- Efficient Cp?Ir Catalysts with Imidazoline Ligands for CO2 Hydrogenation
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We report newly developed iridium catalysts with electron-donating imidazoline moieties as ligands for the hydrogenation of CO2 to formate in aqueous solution. Interestingly, these new complexes promote CO2 hydrogenation much more effectively than their imidazole analogues and exhibit a turnover frequency (TOF) of 1290 h-1 for the bisimidazoline complex compared to that of 20 h-1 for the bisimidazole complex at 1 MPa and 50 C. In addition, the hydrogenation proceeds smoothly even under atmospheric pressure at room temperature. The TOF of 43 h-1 for the bisimidazoline complex is comparable to that of a dinuclear complex (70 h-1, highest TOF reported) [Nat. Chem. 2012, 4, 383], which incorporates proton-responsive ligands with pendent-OH groups in the second coordination sphere. The catalytic activity of the complex with an N-methylated imidazoline moiety is much the same as that of the corresponding pyridylimidazoline analogue. This result and the UV/Vis titrations of the imidazoline complexes indicate that the high activity is not attributable to the deprotonation of NH on the imidazoline under the reaction conditions. A novel complex having imidazoline ligands shows much higher catalytic activity for CO2 hydrogenation than the conventional complex having imidazole ligands. The change from a double bond in imidazole to a single bond in imidazoline leads to a 60-fold increase in the catalytic activity.
- Xu, Shaoan,Onishi, Naoya,Tsurusaki, Akihiro,Manaka, Yuichi,Wang, Wan-Hui,Muckerman, James T.,Fujita, Etsuko,Himeda, Yuichiro
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- Iridium-catalyzed chemoselective transfer hydrogenation of α, β-unsaturated ketones to saturated ketones in water
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A chemoselective iridium-catalyzed transfer hydrogenation of α, β-unsaturated ketones was realized in water. The C[dbnd]C double bonds of 2-benzylidene indanones and analogues were hydrogenated exclusively catalyzed by an iridium complex (0.1 mol%) bearin
- Chen, Jinxun,Chen, Yongsheng,Cui, Xiaofeng,Jiang, Xiaolan,Liu, Qixing,Zhou, Haifeng
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supporting information
(2022/01/24)
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- Hydrogen production from formic acid catalyzed by a phosphine free manganese complex: Investigation and mechanistic insights
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Formic acid dehydrogenation (FAD) is considered as a promising process in the context of hydrogen storage. Its low toxicity, availability and convenient handling make FA attractive as a potential hydrogen carrier. To date, most promising catalysts have been based on noble metals, such as ruthenium and iridium. Efficient non-noble metal systems like iron were designed but manganese remains relatively unexplored for this transformation. In this work, we present a panel of phosphine free manganese catalysts which showed activity and stability in formic acid dehydrogenation. The most promising results were obtained with Mn(pyridine-imidazoline)(CO)3Br yielding >14 l of the H2/CO2 mixture and proved to be stable for more than 3 days. Additionally, this study provides insights into the mechanism of formic acid dehydrogenation. Kinetic experiments, Kinetic Isotopic Effect (KIE), in situ observations, NMR labeling experiments and pH monitoring allow us to propose a catalytic cycle for this transformation.
- Léval, Alexander,Agapova, Anastasiya,Steinlechner, Christoph,Alberico, Elisabetta,Junge, Henrik,Beller, Matthias
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supporting information
p. 913 - 920
(2020/02/27)
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- Cooperative iridium complex-catalyzed synthesis of quinoxalines, benzimidazoles and quinazolines in water
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Herein, an efficient methodology for the synthesis of a diverse class of N-heterocyclic moieties, such as quinoxalines, benzimidazoles and quinazolines, was developed in water using bio-renewable alcohols. The quinoxalines were successfully synthesized from a wide range of diamines and nitroamines with diols in air. Interestingly, benzimidazoles and quinazolines were synthesized with excellent isolated yields without using any external base. Finally, the preparative scale synthesis of various N-heterocycles and pharmaceutically active quinoxalines established the practicability of this protocol. For this iridium system, a metal-ligand cooperative mechanism was proposed based on kinetic and DFT studies.
- Chakrabarti, Kaushik,Maji, Milan,Kundu, Sabuj
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supporting information
p. 1999 - 2004
(2019/04/27)
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- Thermally triggered solid-state single-crystal-to-single-crystal structural transformation accompanies property changes
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The 1D complex [(CuL0.5H2O)·H2O]n (1) (H4 L = 2,2′-bipyridine-3,3′ ,6,6′-tetracarboxylic acid) undergoes an irreversible thermally triggered single-crystal-to-single-crystal (SCSC) transformation to produce the 3D anhydrous complex [CuL0.5]n (2). This SCSC structural transformation was confirmed by single-crystal X-ray diffraction analysis, thermogravimetric (TG) analysis, powder X-ray diffraction (PXRD) patterns, variable-temperature powder X-ray diffraction (VT-PXRD) patterns, and IR spectroscopy. Structural analyses reveal that in complex 2, though the initial 1D chain is still retained as in complex 1, accompanied with the Cu-bound H2O removed and new O(carboxyl)-Cu bond forming, the coordination geometries around the CuII ions vary from a distorted trigonal bipyramid to a distorted square pyramid. With the drastic structural transition, significant property changes are observed. Magnetic analyses show prominent changes from antiferromagnetism to weak ferromagnetism due to the new formed Cu1-O-C-O-Cu4 bridge. The catalytic results demonstrate that, even though both solid-state materials present high catalytic activity for the synthesis of 2-imidazolines derivatives and can be reused, the activation temperature of complex 1 is higher than that of complex 2. In addition, a possible pathway for the SCSC structural transformations is proposed.
- Li, Quan-Quan,Ren, Chun-Yan,Huang, Yang-Yang,Li, Jian-Li,Liu, Ping,Liu, Bin,Liu, Yang,Wang, Yao-Yu
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supporting information
p. 4703 - 4711
(2015/03/18)
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- Efficient synthesis of 2-imidazolines in the presence of molecular iodine under ultrasound irradiation
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An efficient one-pot synthesis process for preparing 2-imidazolines from aldehydes and ethylenediamine using molecular iodine and potassium carbonate in absolute ethanol at 25-30°C under ultrasound irradiation is described. The synthetic strategy has the following advantages: mild conditions and low costs requirements, readily available catalyst, short reaction times, simplicity of operation, and good-to-excellent yields.
- Chen, Guo-Feng,Li, Hong-Yang,Xiao, Nan,Chen, Bao-Hua,Song, Ya-Li,Li, Ji-Tai,Li, Zhi-Wei
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p. 1516 - 1521
(2014/12/11)
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- Palladium-catalyzed multicomponent synthesis of 2-aryl-2-imidazolines from aryl halides and diamines
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An efficient palladium-catalyzed three-component reaction that combines aryl halides, isocyanides, and diamines provides access to 2-aryl-2-imidazolines in yields up to 96%. Through variation of the diamine component, the reaction can be extended to the s
- Geden, Joanna V.,Pancholi, Alpa K.,Shipman, Michael
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p. 4158 - 4164
(2013/05/22)
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- Novel diversely substituted 1-heteroaryl-2-imidazolines for fragment-based drug discovery
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A palladium-catalyzed Buchwald-Hartwig arylation protocol has been applied to achieve high-yielding N-heteroarylation of a diverse set of privileged 2-imidazolines. The resulting compounds are of interest as a novel type of molecular tool for fragment-bas
- Krasavin, Mikhail
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scheme or table
p. 2876 - 2880
(2012/07/28)
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- Trichloroisocyanuric acid as an efficient homogeneous catalyst for the chemoselective synthesis of 2-substituted oxazolines, imidazolines and thiazolines under solvent-free condition
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Trichloroisocyanuric acid, as a commercially available and inexpensive catalyst, was used in a new, facile and efficient procedure for the synthesis of 2-oxazolines, 2-imidazolines and 2-thiazolines through the reaction of nitriles with 2-aminoethanol, ethylenediamine or 2-aminoethanethiol under solvent-free conditions.
- Hojati, Seyedeh Fatemeh,Nezhadhoseiny, Seyede Atefe
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p. 1181 - 1189,9
(2020/09/14)
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- Synthesis, characterisation and application of iridium(III) photosensitisers for catalytic water reduction
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The synthesis of novel, monocationic iridium(III) photosensitisers (Ir-PSs) with the general formula [IrIII(C^N)2(N^N)]+ (C^N: cyclometallating phenylpyridine ligand, N^N: neutral bidentate ligand) is described. The structures obtained were examined by cyclic voltammetry, UV/Vis and photoluminescence spectroscopy and X-ray analysis. All iridium complexes were tested for their ability as photosensitisers to promote homogeneously catalysed hydrogen generation from water. In the presence of [HNEt 3][HFe3(CO)11] as a water-reduction catalyst (WRC) and triethylamine as a sacrificial reductant (SR), seven of the new iridium complexes showed activity. [Ir(6-iPr-bpy)(ppy)2]PF 6 (bpy: 2,2′-bipyridine, ppy: 2-phenylpyridine) turned out to be the most efficient photosensitiser. This complex was also tested in combination with other WRCs based on rhodium, platinum, cobalt and manganese. In all cases, significant hydrogen evolution took place. Maximum turnover numbers of 4550 for this Ir-PS and 2770 for the Fe WRC generated in situ from [HNEt 3][HFe3(CO)11] and tris[3,5- bis(trifluoromethyl)phenyl]phosphine was obtained. These are the highest overall efficiencies for any Ir/Fe water-reduction system reported to date. The incident photon to hydrogen yield reaches 16.4 % with the best system. Copyright
- Gaertner, Felix,Cozzula, Daniela,Losse, Sebastian,Boddien, Albert,Anilkumar, Gopinatan,Junge, Henrik,Schulz, Thomas,Marquet, Nicolas,Spannenberg, Anke,Gladiali, Serafino,Beller, Matthias
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experimental part
p. 6998 - 7006
(2011/07/29)
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- Copper-catalyzed synthesis of 2-imidazolines and their N-hydroxyethyl derivatives under various conditions
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A rapid and efficient method for the synthesis of 2-imidazolines and their N-hydroxyethyl derivatives from the reaction of aromatic nitriles with ethylenediamine (EDA) or N-(2-aminoethyl)ethanolamine (AEEA) using cupric indole-3-acetate (Cu(II)-(IAA)2) as a reusable catalyst under reflux and microwave conditions is reported. And seven new N-hydroxyethyl-imidazolines were reported for the first time.
- Zhang, Jin,Wang, Xiao,Yang, Meipan,Wan, Kerou,Yin, Bing,Wang, Yunxia,Li, Jianli,Shi, Zhen
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experimental part
p. 1578 - 1582
(2011/04/26)
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- Efficient and one-pot catalytic synthesis of 2-imidazolines and bis-imidazolines with p-toluenesulfonic acid under solvent free conditions
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A practical, efficient, and inexpensive method for the synthesis of 2-imidazoline from the reaction of nitriles with ethylenediamine or 1,2-propanediamine using p-toluenesulfonic acid or pyridinium p-toluenesulfonate under reflux conditions is reported. This catalyst can be successfully applied for the chemoselective conversion of dicyanobenzenes to corresponding mono- and bis-imidazolines. The applications of these catalysts are feasible because of easy preparation, easy handling, stability, inexpensive, good activity, and eco-friendly.
- Nasr-Esfahani, Masoud,Montazerozohori, Morteza,Mehrizi, Safie
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experimental part
p. 249 - 254
(2011/05/07)
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- Tricyclic imidazole antagonists of the Neuropeptide S Receptor
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A new structural class of potent antagonists of the Neuropeptide S Receptor (NPSR) is reported. High-throughput screening identified a tricyclic imidazole antagonist of NPSR, and medicinal chemistry optimization of this structure was undertaken to improve potency against the receptor as well as CNS penetration. Detailed herein are synthetic and medicinal chemistry studies that led to the identification of antagonists 15 and NPSR-PI1, which demonstrate potent in vitro NPSR antagonism and central exposure in vivo.
- Trotter, B. Wesley,Nanda, Kausik K.,Manley, Peter J.,Uebele, Victor N.,Condra, Cindra L.,Gotter, Anthony L.,Menzel, Karsten,Henault, Martin,Stocco, Rino,Renger, John J.,Hartman, George D.,Bilodeau, Mark T.
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scheme or table
p. 4704 - 4708
(2010/10/02)
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- 1,3-Dibromo-5,5-dimethylhydantoin as an efficient homogeneous catalyst for the synthesis of 2-arylthiazolines and 2-arylimidazolines
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A simple, facile, and efficient procedure for the synthesis of 2-arylthizolines and 2-arylimidazolines has been developed by the simple condensation of nitriles with 2-aminoethanethiol or ethylenediamine catalyzed by 1,3-dibromo-5,5-dimethylhydantoin under solvent-free conditions. Selective preparation of bisthiozolines and monoimidazolines from dinitriles and also selective conversion of arylnitriles to their corresponding 2-arylthiazolines or imidazolines in the presence of alkylnitriles can be considered as considerable advantages of this method.
- Hojati, Seyedeh Fatemeh,Mohammadpoor-Baltork, Iraj,Maleki, Behrooz,Gholizadeh, Mostafa,Shafiezadeh, Fatemeh,Haghdoust, Mahnaz
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experimental part
p. 135 - 141
(2010/04/04)
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- Efficient catalytic synthesis of 2-imidazolines and bis-imidazolines with silica supported tungstosilicic acid
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A rapid and efficient preparation of 2-imidazolines and bis-imidazolines by the reaction of ethylenediamine or 1,2-propanediamine with nitriles in the presence of catalytic amounts of tungstosilicic acid supported on SiO 2 under reflux condition, is reported. The advantages of this procedure are moderate reaction times, good to high yields and the ability to carry out the large scale reactions. ARKAT USA, Inc.
- Nasr-Esfahani, Masoud,Montazerozohori, Morteza,Moghadam, Majid,Akhlaghia, Parisa
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experimental part
p. 97 - 109
(2010/08/04)
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- Ultrasound promoted synthesis of 2-imidazolines in water: A greener approach toward monoamine oxidase inhibitors
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A series of sixteen 2-substituted-2-imidazolines (where the substituent R = Ph, Me-4-Ph; MeO-4-Ph; (MeO)2-3,4-Ph; (MeO)3-3,4,5-Ph; Ph-4-O-C(O)-Ph; Cl-4-Ph; Cl-2-Ph; Cl2-2,4-Ph; NO2-4-Ph; NO2-3-Ph; Naphth-2-yl; Fur-2-yl; Benzofur-2-yl; Pyridin-2-yl; Quinolin-2-yl) has been synthesized from the reaction of the substituted-aldehydes and ethylenediamine by ultrasound irradiation with NBS in an aqueous medium in high yields (80-99%). The 2-imidazoline ability to inhibit the activity of the A and B isoforms of monoamine oxidase (MAO) was investigated and some of them showed potent and selective MAO inhibitory activity especially for the MAO-B isoform and could become promising candidates for future development.
- Sant' Anna, Gabriela da S.,Machado, Pablo,Sauzem, Patricia D.,Rosa, Fernanda A.,Rubin, Maribel A.,Ferreira, Juliano,Bonacorso, Helio G.,Zanatta, Nilo,Martins, Marcos A.P.
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experimental part
p. 546 - 549
(2011/03/19)
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- Facile preparation of 2-imidazolines from aldehydes with tert-butyl hypochlorite
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An efficient and high-yield preparation of 2-imidazolines was achieved from aldehydes and ethylenediamines in the presence of tert-butyl hypochlorite. By this method, 1,3-bis(imidazolin-2-yl)benzene and 2,6-bis(imidazolin-2-yl) pyridine, which act as chiral ligands, could be prepared directly from the corresponding dialdehydes in high yields. Georg Thieme Verlag Stuttgart.
- Ishihara, Midori,Togo, Hideo
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p. 1939 - 1942
(2008/02/10)
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- One-pot synthesis of imidazolines from aldehydes: detailed study about solvents and substrates
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Imidazolines were prepared in one-pot operation from aldehydes and diamines through oxidation of aminal intermediates by NBS. This method could be applied to various aromatic and aliphatic aldehydes and N-nonsubstituted and N-monosubstituted 1,2-diamines. Furthermore, it was found that CH2Cl2 could be altered to TBME, a more environmentally friendly solvent, in the reaction using N-nonsubstituted 1,2-diamines. The reaction conditions were very mild and chemoselective.
- Fujioka, Hiromichi,Murai, Kenichi,Kubo, Ozora,Ohba, Yusuke,Kita, Yasuyuki
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p. 638 - 643
(2007/10/03)
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- Direct oxidative conversion of aldehydes and alcohols to 2-imidazolines and 2-oxazolines using molecular iodine
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Aldehydes were converted to the corresponding 2-imidazolines and 2-oxazolines in good yields by the reaction with ethylenediamine and aminoethanol, respectively, using molecular iodine and potassium carbonate. Moreover, primary alcohols were directly converted to the corresponding 2-imidazolines and 2-oxazolines via aldehydes in one-pot manner with ethylenediamine and aminoethanol, respectively, using molecular iodine and potassium carbonate.
- Ishihara, Midori,Togo, Hideo
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p. 1474 - 1480
(2007/10/03)
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- Rapid and efficient synthesis of imidazolines and bisimidazolines under microwave and ultrasonic irradiation
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Small assemblies of 2-imidazolines and bisimidazolines from appropriate nitriles and ethylenediamine with catalytic amounts of P2S 5 employing a microwave assisted protocol were prepared. Sonication of this system also led to successful synthesis of 2-imidazolines and bisimidazolines. Another advantage of these systems is the ability to carry out large scale reactions. Springer-Verlag 2007.
- Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Mirkhani, Valiollah,Tangestaninejad, Shahram,Abdollahi-Alibeik, Mohammad,Yousefi, Behrooz H.,Kargar, Hadi
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p. 579 - 583
(2008/02/03)
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- Rapid and efficient synthesis of 2-imidazolines and bis-imidazolines under ultrasonic irradiation
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Rapid and efficient preparation of 2-imidazolines and bis-imidazolines by reaction of ethylenediamine with nitriles in the presence of catalytic amounts of sulfur under ultrasonic irradiation is reported. The advantages of this system are short reaction times, high yields and the ability to carry out large scale reactions.
- Mirkhani, Valiollah,Moghadam, Majid,Tangestaninejad, Shahram,Kargar, Hadi
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p. 2129 - 2132
(2007/10/03)
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- A mild and efficient one-pot synthesis of 2-dihydroimidazoles from aldehydes
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The reactions of various aldehydes and 1,2-diamines followed by NXS treatment proceed at 0°C-rt to give the corresponding dihydroimidazoles in high yields. The reaction is mild, and many functional groups such as halogens, nitriles, and esters can exist.
- Fujioka, Hiromichi,Murai, Kenichi,Ohba, Yusuke,Hiramatsu, Atsushi,Kita, Yasuyuki
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p. 2197 - 2199
(2007/10/03)
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- Synthesis and pharmacological evaluation of imidazoline sites I1 and I2 selective ligands
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Several series of 2-aryl or heterocyclic-imidazoline compounds have been prepared and evaluated in vitro as imidazoline sites (I1 and I2) and α-adrenergic (α1 and α2) receptor ligands. Their pKi values indicate that linkage of the imidazoline moiety at the 2-position with an aromatic substituent dramatically decreases α-adrenergic affinity. I1 sites are more accessible by phenyl imidazolines substituted by a methyl or a methoxy group at the ortho or meta position. Indeed, 2-(2′-methoxyphenyl)-imidazoline (17) is one of the best I1 ligands ever reported (pKi=8.53 and I1/I2>3388). On the other hand, I2 selectivity increases in the presence of a methyl group in the para position. The original compound, 2-(3′-fluoro-4′-tolyl)-imidazoline (31) is a new potent ligand for the I2 sites with high selectivity (pKi=8.53 and I2/I1>3388). Copyright
- Anastassiadou, Maria,Danoun, Sada,Crane, Louis,Baziard-Mouysset, Genevieve,Payard, Marc,Caignard, Daniel-Henri,Rettori, Marie-Claire,Renard, Pierre
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p. 585 - 592
(2007/10/03)
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- Feed compositions containing 2-(α-pyridyl)-Δ2 -heterocyclic compounds
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Selected 2-(α-pyridyl)-Δ2 -heterocyclic compounds are used as active ingredients in animal feed compositions and in methods for increasing the growth or feed efficiency of monogastric animals. An active ingredient for use in this invention is 3,4-dihydro-4-hydroxy-5-(3-hydroxy)-2-pyridinyl)-4-methyl-2H-pyrrole-5-carboxamide.
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