- Rapid ring-opening reactions of epoxides using microwave irradiation
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Copper tetrafluoroborate catalyzes the ring-opening of epoxides with primary, secondary, and tertiary alcohols in short reaction times under microwave irradiation to give β-alkoxyalcohol products in excellent yields. Copyright Taylor & Francis Group, LLC.
- Torborg, Christian,Hughes, David D.,Buckle, Richard,Robinson, Mathew W. C.,Bagley, Mark C.,Graham, Andrew E.
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- Catalytic activities of dicyanoketene acetals in alcoholysis of epoxides
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The catalytic activity of various types of capto-dative ethylenes has been investigated on alcoholysis of epoxides, and dicyanoketene dimethyl acetal (DCKDMA) and dicyanoketene ethylene acetal (DCKEA) are found to be efficient and mild catalysts.
- Miura,Masaki
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- Magnesium hydrogensulfate: A cheap and efficient catalyst for the conversion of epoxides into β-alkoxy alcohols, vicinal-diols, and thiiranes
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The nucleophilic ring opening reactions of epoxides by aliphatic alcohols and water are achieved efficiently in the presence of catalytic amounts of magnesium hydrogensulfate, Mg(HSO4)2, with high degree of regioselectivity. The reactions are chemoselective and many of the other functional groups such as ethereal carbon oxygen bonds as well as carbon-carbon double bond remain intact under the reaction conditions. Epoxides also react with thiourea or ammonium thiocyanate in the presence of Mg(HSO 4)2 to afford the corresponding thiiranes in good to excellent yields.
- Salehi, Peyman,Khodaei, Mohammad Mahdi,Zolfigol, Mohammad Ali,Keyvan, Afsaneh
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- Novel polymer-supported ruthenium and iron complexes that catalyze the conversion of epoxides into diols or diol mono-ethers: Clean and recyclable catalysts
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Polymer-supported metal (Fe or Ru) complexes for epoxide ring opening reactions were successfully prepared by anchoring the bis(2-picolyl)amine ligand onto the polymer poly(chloromethylstyrene-co-divinylbenzene) (PCD); the catalysts showed heterogeneous catalytic activity and easy recyclability in the ring opening reactions of various epoxide substrates with methanol or H 2O at room temperature under mild and neutral conditions. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
- Lee, Sun Hwa,Lee, Eun Yong,Yoo, Dong-Woo,Hong, Sung Jin,Lee, Jung Hwan,Kwak, Han,Lee, Young Min,Kim, Jinheung,Kim, Cheal,Lee, Jin-Kyu
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- Epoxide ring-opening and Meinwald rearrangement reactions of epoxides catalyzed by mesoporous aluminosilicates
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Mesoporous aluminosilicates efficiently catalyze the ring-opening of epoxides to produce β-alkoxyalcohols in high yields under extremely mild reaction conditions. These materials also catalyze the corresponding Meinwald rearrangement in non-nucleophilic solvents to give aldehydes which can be trapped in situ to provide the corresponding acetals in an efficient tandem process. The Royal Society of Chemistry 2009.
- Robinson, Mathew W. C.,Davies, A. Matthew,Buckle, Richard,Mabbett, Ian,Taylor, Stuart H.,Graham, Andrew E.
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- Copper(II) tetrafluoroborate catalyzed ring-opening reaction of epoxides with alcohols at room temperature
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(figure presented) Efficient ring opening of different epoxides by reaction with representative alcohols is presented. These processes were carried out at room temperature and rely on the usefulness of commercial copper tetrafluoroborate as catalyst.
- Barluenga, Jose,Vazquez-Villa, Henar,Ballesteros, Alfredo,Gonzalez, Jose M.
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- Structure and heterogeneous catalytic activity of a coordination polymer containing Cu(NO3)2 and Cu(H2O) 22+ units bridged alternatively by btp ligands (btp=2,6-bis(N′-1,2,4-triazolyl)pyridine)
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The reaction of Cu(NO3)2 containing NH 4PF6 with btp ligands produced a new polymeric compound 1 containing Cu(H2O)22+ and Cu(NO3)2 units alternatively bridged by btp ligands with H-bonds between copper-bonded water and nitrate oxygen atoms. Crystal Data: M=1465.97, space group P2/n, a=11.6300(3) ?, b=12.8000(4) ?, c=19.2960(6) ?, β=98.6200(19)°, V=2840.03(15) ?3, Z=2, μ=0.926 mm-1, Dc=1.714 Mg/m3, R=0.0629, wR=0.1614. The polymeric compound 1 has shown the heterogeneous catalytic activity for the ring opening of epoxides under mild conditions. This catalyst system appears to be an efficient, mild, and easily recyclable method for the alcoholysis of epoxides. In addition, the heterogeneous catalyst 1 has, surprisingly, shown even better catalytic activity than copper salt system in homogeneous condition.
- Sung, Jin Hong,Jin, Soo Seo,Ji, Young Ryu,Jung, Hwan Lee,Kim, Cheal,Kim, Sung-Jin,Kim, Youngmee,Lough, Alan J.
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- Mesoporous aluminosilicate promoted alcoholysis of epoxides
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Mesoporous aluminosilicates efficiently catalyze the ring-opening of epoxides with a range of alcohols to give the corresponding β-alkoxyalcohols in high yields under extremely mild conditions and in short reaction times.
- Robinson, Mathew W.C.,Buckle, Richard,Mabbett, Ian,Grant, Gemma M.,Graham, Andrew E.
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- Fiber-supported Fe(iii) complex catalyst in spinning basket reactor for cleaner ring-opening of epoxides with alcohols
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Herein, a newly designed fiber-supported iron catalyst was successfully synthesized by rooting diamine ligands into the surface layer of commercially available polyacrylonitrile fiber and then utilizing the diamine groups to immobilize Fe(iii) ions for heterogeneous catalytic ring-opening reactions. The resulting materials were characterized and observed in detail by elemental analysis, mechanical properties, FTIR spectroscopy and morphology during both the preparation and the utilization processes. Moreover, the fiber catalyst was used in the spinning basket reactor-mediated ring-opening of various epoxides by a series of alcohols under mild reaction conditions, giving good to quantitative yields of the corresponding β-alkoxy alcohols. In addition, the fiber catalyst in the impellers of the agitation system was shown to be reusable multiple times without leaching of the Fe(iii) ions, and when stored on the shelf remained equally active for at least three months. Furthermore, the catalytic system was convenient and effective for scaling-up experiments and thereby has prospects in industrial applications.
- Shi, Xian-Lei,Sun, Benyu,Hu, Qianqian,Chen, Yongju,Duan, Peigao
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- Novel efficient synthesis of glycol monoethers over a niobium-containing MCM-41 mesoporous molecular sieve
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A niobium-containing MCM-41 mesoporous molecular sieve was synthesized by the hydrolysis of tetraethylorthosilicate and niobium pentachloride, using cetylpyridinium bromide as template in acidic medium, and was found to be highly active in the direct conversion of cyclohexene into trans-2-alkoxycyclohexanol at mild temperature in the presence of H2O2 and alcohol.
- Xin,Suo,Zhang,Zhang
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- Heterogeneous Catalysis of Nucleophilic Substitution
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The opening of an epoxide ring by attack of a nucleophile can be catalysed by the heterogeneous catalyst, crystalline polymeric zirconium phosphate.
- Hodson, Lisa F.,Parker, Tom M.,Whittaker, David
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- 2,3-Dichloro-5,6-dicyano-p-benzoquinone, an efficient, mild, neutral and highly regioselective catalyst for alcoholysis of epoxides
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Ring-opening reactions of epoxides with catalytic amounts of 2,3- Dichloro-5,6-Dicyano-p-Benzoquinone (DDQ) are performed with high regioselectivity under neutral conditions, in primary, secondary and tertiary alcohols as solvents and nucleophiles. The corresponding β- alkoxy alcohols were obtained in excellent yields.
- Iranpoor,Mohammadpour Baltork
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- Fe3+-montmorillonite: An efficient heterogeneous catalyst for highly regioselective alcoholysis of epoxides
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Fe3+- exchanged montmorillonite (Fe3+ -mont) has shown to be a very efficient catalyst for regio and stereoselective alcoholysis of epoxides in primary, secondary and tertiary alcohols as solvents and nucleophiles. Copyright
- Choudary, Boyapati M.,Sudha, Yepuri
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- Carbon tetrabromide: An efficient catalyst for regioselective ring opening of epoxides with alcohols and water
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Epoxides undergo rapid ring opening with a range of alcohols in the presence of catalytic amount of carbon tetrabromide under mild and convenient conditions to afford the corresponding β-alkoxy alcohols and 1,2-diols in high yields with high regioselectivity. Georg Thieme Verlag Stuttgart.
- Yadav,Reddy,Harikishan,Madan,Narsaiah
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- Electrogenerated Acid as an Efficient Catalyst for Alcoholyses and Hydrolyses of Epoxides
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The electrochemical transformation of different epoxides to their corresponding β-alkoxy alcohols and diols was achieved by using an electrogenerated acid-catalyst.A competitive ring-opening reaction of activated epoxides in the presence of deactivated epoxides was also successfully carried out in both alcohols and water.
- Safavi, Afsaneh,Iranpoor, Nasser,Fotuhi, Lida
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- Cross-linked poly(N-vinylpyrrolidone)-titanium tetrachloride complex: A novel stable solid TiCl4 equivalent as a recyclable polymeric Lewis acid catalyst for regioselective ring-opening alcoholysis of epoxides
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Cross-linked poly(N-vinylpyrrolidone) resin beads were prepared as macromolecular ligand precursors by suspension copolymerization of N-vinyl-2-pyrrolidone and N,N′-methylenebisacrylamide (MBA) as a crosslinking agent in water. Subsequently, the resulting polymer carrier precursor was readily combined with titanium tetrachloride to form a stable polymeric coordination complex (PNVP/TiCl4), and this novel stable TiCl4 equivalent evaluated as a heterogeneous and reusable solid Lewis acid catalyst for the regio-and stereoselective nucleophilic ring opening of various epoxides with various alcohols to prepare β-alkoxy alcohols in excellent yields without generating any waste. The MBA-cross-linked PNVP and resultant catalyst were characterized by Fourier transform infrared spectroscopy (FT–IR), field-emission scanning electron microscope (FE–SEM), energy dispersive X-ray (EDX), inductively coupled plasma (ICP), and thermogravimetric analysis (TGA) techniques. Moreover, the catalyst is very stable, easily separated, and reused at least five times without significant loss of activity. In terms of scope, yields, the amount of catalyst used, and reaction time, the PNVP-TiCl4 complex catalyst is an improvement over previously reported heterogeneous catalysts for ring opening of epoxides methods. Further, the experimental outcome revealed that using the copolymer beads as carriers with a high percentage of crosslinking and the high mesh size leads had an adverse effect on the reaction rate.
- Rahmatpour, Ali,Sajjadinezhad, Seyed Mehrzad
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- MBA-cross-linked poly(N-vinyl-2-pyrrolidone)/ferric chloride macromolecular coordination complex as a novel and recyclable Lewis acid catalyst: Synthesis, characterization, and performance toward for regioselective ring-opening alcoholysis of epoxides
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A novel macromolecular-metal coordination complex, MBA-cross-linked PNVP/FeCl3 material was fabricated by immobilization of water intolerant ferric chloride onto the porous cross-linked poly(N-vinyl-2-pyrrolidone) carrier beads as a macromolecular ligand or carrier which was prepared by suspension free-radical copolymerization of N-vinyl-2-pyrrolidone (NVP) and N,N′-methylene bis-acrylamide (MBA) as a crosslinking agent in water. The obtained PNVP/FeCl3 was characterized by UV/vis and FT-IR spectroscopies, TGA, FE-SEM, EDX, and ICP techniques. This heterogenized version of ferric chloride is a convenient and safe alternative to highly water intolerant ferric chloride. The catalytic performance of (PNVP/FeCl3) as an efficient and recyclable polymeric Lewis acid catalyst was appropriately probed in the regio-and stereoselective nucleophilic ring opening of various epoxides with various alcohols in excellent yields with TOF up to 182.48 h?1 without generating any waste. The activity data indicate that this heterogeneous catalyst is very active and could be easily recovered, and reused at least six times without appreciable loss of activity indicating its stability under experimental conditions.
- Rahmatpour, Ali,Zamani, Maryam
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- The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Br?nsted acid catalysts
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The acid–base neutralization reaction of commercially available disodium 2,6-naphthalenedisulfonate (NDS, 2 equivalents) and the tetrahydrochloride salt of tetrakis(4-aminophenyl)methane (TAPM, 1 equivalent) in water gave a novel three-dimensional charge-assisted hydrogen-bonded framework (CAHOF, F-1). The framework F-1 was characterized by X-ray diffraction, TGA, elemental analysis, and 1H NMR spectroscopy. The framework was supported by hydrogen bonds between the sulfonate anions and the ammonium cations of NDS and protonated TAPM moieties, respectively. The CAHOF material functioned as a new type of catalytically active Br?nsted acid in a series of reactions, including the ring opening of epoxides by water and alcohols. A Diels–Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate, providing some dissolved F-1 as the real catalyst. In all cases, the catalyst could easily be recovered and recycled.
- Belokon, Yuri N.,Dmitrienko, Artem O.,Gak, Alexander S.,Gerasimov, Igor S.,Kuznetsova, Svetlana A.,Larionov, Vladimir A.,Li, Han,Medvedev, Michael G.,Nelyubina, Yulia V.,North, Michael,Saghyan, Ashot S.,Smol'yakov, Alexander F.,Zhereb, Vladimir P.
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supporting information
p. 1124 - 1134
(2020/07/10)
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- Synthesis and structure of an air-stable bis(pentamethylcyclopentadienyl) zirconium pentafluorbezenesulfonate and its application in catalytic epoxide ring-opening reactions
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An air-stable mononuclear complex of bis(pentamethylcyclopentadienyl) zirconium pentafluorbezenesulfonate was successfully synthesized by treating C6F5SO3Ag with [(CH3)5Cp]2ZrCl2, which showed the cationic uninuclear structure of [{(CH3)5Cp}2Zr(CH3CN)2(H2O)][OSO2C6F5]2·CH3CN (1) confirmed by the X-ray analysis. Complex 1 was also characterized by other techniques and found to have the good nature of air-stability, water tolerance, thermally-stability and strong Lewis-acidity. Moreover, the complex showed high catalytic activity and recyclability in catalytic epoxide ring-opening reactions by amines or alcohols. This catalytic system affords a simple and efficient approach for synthesis of β-amino alcohols or β-alkoxy alcohols.
- Li, Ningbo,Wang, Lingxiao,Wang, Haojiang,Qiao, Jie,Zhao, Wenjie,Xu, Xinhua,Liang, Zhiwu
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p. 1033 - 1039
(2018/02/06)
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- Introduction of an effective and economical heterogeneous ruthenium catalyst for regioselective ring-opening of epoxides and the friedel-crafts alkylation reaction of indoles and pyrroles
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Background: Metal organic frameworks square measure crystalline materials with fascinating chemical and physical attributes that include metal ions or clusters and multidentate organic particles. MOFs acquire the expected traits to be employed in classical applications similar to heterogeneous catalysis and storage and separation of gases and different Compounds. Post-synthetic modification (PSM) is an associate replacement method to prepare functionalized MOFs. Methods: The IRMOF-3-PI-RuCl3 was prepared by refluxing a combination of IRMOF-3-PI, [H(DMSO)2][RuCl4(DMSO)2] and ethanol. The amount of ruthenium metal in catalyst was found to be 2.35 w% based on ICP analysis. To perform the ring opening reaction, a solution of styrene oxide, indole, pyrole or alcohol nucleophile, in methanol, IRMOF-3-PI-RuCl3 was added. After completion of the reaction, the catalyst was precipitated. Results: A MOF-supported metal catalyst (IRMOF-3-PI-RuCl3) was designed and synthesized by postsynthetic method. The BET surface area of the final catalyst was slightly reduced as determined by N2 sorption experiments. The results showed that the provided catalyst has a high potential for the ring opening of epoxides with alcohols, indoles and pyrroles under gentle conditions. Conclusion: In summary, a simple, rapid, economical and an effective route for the alcoholysis of epoxides and therefore the Friedel-Crafts alkylation of indoles and pyrroles via an basically regioselective ring opening of epoxides with aliphatic and aromatic amines using IRMOF-3-PI-RuCl3 with cage type poriferous structure as heterogeneous catalysts, has been established. This methodology is very regioselective in numerous instances that give the products with high yield for e.g. in aromatic and aliphatic amines. Ease of separation and straightforward workup are among other advantages of this catalyst.
- Tabatabaeian, Khalil,Zanjanchi, Mohammad Ali,Mahmoodi, Nosrat O.,Eftekhari, Tooraj
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p. 207 - 217
(2017/06/21)
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- A highly efficient protocol for regioselective ring-opening of epoxides with alcohols, water, acetic acid, and acetic anhydride catalyzed by SbF3
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SbF3as an efficient catalyst has been used for regioselective alcoholysis, acetolysis and hydrolysis of epoxides to the corresponding β-alkoxy, β-acetoxy alcohols, and 1,2-diols in high to excellent yields. This study also represents a convenient synthesis of vic-diacetates from ring-opening of epoxides with acetic anhydride.
- Zeynizadeh, Behzad,Gilanizadeh, Masumeh,Aminzadeh, Farkhondeh Mohammad
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p. 1051 - 1056
(2016/07/06)
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- Design and preparation of a polymer resin-supported organoselenium catalyst with industrial potential
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Hexavalent Se? Yes! Selenium on polymers exhibits quite different properties compared to that in small molecules. Hexavalent Se, rare in organoselenium chemistry, was found to be the major species on polymers. The high-valent Se species on recyclable polymer resins could quickly catalyze the oxidation reaction of cyclohexene with H2O2 in water to produce industrially important intermediate trans-1,2-cyclohexanediol in almost quantitative yield. In the catalytic cycle, high valent Se species were reduced to divalent Se, a highly activated species that could be re-oxidized by air so that no excess H2O2 was required for the reaction. The results were superior to those of reactions catalyzed by small molecules, for which excess H2O2, long reaction time or expensive CF3-activated catalysts and environmentally unfriendly MeCN solvent were required.
- Wang, Yuguang,Yu, Lihua,Zhu, Bingchun,Yu, Lei
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p. 10828 - 10833
(2016/07/21)
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- Mild regiospecific alcoholysis and aminolysis of epoxides catalyzed by zirconium(IV) oxynitrate
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A regiospecific method for the ring-opening reaction of epoxides by the primary, secondary, tertiary alcohols, and aryl, aliphatic amines has been developed using non-toxic metal nitrate salt as a catalyst. The best results were obtained using zirconium(IV) oxynitrate among the various screened metal nitrate salts. The reported protocol works efficiently for styrene epoxide and aliphatic as well.
- Shinde, Sandip S.,Said, Madhukar S.,Surwase, Trupti B.,Kumar, Pradeep
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supporting information
p. 5916 - 5919
(2015/11/02)
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- Comparative studies on the catalytic activity and structure of a Cu-MOF and its precursor for alcoholysis of cyclohexene oxide
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The wide use of metal-organic frameworks (MOFs) in heterogeneous catalysis has been limited due to the fact that the coordination sphere of the metal ions in most known MOF structures is completely blocked by the organic linkers. In this work, a comparative structural study of the precursor Cu(BF4)2·nH2O (active metal salt catalyst) and the derived Cu-MOF was carried out by using solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) techniques combined with the study of the interaction of the materials with different reactant molecules by thermogravimetry coupled with mass spectrometry (TG-MS). We clarify how an ideal MOF catalyst can keep the same high reactivity as its metal precursor, and how the existing efficient metal salt/complex catalysts can be linked to analogously reactive MOF catalysts. By choosing proper precursors and organic linkers, MOFs can keep an unsaturated and flexible coordination sphere, which endows them with unique guest-induced reactivity and reactant shape selectivity. The labile coordination facilitates MOFs to perform as well as metal complexes in alcoholysis of cyclohexene oxide but affording good recyclability.
- Jiang, Yijiao,Huang, Jun,Hunger, Michael,Maciejewski, Marek,Baiker, Alfons
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p. 897 - 902
(2015/02/19)
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- Temperature-dependent immobilization of a tungsten peroxo complex that catalyzes the hydroxymethoxylation of olefins
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Abstract A tungsten peroxo complex stabilized by the bidentate picolinato ligand has been synthesized and then immobilized successfully on imidazole-functionalized silica. The immobilized tungsten-based catalyst was employed as an efficient catalyst for the one-pot synthesis of β-alkoxy alcohols from olefins and methanol with H2O2. Regarding the catalyst evaluation and the results of characterization by the various methods, it was demonstrated that the immobilization of tungsten peroxo complex was highly temperature-dependent. The tungsten peroxo complex can dissociate and diffuse into the liquid phase at reaction temperature, resulting in a homogeneous reaction. Nevertheless, the catalytically active species was anchored on the imidazole-functionalized silica by hydrogen bonding as the temperature was lowered to 0°C after the reaction, which thus offered a highly effective approach for recycling the catalyst for consecutive cycles. In addition, various olefins can be converted to the corresponding β-alkoxy alcohols with good conversion and selectivity under relative mild conditions by H2O2. Running hot and cold: A tungsten peroxo complex (see picture) can dissociate and diffuse into the liquid phase at the reaction temperature, resulting in a homogeneous reaction. After reaction, the catalytically active species was anchored on the functionalized silica by hydrogen-bonding as the temperature was lowered to 0°C. This offers an effective approach for catalyst recovery and recycling.
- Chen, Jizhong,Hua, Li,Chen, Chen,Guo, Li,Zhang, Ran,Chen, Angjun,Xiu, Yuhe,Liu, Xuerui,Hou, Zhenshan
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p. 1029 - 1037
(2015/06/08)
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- Ring opening of epoxides with alcohols using Fe(Cp)2BF 4 as catalyst
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Fe(Cp)2BF4 is an efficient catalyst for the alcoholysis of aromatic, aliphatic, and cyclic epoxides giving excellent yields of the corresponding β-alkoxy alcohols under ambient conditions. The methanolysis of styrene oxide using Fe(Cp)2BF4 as a catalyst (5 mol %) gave excellent yield of 2-methoxy-2-phenylethanol with complete regio-selectivity. The ring opening of cyclic epoxides gave 77-97% yields of trans-β-methoxy alcohols, in 0.5-6 h. The use of 1,2-epoxyhexane and 1,2-epoxydodecane as substrates gave both regioisomers in excellent yields. The first order rate of reaction with respect to catalyst was observed for the kinetics of ring opening of 1,2-epoxyhexane with methanol.
- Yadav, Geeta Devi,Singh, Surendra
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supporting information
p. 3979 - 3983
(2014/07/08)
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- Efficient and regioselective ring-opening of epoxides with alcohols and sodium azide by using catalytic amounts of gacl3/polyvinylpyrrolidone
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A new polymeric catalyst was prepared by supporting GaCl3 on cross-linked polyvinylpyrrolidone (GaCl3/ PVP). This catalyst was employed for efficient and regioselective ring-opening reaction of epoxides by various alcohols under solvent-free conditions at room temperature. In our procedure, this heterogeneous catalyst was used at neutral and mild reaction conditions to afford high yields of β-alkoxy alcohols. Also, regioselective conversion of epoxides to β-azidohydrines was accomplished by sodium azide in MeOH in the presence of GaCl3/PVP at room temperature. GaCl3/PVP is a non-hygroscopic and recoverable catalyst and is easily separated from reaction mixture by a simple filtration and re-used repeatedly. Also, this catalyst has good handling and can be stored for long time without any reducing of its reactivity.
- Pourali, Ali Reza,Ghayeni, Samaneh,Afghahi, Fatemeh
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p. 1741 - 1744
(2013/07/26)
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- Olefin metathesis as a tool for multinuclear Co(III)salen catalyst construction: Access to cooperative catalysts
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The construction of novel (macrocyclic) multinuclear Co(iii)salen catalysts is reported. Olefin metathesis has been used as a key construction tool for the multimetallic structures starting from versatile allyl-substituted salen scaffolds. The Co(iii) complexes were tested in the hydrolytic kinetic resolution of (rac)-1,2-epoxyhexane and epoxide ring opening reactions using methanol as the nucleophile. The preliminary results suggest a cooperative mode of catalysis in the case of bis-Co(iii)salen macrocycle 10. The Royal Society of Chemistry.
- Haak, Robert M.,Martinez Belmonte, Marta,Escudero-Adan, Eduardo C.,Benet-Buchholz, Jordi,Kleij, Arjan W.
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experimental part
p. 593 - 602
(2010/04/04)
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- Copper-based metal-organic framework for the facile ring-opening of epoxides
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A simplified, facile route was applied for the synthesis of Cu(bpy)(H2O)2(BF4)2(bpy) [Cu-MOF] from Cu(BF4)2sH2O and 4,4′-bipyridine in aqueous ethanol. The Cu-MOF catalyst was characterized by XRD, elemental analysis, N2 adsorption, SEM, TEM, and electron diffraction. The crystalline Cu-MOF is an efficient catalyst in the ring-opening reactions of epoxides with alcohols and aniline under ambient, solvent-free conditions. The catalytic activity of Cu-MOF was comparable to that of the homogeneous catalyst Cu(BF4)2sH2O in the case of methanolysis, but the relative activity dropped significantly with increasing steric bulkiness of the alcohol, indicating the location of active sites in micropores. Although the catalyst was found to be truly heterogeneous and recyclable with no loss of activity, XRD revealed some restructuring due to interaction with methanol. This restructuring is attributed to the partial replacement of the structural water molecules by methanol, leading to significant changes in the H-bonding system of Cu-MOF.
- Jiang, Dongmei,Mallat, Tamas,Krumeich, Frank,Baiker, Alfons
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experimental part
p. 390 - 395
(2009/02/05)
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- Hydrogen bonding lowers intrinsic nucleophilicity of solvated nucleophiles
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The relationship between nucleophilicity and the structure/environment of the nucleophile is of fundamental importance in organic chemistry. In this work, we have measured nucleophilicities of a series of substituted alkoxides in the gas phase. The functional group substitutions affect the nucleophiles through ion-dipole, ion-induced dipole interactions and through hydrogen bonding whenever structurally possible. This set of alkoxides serves as an ideal model system for studying nucleophiles under microsolvation settings. Marcus theory was applied to analyze the results. Using Marcus theory, we separate nucleophilicity into two independent components, an intrinsic nucleophilicity and a thermodynamic driving force determined solely by the overall reaction exothermicity. It is found that the apparent nucleophilicities of the substituted alkoxides are always much lower than those of the unsubstituted ones. However, ion-dipole, ion-induced dipole interactions, by themselves, do not significantly affect the intrinsic nucleophilicity; the decrease in the apparent nucleophilicity results from a weaker thermodynamic driving force. On the other hand, hydrogen bonding not only stabilizes the nucleophile but also increases the intrinsic barrier height by 3 to ~4 kcal mol-1. In this regard, the hydrogen bond is not acting as a perturbation in the sense of an external dipole but more directly affects the electronic structure and reactivity of the nucleophilic alkoxide. This finding offers a deeper insight into the solvation effect on nucleophilicity, such as the remarkably lower reactivities in nucleophilic substitution reactions in protic solvents than in aprotic solvents.
- Chen, Xin,Brauman, John I.
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scheme or table
p. 15038 - 15046
(2009/03/12)
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- ASYMMETRIC CATALYTIC HYDROGENATION OF PROCHIRAL KETONES AND ALDEHYDES
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Process for stereoselective hydrogenation by reacting racemic aldehydes or ketones having a stereogenic carbon atom in the position relative to the C(O) group and containing the structural element -(O)C-C-CH- by means of hydrogen in the presence of a base and a ruthenium complex containing a bidentate ligand having coordinating P and N atoms, a monophosphine ligand and anionic and/or uncharged ligands as homogeneous catalyst, with the charge being balanced by one or two monovalent acid anions or a divalent acid anion when uncharged ligands are present.
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Page/Page column 27
(2010/11/28)
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- Mild and efficient ring opening of epoxides catalyzed by potassium dodecatungstocobaltate(III)
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Efficient ring opening of epoxides under mild conditions is reported. Potassium dodecatungstocobaltate(III) trihydrate was used as an efficient catalyst for the alcoholysis and acetolysis of epoxides. Conversion of epoxides to thiiranes was also performed efficiently in the presence of this catalyst. Springer-Verlag 2005.
- Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Yadollahi, Bahram,Mirmohammadi, S. Mohammad R.
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p. 235 - 242
(2007/10/03)
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- Reduction of carbonyl compounds by lanthanide metal/2-propanol: In-situ generation of samarium isopropyloxide for stereoselective Meerwein-Ponndorf- Verley reduction
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The reduction of ketones and aldehydes with lanthanide metals (La, Ce, Sm, Yb) and a catalytic amount of iodine (5 mol %) in iPrOH proceeded smoothly to produce the corresponding alcohols as the major products in good yield, while in THF, methanol, and ethanol the pinacols were mainly produced. The yields of alcohols were improved most effectively by the use of Sm metal, the amount of pinacol produced thus being minimized. The actual reducing agent may be samarium isopropyloxide, which mediates the Meerwein-Ponndorf-Verley-type hydride-transfer reaction, since the reaction can be carried out catalytically with respect to samarium. The stereoselectivities of the reductions of the 2- and 4-substituted cyclohexanones with Sm/iPrOH were higher than those achieved with SmI2/iPrOH or Sm/ H20. The asymmetric reduction of acetophenone could be achieved to give the 1-phenylethanol in up to 95% ee in the presence of the chiral ligand 7. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Fukuzawa, Shin-Ichi,Nakano, Narihito,Saitoh, Takahide
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p. 2863 - 2867
(2007/10/03)
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- Rapid and efficient ring opening of epoxides catalyzed by a new electron deficient tin(IV) porphyrin
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The new electron deficient tin(IV) tetraphenylporphyrinato trifluoromethanesulfonate, [SnIV(tpp)(OTf)2], was used as an efficient catalyst for the alcoholysis, hydrolysis and acetolysis of epoxides. Conversion of epoxides to thiiranes and acetonides were also performed efficiently in the presence of this catalyst.
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Shaibani, Reza
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p. 6105 - 6111
(2007/10/03)
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- Silica sulfuric acid; an efficient and reusable catalyst for regioselective ring opening of epoxides by alcohols and water
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The nucleophilic ring opening reactions of epoxides by aliphatic alcohols and water are achieved efficiently in the presence of catalytic amounts of silica sulfuric acid with high degree of regioselectivity. The catalyst is reusable and can be applied several times without any decrease in the yield of reactions.
- Salehi, Peyman,Dabiri, Minoo,Zolfigol, Mohammad Ali,Fard, Mohammad Ali Bodaghi
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p. 1113 - 1121
(2007/10/03)
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- Scandium-bipyridine-catalyzed enantioselective addition of alcohols and amines to meso-epoxides
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A winning combination of metal and ligand: The catalyst formed in situ from Sc(OTf)3 and bipyridine 1 (10 mol%) mediates the alcoholysis and aminolysis of Mieso-epoxides in high enantioselectivities and furnishes valuable chiral 1,2-diol monoethers 2 and 1,2-amino alcohols 3 as products (PMB = para-methoxybenzyl).
- Schneider, Christoph,Sreekanth, Anakallil R.,Mai, Enzo
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p. 5691 - 5694
(2007/10/03)
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- Efficient regio- and stereoselective ring opening of epoxides with alcohols, acetic acid and water catalyzed by ammonium decatungstocerate(IV)
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Epoxides can be cleaved in a regio- and stereoselective manner under neutral conditions with alcohols and acetic acid in the presence of catalytic amounts of decatungstocerate(IV) ion, ([CeW10O36] 8-), affording the corresponding β-alkoxy and β-acetoxy alcohols in high yields. In water, ring opening of epoxides occurs with this catalyst to produce the corresponding diols in good yields.
- Mirkhani, Valiollah,Tangestaninejad, Shahram,Yadollahi, Bahram,Alipanah, Ladan
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p. 8213 - 8218
(2007/10/03)
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- Synthesis, structure and heterogeneous catalytic activity of a coordination polymer containing tetranuclear Cu(II)-btp units connected by nitrates
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Synthesis, structure and heterogenous catalytic activity of a coordination polymer containing tetranuclear Cu(II)-btp units connected by nitrates were studied. Blue block-type crystals were obtained from the direct diffusion technique. With acetate counteranions, a discrete Cu(II) molecule was obtained. This polymer is an effective heterogeneous catalyst for regioselective ring opening of epoxide by methanol.
- Yoo, Sang-Kun,Ryu, Ji Young,Lee, Jun Yong,Kim, Cheal,Kim, Sung-Jin,Kim, Youngmee
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p. 1454 - 1456
(2007/10/03)
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- Hydrogenation of α-Keto Ethers: Dynamic Kinetic Resolution with a Heterogeneous Modified Catalyst and a Heterogeneous Base
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The first successful example of the asymmetric hydrogenation of substituted α-keto ethers with Cinchona-modified Pt/Al2O3 is reported. In the absence of an additional base, kinetic resolution of the racemic starting material was observed with high diastereoselectivity and ee's up to 98% at conversions of a strong reaction acceleration but racemic product. Immobilization of OH- on solid ion exchangers resulted in the desired dynamic kinetic resolution, and ee's of >80% were obtained at >95% conversion. These effects are rationalized on the basis of a simple kinetic and structural model.
- Studer, Martin,Blaser, Hans-Ulrich,Burkhardt, Stephan
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p. 511 - 515
(2007/10/03)
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- Aminopropyl silica gel supported iodine as catalyst in nucleophilic ring opening of epoxides and episulfides
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Silica gel functionalized by aminopropyl group was prepared. Iodine was then supported on this inorganic polymer and used as a stable and efficient heterogeneous catalyst for nucleophilic ring opening reactions of epoxides and episulfides in different nucleophilic solvents such as alcohols, water and acetic acid.
- Tamami,Iranpoor,Mahdavi
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p. 1251 - 1258
(2007/10/03)
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- Reactions of epoxides and episulfides with electrophilic halogens
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A novel method is described for the conversion of epoxides into β-bromoformates using Ph3PBr2, Ph3P/N-bromosuccinimdes (NBS) and or Ph3P/2,4,4,6-tetrabromo-2,5-cyclohexadiene-1-one (TABCO) in DMF. Epoxides in the presence of Ph3P/I2 were converted into olefins immediately in excellent yields. The application of NBS, NCS, and TABCO as compounds carrying electrophilic halogens for the highly selective alcoholysis of epoxides and dimerization or alcoholysis dimerization of episulfides are also described.
- Iranpoor, Nasser,Firouzabadi, Habib,Chitsazi, Maryam,Ali Jafari, Abbas
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p. 7037 - 7042
(2007/10/03)
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- A novel mononuclear Fe(III) mono(terpyridine) complex having labile solvent ligands and its catalytic activity
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A novel Fe mono(terpyridine) complex was successfully prepared by deliberately choosing the polymer surface-anchored terpyridine as a chelating ligand and it showed an excellent catalytic activity with an easy reusability on the ring-opening reaction of various epoxides by alcohol and water under mild and neutral conditions to give stereospecific and regioselective products.
- Yoo, Dong-Woo,Yoo, Sang-Kun,Kim, Cheal,Lee, Jin-Kyu
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p. 3931 - 3932
(2007/10/03)
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- Reduction of aliphatic and aromatic cyclic ketones to sec-alcohols by aqueous titanium trichloride/ammonia system. Steric course and mechanistic implications
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In contrast to the dissolved metal and metal hydride reductions, the reduction of cyclic ketones by the aqueous TiCl3/NH3 system favours the formation of the less thermodynamically stable axial alcohol. The ammonium ion formed in situ is essential for the reduction to proceed because it behaves as a mild Br?nsted acid in basic medium and favours the protonation of the intermediate ketyl. The corresponding α-hydroxy radical is then rapidly reduced under conditions where the first electron transfer to the substrate takes place. We suggest that the stereoselectivity is determined by the second reduction step, which occurs through the less hindered transition state, regardless of whether the radical to be reduced is thermodynamically favoured or not.
- Clerici, Angelo,Pastori, Nadia,Porta, Ombretta
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p. 2235 - 2243
(2007/10/03)
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- Ytterbium trifluoromethanesulfonate Yb(OTf)3: An efficient, reusable catalyst for highly selective formation of β-alkoxy alcohols via ring-opening of 1,2-epoxides with alcohols
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Ytterbium(III)triflate-catalysed ring-opening reactions of epoxides derived from styrene, cyclohexene, norbornene and stilbene, in the presence of alcohols (C1-C4 1°, 2° and 3° aliphatic alcohols, cyclohexyl alcohol, allyl and propargyl alcohol) resulted in the formation of β-alkoxy alcohols in good to excellent yield with high regio-, and, where applicable, stereoselectivity. Reaction of stilbene oxide with methanol in the presence of the diethyl ester of L-(+)-tartaric acid afforded the threo form of 1,2-diphenyl-2-methoxy ethanol with high diastereoselectivity (de 94%). Mechanistic implications of the results are discussed.
- Likhar,Kumar,Bandyopadhyay
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p. 836 - 838
(2007/10/03)
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- Bismuth(III) chloride (BiCl3); an efficient catalyst for mild, regio- and stereoselective cleavage of epoxides with alcohols, acetic acid and water
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Epoxides can be cleaved in a regio- and stereoselective manner with alcohols, acetic acid and water in the presence of catalytic amounts of bismuth(III) chloride, affording the corresponding β-alkoxy and β-acetoxy alcohols and diols in high yields.
- Mohammadpoor-Baltork,Tangestaninejad,Aliyan,Mirkhani
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p. 2365 - 2374
(2007/10/03)
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- Iron(III) trifluoroacetate as an efficient catalyst for solvolytic and nonsolvolytic nucleophilic ring opening of epoxides
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Iron(III) trifluoroacetate was used as an efficient and nonhygroscopic catalyst for the alcoholysis, hydrolysis, and acetolysis of epoxides. The addition of chloride, bromide, iodide, and nitrate ions to epoxides to produce the corresponding 2-halo and 2-nitratoalkanols and also the conversion of epoxides to acetonides and thiiranes were also performed efficiently in the presence of this catalyst.
- Iranpoor, Nasser,Adibi, Hadi
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p. 675 - 680
(2007/10/03)
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- Ferric perchlorate: An efficient reagent for regio- and stereoselective alcoholysis and hydrolysis of epoxides
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Regio- and stereoselective ring opening reaction of epoxides is achieved efficiently by aliphatic alcohols and water in the presence of catalytic amounts of ferric perchlorate.
- Salehi, Peyman,Seddighi, Behnam,Irandoost, Mohsen,Kargar Behbahani, Farahnaz
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p. 2967 - 2973
(2007/10/03)
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- Rhodium-catalyzed ring opening of vinyl epoxides with alcohols and aromatic amines
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(equation presented) [Rh(CO)2Cl]2 is an effective catalyst for the ring opening of vinyl epoxides with alcohols and aromatic amines under neutral conditions at room temperature. The reaction occurs with excellent diastereo- and regioselectivity (>20:1) giving the trans-1,2-amino alcohols or alkoxy alcohols for a wide range of substrates. The regio- and stereochemistry of these reactions is complementary to that typically obtained with palladium-catalyzed ring openings of vinyl epoxides.
- Fagnou, Keith,Lautens, Mark
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p. 2319 - 2320
(2007/10/03)
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- Optical resolution of racemic alcohols via diastereoisomeric supramolecular compound formation with O,O'-dibenzoyl-(2R,3R)-tartaric acid
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O,O'-Dibenzoyl-(2R,3R)-tartaric acid (DBTA) forms a hydrogen bonded supramolecular compound with alcohols. The supra-molecular compound formation is enantioselective for a large number of chiral alcohols, therefore DBTA can be used as resolving agent, also for compounds having no basic group. The condition of the complex formation is that the guest molecule should contain a proton donating group and a fitting aliphatic chain or cycloalkane ring. (C) 2000 Elsevier Science Ltd.
- Kassai, Csaba,Juvancz, Zoltán,Bálint, József,Fogassy, Elemér,Kozma, Dávid
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p. 8355 - 8359
(2007/10/03)
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- TiCl3(OTf) and TiO(TFA)2 efficient catalysts for ring opening of epoxides with alcohols, acetic acid and water
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TiCl3 (OTf) and TiO(TFA)2 can efficiently catalyze nucleophilic ring opening of epoxides in primary, secondary and tertiary alcohols, acetic acid and water to give the corresponding β-alkoxy alcohols, β-acetoxy alcohols and vicinal diols with high stereo- and regioselectivity in excellent yields. The reaction of optically active styrene oxide in MeOH with two titanium reagents was found to be highly stereospecific and afforded the corresponding S-(+)-2-methoxy-2-phenyl ethanol in 89-95% ee.
- Iranpoor, Nasser,Zeynizadeh, Behzad
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p. 1017 - 1024
(2007/10/03)
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- Highly efficient, regio- and stereoselective ring opening of epoxides and thiiranes with Ce(OTf)4
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Ceric triflate, Ce(OTf)4 is used as an efficient catalyst for ring opening of epoxides in the presence of alcohols, water, and acetic acid. The reactions proceed with high regio and stereoselectivity and in excellent yields. The reaction of R(+) styrene oxide with methanol occurs with excellent optical purity. Ring opening of thiiranes in alcohols, water and acetic acid followed by dimerisation to the corresponding disulfides occur efficiently in the presence of this reagent. A mild method for the preparation of dithianes from thiiranes and Ce(OTf)4 is also described.
- Iranpoor,Shekarriz,Shiriny
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p. 347 - 366
(2007/10/03)
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- An unusual reaction of cyclic enol ethers with titanium(III) tetrahydroborate
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Titanium(III) Tetrahydroborate formed in situ from titanium tetrachloride and benzyltriethylammonium tetrahydroborate (1:4) readily reacts with cyclic enol ethers in dichloromethane at -20°C to give the corresponding acyclic diols in high yields after simple aqueous work-up.
- Ravikumar,Chandrasekaran, Srinivasan
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p. 2973 - 2978
(2007/10/03)
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- Iodine and iodine supported on polyvinylpyrrolidone as catalysts and reagents for alcoholysis, hydrolysis, and acetolysis of epoxides and thiiranes
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Iodine and iodine supported on polyvinylpyrrolidone (betadine) have been used as catalysts for ring opening of epoxides and as reagent for ring-opening dimerization of thiiranes in alcohols, water, and acetic acid. The reactions occur with high regio-, chemo-, and stereoselectivity. The reaction of R-(+)-styrene oxide with I2 supported on PVP in methanol was found to be very stereospecific and the product was isolated in 93% ee.
- Iranpoor, Nasser,Tamami, Bahman,Niknam, Khodabakhsh
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p. 1913 - 1919
(2007/10/03)
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- Methyltrioxorhenium supported on silica tethered with polyethers as catalyst for the epoxidation of alkenes with hydrogen peroxide
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Methyltrioxorhenium has been supported on silica functionalized with polyether tethers; in the absence of an organic solvent, this catalytic assembly catalysed the epoxidation of alkenes with 30% aqueous H2O2 in high selectivity compared to the ring opening products observed in homogeneous media.
- Neumann, Ronny,Wang, Tie-Jun
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p. 1915 - 1916
(2007/10/03)
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