- Regio- and Stereoselective Alkylation of a Pyrrolidinic System: Structural and Conformational Studies by High Field NMR Techniques
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A new merocyanine was prepared by addition of the pyrrolidine enamine of N-ethoxycarbonylpyrrolidine-3-one to 1-octyne-3-one.This addition was regioselective (with an unexpected C-4 alkylation of the pyrrolidinone-3-enamine) and stereospecific (exclusively trans addition to the triple bond).The structure and conformational equilibrium were studied by high resolution proton magnetic resonance (NOE and variable temperature effects).Activation parameters ΔH*, ΔS* and ΔG* are given, and the behaviour on protonation examined.
- Schaefer, M.,Faller, P.,Nicole, D.
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Read Online
- Isoketals form cytotoxic phosphatidylethanolamine adducts in cells
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Levuglandins and their stereo- and regio-isomers (termed isolevuglandins or isoketals) are γ-ketoaldehydes (IsoK) that rapidly react with lysines to form stable protein adducts. IsoK protein adduct levels increase in several pathological conditions including cardiovascular disease. IsoKs can induce ion channel dysfunction and cell death, potentially by adducting to cellular proteins. However, IsoKs also adduct to phosphatidylethanolamine (PE) in vitro, and whether PE adducts form in cells or contribute to the effects of IsoKs is unknown. When radiolabeled IsoK was added to HEK293 cells, 40% of the radiolabel extracted into the chloroform lower phase suggesting the possible formation of PE adducts. We therefore developed methods to measure IsoK-PE adducts in cells. IsoK-PE was quantified by LC/MS/MS after hydrolysis to IsoK-ethanolamine by Streptomyces chromofuscus phospholipase D. In HEK293 and human umbilical vein endothelial cells (HUVEC), IsoK dose-dependently increased PE adduct concentrations to a greater extent than protein adduct. To test the biological significance of IsoK-PE formation, we treated HUVEC with IsoK-PE. IsoK-PE dose dependently induced cytotoxicity (LC50 2.2 μM). These results indicate that cellular PE is a significant target of IsoKs, and that formation of PE adducts may mediate some of the biological effects of IsoKs relevant to disease. Copyright
- Sullivan, C. Blake,Matafonova, Elena,Roberts II, L. Jackson,Amarnath, Venkataraman,Davies, Sean S.
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Read Online
- Chemoselective photocatalytic oxidation of alcohols to aldehydes and ketones by nitromethane on titanium dioxide under violet 400 nm LED light irradiation
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In this study, for the first time, nitroalkanes, especially nitromethane, have been used as electron acceptors for the highly chemoselective oxidation of alcohols in the presence of a TiO2 photocatalyst under 400 nm LED irradiation. The reactions showed excellent selectivity for the production of aldehydes. Interestingly, aldehydes such as benzaldehyde and p-methoxybenzaldehyde are stable under the reaction conditions. In the case of the use of 2-nitropropane and 2-methyl-2-nitropropane, the product imine, which is the result of the reaction of the aldehyde with aliphatic amine, is also obtained.
- Kaboudin, Babak,Kazemi, Foad,Rahimi Niaraki, Azam,Saraee, Mohammad Reza
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p. 2326 - 2330
(2020/04/03)
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- Aerobic oxidation of alcohols catalyzed by in situ generated gold nanoparticles inside the channels of periodic mesoporous organosilica with ionic liquid framework
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In situ generated gold nanoparticles inside the nanospaces of periodic mesoporous organosilica with an imidazolium framework (Au?PMO-IL) were found to be highly active, selective, and reusable catalysts for the aerobic oxidation of activated and nonactivated alcohols under mild reaction conditions. The catalyst was characterized by nitrogen adsorption-desorption measurement, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), elemental analysis (EA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The catalyst exhibited excellent catalytic activity in the presence of either Cs2CO3 (35 °C) or K2CO3 (60 °C) as reaction bases in toluene as a reaction solvent. Under both reaction conditions, various types of alcohols (up to 35 examples) including activated benzylic, primary and secondary aliphatic, heterocyclic, and challenging cyclic aliphatic alcohols converted to the expected carbonyl compounds in good to excellent yields and selectivity. The catalyst was also recovered and reused for at least seven reaction cycles. Data from three independent leaching tests indicated that amounts of leached gold particles were negligible (0.2 ppm). It is believed that the combination of bridged imidazolium groups and confined nanospaces of PMO-IL might be a major reason explaining the remarkable stabilization and homogeneous distribution of in situ generated gold nanoparticles, thus resulting in the highly active and recyclable catalyst system.
- Bigdeli, Akram,Karimi, Babak,Khodadadi Karimvand, Somaiyeh,Khorasani, Mojtaba,Safari, Ali Asghar,Vali, Hojatollah
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supporting information
p. 70 - 79
(2020/06/08)
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- 1,1-Diphosphines and divinylphosphines via base catalyzed hydrophosphination
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A catalytic hydrophosphination route to 1,1-diphosphines is yet to be reported: these narrow bite angle pro-ligands have been used to great effect as ligands in homogeneous catalysis. We herein demonstrate that terminal alkynes readily undergo double hydrophosphination with HPPh2 and catalytic potassium hexamethyldisilazane (KHMDS) to generate 1,1-diphosphines. A change to H2PPh leads to the formation of P,P-divinyl phosphines.
- Coles,Mahon,Webster
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p. 10443 - 10446
(2018/09/21)
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- Styrene as 4π-Component in Zn(II)-Catalyzed Intermolecular Diels-Alder/Ene Tandem Reaction
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A mild Zn-catalyzed intermolecular Diels-Alder/ene tandem reaction with styrene as a 4π-component is reported. A variety of dihydronaphthalene products could be prepared in moderate to good yields. Moreover, a combination of DFT calculations and experiments was performed to further understand the mechanism of this unique tandem reaction.
- Zheng, Min,Wu, Feng,Chen, Kai,Zhu, Shifa
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p. 3554 - 3557
(2016/08/16)
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- Synergistic catalysis within TEMPO-functionalized periodic mesoporous organosilica with bridge imidazolium groups in the aerobic oxidation of alcohols
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Anchoring 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) within the nanospaces of a periodic mesoporous organosilica with bridged imidazolium groups led to an unprecedented powerful bifunctional catalyst (TEMPO@PMO-IL-Br), which showed enhanced activity in the metal-free aerobic oxidation of alcohols. The catalyst and its precursors were characterized by N2 adsorption-desorption analysis, transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), thermal gravimetric analysis (TGA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), solid state electron paramagnetic resonance (EPR) spectroscopy, elemental analysis, transmission electron microscopy (TEM) and high resolution TEM. It was clearly found that the catalytic activity of SBA-15-functionalized TEMPO (TEMPO@SBA-15) not bearing IL, TEMPO@PMO-IL-Cl, PMO-IL-AMP, or individual catalytic functionalities (PMO-IL/TEMPO@SBA-15) was inferior as compared with those obtained from TEMPO@PMO-IL-Br in the metal-free aerobic oxidation of benzyl alcohol, suggesting the critical role of co-supported TEMPO and imidazolium bromide in obtaining high catalytic activity in the described catalyst system. Our observation clearly points to the fact that the combination of imidazolium bromide units in close proximity to TEMPO moieties in the nanospaces of TEMPO@PMO-IL-Br might be indeed one of the key factors explaining the enhanced catalytic activity observed for this catalyst in the oxidation of benzyl alcohol, possibly through a synergistic catalysis relay pathway. A proposed model was suggested for the observed synergistic effect.
- Karimi, Babak,Vahdati, Saleh,Vali, Hojatollah
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p. 63717 - 63723
(2016/07/19)
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- A propargyl alcohol oxidation system acetylenic ketone method
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The invention provides a method for preparing acetylenic ketone through oxidizing propargyl alcohol. The method comprises the following steps: in a liquid phase, taking 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) as the catalyst, nitric acid as the co-catalyst, and oxygen gas as the oxidant, and oxidizing propargyl alcohol in an organic solvent so as to produce acetylenic ketone. The method has the advantages of mild conditions, convenient operation, no metal, and little pollution, and is a green and environment-friendly novel method for preparing ketone through oxidizing alcohol with a non-metal catalyst.
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Paragraph 0051; 0052; 0053
(2016/10/10)
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- SBA-15-Functionalized 3-Oxo-ABNO as Recyclable Catalyst for Aerobic Oxidation of Alcohols under Metal-Free Conditions
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The nitroxyl radical 3-oxo-9-azabicyclo [3.3.1]nonane-N-oxyl (3-oxo-ABNO) has been prepared using a simple protocol. This organocatalyst is found to be an efficient catalyst for the aerobic oxidation of a wide variety of alcohols under metal-free conditions. In addition, the preparation and characterization of a supported version of 3-oxo-ABNO on ordered mesoporous silica SBA-15 (SABNO) is described for the first time. The catalyst has been characterized using several techniques including simultaneous thermal analysis (STA), transmission electron microscopy (TEM), and nitrogen sorption analysis. This catalyst exhibits catalytic performance comparable to its homogeneous analogue and much superior catalytic activity in comparison with (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO) for the aerobic oxidation of almost the same range of alcohols under identical reaction conditions. It is also found that SABNO can be conveniently recovered and reused at least 12 times without significant effect on its catalytic efficiency.
- Karimi, Babak,Farhangi, Elham,Vali, Hojatollah,Vahdati, Saleh
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p. 2735 - 2741
(2016/12/23)
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- A simple and efficient method for mild and selective oxidation of propargylic alcohols using TEMPO and calcium hypochlorite
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Oxidation of propargylic alcohols to the corresponding aldehydes and ketones was achieved at room temperature using 2,2,6,6-tetramethylpiperidine-1- oxyl (TEMPO) and calcium hypochlorite (Ca(OCl)2). Propargylic diols yielded corresponding dialdehydes as the product. This system was found to be very efficient for both the electron donating and electron withdrawing groups such as methoxy and nitro substituted alcohols, respectively. This method does not require any additives and demonstrates the controlled, selective oxidation of propargylic alcohols affording up to 97% isolated yield. The Royal Society of Chemistry 2013.
- Reddy, Sabbasani Rajasekhara,Chadha, Anju
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p. 14929 - 14933
(2013/09/02)
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- Oxidation of propargylic alcohols with a 2-quinoxalinol salen copper(II) complex and tert-butyl hydroperoxide
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The copper(II) complex of 2-quinoxalinol salen (salqu) is an efficient catalyst for the selective oxidation of propargylic alcohols to yield the corresponding α,β-acetylenic carbonyl compounds when used in combination with the oxidant tert-butyl hydroperoxide (TBHP). Excellent yields (up to 99 %) are achieved for a variety of propargylic alcohols within 1 h of reaction time. The (salqu)copper(II) complex with TBHP can be used with propargylic alcohols that contain alkyl groups in the α-position, which can be difficult to oxidize selectively with other commonly available methods. By using this catalytic protocol, excellent selectivity was also achieved for the oxidation of propargylic alcohols over that of isolated hydroxy groups, triple bonds, or propargylic methylene groups. The 2-quinoxalinol salen copper(II) complex is an efficient catalyst when used with tert-butyl hydroperoxide for the oxidation of propargylic alcohols to yield the corresponding carbonyl compounds. This catalytic system provides excellent selectivity for the reaction with propargylic alcohols, and high yields (up to 99 %) are achieved within 1 h and with 1 mol-% of catalyst loading. Copyright
- Weerasiri, Kushan C.,Gorden, Anne E. V.
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p. 1546 - 1550
(2013/04/10)
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- Coupling biocatalysis and click chemistry: One-pot two-step convergent synthesis of enantioenriched 1,2,3-triazole-derived diols
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A fully convergent one-pot two-step synthesis of different chiral 1,2,3-triazole-derived diols in high yields and excellent enantio- and diastereoselectivities has been achieved under very mild conditions in aqueous medium by combining a single alcohol dehydrogenase (ADH) with a Cu-catalysed 'click' reaction. The Royal Society of Chemistry 2013.
- Cuetos, Aníbal,Bisogno, Fabricio R.,Lavandera, Iván,Gotor, Vicente
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supporting information
p. 2625 - 2627
(2013/04/23)
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- NOVEL DEORDORISING COMPOSITIONS AND DEODORISING PRODUCTS CONTAINING SAME
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The invention relates to novel deodorant compositions containing at least one compound of the family of acetylenic ketones and the deodorant products containing them. A particularly preferred composition according to the invention comprises at least one compound of the family of the α-acetylenic ketones and a mixture of aldehydes chosen from two different families.
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- Three-component reaction for the C2-functionalization of 1-substituted imidazoles with acetylenic ketones and isocyanates
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An efficient method for the direct C2-amidation of 1-substituted imidazoles with acetylenic ketones and isocyanates is reported. This three-component procedure has the advantages of catalyst-free, operational simplicity, mild reaction conditions, and good to excellent yields.
- Shen, Yang,Cai, Shuying,He, Chi,Lin, Xufeng,Lu, Ping,Wang, Yanguang
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p. 8338 - 8342
(2011/11/12)
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- A highly recyclable magnetic core-shell nanoparticle-supported TEMPO catalyst for efficient metal- and halogen-free aerobic oxidation of alcohols in water
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The selective oxidation of primary and secondary alcohols to the corresponding carbonyl compounds is one of the most challenging reactions in organic chemistry. Many oxidizing reagents such as stoichiometric CrVI salts, DMSOcoupled reagents, and hypervalent iodine have been traditionally used to accomplish this transformation. However, these reagents show poor atom efficiency and are often toxic; their widespread use thereby causes significant environmental concerns that render them impractical. As a consequence, due to ever-increasing environmental standards and economic pressures, there is substantial interest towards the use of heterogeneous and recyclable catalysts to achieve the efficient oxidation of alcohols with molecular oxygen or air as the oxidant. Whereas methodologies for the improvement of catalytic activities and selectivities have been developed considerably, they may possibly leave toxic traces of heavy metals in the products. Moreover, many of the metal-based catalyst systems are often deactivated because of the occupation of coordination sites with the by-produced water and so they generally require the use of organic solvents. Therefore, it seems that there is still a great interest in developing efficient and non-metallic catalysts for the aerobic oxidation of alcohols from the viewpoint of socalled green and sustainable chemistry. Of particular interest in this area is the application of the stable nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in combination with various types of non-metallic, stoichiometric co-oxidants as an alternative to metal-based oxidants.
- Karimi, Babak,Farhangi, Elham
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supporting information; experimental part
p. 6056 - 6060
(2011/06/26)
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- Gold-catalyzed ethynylation of arenes
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(Figure Presented) A novel gold-catalyzed ethynylation of aromatic rings with electron-deficient alkynes via gold catalyzed C-H activation of both C sp-H and Csp2-H bonds has been developed. This transformation provides aromatic propiolates difficult to prepare by other methods, highlighting the synthetic potential of gold chemistry.
- De Haro, Teresa,Nevado, Cristina
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supporting information; experimental part
p. 1512 - 1513
(2010/04/04)
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- 2-iodoxybenzenesulfonic acid as an extremely active catalyst for the selective oxidation of alcohols to aldehydes, ketones, carboxylic acids, and enones with oxone
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Electron-donating group-substituted 2-iodoxybenzoic acids (IBXs) such as5-Me-IBX (1g), 5-MeO-IBX (1h), and 4,5-Me2-IBX were superior to IBX 1a as catalysts for the oxidation of alcohols with Oxone (a trad emark of DuPont) under nonaqueous conditions, although Oxone was almost insoluble in most organic solvents. The catalytic oxidation proceeded more rapidly and cleanly in nitromethane. Furthermore, 2-iodoxybenzenesulfonic acid (IBS, 6a) was much more active than modified IBXs. Thus, we established a highly efficient and selective method for the oxidation of primary and secondary alcohols to carbonyl compounds such as aldehydes, carboxylic acids, and ketones with Oxone in nonaqueous nitromethane, acetonitrile, or ethyl acetate in the presence of 0.05-5molpercentof 6a, which was generated in situ from 2-iodobenzenesulfonic acid (7a) or its sodium salt. Cycloalkanones could be further oxidized to α,β- cycloalkenones or lactones by controlling the amounts of Oxone under the same conditions as above. When Oxone was used under nonaqueous conditions, Oxone wastes could be removed by simple filtration. Based on theoretical calculations, we considered that the relatively ionic character of the intramolecular hypervalent iodine-OSO2 bond of IBS might lower the twisting barrier of the alkoxyperiodinane intermediate 16.
- Uyanik, Muhammet,Akakura, Matsujiro,Ishihara, Kazuaki
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supporting information; experimental part
p. 251 - 262
(2009/06/28)
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- Remarkable high-yielding chemical modification of gold nanoparticles using uncatalyzed click-type i ,3-dipolar cycloaddition chemistry and hyperbaric conditions
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Azide-terminated alkyl thiolate monolayer-protected gold nanoparticles (1-C,12MPN) with a core size of 1.8 ± 0.2 nm were prepared. 1-C,12MPN was modified in high yields via an uncatalyzed 1,3-dipolar cycloaddition (clicktype reaction) with a variety of terminal acyl alkynes under hyperbaric conditions at 11 000 atm. The resulting 1,2,3-tria- zole modified MPNs (2-C,12MPN) were characterized using 1H NMR spectroscopy and were verified by comparison of the spectra to those obtained for the products of the model reactions of 1-azidododecane with the same alkynes. TEM analysis showed that the high-pressure conditions did not affect the size of the gold core, suggesting that the only effect is to facilitate the chemical reaction on the particles.
- Ismaili, Hossein,Alizadeh, Abdoihamid,Snell, Kristen E.,Workentin, Mark S.
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experimental part
p. 1708 - 1715
(2010/01/29)
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- Low temperature organocopper-mediated two-component cross coupling/cycloisomerization approach toward N-fused heterocycles
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(Chemical Equation Presented) Organocopper reagents smoothly react with heterocyclic propargyl mesylates at low temperature to produce N-fused heterocycles. The copper reagent plays a "double duty" in this novel cascade transformation, which proceeds via an SN2′ substitution followed by a subsequent cycloisomerization step.
- Chernyak, Dmitri,Gadamsetty, Surendra Babu,Gevorgyan, Vladimir
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supporting information; experimental part
p. 2307 - 2310
(2009/05/11)
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- Emulation of racemase activity by employing a pair of stereocomplementary biocatalysts
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Racemization is the key step to turn a kinetic resolution process into dynamic resolution. A general strategy for racemization under mild reaction conditions by employing stereoselective biocatalysts is presented, in which racemization is achieved by employing a pair of stereocomplementary biocatalysts that reversibly interconvert an sp3 to a sp2 center. The formal interconversion of the enantiomers proceeds via a prochiral sp 2 intermediate the formation of which is catalyzed either by two stereocomplementary enzymes or by a single enzyme with low stereoselectivity. By choosing appropriate reaction conditions, the amount of the prochiral intermediate is kept to a minimum. This general strategy, which is applicable to redox enzymes (e.g., by acting on R2CHOH and R2CHNHR groups) and lyase-catalyzed addition-elimination reactions, was proven for the racemization of secondary alcohols by employing alcohol dehydrogenases. Thus, enantiopure chiral alcohols were used as model substrates and were racemized either with highly stereoselective biocatalysts or by using (rarely found) non-selective enzymes.
- Gruber, Christian C.,Nestl, Bettina M.,Gross, Johannes,Hildebrandt, Petra,Bornscheuer, Uwe T.,Faber, Kurt,Kroutil, Wolfgang
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p. 8271 - 8276
(2008/04/01)
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- Highly efficient and selective oxidation of secondary alcohols to ketones under organic solvent and transition metal free conditions
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The aqueous HBr/H2O2 was found to be highly efficient and green catalytic system for the selective oxidation of the secondary alcohols to ketones in excellent yields under organic solvent free conditions. The results of the oxidation of the secondary alcohols with solid alternatives of the aqueous hydrogen peroxide like SPC or SPB are also described.
- Jain, Suman L.,Sharma, Vishal B.,Sain, Bir
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p. 6841 - 6847
(2007/10/03)
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- An unprecedented highly efficient solvent-free oxidation of alkynes to α,β-acetylenic ketones with tert-butyl hydroperoxide catalyzed by water-soluble copper complex
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The catalytic system composed of CuCl2 and 2,2′-biquinoline-4,4′-dicarboxylic acid dipotassium salt (BQC) was found to be highly efficient for the selective α-oxidation of internal alkynes to the corresponding α,β-acetylenic ketones, with aqueous tert-butyl hydroperoxide under mild conditions. For the first time, full conversions of alkynes were reached with excellent selectivities, and propargylic tert-butylperoxy ethers were observed and suggested as the reaction intermediates. In the case of terminal alkynes, the oxidations are sluggish and low yields ranging from 32% to 40% were obtained.
- Nait Ajjou, Abdelaziz,Ferguson, Gabriel
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p. 3719 - 3722
(2007/10/03)
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- Mechanistic diversity of the selective oxidations mediated by supported iron phthalocyanine complexes
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Selective oxidations of (i) phenols and condensed aromatics to quinones and (ii) alkynes to α,β-acetylenic ketones mediated by supported iron phthalocyanine complexes exhibit very different mechanistic features as evidenced by 18O labelling and kinetic isotope effect studies. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.
- Perollier, Celine,Pergrale-Mejean, Corinne,Sorokin, Alexander B.
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p. 1400 - 1403
(2007/10/03)
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- A new and efficient transition metal-free oxidation of secondary alcohols to ketones using aqueous HBr and H2O2
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Aqueous HBr/H2O2 was found to be an efficient and green system for the oxidation of secondary alcohols in excellent yields under very mild conditions.
- Sharma, Vishal B.,Jain, Suman L.,Sain, Bir
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p. 173 - 175
(2007/10/03)
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- Calcium phosphate-vanadate apatite (CPVAP)-catalyzed aerobic oxidation of propargylic alcohols with molecular oxygen
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Calcium phosphate-vanadate apatite (CPVAP) works effectively as a catalyst for the aerobic oxidation of propargylic alcohols to the corresponding carbonyl compounds under an atmospheric pressure of molecular oxygen. Moreover, CPVAP can be readily separated by filtration and reused at least 10 times without appreciable loss of the catalytic activity.
- Maeda, Yasunari,Washitake, Yosuke,Nishimura, Takahiro,Iwai, Keisuke,Yamauchi, Takayoshi,Uemura, Sakae
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p. 9031 - 9036
(2007/10/03)
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- Solvent-free oxidation of alcohols by t-butyl hydroperoxide catalyzed by water-soluble copper complex
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The catalytic system composed of CuCl2 and 2,2'-biquinoline-4,4'-dicarboxylic acid dipotassium salt (BQC), was found to be highly efficient for the selective oxidation of secondary benzylic, allylic and propargylic alcohols to the corresponding ketones, with aqueous t-butyl hydroperoxide under phase-transfer catalysis conditions. The catalytic system is stable and can be recycled and reused several times without loss of activity.
- Ferguson, Gabriel,Ajjou, Abdelaziz Nait
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p. 9139 - 9142
(2007/10/03)
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- Cobalt phthalocyanine catalyzed aerobic oxidation of secondary alcohols: An efficient and simple synthesis of ketones
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A variety of activated and non-activated secondary alcohols have been efficiently oxidized to their corresponding ketones in excellent yields with molecular oxygen using cobalt phthalocyanine as catalyst in the presence of powdered potassium hydroxide.
- Sharma, Vishal B.,Jain, Suman L.,Sain, Bir
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p. 383 - 386
(2007/10/03)
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- Chromium catalyzed oxidation of (homo-)allylic and (homo-)propargylic alcohols with sodium periodate to ketones or carboxylic acids
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Primary and secondary (homo-)allylic and (homo-)propargylic alcohols can be oxidized under slightly acidic conditions at or below room- temperature with sodium periodate in the presence of sodium dichromate as the catalyst to the corresponding carboxylic acids and ketones, respectively.
- De Vondervoort, Lizette Schmieder-Van,Bouttemy, Sabine,Padrón, José M.,Le Bras, Jean,Muzart, Jacques,Alsters, Paul L.
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p. 243 - 246
(2007/10/03)
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- Preparation of α,β-acetylenic ketones by catalytic heterogeneous oxidation of alkynes
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Covalent grafting of iron phthalocyanines onto silica affords active catalysts for selective oxidation of alkynes and propargylic alcohols to α,β-acetylenic ketones, highly valuable precursors in the preparation of fine chemicals.
- Perollier, Celine,Sorokin, Alexander B.
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p. 1548 - 1549
(2007/10/03)
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- Oxovanadium complex-catalyzed aerobic oxidation of propargylic alcohols
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A catalytic system consisting of vanadium oxyacetylacetonate [VO(acac)2] and 3 A molecular sieves (MS3A) in acetonitrile works effectively for the aerobic oxidation of propargylic alcohols [R1CH-(OH)C≡CR2] to the corresponding carbonyl compounds under an atmospheric pressure of molecular oxygen. Although the reactivity of α-acetylenic alkanols (R1 = alkyl) is lower compared to that of the alcohols of R1 = aryl, alkenyl, and alkynyl, the use of VO(hfac)2 as a catalyst and the addition of hexafluoroacetylacetone improve the product yield in these cases. A catalytic cycle involving a vanadium(V) alcoholate species and β-hydrogen elimination from it has been proposed for this oxidation.
- Maeda, Yasunari,Kakiuchi, Nobuyuki,Matsumura, Satoshi,Nishimura, Takahiro,Kawamura, Takashi,Uemura, Sakae
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p. 6718 - 6724
(2007/10/03)
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- Oxovanadium complex-catalyzed oxidation of propargylic alcohols using molecular oxygen
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Oxovanadium complexes work as useful catalysts for the oxidation of propargylic alcohols to the corresponding carbonyl compounds in the presence of 3 ? molecular sieves under an atmospheric pressure of molecular oxygen.
- Maeda, Yasunari,Kakiuchi, Nobuyuki,Matsumura, Satoshi,Nishimura, Takahiro,Uemura, Sakae
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p. 8877 - 8879
(2007/10/03)
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- Oxygenation of alkynes to α,β-acetylenic ketones with dioxygen catalyzed by N-hydroxyphthalimide combined with a transition metal
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Alkynes were successfully converted into α,β-acetylenic carbonyl compounds through radical-catalyzed aerobic oxidation using N-hydroxyphthalimide (NHPI) combined with a transion metal under mild conditions.
- Sakaguchi, Satoshi,Takase, Tomoyuki,Iwahama, Takahiro,Ishii, Yasutaka
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p. 2037 - 2038
(2007/10/03)
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- Zeolite-catalyzed oxidation of benzylic and acetylenic alcohols with t-butyl hydroperoxide
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4 A molecular sieves catalyze the mild conversion of activated secondary alcohols into the corresponding carbonyl compounds with t-butyl hydroperoxide (TBHP).
- Palombi, Laura,Arista, Luca,Lattanzi, Alessandra,Bonadies, Francesco,Scettri, Arrigo
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p. 7849 - 7850
(2007/10/03)
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- Reduction of Ketones with LiAlH4 Complexes of α,α,α′,α′-Tetraaryl-1,3-dioxolane-4,5- dimethanols (TADDOLs): A Combination of Enantioselective Reduction and Clathrate Formation with a Discussion of LAH Reagents Bearing C2-Symmetrical Ligands
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A complex prepared from one equivalent each of LiAlH4, EtOH and a TADDOL (α,α,α′,α′-tetraaryl-1,3-dioxolane-4,5- dimethanol) reduces aryl alkyl ketones to sec. alcohols with enantiomer ratios (er) up to 96:4. The chiral LAH derivative is used in two-fold excess in THF solution and at dry ice temperatures. The ability of TADDOLs to form clathrates diastereoselectively can be exploited to increase the er of the initially formed alcohols by a simple modification of the work-up procedure and hence, products of very high enantiopurity (er 99:1) can be isolated. When (R,R)-TADDOLs (from (R,R)-tartrate) are applied in the reaction, the 1-aryl-alkanols formed preferentially have (S) configuration, as for the products obtained with the corresponding (P)-BINOL and (P)-BIPHENOL derivatives. A common mechanistic model is discussed.
- Seebach, Dieter,Beck, Albert K.,Dahinden, Robert,Hoffmann, Matthias,Kuehnle, Florian N. M.
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p. 459 - 484
(2007/10/03)
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- Vitamin B12, a Catalyst in the Synthesis of Prostaglandins
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A prostaglandin F2α precursor containing all structural features from C6 to C20 with 8R,9S, 11R and 12R chirality is obtained by the one step formation of two C-C bonds in the B12-catalyzed radical cyclization-addition sequence starting from a chiral cyclopentene bromoacetal and 1-octyne-3-one.The B12-catalyzed radical cyclization-elimination sequence of a chiral cyclopentene precursor leads to (-)-(3aR,6aS)-3,3a,6,6a-tetrahydro-2H-cyclopentafuran-2-one.Its (+)-(3aS,6aR)-enantiomer is obtained via B12-catalyzed, enantioselective isomerization of cyclopentene oxide to (R)-2-cyclopentene-1-ol followed by the B12-catalyzed cyclization-elimination sequence of its bromoacetal.
- Busato, Stephan,Tinembart, Olivier,Zhang, Zhong-da,Scheffold, Rolf
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p. 3155 - 3166
(2007/10/02)
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- Oxidation of Alcohols with Electrolytic Manganese Dioxide. Its Application for the Synthesis of Insect Pheromones
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Oxidation of alcohols with electrolytic manganese dioxide under mild conditions afforded aldehydes and ketones in good yields.The method was applied for the syntheses of cystophorene (15) and a sex pheromone of forest tent cater pillar .
- Tsuboi, Sadao,Ishii, Naomi,Sakai, Takashi,Tari, Isao,Utaka, Masanori
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p. 1888 - 1893
(2007/10/02)
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- REDUCTION DE DERIVES D'ALCOOLS PROPARGYLIQUES CATALYSEE PAR UN COMPLEXE DE PALLADIUM ZEROVALENT
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Catalysis by tetrakis(triphenylphosphine)palladium of the reaction of hydride donnors with secondary propargylic bromides, mesylates and phosphates increases markedly the amount of allene produced.The best results in that direction are obtained with mesylates and phosphates by using lithium triethylborohydride.The reaction then occurs with an ANTI introduction of the hydride with respect to the leaving group.A mechanism is proposed which explains the influence of the various parameters of the reaction.
- Colas, Yann,Cazes, Bernard,Gore, Jacques
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p. 165 - 173
(2007/10/02)
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- A NEW Cr(VI) REAGENT FOR THE CATALYTIC OXIDATION OF SECONDARY ALCOHOLS TO KETONES
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A new process is described for the oxidation of secondary alcohols to ketones using peroxyacetic acid in the presence of a catalytic amount of 2,4-dimethylpentane-2,4-diol cyclic chromate.
- Corey, E. J.,Barrette, Ernie-Paul,Magriotis, Plato A.
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p. 5855 - 5858
(2007/10/02)
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