- Glucose:urea:NH4Cl low melting mixture for the synthesis of symmetric azines
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Alternate reaction media have become very important due to the problems created by the highly volatile nature of the solvents. The deep eutectic mixture is a kind of an alternate reaction medium which has emerged in recent years. Low melting mixtures were introduced by making the deep eutectic mixture more cost-effective and renewable by introducing carbohydrates into it. The properties of low melting mixtures include easiness to prepare, usage of low-cost components, biodegradability, solubility in water, easy separation from organic compounds, etc. The low melting mixtures such as glucose:urea:NH4Cl, glucose:ChCl, glucose:urea:ChCl, glycerol:urea:NH4Cl, and ethylene glycol:urea:NH4Cl were used in different ratios for the reactions. The properties such as viscosity, density, acidity, glass transition temperature, and thermal stability were studied. An unusual method for the synthesis of symmetrical azines is introduced wherein benzaldehyde and hydroxylamine are reacted in the presence of glucose:urea:NH4Cl. The method of synthesis needs only less reaction time, temperature and the product was easily separated. The products were confirmed using GC-MS and NMR techniques. The recyclability of glucose:urea:NH4Cl was studied.
- Theresa, Letcy V.,Shaibuna,Sreekumar
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p. 3148 - 3160
(2019/09/03)
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- Unusual synthesis of azines and their oxidative degradation to carboxylic acid using iodobenzene diacetate
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Reaction of 3-hydrazonobutan-2-one oxime with aromatic aldehydes resulted in the formation of 1,2-bis(arylidene)hydrazine commonly referred as azine as an unexpected product, instead of expected product 3-(aryl)methylenehydrazonobutan-2-one oxime, which were subsequently oxidized to corresponding aromatic acids with an ecofriendly oxidizing agent iodobenzene diacetate. Azines and carboxylic acids were characterized by IR and NMR (1H, 13C, HMBC, and HMQC) studies.
- Sumran, Garima,Aggarwal, Ranjana,Hooda, Mona,Sanz, Dionisia,Claramunt, Rosa M.
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supporting information
p. 439 - 446
(2018/02/06)
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- Selective Reduction of Azines to Benzyl Hydrazones with Sodium Borohydride Catalyzed by Mesoporous Silica-Supported Silver Nanoparticles: A Catalytic Route towards Pyrazole Synthesis
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The catalytic activity of supported silver nanoparticles on mesoporous silica was studied, for the selective reduction of azines into benzyl hydrazones using sodium borohydride as mild reducing agent. Different sizes of silver nanoparticles supported on mesoporous silica (Ag/HMS) were successfully prepared by two methods, i.e., wet impregnation followed by reduction with hydrogen at 350 °C and in situ deposition/reduction with a mixture of amines (ethanolamine and ethylenediamine). The Ag/HMS (amines) catalyst was found to promote the selective 1,2-reduction of aryl-substituted azines, compared to the corresponding 1,4-reduction that occurs in general reduction processes. This catalytic transfer hydrogenation process found to be clean, fast and quantitative (>99% yields and selectivity) towards benzyl hydrazone synthesis under mild conditions. Of great importance is that under the present catalytic conditions reducible functional groups remain intact. Formal kinetics, support the in situ formation of silver hydride species being responsible for the reduction process. The presence of protic polar methanol enhanced the catalytic activity of Ag/HMS. Based on the recycling studies the catalytic system Ag/HMS-NaBH4 was found to catalyze the selective reduction of azines nine times without significant loss of its activity. Finally, a one-pot reaction between the in situ produced benzyl hydrazones and a series of nitrostyrenes readily provided the regioselective synthesis of 1,3,5-subtituted pyrazoles, highlighting a useful synthetic application of the catalytic protocol. (Figure presented.).
- Charistoudi, Evangelia,Kallitsakis, Michael G.,Charisteidis, Ioannis,Triantafyllidis, Kostas S.,Lykakis, Ioannis N.
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supporting information
p. 2949 - 2960
(2017/09/08)
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- Cs2CO3-mediated decomposition of N-tosylhydrazones for the synthesis of azines under mild conditions
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Abstract: A facile, environmentally and efficient Cs2CO3-mediated decomposition of N-tosylhydrazones reaction has been developed for the synthesis of functionalized azines under mild conditions. This method offers broad substrate scope, occurs as additive-free, without strong base conditions, utilizes readily available reactants, and forms products in good to high yields. Graphical Abstract: [Figure not available: see fulltext.]
- Luo, Zai-Gang,Liu, Peng,Fang, Yu-Yu,Xu, Xue-Mei,Feng, Cheng-Tao,Li, Zhong,Zhang, Xiao-Mei,He, Jie
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p. 1139 - 1148
(2017/02/10)
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- A Copper-Benzotriazole-Based Coordination Polymer Catalyzes the Efficient One-Pot Synthesis of (N′-Substituted)-hydrazo-4-aryl-1,4-dihydropyridines from Azines
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A series of new (N′-substituted)-hydrazo-4-aryl-1,4-dihydropyridines was successfully synthesized via a facile one-pot catalytic pathway utilizing azines and propiolate esters as starting materials and a one-dimensional copper benzotriazole-based coordination polymer as catalyst. In the absence of catalyst, the corresponding 5-substituted 4,5-dihydropyrazoles were formed in moderate to high yields. Fine-tuning of the catalysts allowed us to gain more insights regarding the plausible reaction mechanism. (Figure presented.).
- Kallitsakis, Michael,Loukopoulos, Edward,Abdul-Sada, Alaa,Tizzard, Graham J.,Coles, Simon J.,Kostakis, George E.,Lykakis, Ioannis N.
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supporting information
p. 138 - 145
(2017/01/14)
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- An efficient synthesis of perhydro[1,2,4]triazolo[1,2-a][1,2,4]triazole-1,5-dithiones catalyzed by TiO2-functionalized nano-Fe3O4 encapsulated-silica particles as a reusable magnetic nanocatalyst
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Immobilization of a nano-TiO2 catalyst on the surface of a magnetic SiO2 support was performed through the reaction of a Fe3O4@SiO2 composite with Ti(OC4H9)4via a simple process. The Fe3O4@SiO2-TiO2 nanocomposite was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), and a vibrating sample magnetometer (VSM). The Fe3O4@SiO2-TiO2 nanocomposite has been found to be an efficient catalyst for the synthesis of perhydro[1,2,4]triazolo[1,2-a][1,2,4]triazole-1,5-dithiones from the condensation of various aldazines and potassium thiocyanate in acetonitrile solvent at room temperature. It has been found that the nanocatalyst was recycled for up to 6 cycles with minimal loss in catalytic activity. The purpose of this research was to provide an easy method for the synthesis of perhydrotriazolotriazole derivatives by a robust and magnetically recoverable catalyst.
- Safari, Javad,Javadian, Leila
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p. 104973 - 104980
(2015/12/26)
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- An expeditious synthetic approach towards the synthesis of Bis-Schiff bases (aldazines) using ultrasound
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Aldazines (Bis-Schiff bases) 1-24 were synthesized using aromatic aldehydes (heterocyclic and benzaldehydes) and hydrazine hydrate under reflux using conventional heating and/or via ultrasound irradiation using BiCl3 as catalyst. Ultrasonication conditions with cat. BiCl3 proved to be an effective, environmentally friendly synthetic procedure. This methodology is robust in the presence of electron donating and electron withdrawing groups affording desired products with high yields (>95%) in just a couple of minutes vs. hours using conventional heating.
- Khan, Khalid M.,Jamil, Waqas,Ambreen, Nida,Taha, Muhammad,Perveen, Shahnaz,Morales, Guillermo A.
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p. 1200 - 1205
(2014/02/14)
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- A family of highly selective allosteric modulators of the metabotropic glutamate receptor subtype 5
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We have identified a family of highly selective allosteric modulators of the group I metabotropic glutamate receptor subtype 5 (mGluR5). This family of closely related analogs exerts a spectrum of effects, ranging from positive to negative allosteric modu
- O'Brien, Julie A.,Lemaire, Wei,Chen, Tsing-Bau,Chang, Raymond S. L.,Jacobson, Marlene A.,Ha, Sookhee N.,Lindsley, Craig W.,Schaffhauser, Herve J.,Sur, Cyrille,Pettibone, Douglas J.,Conn, P. Jeffrey,Williams Jr., David L.
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p. 731 - 740
(2007/10/03)
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- A novel approach to fluoro-containing alkenes
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A new and general one-pot transformation of aromatic aldehydes to fluorinated olefins containing -CH=C(Cl)CF3 or -CH=C(F)CClF2 moieties is described. Freons CCl3CF3 and CCl2FCClF2 were used as trifluoromethyl and difluoromethyl C2-building blocks respectively. A proposed mechanism for the reaction is discussed.
- Korotchenko, Vasily N,Shastin, Alexey V,Nenajdenko, Valentine G,Balenkova, Elisabeth S
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p. 7519 - 7527
(2007/10/03)
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- 2,3-Diaza-1,3-dienes (azines) as substrates for the Staudinger reaction. Synthesis and reactivity of N-imino-β-lactams
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The reaction of aromatic and aliphatic azines with different ketene precursors, such as the acid chloride/Et3N system, alkoxychromium(0) carbenes, and free diphenyl ketene, gives N-imino-β-lactams in good to excellent yields, with good levels of cis,trans-selectivity. A wide variety of symmetrically-substituted azines derived from aldehydes and ketones are compatible with the Staudinger reaction. Chiral N-imino-β-lactams derived from symmetrically or unsymmetrically (mixed) chiral azines are also obtained in good yields as essentially single enantiomers (de > 95%). Different reaction intermediates, including hemiaminals, oxadiazols, and hydrazides have been isolated. Free diphenyl ketene forms Diels-Alder adducts and N-acylazadienes in addition to the previously reported N-imino-β-lactams. The usual reactivity of the β-lactam ring is modified in N-imino-β-lactams by the presence of the imino group. Thus, β-hydrazonoesters, N-alkylamino-β-lactams, and NH-β-lactams can be efficiently obtained by base-catalyzed 2-azetidinone ring opening, catalytic hydrogenation, and ozonolysis, respectively.
- Alcaide,Miranda,Perez-Castells,Polanco,Sierra
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p. 8003 - 8010
(2007/10/02)
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- Oxidative Transformations of Aldazines and Ketazines with Organic Peroxyacids
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Oxidation of aromatic aldazines and ketazines with various peroxycarboxylic acids was investigated.It was found that one part of azine molecule 2 was converted into carbonyl compound 1 or related acid 3 while the second part was transformed into carboxylic ester 4 related to peroxyacid used as an oxidant.It was revealed that aromatic azines could be used as a source of diazaarylmethanes and mechanisms of reactions studied were postulated. aldazines, carboxylic esters, ketazines, oxidation, peroxycarboxylic acids
- Mlochowski, J.,Giurg, M.
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p. 2333 - 2342
(2007/10/02)
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- ZEOLITE-CuNaY CATALYZED DECOMPOSITION OF ARYLDIAZOMETHANE
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Decomposition of aryldiazomethanes is catalyzed by copper ion-exchanged Y-type zeolite to afford cis-1,2-diarylethylenes in high selectivity.The catalytic activity and selectivity are found to be affected by the exchange level of copper ions in zeolite and the solvent used.
- Onaka, Makoto,Kita, Hiroshi,Izumi, Yusuke
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p. 1895 - 1898
(2007/10/02)
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