- A rapid and green synthetic approach for hierarchically assembled porous ZnO nanoflakes with enhanced catalytic activity
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Three dimensionally (3D) assembled hierarchical porous ZnO structures are of key importance for their applications in sensors, lithium-ion batteries, solar cells and in catalysis. Here, the controlled synthesis of 3D hierarchically porous ZnO architectures constructed of two dimensional (2D) nano-sheets through the calcination of a hydrozincite [Zn5(CO 3)2(OH)6] intermediate is presented. The intermediate 3D hierarchical hydrozincite has been synthesized by a novel organic surfactant and solvent free aqueous protocol at room temperature using an aqueous solution of ammonium carbonate and laboratory grade bulk ZnO in a short time (20-30 min). The amount of carbonate and the reaction temperature play a crucial role in the formation of the 3D hierarchical morphology and on the basis of the experimental results a probable reaction mechanism is proposed. On calcination, the synthesized 3D hierarchical hydrozincite resulted in ZnO with an almost identical morphology to the parental hydrozincite. On decomposition a porous structure having a surface area of 44 m2 g-1 is obtained. The synthesized hierarchical ZnO morphology exhibits an improved catalytic activity for the synthesis of 5-substituted-1H-tetrazoles with different nitriles and sodium azide than that of nanocrystalline ZnO and bulk ZnO, as well as other developed solid catalysts. The catalyst is easily recyclable without a significant loss in catalytic activity. The Royal Society of Chemistry 2012.
- Sinhamahapatra, Apurba,Giri, Arnab Kanti,Pal, Provas,Pahari, Sandip Kumar,Bajaj, Hari C.,Panda, Asit Baran
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- 1-Disulfo-[2,2-bipyridine]-1,1-diium chloride ionic liquid as an efficient catalyst for the green synthesis of 5-substituted 1H-tetrazoles
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A simple, green and efficient method has been developed for the synthesis of 5-substituted 1H-tetrazole derivatives through [2+3] cycloaddition reaction in good to excellent yields between various benzonitriles and sodium azide. For this purpose, 1-disulfo-[2,2-bipyridine]-1,1-diium chloride ([BiPy](HSO3)2Cl2) system as an ionic liquid catalyst have been extended for the construction of these valuable products. This procedure has significant advantages, including using ethylene glycol as a green solvent. The other advantages of this method are inexpensive and ease the preparation of the catalyst, mild reaction conditions, green reaction medium, easy workup, short reaction time, and simple experimental process.
- Aali, Elaheh,Gholizadeh, Mostafa,Noroozi-Shad, Nazanin
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- Practical synthesis of tetrazoles from amides and phosphorazidates in the presence of aromatic bases
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Tetrazoles were effectively synthesized from amides using diphenyl phosphorazidate or bis(p-nitrophenyl) phosphorazidate in the presence of aromatic bases. Various amides underwent the proposed cycloaddition reaction to provide the corresponding tetrazoles. Studies on the racemization of chiral substrates were also performed. Overall, the proposed synthesis method enables the preparation of 1,5-disubstituted and 1-substituted tetrazoles, and 5-substituted 1H-tetrazoles without using toxic or explosive reagents.
- Ishihara, Kotaro,Ishihara, Kazuki,Tanaka, Yota,Shioiri, Takayuki,Matsugi, Masato
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supporting information
(2022/02/02)
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- Fe3O4@L-lysine-Pd(0) organic–inorganic hybrid: As a novel heterogeneous magnetic nanocatalyst for chemo and homoselective [2 + 3] cycloaddition synthesis of 5-substituted 1H-tetrazoles
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An efficient and sustainable synthetic protocol has been presented to synthesis and 5-substituted 1H-tetrazole privileged heterocyclic substructures. The synthetic protocol involves two-component reaction between aryl nitriles and NaN3 in water using complex of L-lysine-palladium nanoparticles (NPs) modified Fe3O4 nanoparticles as magnetically separable, recyclable, and reusable heterogeneous catalyst. Magnetically retrievable L-lysine-Pd(0) modified Fe3O4 nanoparticles were applied in [2 + 3] cycloaddition synthesis of 5-substituted 1H-tetrazoles. The advantages of this strategy include easy recovery and efficient reusability of the expensive Pd NPs, obtaining high yields of [2 + 3] cycloaddition, short reaction times, and all of the reported synthetic strategies are being performed in water as green solvent for a wide range of substrates.
- Ashraf, Muhammad Aqeel,Liu, Zhenling,Li, Cheng,Zhang, Dangquan
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- Sustainable and recyclable magnetic nanocatalyst of 1,10-phenanthroline Pd(0) complex in green synthesis of biaryls and tetrazoles using arylboronic acids as versatile substrates
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A magnetic nanocatalyst was purveyed as a heterogeneous recoverable palladium-based catalyst anchored on green, sustainable and phosphine free support. Resulted Fe3O4@SiO2-Phen-Pd(0) nanocatalyst bearing powerful phenanthroline ligand was thoroughly characterized by physicochemical approaches like UV–vis, FT-IR, EDX, XRD, TGA, ICP, VSM, DLS, FESEM, and TEM analyses. After finding trustable data, the obtained magnetic catalyst was considered to be applied in the Suzuki-Miyaura type C-C couplings and getting corresponding tetrazoles using arylboronic acid derivatives as alternate precursors of aromatic halides and stupendous data were observed.
- Bagherzadeh, Nastaran,Sardarian, Ali Reza,Eslahi, Hassan
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- Magnetic nitrogen-doped carbon derived from silk cocoon biomass: a promising and sustainable support for copper
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In this study, a magnetic nitrogen-doped carbon-based copper (MNC-Cu) catalyst was fabricated so that natural silk cocoons undergo thermal processes and then activate by combining with Fe3O4 MNPs as a suitable substrate for placement copper metal. The efficiency of the generated catalyst in the synthesis of 5-substituted 1H-tetrazole derivatives was evaluated by the [3 + 2] cycloaddition reaction of aromatic aldehydes, azide ions, and hydroxylamines. FT-IR, FE-SEM, EDS, TEM, XRD, TGA, and VSM techniques have been adopted to identify and validate this heterogeneous catalyst. The observation from EDS, elemental mapping, XRD, and FT-IR analysis confirms the immobilization of Cu metals on the MNC surface and uniform distribution of species and then no aggregation occurs during functionalization. VSM results show the magnetic feature of fabricated catalyst, and based on the leaching test, the amount of catalyst leaching was negligible. Moreover, this reaction is a one-pot multicomponent reaction (MCRs) or more precisely a one-pot, three-component reaction, which is one of the advantages of this work. The fabricated catalyst shows high efficiency, good stability, and considerable reactivity in synthesizing 5-substituted 1H-tetrazole derivatives. So it can be seen that the fabricated magnetic catalyst is a useful and practical catalyst for synthesizing [3 + 2] cycloaddition reactions. Reusability and recyclability for five sequential runs without notable increase and reduction in activity are other advantages. In addition, the magnetic properties of this heterogeneous catalyst led to easy and quickly recovered and striking copper leaching. Graphical abstract: [Figure not available: see fulltext.]
- Akbarzadeh, Parisa,Koukabi, Nadiya,Tahmasbi, Marzieh
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- Guanidine complex of copper supported on boehmite nanoparticles as practical, recyclable, chemo and homoselective organic–inorganic hybrid nanocatalyst for organic reactions
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Boehmite (BO) nanoparticles (NPs) were prepared via the injection of aqueous NaOH solution to aqueous aluminum nitrate solution at room temperature. Afterwards, a new complex of copper was immobilized on BO-NPs (Cu-Guanidine@BO-NPs). This heterogeneous nanocatalyst was used as a practical, recyclable, chemo and homoselective nanocatalyst in the organic processes, i.e. the preparation of tetrazole five-membered heterocycles and chemoselective sulfoxidation of sulfides using H2O2 as oxidant. In this sense, the prepared nanocatalyst was characterized by AAS, N2 adsorption–desorption isotherms, WDX, EDS, SEM, and TGA techniques. The reusability of this catalyst was investigated in the described organic reactions for several runs without notable loss of its catalytic activity. Moreover, all of the tetrazole and sulfoxide derivatives were isolated in high Turn Over Number (TON) and Turn Over Frequency (TOF) numbers indicating the high activity and selectivity of Cu-Guanidine@BO-NPs in the described reactions.
- Jafari, Fariba,Ghorbani-Choghamarani, Arash,Hasanzadeh, Neda
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- A robust and recyclable ionic liquid-supported copper(II) catalyst for the synthesis of 5-substituted-1H-tetrazoles using microwave irradiation
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Abstract: A novel and robust ionic liquid-supported copper(II) catalyst has been developed and explored for the efficient synthesis of 5-substituted-1H-tetrazoles using microwave irradiation. The ionic liquid-supported catalyst facilitated the efficient isolation of tetrazole products with high purity by simple extraction with organic solvent. Recovered ionic liquid-supported copper(II) catalyst could be recycled for three times for the synthesis of tetrazole products with high purity. This synthetic protocol offers a very clean, convenient, and microwave-assisted environment-friendly method for the efficient synthesis of 5-substituted-1H-tetrazoles with high yield. Graphic abstract: [Figure not available: see fulltext.].
- Padmaja,Chanda, Kaushik
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p. 1307 - 1317
(2019/11/14)
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- Novel Hybrid Thioamide Ligand Supported Copper Nanoparticles on SBA-15: A Copper Rich Robust Nanoreactor for Green Synthesis of Triazoles and Tetrazoles in Water Medium
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Abstract: In this work, a new thioamide based ligand with reductive nature was designed for modification of mesoporous SBA-15. For this purpose, the channels of SBA-15 were modified with Tris(2-aminoethyl)amine (TAEA) groups and then reacted with S8 and phenyl acetylene to form thioamide groups via Willgerodt-Kindler reaction. This porous material proved to be an effective host for the immobilization of inexpensive Cu(II) ions. The catalytically active Cu(I) species were generated automatically due to the reductive nature of thioamide modified surface of catalyst without use of any toxic reducing agents. The well stabilized Cu(I) species into the nano-channels of SBA-15 were used for synthesis of various triazoles from sodium azide, phenyl acetylene and alkyl/benzyl halides or alkyl epoxides and various tetrazoles from sodium azide and aryl/alkyl nitriles under green mild aqueous reaction conditions. This catalytic system was used for 9 and 11 consecutive runs for synthesis of triazoles and tetrazoles, respectively. Graphic Abstract: [Figure not available: see fulltext.]
- Pourhassan, Fatemeh,Eshghi, Hossein
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p. 1287 - 1300
(2019/11/21)
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- Palladium fabricated on boehmite as an organic-inorganic hybrid nanocatalyst for C-C cross coupling and homoselective cycloaddition reactions
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Herein, boehmite nanoparticles were prepared using an aqueous solution of NaOH and Al(NO3)3?9H2O at room temperature. After modification of the boehmite nanoparticle (BNP) surface by 3-choloropropyltrimtoxysilane (CPTMS), adenine was anchored on the surface. Finally, a complex of palladium was fabricated on the BNP surface (Pd-adenine@boehmite). The obtained nanoparticles were identified by TGA, FT-IR, BET, EDS, WDX, SEM, XRD and AAS techniques. In continuation, the Pd-adenine@boehmite was employed as an efficient, reusable and organic-inorganic hybrid catalyst in the C-C cross coupling reactions without a phosphine ligand or an inert atmosphere. Moreover, the homoselective synthesis of tetrazoles was studied in the presence of Pd-adenine@boehmite as a heterogeneous and practical nanocatalyst which can be recovered and reused in the described organic reactions. Besides, organic products which were isolated in suitable TOF and TON numbers in the presence of Pd-adenine@boehmite as a catalyst revealed the practicality of this catalyst. The heterogeneous nature of this catalyst was confirmed by TEM, EDS, WDX, AAS, and FT-IR techniques and, then, compared to the fresh catalyst.
- Tahmasbi, Bahman,Ghorbani-Choghamarani, Arash,Moradi, Parisa
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p. 3717 - 3727
(2020/03/17)
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- Synthesis of 5-Substituted 1 H-Tetrazoles from Nitriles by Continuous Flow: Application to the Synthesis of Valsartan
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An efficient continuous flow process for the synthesis of 5-substituted 1H-tetrazoles is described. The process involves the reaction between a polymer-supported triorganotin azide and organic nitriles. The polymer-supported organotin azide, which is in situ generated with a polystyrene-supported triorganotin alkoxide and trimethylsilylazide, is immobilized in a packed bed reactor. This approach is simple, fast (it takes from 7.5 to 15 min), and guarantees a low concentration of tin residues in the products (5 ppm). The process was developed to aryl-, heteroaryl-, and also alkylnitriles and was applied for the synthesis of valsartan, an angiotensin II receptor antagonist.
- Carpentier, Florian,Felpin, Fran?ois-Xavier,Zammattio, Fran?oise,Le Grognec, Erwan
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p. 752 - 761
(2020/03/13)
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- Copper coordinated-poly(α-amino acid) decorated on magnetite graphene oxide as an efficient heterogeneous magnetically recoverable catalyst for the selective synthesis of 5- and 1-substituted tetrazoles from various sources: A comparative study
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In this work, poly(α-amino acid)-Cu(II) complex immobilized on magnetite graphene oxide (GO/Fe3O4?PAA-Cu-complex) was prepared via a multistep synthesis and employed as an efficient, heterogeneous, magnetically recyclable nanocatalyst for one-pot, three component synthesis of 5- and 1-substituted tetrazoles using different substrates including benzaldehydes, benzonitriles, and anilines in mild conditions. The different approaches were mechanically investigated and compared. The catalyst was fully characterized by Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), energy dispersive X-ray spectroscopy (EDX), inductively coupled plasma (ICP), FE-SEM and TEM analyses. The magnetic nanocatalyst could be readily separated from the reaction mixture by an external magnet and reused for several times without significant loss of catalytic activity. Also, the spectroscopic analysis revealed the stability and durability of the catalyst. Finally, the chemoselectivity of the method was investigated by the various combinations of aldehyde, nitrile, and oxime.
- Kazemnejadi, Milad,Mahmoudi, Boshra,Sharafi, Zeinab,Nasseri, Mohammad A.,Allahresani, Ali,Esmaeilpour, Mohsen
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- Ordered mesoporous SBA-15 functionalized with yttrium(III) and cerium(III) complexes: Towards active heterogeneous catalysts for oxidation of sulfides and preparation of 5-substituted 1H-tetrazoles
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Mesoporous SBA-15 was synthesized and modified with 3-chloropropyltrimethoxysilane and then used in immobilization of creatinine groups, which were employed to introduce Y3+ and Ce3+ to give rise to two novel yttrium and cerium catalysts: SBA-15@Creatinine@M (M?=?Y and Ce). The structures of the SBA-15@Creatinine@M catalysts were determined using various techniques. These catalysts offered outstanding catalytic performances in the oxidation of sulfides to sulfoxides and in the preparation of 5-substituted 1H-tetrazoles. An important characteristic of the SBA-15@Creatinine@M catalysts is that they are very stable without a considerable decrease in their catalytic performance lasting seven cycles.
- Molaei, Somayeh,Tamoradi, Taiebeh,Ghadermazi, Mohammad,Ghorbani-Choghamarani, Arash
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- Immobilization of cerium (IV) and erbium (III) in mesoporous MCM-41: Two novel and highly active heterogeneous catalysts for the synthesis of 5-substituted tetrazoles, and chemo- and homoselective oxidation of sulfides
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Two well-ordered 2D-hexagonal cerium (IV) and erbium (III) embedded functionalized mesoporous MCM-41(MCM-41@Serine/Ce and MCM-41@Serine/Er) have been developed via functionalization of mesoporous MCM-41. The surface modification method has been used in the preparation of serine-grafted MCM-41 and led to the development of MCM-41@Serine. The reaction of MCM-41@Serine with Ce (NH4)2(NO3)6·2H2O or ErCl3·6H2O in ethanol under reflux led to the organization of MCM-41@Serine/Ce and MCM-41@Serine/Er catalysts. The structures of these catalysts were determined using scanning electron microscopy, mapping, energy-dispersive X-ray spectroscopy, Fourier transform-infrared, thermogravimetric analysis, X-ray diffraction, inductively coupled plasma, and Brunauer–Emmett–Teller analysis. These MCM-41@Serine/Ce and MCM-41@Serine/Er catalysts show outstanding catalytic performance in sulfides oxidation and synthesis of 5-substituted tetrazoles. These catalysts can be recycled for seven repeated reaction runs without showing a considerable decrease in catalytic performance.
- Molaei, Somayeh,Ghadermazi, Mohammad
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- Lithiation Substitution of Unprotected Benzyltetrazoles
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1H-Tetrazoles occupy an important role in modern medicinal chemistry, but few methods for their modification exist. Many extant protocols require the use of a difficult to remove N-alkyl-protecting group, precluding the products from use as carboxylate bioisosteres, the major role of tetrazoles in pharmaceuticals. We herein report a convenient, protecting-group-free lithiation-substitution protocol for benzylic tetrazoles. Metalation with n-BuLi at 0 °C followed by electrophilic trapping gave a range of α-functionalized benzyltetrazoles in up to 91% yield.
- Wong, Jeff Y. F.,Lewandowska, Agnieszka,Trowse, Benjamin R.,Barker, Graeme
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supporting information
p. 7069 - 7072
(2019/09/30)
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- Iron (III)-porphyrin Complex FeTSPP as an efficient catalyst for synthesis of tetrazole derivatives via [2?+?3]cycloaddition reaction in aqueous medium
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The metal complex (5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin-iron (III) chloride (FeTSPP) was new employed in an environmentally benign protocol as an efficient catalyst for a “click” chemistry approach for the synthesis of tetrazole and guanindinyltetrazole derivatives via [2?+?3] cycloaddition reaction of nitriles and azide derivatives in aqueous medium. The synthesized compounds were obtained in excellent yield, short reaction times and a recoverable catalyst.
- El-Remaily, Mahmoud Abd El Aleem Ali Ali,Elhady
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- Synthesis of α-Aminonitriles and 5-Substituted 1H-Tetrazoles Using an Efficient Nanocatalyst of Fe3O4@SiO2–APTES-supported Trifluoroacetic Acid
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Fe3O4@SiO2–APTES-supported trifluoroacetic acid nanocatalyst was used for the one-pot synthesis of α-aminonitriles via a three-component reaction of aldehydes (or ketones), amines, and sodium cyanide. This method produced a high yield of 75–96% using only a small amount of the catalyst (0.05?g) in EtOH at room temperature. The catalyst was also employed for the synthesis of 5-substituted 1H-tetrazoles from nitriles and sodium azide in EtOH at 80°C. The tetrazoles were produced with good-to-excellent yields in a short reaction time of 4?h. Both synthetic methods were carried out in the absence of an organic volatile solvent. Because the supported trifluoroacetic acid generated a solid acid on the surface, thus the acid corrosiveness was not a serious challenge. This heterogeneous nanocatalyst was magnetically recovered and reused several times without significant loss of catalytic activity.
- Fatahi, Hosna,Jafarzadeh, Mohammad,Pourmanouchehri, Zahra
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p. 2090 - 2098
(2019/07/05)
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- Tin-Catalyzed Synthesis of 5-Substituted 1H-Tetrazoles from Nitriles: Homogeneous and Heterogeneous Procedures
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The preparation of 5-substituted 1H-tetrazoles was efficiently achieved by reaction of trimethylsilylazide with nitriles using a triorganotin alkoxide precatalyst. The reaction mechanism was first investigated using a homogeneous tributyltin derivative and was explored through experimental investigations and DFT calculations. A heterogeneous version was then developed using a polymer-supported organotin alkoxide and afforded an efficient method for the preparation of tetrazoles in high yields with an easy work-up and a residual tin concentration in the desired products compatible for pharmaceutical applications (less than 10 ppm). (Figure presented.).
- Chrétien, Jean-Mathieu,Kerric, Gaelle,Zammattio, Fran?oise,Galland, Nicolas,Paris, Michael,Quintard, Jean-Paul,Le Grognec, Erwan
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supporting information
p. 747 - 757
(2019/01/04)
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- Enhanced Thermocatalytic Activity of Porous Yellow ZnO Nanoflakes: Defect- and Morphology-Induced Perspectives
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Herein, we report a simple and effective strategy for the synthesis of yellow ZnO (Y-ZnO) nanostructures with abundant oxygen vacancies on a large scale, through the sulfidation of ZnO followed by calcination. The developed strategy allows retention of the overall morphology of Y-ZnO compared with pristine ZnO and the extent of oxygen vacancies can be tuned. The influence of oxygen deficiencies, the extent of defect sites, and the morphology of ZnO on its solution-phase thermocatalytic activity has been evaluated in the synthesis of 5-substituted-1H-tetrazoles with different nitriles and sodium azide. A reasonable enhancement in the reaction rate was achieved by using Y-ZnO nanoflakes (Y-ZnO NFs) as a catalyst in place of pristine ZnO NFs. The reaction was complete within 6 h at 110 °C with Y-ZnO NFs, whereas it took 14 h at 120 °C with pristine ZnO NFs. The catalyst is easy to recycle without a significant loss in catalytic activity.
- Galani, Sunil M.,Panda, Asit Baran
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p. 612 - 620
(2019/02/14)
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- Humic acid as an efficient and reusable catalyst for one pot three-component green synthesis of 5-substituted 1: H -tetrazoles in water
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Humic acid is a non toxic, inexpensive, easily available high-molecular weight polymer. A simple and facile one pot three-component synthesis of 5-substituted 1H-tetrazoles from aldehydes, hydroxyamine hydrochloride and sodium azide using humic acid as an efficient catalyst in water is described. The method reported has several advantages such as high to excellent yields, easy work-up, mild reaction conditions, use of water as a green solvent, and a commercially available, nontoxic and reusable catalyst.
- Wang, Hongshe,Wang, Yichun,Han, Yinfeng,Zhao, Weixing,Wang, Xiaomei
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p. 784 - 789
(2020/01/23)
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- Cationic organotin cluster [t-Bu2Sn(OH)(H2O)]2 2+2OTf?-catalyzed one-pot three-component syntheses of 5-substituted 1H-tetrazoles and 2,4,6-triarylpyridines in water
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The cationic organotin cluster [t-Bu2Sn(OH)(H2O)]2 2+2OTf? is easy to prepare and stable in air. The catalytic activity of [t-Bu2Sn(OH)(H2O)]2 2+2OTf? as a neutral organotin Lewis acid catalyst is probed through the one-pot three-component syntheses of 5-substituted 1H-tetrazoles from aldehydes, hydroxylamine hydrochloride and sodium azide, and of 2,4,6-triarylpyridines from aromatic aldehydes, substituted acetophenones and ammonium acetate. The reactions proceed well in the presence of 1?mol% of [t-Bu2Sn(OH)(H2O)]2 2+2OTf? in water and provide the corresponding 5-substituted 1H-tetrazoles and 2,4,6-triarylpyridines in good to excellent yields. The method reported has several advantages such as the catalyst being neutral, low catalyst loading and use of water as a green solvent.
- Wang, Hongshe,Zhao, Weixing,Du, Juan,Wei, Fenyan,Chen, Qi,Wang, Xiaomei
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- Indium-, Magnesium-, and Zinc-Mediated Debenzylation of Protected 1 H -Tetrazoles: A Comparative Study
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5-Substituted 1-benzyltetrazoles are easily debenzylated to give the corresponding deprotected tetrazoles using dissolved metals under protic conditions: Mg/MeOH, In/MeOH, or Zn/MeCO 2 H are the procedures of choice for this transformation.
- Behloul, Cherif,Benlahrech, Meriem,Foubelo, Francisco,Nájera, Carmen,Yus, Miguel
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supporting information
p. 3430 - 3435
(2018/07/02)
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- Engineering a Cu-MOF Nano-Catalyst by using Post-Synthetic Modification for the Preparation of 5-Substituted 1H-Tetrazoles
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A new nano scale Cu-MOF has been obtained via post-synthetic metalation by immersing a Zn-MOF as a template in DMF solutions of copper(II) salts. The Cu-MOF serves as recyclable nano-catalyst for the preparation of 5-substituted 1H-tetrazoles via [3?+?2] cycloaddition reaction of various nitriles and sodium azide in a green medium (PEG). The post-synthetic metalated MOF were characterized by FT-IR spectroscopy, powder X-ray diffraction (PXRD), atomic absorption spectroscopy (AAS), and energy dispersive X-ray spectroscopy (EDX) techniques. The morphology and size of the nano-catalyst were determined by field emission scanning electron microscopy (FE-SEM).
- Salahshournia, Behrang,Hamadi, Hosein,Nobakht, Valiollah
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- Anchoring Ni (II) on Fe3O4@tryptophan: A recyclable, green and extremely efficient magnetic nanocatalyst for one-pot synthesis of 5-substituted 1H-tetrazoles and chemoselective oxidation of sulfides and thiols
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A green, novel and extremely efficient nanocatalyst was successfully synthesized by the immobilization of Ni as a transition metal on Fe3O4 nanoparticles coated with tryptophan. This nanostructured material was characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, inductively coupled plasma optical emission spectroscopy, vibrating sample magnetometry and X-ray diffraction. The prepared nanocatalyst was applied for the oxidation of sulfides, oxidative coupling of thiols and synthesis of 5-substituted 1H-tetrazoles. The use of non-toxic, green and inexpensive materials, easy separation of magnetic nanoparticles from a reaction mixture using a magnetic field, efficient and one-pot synthesis, and high yields of products are the most important advantages of this nanocatalyst.
- Moeini, Nazanin,Tamoradi, Taiebeh,Ghadermazi, Mohammad,Ghorbani-Choghamarani, Arash
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- A zinc Lewis acid surface active agent for the preparation of 5' - substituted tetrazole compounds
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The invention belongs to the field of organic synthetic technology, and specifically relates to a zinc Lewis acid surfactant as catalysts for preparing the 5' - substituted compound four azole class method. The method comprises the following steps: 1) to zinc Lewis acid surfactant Zn (OSO2 Cn H2 N + 1 )2 As the catalyst, R cyanide and sodium azide in water reaction to obtain the 5' - R base four nitrogen zuo compound of zinc salt and by-product NaOSO2 Cn H2 N + 1 ; 2) In the step 1) of the obtained 5 '- R base four nitrogen zuo compound of zinc salt in the acidification is carried out under acidic conditions, to obtain the 5' - R base four nitrogen zuo compounds and by-product zinc bromide; 3) by-product NaOSO2 Cn H2 N + 1 And by-product zinc bromide in the substitution reaction under acidic conditions, to obtain zinc Lewis acid surfactant Zn (OSO2 Cn H2 N + 1 )2 . Method can be used in "one-pot" strategy, the starting material by continuous cyclization reaction, the acidification reaction directly preparation containing the tetrazole compound of the structural unit; the method used in the zinc Lewis acid surfactant can be recovered after the reaction.
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Paragraph 0124-0132
(2018/09/08)
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- [3 + 2] Cycloaddition promoted by zinc oxide nanoparticles anchored on reduced graphene oxide using green solvent
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ZnO anchored on RGO-catalyzed [3 + 2] cycloaddition of nitriles and sodium azide in the synthesis of 5-substituted 1H-tetrazoles in water is an efficient and simple protocol with low catalyst loading under reflux condition. It is applied to a wide range of substrates with an excellent yield, simple workup procedure, recovery, and reusability of catalyst with consistent activity and high turnover number. It is proposed that the functional groups present in RGO surface are effective for preventing the aggregation of catalytically active ZnO species during the reaction. Moreover, the excellent performance of ZnO–RGO nanocomposite is ascribed to the excellent dispersity of catalyst in water, hydrophilic nature of the RGO for the accumulation of organic substrates in water, and the “Breslow effect.”.
- Clarina, Thanaraj,Rama, Velladurai
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supporting information
p. 175 - 187
(2018/01/01)
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- L -Proline: An Efficient Organocatalyst for the Synthesis of 5-Substituted 1 H -Tetrazoles via [3+2] Cycloaddition of Nitriles and Sodium Azide
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A simple and efficient route for the synthesis of a series of 5-substituted 1 H -tetrazoles using l -proline as a catalyst from structurally diverse organic nitriles and sodium azide is reported. The prominent features of this environmentally benign, cost effective, and high-yielding l -proline-catalyzed protocol includes simple experimental procedure, short reaction time, simple workup, and excellent yields making it a safer and economical alternative to hazardous Lewis acid catalyzed methods. The protocol was successfully applied to a broad range of substrates, including aliphatic and aryl nitriles, organic thiocyanates, and cyanamides.
- Bhagat, Saket B.,Telvekar, Vikas N.
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supporting information
p. 874 - 879
(2018/02/16)
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- Preparation of Ag-doped g-C3N4 Nano Sheet Decorated Magnetic γ-Fe2O3@SiO2 Core–Shell Hollow Spheres through a Novel Hydrothermal Procedure: Investigation of the Catalytic activity for A3, KA2 Coupling Reactions and [3?+?2] Cycloaddition
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Taking advantageous of both g-C3N4 and magnetic core-shell hollow spheres, for the first time a heterogeneous and magnetically separable hybrid system was prepared through a novel and simple hydrothermal procedure and used for immobilization of bio-synthesized Ag(0) nanoparticles. The hybrid system was fully characterized by using SEM/EDS, FTIR, VSM, TEM, XRD, TGA, DTGA, ICP-AES, BET and elemental mapping analysis. The catalytic utility of the obtained system, h-Fe2O3@SiO2/g-C3N4/Ag, for promoting ultrasonic-assisted A3, KA2 coupling reactions and [3?+?2] cycloaddition has been confirmed. The results established that the catalyst could efficiently catalyze the reaction to afford the corresponding products in high yields in short reaction times. The reusability study confirmed that the catalyst could be recovered and reused for at least five reaction runs with only slight loss of the catalytic activity. The hot filtration test also proved low silver leaching, indicating the heterogeneous nature of the catalysis.
- Sadjadi, Samahe,Malmir, Masoumeh,Heravi, Majid M.
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- Urea mediated 5-substituted-1H-tetrazole via [3?+?2] cycloaddition of nitriles and sodium azide
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A simple, new and convenient metal free procedure for the synthesis of 5-substituted 1H-tetrazoles using various nitriles and sodium azide in the presence of urea and acetic acid with good to high yields is developed. The reaction plausibly proceeds through in situ formation of urea azide active complex without toxic and/or expensive metal catalysts.
- Yakambram,Jaya Shree,Srinivasula Reddy,Satyanarayana,Naveen,Bandichhor, Rakeshwar
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supporting information
p. 445 - 449
(2018/01/03)
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- Antibacterial assessment of heteroaryl, Vinyl, Benzyl, and Alkyl tetrazole compounds
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Background: In previous reports, the antibacterial properties of certain tetrazole derivatives have been described. We have previously reported the antibacterial properties of aryl 1H-tetrazole compounds. Objective: To study the antibacterial activity of 5-substituted heteroaryl, vinyl, benzyl, and alkyl 1H-tetrazole derivatives. Methods: The antibacterial properties of heteroaryl, vinyl, benzylic, and aliphatic tetrazole derivatives were investigated against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The activity was assessed by determining the minimum inhibitory concentration of these tetrazole derivatives and comparing them to the known antibiotics amoxicillin, trimethoprim and sulfamethoxazole. Results: The tetrazole compounds were prepared utilizing cerium(III) chloride heptahydrate catalysis at 160o C for 1-4 h in a microwave reactor using an aqueous solvent mixture. The most active derivatives exhibited minimum inhibitory concentration values between 125-250 μg/mL against Escherichia coli. More importantly, these compounds were considerably more active when used in combination with trimethoprim and a significant synergistic effect was observed (MIC = 0.98-7.81 μg/mL) against E. coli and S. aureus. Conclusion: The tetrazole derivatives were synthesized in high yield and short reaction times in water. Several of the tetrazole compounds showed a significant synergistic antibacterial effect when used with trimethoprim.
- Dudley, Joshua,Feinn, Liana,Defrancesco, Heather,Lindsay, Erica,Coca, Adiel,Roberts, Elizabeth Lewis
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p. 550 - 555
(2018/08/17)
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- A Practical Synthesis of 5-Substituted 1 H -Tetrazoles from Aldoximes Employing the Azide Anion from Diphenyl Phosphorazidate
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5-Substituted 1 H -tetrazoles were effectively synthesized from aldoximes and diphenyl phosphorazidate (DPPA) under reflux conditions in xylenes. Various aldoximes underwent the cycloaddition reaction to afford the corresponding 5-substituted 1 H -tetrazoles in short reaction times and in good yields. Chiral aldoximes derived from amino acids also gave aminotetrazoles with almost no racemization.
- Ishihara, Kotaro,Kawashima, Mayumi,Matsumoto, Takatoshi,Shioiri, Takayuki,Matsugi, Masato
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p. 1293 - 1300
(2017/12/26)
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- 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
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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.
- Esmaeilpour, Mohsen,Sardarian, Ali Reza,Firouzabadi, Habib
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- Regioselective and Stereoselective Addition of Tetrazole Derivatives to Electron-poor Acetylenic Esters in the Presence of Triphenylphosphine
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Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine and acetylenic esters by tetrazole derivatives leads to the formation of vinyltriphenylphosphonium salts. The cation of these salts undergoes an addition reaction with the counter anion in CH2Cl2at room temperature to yield the corresponding stabilized phosphorus ylides. Elimination of triphenylphosphine from the stabilized phosphorus ylides leads to the corresponding electron-poor N-vinyl tetrazoles in fairly high yields. Structures of N-vinyl tetrazoles were determined by IR,1H NMR,13C NMR and single crystal X-ray structure analyses. The reaction is fairly regioselective and stereoselective.
- Ramazani, Ali,Nasrabadi, Fatemeh Zeinali,?lepokura, Katarzyna,Lis, Tadeusz,Joo, Sang Woo
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- Tetrazolylmethyl quinolines: Design, docking studies, synthesis, anticancer and antifungal analyses
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A new series of 2,5 and 1,5-regioisomers of the tetrazolyl group viz., 3-[(5-benzyl/benzylthio-2H-tetrazol-2-yl) methyl]-2-chloro-6-substituted quinoline 6h-q and 3-[(5-benzyl/benzylthio-1H-tetrazol-1-yl) methyl]-2-chloro-6-substituted quinolines 7h-q were synthesized. Docking studies of all these compounds with DNA as target using PDB: 1AU5 and 453D revealed that the compounds 6h and 6i act as covalent cross linker on the DNA helix of the former and intercalate the latter both with higher C score values. Another set of docking studies in the active pocket of dihydrofolate reductase and N-myristoyl transferase as targets to assess antifungal activity revealed that compounds 6k, 6l, 6p and 7q (with bromo and fluro substituents) showcases different binding modes and hydrogen bonding. Further, the compounds were screened for anticancer activity (primary cytotoxicity) against NCI-60 Human tumor cell line at a single high dose (10?5M) concentration assay. Among the tested compounds, 6h has shown 99.28% of GI against Melanoma (SK-MEL-5) and compound 6i has shown 97.56% of GI against Breast Cancer (T-47D). Further, in vitro antifungal assay against A. fumigatus and C. albicans for these compounds 6h-q and 7h-q revealed potential to moderate activities as compared to the standard.
- Shaikh, Saba Kauser J.,Kamble, Ravindra R.,Somagond, Shilpa M.,Devarajegowda,Dixit, Sheshagiri R.,Joshi, Shrinivas D.
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p. 258 - 273
(2017/02/15)
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- Syntheses of 5-substituted 1H-tetrazoles catalyzed by reusable Cu(II)-NaY zeolite from nitriles
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Cu(II)-NaY heterogeneous catalyst is used for the synthesis of 5-substituted 1H-tetrazoles by [2+3]-cycloaddition of sodium azide and nitriles. The salient features of this process are low reaction times, mild reaction conditions and high yields. The catalyst is recovered and reused for several cycles with consistent activity.
- Sudhakar,Purna Chandra Rao,Prem Kumar,Suresh,Ravi
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p. 864 - 866
(2017/02/10)
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- Anchoring of Cu(II)–vanillin Schiff base complex on MCM-41: A highly efficient and recyclable catalyst for synthesis of sulfides and 5-substituted 1H–tetrazoles and oxidation of sulfides to sulfoxides
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A copper(II)–vanillin complex was immobilized onto MCM-41 nanostructure and was used as an inexpensive, non-toxic and heterogeneous catalyst in the synthesis of symmetric aryl sulfides by the cross-coupling of aromatic halides with S8 as an effective sulfur source, in the oxidation of sulfides to sulfoxides using 30% H2O2 as a green oxidant and in the synthesis of 5-substituted 1H–tetrazoles from a smooth (3?+?2) cycloaddition of organic nitriles with sodium azide (NaN3). The products were obtained in good to excellent yields. This catalyst could be reused several times without loss of activity. Characterization of the catalyst was performed using Fourier transform infrared, energy-dispersive X-ray and atomic absorption spectroscopies, X-ray diffraction, thermogravimetric analysis, and scanning and transmission electron microscopies.
- Khanmoradi, Maryam,Nikoorazm, Mohsen,Ghorbani-Choghamarani, Arash
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- [Cu(phen)(PPh3)2]NO3-catalyzed microwave-assisted green synthesis of 5-substituted 1H-tetrazoles
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Abstract: An efficient synthetic methodology for construction of 5-substituted 1H-tetrazoles under microwave irradiation in green medium is described. With [Cu(phen)(PPh3)2]NO3 as catalyst and H2O-isopropyl alcohol (IPA) as reaction medium, various substituted nitriles underwent (3?+?2) cycloaddition reaction with NaN3 under microwave irradiation to provide corresponding 5-substituted 1H-tetrazoles in high yield. This method is not only efficient and general but also benefits from high functional group tolerance. This environmentally friendly synthetic methodology is visualized as an alternative to existing procedures, providing a simple route to privileged scaffolds.
- Padmaja,Meena,Maiti, Barnali,Chanda, Kaushik
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p. 7365 - 7374
(2017/09/06)
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- Mechanism of the zinc-catalyzed addition of azide ion to unsaturated compounds: Synthesis of 5-substituted 1Н-tetrazoles from nitriles and of 1-substituted 1Н-tetrazole-5-thiols from isothiocyanates
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The mechanism of the formation of 5-substituted 1H-tetrazoles from organic nitriles and thiocyanates in the presence of NaN3 and ZnCl2 in aliphatic alcohols was studied. The results of this study allowed efficient methods of synthesis of substituted tetrazoles from nitriles, thiocyanates, and isothiocyanates to be proposed.
- Myznikov,Vorona,Artamonova,Zevatskii, Yu. E.
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p. 731 - 738
(2017/05/29)
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- Cu(II) immobilized on Fe3O4@APTMS-DFX nanoparticles: An efficient catalyst for the synthesis of 5-substituted 1: H -tetrazoles with cytotoxic activity
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Cu(ii) immobilized on deferasirox loaded amine functionalized magnetic nanoparticles (Cu(ii)/Fe3O4@APTMS-DFX) as a novel magnetically recyclable heterogeneous catalyst is able to catalyze the [3 + 2] cycloaddition reactions of various organic nitriles with sodium azide. Using this method, a series of 5-substituted-1H-tetrazoles under mild conditions in DMSO were prepared. The reaction involves mild reaction conditions with efficient transformation capability. The developed catalyst could be easily separated by applying an external magnetic field. Furthermore, it could be recycled for 5 runs with negligible leaching of copper from the surface of the catalyst. The catalyst was characterized by various techniques such as FT-IR, TGA, VSM, SEM-EDX, and ICP-OES. Several derivatives of 1H-tetrazoles were prepared using this catalyst, and their structures were confirmed using different techniques. Then, the synthesized anthraquinones were evaluated for their cytotoxicity against several cell lines including MCF-7, MAD-MD-231, HT-29, HeLa, neuro-2a and L-929. The results obtained from the MTT assay revealed that the 6 derivatives exhibited a high level of cytotoxicity. In order to determine the cytotoxicity mechanism, 2 derivatives with the highest cytotoxic activity were selected, and an apoptosis assay was carried out by flow cytometry, which supported that apoptosis is the major mechanism.
- Taghavi, Faezeh,Gholizadeh, Mostafa,Saljooghi, Amir Sh.,Ramezani, Mohammad
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p. 1953 - 1964
(2017/10/27)
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- First report of the direct supporting of palladium–arginine complex on boehmite nanoparticles and application in the synthesis of 5-substituted tetrazoles
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Boehmite nanoparticles are aluminium oxide hydroxide (γ-AlOOH) particles, which were prepared using a simple and inexpensive procedure in water at room temperature and further modified using arginine. Subsequently palladium particles were immobilized on their surface to prepare Pd-Arg@boehmite. This novel nanostructured compound was fully characterized using thermogravimetric analysis, X-ray diffraction, inductively coupled plasma optical emission (ICP-OES) and energy-dispersive X-ray spectroscopies, and scanning and transmission electron microscopies. Finally, this catalyst was applied as a moisture- and air-stable heterogeneous material for the synthesis of 5-substituted 1H–tetrazole derivatives. The leaching of palladium and heterogeneity of the catalyst were studied using hot filtration and ICP-OES. This catalyst demonstrated remarkable recyclability. The novelty of this work is that it represents the first time an amino acid has been grafted on boehmite nanoparticles.
- Tahmasbi, Bahman,Ghorbani-Choghamarani, Arash
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- Cu(NO3)2-catalysed direct synthesis of 5-substituted 1H-tetrazoles from alcohols or aldehydes
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A simple, convenient and practical protocol to synthesise 5-substituted 1H-tetrazoles from alcohols or aldehydes is reported. Using ammonia and sodium azide as nitrogen sources and Cu(NO3)2 as catalyst, benzylic alcohols and benzaldehydes were directly converted into 5-substituted 1H-tetrazoles in a one-pot procedure.
- Tao, Chuanzhou,Wang, Bin,Sun, Lei,Yi, Jiuyin,Shi, Dahua,Wang, Jian,Liu, Weiwei
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- Design, synthesis and evaluation of 5-substituted 1-H-tetrazoles as potent anticonvulsant agents
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Abstract: A series of 5-substituted 1-H-tetrazoles were designed and synthesized as potent anticonvulsant agents. Their preliminary anticonvulsant activities were evaluated using maximal electroshock and subcutaneous pentylenetetrazole (scPTZ) seizure tests. Neurotoxicity was determined using rotarod test. The results indicated that the compound 2j in scPTZ model exhibited the ED50 values of 83.3?mg/kg, superior to the standard drug ethosuximide with the maximum activity. In addition, compound 2k showed the most potent activity in MES model with ED50 value of 9.6?mg/kg and TD50 value of 189.5?mg/kg after intraperitoneal injection in mice, and displayed a high protective index (TD50/ED50) of 19.7 compared to reference antiepileptic drugs. Graphical Abstract: [Figure not available: see fulltext.]
- Liao, Ai-Mei,Wang, Tiantian,Cai, Bangrong,Jin, Yi,Cheon, Seunghoon,Chun, Chang Ju,Wang, Zengtao
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p. 435 - 443
(2017/04/13)
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- Use of purine compound in treatment or prevention of hyperuricemic or gouty diseases
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The invention belongs to the technical field of medicines, relates to a use of a purine compound in treatment or prevention of hyperuricemic or gouty diseases, and concretely relates to a use of the purine compound concretely is a compound represented by formula (I), a pharmaceutically acceptable salt thereof, a solvate thereof or a composition containing anyone of the compound, the pharmaceutically acceptable salt and the solvate in the preparation of medicines for treating and/or preventing hyperuricemia, gouts, gouty inflammations and uratic nephropathy. In the formula (I), X represents a heteroaryl group selected from nitrogen-containing hetero atoms, Y represents a group selected from aryl groups or heteroaryl groups, the aryl groups or the heteroaryl groups are unsubstituted or are substituted with one or more halogen atoms or C-6 halogenated alkyl groups, m represents 3 or 4, and n represents 0 or 1.
- -
-
Paragraph 0147; 0148; 0149
(2017/01/02)
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- Zn/MeOH-Mediated Practical and Easy Detritylation of Protected 1-Trityltetrazoles
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A practical and low-cost method for the detritylation of 1-titryltetrazoles using zinc and methanol is described. This procedure is versatile and efficient in the deprotection of several protected tetrazoles bearing aliphatic, aromatic, and heteroaromatic substituents, as well as some functional groups, without decomposition of the tetrazole ring.
- Behloul, Cherif,Bouchelouche, Kenza,Hadji, Yasmine,Benseghir, Saadia,Guijarro, David,Nájera, Carmen,Yus, Miguel
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supporting information
p. 2455 - 2460
(2016/07/28)
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- Magnetically separable Fe3O4@chitin as an eco-friendly nanocatalyst with high efficiency for green synthesis of 5-substituted-1H-tetrazoles under solvent-free conditions
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The present study describes an efficient, eco-friendly and simple method for the synthesis of 5-substituted-1H-tetrazoles catalyzed by magnetite-chitin (Fe3O4@chitin) as a green and recyclable catalyst. Fe3O4@chitin was initially prepared using hydrothermal synthesis. Subsequently, the structure, morphology, and magnetic properties of the prepared nanocatalyst were studied with some different spectroscopic, microscopic and thermogravimetric techniques such as FT-IR, XRD, SEM, TEM, VSM and TGA. Obtained results showed that Fe3O4@chitin nanoparticles exhibited uniform cubic shape and were well monodispersed. Also, magnetic measurement revealed that the synthesized nanocatalyst had superparamagnetic features. The application of this new nanocatalyst allows the synthesis of a variety of tetrazoles through the reaction of nitriles with 1-butyl-3-methylimidazolium azide ([bmim][N3]) under solvent-free conditions. This synthetic pathway is a green protocol offering significant advantages, such as excellent yield of products in short reaction times, mild reaction conditions, minimization of chemical waste, easy preparation of the catalyst and its recyclability up to six cycles without any considerable loss of efficiency.
- Zarghani, Monireh,Akhlaghinia, Batool
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p. 31850 - 31860
(2016/04/26)
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- A comparative study between heterogeneous stannous chloride loaded silica nanoparticles and a homogeneous stannous chloride catalyst in the synthesis of 5-substituted 1: H -tetrazole
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Heterogeneous SnCl2-nano-SiO2 efficiently catalyzed 5-substituted 1H-tetrazole synthesis with excellent yield. The catalyst was characterized by using FT-IR, TGA, TEM, and EDX. It is widely applicable on aliphatic, aromatic, heteroaromatic and sterically hindered nitriles with five time recyclability. Being simple and an economically viable approach for the synthesis of SnCl2-nano-SiO2 are additional advantages.
- Kumar, Arvind,Kumar, Satyanand,Khajuria, Yugal,Awasthi, Satish Kumar
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p. 75227 - 75233
(2016/08/24)
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- One-pot synthesis of 1- and 5-substituted 1H-tetrazoles using 1,4-dihydroxyanthraquinone–copper(II) supported on superparamagnetic Fe3O4@SiO2 magnetic porous nanospheres as a recyclable catalyst
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An effective one-pot, convenient process for the synthesis of 1- and 5-substituted 1H-tetrazoles from nitriles and amines is described using1,4-dihydroxyanthraquinone–copper(II) supported on Fe3O4@SiO2 magnetic porous nanospheres as a novel recyclable catalyst. The application of this catalyst allows the synthesis of a variety of tetrazoles in good to excellent yields. The preparation of the magnetic nanocatalyst with core–shell structure is presented by using nano-Fe3O4 as the core, tetraethoxysilane as the silica source and poly(vinyl alcohol) as the surfactant, and then Fe3O4@SiO2 was coated with 1,4-dihydroxyanthraquinone–copper(II) nanoparticles. The new catalyst was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, thermogravimetric analysis, vibration sample magnetometry, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption isotherm analysis and inductively coupled plasma analysis. This new procedure offers several advantages such as short reaction times, excellent yields, operational simplicity, practicability and applicability to various substrates and absence of any tedious workup or purification. In addition, the excellent catalytic performance, thermal stability and separation of the catalyst make it a good heterogeneous system and a useful alternative to other heterogeneous catalysts. Also, the catalyst could be magnetically separated and reused six times without significant loss of catalytic activity. Copyright
- Esmaeilpour, Mohsen,Javidi, Jaber,Zahmatkesh, Saeed
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p. 897 - 904
(2016/10/18)
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- An efficient and economical synthesis of 5-substituted 1 H -tetrazoles via Pb(II) salt catalyzed [3+2] cycloaddition of nitriles and sodium azide
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A simple, mild and efficient method is developed for the synthesis of 5-substituted 1H-tetrazoles. Out of three used Pb(II) catalysts, lead chloride (PbCl2) has been found to be an efficient catalyst for [3+2] cycloaddition of NaN3 with aromatic and aliphatic nitriles to afford 5-substituted 1H-tetrazoles. The catalyst is reusable up to four cycles with consistent activity. The cost effectiveness and easy availability of the catalyst, simple methodology, excellent yield and easy work-up are the additional advantages.
- Kant, Rama,Singh, Vishal,Agarwal, Alka
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p. 305 - 312
(2016/04/20)
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- Ni-S-methylisothiourea complexes supported on boehmite nanoparticles and their application in the synthesis of 5-substituted tetrazoles
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Boehmite nanoparticles are aluminum oxide hydroxide (γ-AlOOH) particles, which were prepared by a simple and inexpensive procedure and immobilized further with nickel-S-methylisothiourea complexes (Ni-SMTU@boehmite), and characterized by FT-IR spectroscopy, TGA, XRD, ICP-OES, EDS, SEM and TEM techniques. Finally, we investigated the catalytic activity of Ni-SMTU@boehmite as a new, heterogeneous, stable and highly reusable nanocatalyst for the synthesis of 5-substituted 1H-tetrazole derivatives in PEG-400 as a green solvent. This catalyst was recovered by simple filtration and reused several times without significant loss of its catalytic efficiency or nickel leaching. The heterogeneity of this catalyst has been studied using hot filtration and ICP-OES technique.
- Ghorbani-Choghamarani, Arash,Moradi, Parisa,Tahmasbi, Bahman
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p. 56638 - 56646
(2016/07/06)
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- Ag-doped nano magnetic γ-Fe2O3@DA core-shell hollow spheres: An efficient and recoverable heterogeneous catalyst for A3 and KA2 coupling reactions and [3 + 2] cycloaddition
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An effective protocol for the fabrication of Ag-doped nano magnetic γ-Fe2O3@DA core-shell hollow spheres (h-Fe2O3@DA/Ag) by a simple hydrothermal method is demonstrated without any templates in the reaction system. The synthesized core-shell structure was successfully characterized in terms of the chemical composition, surface morphology, and magnetic properties using FT-IR, VSM, TGA, TEM, FE-SEM, EDS, and XRD patterns. The possible formation mechanism of this magnetic γ-Fe2O3@DA/Ag hollow sphere structure is described based on the experimental results. In addition, as a physical property, the apparent shell density was determined using the specific surface area (BET) and shell thickness (BJH). The important, novel and unique catalyst with a hollow structural character and strong magnetic behavior exhibited a high catalytic activity in the A3 and KA2 coupling reactions and [3 + 2] cycloaddition for the synthesis of 1H-tetrazoles. Furthermore, the recovered catalyst of the reaction mixture was facilitated by a magnetic field and multiple recycling was carried out without any significant loss in the catalytic activity.
- Elhampour,Malmir,Kowsari,Boorboor Ajdari,Nemati
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p. 96623 - 96634
(2016/10/25)
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- Piperazinium dihydrogen sulfate: An acidic ionic liquid for the [3+2] cycloaddition reaction of sodium azide with organic nitriles
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Background: Tetrazoles are imperative nitrogen rich heterocyclic compounds with a wide range of applications in the field of organic synthesis, coordination chemistry, material sciences, and medicinal chemistry. A most common approach for the synthesis of 5-substituted-1H-Tetrazoles is achieved by [3+2] cycloaddition reaction of azides to nitriles. In this paper a new acidic ionic liquid is introduced as a catalyst to promote the mentioned reaction. Methods: Piperazinium dihydrogen sulfate:as a new acidic ionic compound was obtained by treatment of piperazine with sulfuric acid, which is further was applied as a catalyst for the [3+2] cycloaddition reaction of azides to organic nitriles. Results: The [3+2] cycloaddition reaction of sodium azide with structurally different organic nitriles using only 1.5 mol% of the piperazinium dihydrogen sulfate proceeded well at 100°C and 5-substituted-1H-Tetrazoles were prepared in good to excellent yields. Herein, piperazinium dihydrogen sulfate has a dual role of catalyst and reaction medium, which circumvents the use of any organic solvent. The catalyst is also recyclable. This method is particularly suitable for benzonitriles carrying deactivating groups which furnished the corresponding products in excellent yields. By this method, mono [3+2] cycloaddition product of dicyanides was obtained. Conclusion: In conclusion, piperazinium dihydrogen sulfate as a new acidic ionic compound was applied to promote synthesis of 5-substituted-1H-Tetrazoles through [3+2] cycloaddition reaction of organic nitriles with sodium azide. This new ionic compound can be easily separated from the reaction mixture which resulted to a simple work-up of the products.
- Nowrouzi, Najmeh,Farahi, Soghra,Irajzadeh, Maryam
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p. 113 - 119
(2016/02/27)
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