile accessibility, and simple handling are the merits of this magnetic-heterogeneous acid catalyst. Graphical Abstract: [Figure not available: see fulltext.].
- Shahamat, Zahra,Nemati, Firouzeh,Elhampour, Ali
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p. 6649 - 6666
(2018/06/25)
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- From Zn(II) to Cu(II) framework via single-crystal to single-crystal metathesis with superior gas uptake and heterogeneous catalytic properties
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In this work, a Zn(II) framework, {[Zn2(L)4(H2O)4]·(7DMF)(7H2O)}n (1Zn), has been synthesized using a bent tetracarboxylic acid ligand (H4L). The structure of 1Zn contains [Zn2(COO)4] paddle-wheel secondary building units with axial sites occupied by water molecules. Interestingly, the isostructural Cu(II) framework {[Cu2(L)4(H2O)4]·(7DMF)(7H2O)}n (1Cu) has been obtained via single-crystal to single-crystal metathesis reaction. The activated 1Cu (denoted as a1Cu; a stands for activated) has open coordination sites. This species showed enhanced CO2 adsorption and heterogeneous catalytic properties for the Hantzsch coupling reaction involving condensation of an aldehyde with ethyl acetoacetate and ammonium acetate to produce 1,4-dihydropyridines, and three-component coupling of amines, aldehydes and alkynes to generate propargylic amines with high efficiency.
- Gupta, Mayank,De, Dinesh,Tomar, Kapil,Bharadwaj, Parimal K.
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p. 925 - 934
(2018/08/06)
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- Method for synthesizing 1,4-dihydropyridines derivatives
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The invention relates to a method for synthesizing 1,4-dihydropyridines derivatives. According to the method, a fluorescence-marked nonmetal organic boron-nitrogen lewis acid-alkali dual-functional complex is used as a catalyst, so that the pollution of heavy metals is effectively avoided; the catalyst can be recycled, and a residual amount of the catalyst in a product can be rapidly detected; and the source of raw materials is wide, the target yield is close to 100 percent, the reaction process is a homogenous reaction, and a product is obtained by virtue of chromatographic separation. The whole reaction system can be directly amplified, and the industrialization prospect is significant.
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Paragraph 0112; 0113
(2017/10/27)
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- A New Type of Magnetically-Recoverable Heteropolyacid Nanocatalyst Supported on Zirconia-Encapsulated Fe3O4 Nanoparticles as a Stable and Strong Solid Acid for Multicomponent Reactions
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Abstract: A novel highly efficient magnetically retrievable catalyst was developed by the immobilization of H3PW12O40 (20–60 wt%) on the surface of zirconia-encapsulated Fe3O4 nanoparticles. The prepared HPW supported on nano-Fe3O4@ZrO2 heterogeneous acid catalyst (or n-Fe3O4@ZrO2/HPW) was fully characterized by several physicochemical techniques such as: Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, vibrating sample magnetometry and thermogravimetric analysis. The FT-IR spectroscopic data revealed that H3PW12O40 molecules on the nano-Fe3O4@ZrO2 support existed in the Keggin structure. The acidity of the catalyst was measured by the help of a potentiometric titration with n-butylamine. It was surprising that this very strong solid acid catalyst exhibited an excellent acid strength which was as a result of possessing a higher number of surface active sites compared to its homogeneous analogues. The catalytic activity of the as-prepared novel nano-Fe3O4@ZrO2/HPW was explored through the one-pot three-component synthesis of different 3,4-dihydropyrimidin-2(1H)-ones (i.e. Biginelli reaction) and 1,4-dihydropyridines (i.e. Hantzsh reaction) under solvent free condition. The sample of 40 wt% showed higher acidity and activity in the catalytic transformation. After the reaction, the catalyst/product isolation could be easily achieved with an external magnetic field and the catalyst could be easily recycled for at least five times without any decrease in its high catalytic activity. The excellent recyclability was attributed to the strong interaction between the hydroxyl groups of the nano-Fe3O4@ZrO2 support and the HPW species. Graphical Abstract: [Figure not available: see fulltext.].
- Zolfagharinia, Somayeh,Kolvari, Eskandar,Koukabi, Nadiya
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p. 1551 - 1566
(2017/05/17)
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- Highly effective Br?nsted base/lewis acid cooperative catalysis: A new Cd metal-organic framework for the synthesis of Hantzsch 1,4-DHPs at ambient temperature
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A new 3D metal-organic framework {[Cd3(BDC)3(OPP)(DMF)2]·2DMA}n (TMU-33) has been synthesized using a novel V-shaped imine-functionalized ligand, N,N′-(oxybis(4,1-phenylene))bis(1-(pyridin-4-yl)methanimine) (OPP), terephthalic acid (H2BDC), and Cd(NO3)2·4H2O and has been fully characterized. The function of the imine moiety of the OPP ligand as a Br?nsted base and open Cd site as a Lewis acid in this framework was investigated to determine the role of the cooperative catalyst in the synthesis of Hantzsch 1,4-dihydropyridines simultaneously and separately at ambient temperature. In addition, nanorods and nanoplates of TMU-33 were synthesized via a sonochemical reaction by the coordination modulation method, and the effect of the nanostructure on the relative accessibility of the catalytic site was studied. Moreover, the catalytic performance of TMU-33 with different morphologies was evaluated in this reaction. Efficient catalytic activity was observed for the nanoscale catalysts at ambient temperature, and the acidic sites in the cooperative catalyst were found to be more effective than the existing basic sites in the structure. TMU-33 can be reused by washing with ethanol at least four times with no significant degradation of the catalytic activity (less than 7%).
- Rouhani, Farzaneh,Morsali, Ali
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p. 15475 - 15484
(2017/12/15)
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- Sulfated polyborate: An efficient and reusable catalyst for one pot synthesis of Hantzsch 1,4-dihydropyridines derivatives using ammonium carbonate under solvent free conditions
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A simple and efficient method for the synthesis of four-component 1,4-dihydropyridines of various aldehydes, β-ketoesters and ammonium carbonate catalyzed by sulfated polyborate with high yields under a solvent free condition at 90?°C is described. The key advantages of the present method are high yields, short reaction time, solvent free condition, easy workup, recyclability of catalyst and ability to tolerate a variety of functional groups which gives economical as well as ecological rewards.
- Rekunge, Deelip S.,Khatri, Chetan K.,Chaturbhuj, Ganesh U.
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supporting information
p. 1240 - 1244
(2017/03/02)
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- An efficient and recyclable 3D printed α-Al2O3 catalyst for the multicomponent assembly of bioactive heterocycles
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A catalytic methodology is reported that enables the efficient, operationally simple and environmentally friendly synthesis of diverse 1,4-dihydropyridines and 3,4-dihydropyrimidin-2(1H)-ones, including some relevant drugs and pharmacologically active derivatives. This strategy is based on the use of a 3D printed Al2O3 woodpile material that was sintered to generate a rigid structure with controlled porosity and noteworthy catalytic performance. The 3D printed Al2O3 catalyst exhibits remarkable efficacy as a Lewis acid in Biginelli and Hantzsch reactions and it can be recovered and reused ten times without any decrease in the activity. Remarkable E factors, excellent recyclability and scalability, broad substrate scope, short reaction times, excellent yields, solvent-free conditions and easy isolation procedures are key features of this methodology.
- Azuaje, Jhonny,Tubío, Carmen R.,Escalante, Luz,Gómez, Mónica,Guitián, Francisco,Coelho, Alberto,Caama?o, Olga,Gil, Alvaro,Sotelo, Eddy
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p. 203 - 210
(2016/12/09)
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- A new magnetically recoverable catalyst promoting the synthesis of 1,4-dihydropyridine and polyhydroquinoline derivatives via the Hantzsch condensation under solvent-free conditions
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In the current study, 1,4-dihydropyridine and polyhydroquinoline derivatives were efficiently synthesized under solvent-less conditions with a magnetic catalyst containing novel acidic ionic liquid functionalized silica modified Fe3O4 nanoparticles through a four component combination of β-ketoester, aldehydes and ammonium acetate (1, 2, 2). Several approaches have been reported for synthesizing these derivatives, while each of these approaches have some weaknesses including long time of reaction, excess of volatile organic solvent, low efficiency, costly reagents, complex operation, high temperatures, production of a number of side products, and difficult catalyst recovery. The simple operation, short time of reaction (5–30?min) and the high efficiency (80–94%) are the special advantages of this technique. The immobilized catalyst exhibited an appropriate thermal stability and excellent recyclability. Different methods such as FT-IR, SEM, EDX, TGA-DTA, and VSM were used to confirm and characterize the catalyst.
- Taheri, Narges,Heidarizadeh, Fariba,Kiasat, Alireza
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p. 481 - 487
(2017/01/12)
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- Fe3O4@SiO2 supported aza-crown ether complex cation ionic liquids: preparation and applications in organic reactions
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A series of aza-crown ether ionic liquids supported on magnetic Fe3O4@SiO2 core-shell particles were designed, synthesized and characterized by elemental analysis, TEM, TG and FT-IR. These new aza-crown ether complex cation ionic liquids were utilized as heterogeneous acidic catalysts in Friedel-Crafts alkylation and Hantzsch reaction in good yields under convenient reaction conditions. Moreover, these magnetic particle supported IL catalysts could be readily recovered by an external magnet and reused five times without obvious loss of activity.
- Li, Dandan,Wang, Jinyuan,Chen, Fengjuan,Jing, Huanwang
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p. 4237 - 4242
(2017/02/05)
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- Computational investigations on structural and electronic properties of CuI nanoparticles immobilized on modified poly(styrene-co-maleic anhydride), leading to an unexpected but efficient catalyzed synthesis of 1,4-dihydropyridine via Hantzsch pyridine synthesis
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A, quantitative description for the interaction of Cu(I) with poly(styrene-co-maleic anhydride) modified with 4-aminopyridine (denoted as CuI/SMI complex) is presented using density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) approaches. Topological analysis of electron density revealed the existence of effective interactions between Cu(I) ions and the nitrogen in the pyridine ring. Interestingly, the results also showed that there is considerable interaction between Cu(I) and the oxygen of the carbonyl motif in the SMI ligand. Thus, CuI/SMI was examined as a heterogeneous and recyclable catalyst in Hantzsch pyridine synthesis under solvent-free conditions, affording diverse 1,4-dihydropyridines (1,4-DHPs) in excellent yields with relatively short reaction times.
- Heravi, Majid M.,Hosseinnejad, Tayebeh,Nazari, Niousha
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p. 530 - 536
(2017/05/31)
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- Aqua-mediated one-pot synthesis of Biginelli dihydropyrimidinone/thiones (DHPMs), Hantzsch dihydropyridines (DHPs), and polysubstituted pyridines sonocatalyzed by metal-supported nanocatalysts
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In this work, catalyst composition-activity relationship of supported catalysts in Biginelli and Hantzsch reactions was investigated under mild conditions. Biginelli dihydropyrimidinone/thiones were prepared over Fe-Cu/ZSM-5 as an efficient, convenient, and environmentally benign catalyst under ultrasonic irradiation in aqueous media in very good yields. The Fe-Cu/ZSM-5-catalyzed synthesis of 1,4-dihydropyridines and their aromatization to polysubstituted pyridines and also a new one-pot, two-step, and sequential protocol for the synthesis of pyridine derivatives, employing an aldehyde, ethyl acetoacetate, and ammonium acetate under the same green experimental conditions were illustrated. Three-component condensation in the presence of supported reagent with operational simplicity, inexpensive reagents, short reaction time, high yield of products, and use of non-toxic reagents makes this synthetic protocol an attractive one.
- Safa, Kazem D.,Esmaili, Maryam,Allahvirdinesbat, Maryam
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p. 267 - 277
(2016/01/09)
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- Synthesis and characterization of Ni(II)-Vanillin-Schiff base-MCM-41 composite as an efficient and reusable nanocatalyst for multicomponent reactions
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An efficient heterogeneous catalyst (Ni(ii)-Vanillin-Schiff base-MCM-41) has been synthesized by immobilization of nickel(ii)-vanillin complex on MCM-41 nanostructure and characterized by XRD, TGA, BET, EDS, SEM, ICP-OES, TEM and FT-IR spectroscopy. The catalytic activity and stability of the prepared compound has been studied in some multicomponent reactions with polyhydroquinoline, 1H-indazolo[1,2-b]phthalazine-trione and 2,3-dihydroquinazolin-4(1H)-one derivatives under mild condition reactions. All the reactions were carried out in the presence of water as the solvent and under solvent-free conditions. The simple work up, mild conditions, excellent yield, inexpensive and non-toxic catalyst; makes this protocol both attractive and economically viable. More importantly, this catalyst can be reused several times without any significant loss of its catalytic activity.
- Nikoorazm, Mohsen,Ghorbani-Choghamarani, Arash,Khanmoradi, Maryam
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p. 56549 - 56561
(2016/07/06)
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- A Simple and Efficient One-pot Synthesis of 1,4-dihydropyridines Using Nano-WO3-supported Sulfonic Acid as an Heterogeneous Catalyst under Solvent-free Conditions
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Nano-tungsten trioxide-supported sulfonic acid (n-WSA) was found to be an effective heterogeneous catalyst for the one-pot reaction of aromatic aldehydes, β-dicarbonyl compounds and ammonium acetate to afford 1,4-dihydropyridine derivatives in good to excellent yields. The other main advantages of the present method are short reaction times, simple workup, ease in purification and environmentally benign methodology. The reaction conditions were optimized employing Response Surface Method technique (Central Composite Design (CCD)) which is economically considerable because of the minimum number of experiments required to evaluate the effects of multiple parameters on the response.
- Bitaraf, Mehrnoosh,Amoozadeh, Ali,Otokesh, Somayeh
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p. 336 - 344
(2016/05/09)
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- Novel Magnetically Separable Sulfated Boric Acid Functionalized Nanoparticles for Hantzsch Ester Synthesis
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A novel, separable, solid-acid catalyst consisting of sulfated boric acid nanoparticles immobilized on a silica-coated magnetite support was prepared. This catalyst permits the preparation of dihydropyridine derivatives (Hantzsch esters) by condensation of an aldehyde with two equivalents of a β-keto ester in the presence of ammonium acetate. The catalyst can be recovered and recycled.
- Azizi, Kobra,Azarnia, Jamshid,Karimi, Meghdad,Yazdani, Elahe,Heydari, Akbar
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p. 1810 - 1813
(2016/07/16)
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- Heterogeneous bimetallic ZnFe2O4nanopowder catalyzed synthesis of Hantzsch 1,4-dihydropyridines in water
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The mixed metal oxide ZnFe2O4nanopowder, a dual Lewis acid–base combined catalyst is found to efficiently catalyze a multicomponent synthesis of 1,4-dihydropyridines from aldehydes, ethyl acetoacetate, and ammonium acetate in water. This procedure offers several advantages including high yields, short reaction times, a simple work-up procedure, and a benign eco-footprint. This method takes advantage of the fact that water, a green solvent is used in combination with ZnFe2O4nanoparticles as catalyst which can be easily recovered magnetically and reused for further runs.
- Ravikumar Naik,Shivashankar
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supporting information
p. 4046 - 4049
(2016/08/18)
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- Synthesis of hantzsch 1,4-dihydropyridines in a continuous flow microreactor
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A simple and efficient synthesis of Hantzsch 1,4-dihydropyridines from the condensation of benzaldehydes with alkyl acetoacetates/benzoylacetate and aqueous ammonia in the absence of catalyst has been developed by using a continuous flow microreactor. Under optimized condition, various 1,4-dihydropyridines were obtained in 80-93% yield with high atom efficiency. Compared with using batch system, the present smooth procedure greatly accelerated the reaction due to the excellent mixing and mass transfer of reactant in micro flow system.
- Gao, Peiyuan,Sun, Xuan,Lei, Ming,Zhang, Hong
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p. 755 - 761
(2017/04/10)
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- 2-Hydroxyethylammonium acetate: An efficient and reusable homogeneous catalyst for the synthesis of Hantzsch 1, 4-dihydropyridines
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2-Hydroxyethylammonium acetate ionic liquid was found to be an excellent catalyst for the one-pot synthesis of 1,4-dihydropyridine derivatives via Hantzsch reaction of ethyl acetoacetate or acetoacetanilide, ammonium acetate, and various aromatic aldehyde
- Kang, Li-Qin,Cao, Zhi-Jun,Lei, Ze-Jun
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p. 1125 - 1128
(2016/09/09)
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- Tetraethylammonium 2-(carbamoyl)benzoate as a bifunctional organocatalyst for one-pot synthesis of Hantzsch 1,4-dihydropyridine and polyhydroquinoline derivatives
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Abstract: A green, convenient, and environment-friendly approach for the synthesis of biologically active Hantzsch 1,4-dihydropyridine and polyhydroquinoline derivatives in the presence of tetraethylammonium 2-(carbamoyl)benzoate, as an effective bifunctional metal-free catalyst, has been developed via a one-pot multicomponent reaction of various aldehydes, ethyl acetoacetate or cyclic 1,3-dicarbonyl compounds, and ammonium acetate in EtOH under reflux conditions. The proposed methodology is capable of providing the desired products in good to excellent yields and short reaction time with straightforward work-up and a low-cost procedure. Graphical abstract: [Figure not available: see fulltext.]
- Yarhosseini, Mahsa,Javanshir, Shahrzad,Dekamin, Mohammad G.,Farhadnia, Mohammad
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p. 1779 - 1787
(2016/09/28)
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- USE OF COMPOSITIONS OBTAINED BY CALCINING PARTICULAR METAL-ACCUMULATING PLANTS FOR IMPLEMENTING CATALYTICAL REACTIONS
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The use of metal-accumulating plants for implementing chemical reactions especially catalytical reactions.
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Paragraph 0849-0850
(2016/01/25)
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- Synthesis of diethyl 4-substituted-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylates as a new series of inhibitors against yeast α-glucosidase
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1,4-Dihydropyridine-3,5-dicarboxylate derivatives (1-25) were synthesized in high yields via Hantzsch reaction and evaluated for their α-glucosidase inhibitory activity. Compounds 1, 2, 6-8, 11, 13-15, and 23-25 showed a potent inhibitory activity against yeast α-glucosidase with IC50 values in the range of 35.0-273.7 μM, when compared with the standard drug acarbose (IC50 = 937 ± 1.60 μM). Their structures were characterized by different spectroscopic techniques. The kinetics, selectivity, and toxicity studies on these compounds were also carried out. The kinetic studies on most active compounds 14 and 25 determined their modes of inhibition and dissociation constants Ki. Compound 14 was found to be a non-competitive inhibitor with Ki = 25.0 ± 0.06, while compound 25 was identified as a competitive inhibitor with Ki = 66.0 ± 0.07 μM.
- Niaz, Huma,Kashtoh, Hamdy,Khan, Jalaluddin A. J.,Khan, Ajmal,Wahab, Atia-Tul,Alam, Muhammad Tanveer,Khan, Khalid Mohammed,Perveen, Shahnaz,Choudhary, M. Iqbal
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p. 199 - 209
(2015/04/14)
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- Silica functionalized sulphonic acid coated with ionic liquid: An efficient and recyclable heterogeneous catalyst for the one-pot synthesis of 1,4-dihydropyridines under solvent-free conditions
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Silica-supported sulphonic acid catalysts were prepared and coated with ionic liquid, and their catalytic activities were evaluated for the one-pot synthesis of 1,4-dihydropyridines. Different catalysts with an ionic liquid layer (SCILLs) have been prepared with a view to determine the most active catalyst. Silica sulphonic acid coated with [BMIM][PF6] was found to be the most active catalyst and can be recycled for several runs without the loss of significant activity. It was characterized using SEM, TEM, TGA and FTIR.
- Sharma, Pankaj,Gupta, Monika
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p. 1100 - 1106
(2015/03/04)
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- Urease: A highly biocompatible catalyst for switchable Biginelli reaction and synthesis of 1,4-dihydropyridines from the in situ formed ammonia
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Urease is a superior biocompatible catalyst for switching from the Biginelli reaction to urea-based synthesis of 1,4-dihydropyridines in water, where 100% switching occurs at 0.02 g/mL of enzyme. Hantzsch reaction with ammonium acetate (NH4OAc) is inefficiently catalyzed by urease (70%, 4 h), and heavy metal ions inhibit the urease-catalyzed reactions with urea or NH4OAc. Promotion of the urea-based Hantzsch reaction by urease and its inhibition with Hg2 + supports specificity of urease for in situ generation of ammonia, whereas the role of urease in further transformations is not so specific. The features of this enzymatic method are reusability, mild reaction conditions, biocompatibility, generality, and high yield of products.
- Tamaddon, Fatemeh,Ghazi, Somayeh
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- Cu-doped ZnO nanocrystalline powder as a catalyst for green and convenient multi-component synthesis of 1,4-dihydropyridine
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Abstract A simple, efficient, and convenient one-step method for synthesis of Hantzsch 1,4-dihydropyridine, using Cu-doped ZnO nanocrystalline powder as a catalyst is reported. The method offers several advantages including excellent yields, green solvent, easy work-up, simplicity in operation and catalyst reusability.
- Alinezhad, Heshmatollah,Mohseni Tavakkoli, Sahar
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p. 5931 - 5940
(2015/08/18)
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- Ultrasound-mediated, uranyl nitrate hexahydrate-catalyzed synthesis of 1,4-dihydropyridines under mild conditions
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Abstract Synthesis of 1,4-dihydropyridines by three-component condensation reaction of aldehyde, 1,3-dicarbonyl compounds, and ammonium acetate have been found to be efficiently catalyzed by uranyl nitrate hexahydrate [UO2(NO3)2 ·6H2O] at room temperature under ultrasound irradiation. This novel synthetic method offers the advantages of high yields, short reaction times, simplicity, and easy workup compared to the conventional methods reported in the literature.
- Palakshi Reddy,Sarveswari,Vijayakumar
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p. 6877 - 6883
(2015/08/18)
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