- Comparative study of the reactions of n-BuMgBr and n-BuLi with cyclododecanone
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The composition of the products obtained in the reaction of n-BuMgBr and n-BuLi with cyclododecanone (1) has revealed that 1 exhibits the properties of a sterically hindered ketone.The highest yield of 1-butylcyclododecanol (2) was achieved with the use of n-BuMgBr, but in this case cyclododecanol was also formed, whereas the use of n-BuLi led to the tertiary alcohol more distinctly.Dehydration of alcohol 2 resulted in a mixture of three olefins containing up to 90percent of E- and Z- isomers of 1-butylcyclododecene.
- Zakharkin, L. I.,Churilova, I. M.,Petrovskii, P. V.
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- The effect of vanadium sources on the synthesis and catalytic activity of VMCM-41
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Mesoporous VMCM-41 was synthesized hydrothermally using various vanadium sources, viz, tetravalent vanadium such as vanadyl sulfate and vanadyl acetylacetonate, as well as pentavalent vanadium like sodium vanadate and ammonium vanadate. The influence of different vanadium sources on the framework substitution of vanadium, as well as their catalytic activity for the oxidation of cyclohexane, was investigated. Among the different vanadium stocks, the tetravalent vanadium sources showed maximum vanadium incorporation in the silicate framework of MCM-41. As a consequence, these catalysts gave much higher substrate conversion and excellent product selectivity. On the other hand, the catalysts prepared from pentavalent vanadium sources showed lower activity owing to the smaller amounts of vanadium in the matrix. Although the activity of the catalyst slightly decreased after first recycle as due to leaching of small amounts of active vanadium species, it however remained nearly the same even after several recycles. This was further confirmed by washing experiments wherein non-framework vanadium ions were removed upon ammonium acetate treatment; the washed catalysts showed a similar activity to those of the recycled catalysts. Thus, recycled/washed VMCM-41 behaves truly as heterogeneous catalyst. Furthermore, the influence of pore size of the catalyst was tested for the oxidation of bulkier substrate, viz, cyclododecane.
- Selvam,Dapurkar
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- SELECTIVE OXIDATION OF SATURATED HYDROCARBONS USING AN ELECTROCHEMICAL MODIFICATION OF THE GIF SYSTEM.
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The Gif system for selective hydrocarbon oxidation can be carried out replacing the zinc by a cathodic electrochemical reduction; the yields obtained and the selectivities observed are very similar.
- Balavoine, Gilbert,Barton, Derek H. R.,Boivin, Jean,Gref, Aurore,Ozbalik, Nubar,Riviere, Henriette
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- An original one-pot approach to boronic esters using the titanium-catalyzed reaction of cyclic olefins with alkyldichloroboranes
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Boronic esters (dicycloheptylalkylboronates, dicyclooctylalkylboronates, dicyclododecylalkylboronates, dibicyclo[2.2.1]hept-2-ylalkylboronates) are produced with yields ranging from moderate to excellent (52–96%) by the reaction between cyclic olefins (cycloheptene, cis-cyclooctene, cis/trans-cyclododecene, norbornene) and alkyldichloroboranes (alkyl = Et, n-Pent) in the presence of metallic magnesium and the Cp2TiCl2 catalyst with subsequent addition of water.
- Khusainova, Liliya I.,Khafizova, Leila O.,Tyumkina, Tatyana V.,Ryazanov, Kirill S.,Popodko, Natalya R.,Dzhemilev, Usein M.
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- Synergistic oxidation of cyclohexane and hydrogen sulfide under Gif conditions
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Saturated hydrocarbons and hydrogen sulfide can be synergistically oxidised by oxygen (or air) to give efficiently ketones (and the corresponding alcohols) and sulfur in the presence of a Gif catalyst based on FeII, picolinic acid and 4-tert-butylpyridine with acetonitrile as solvent at room temperature and nearly neutral pH.
- Barton, Derek H. R.,Li, Tingsheng,MacKinnon, John
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- An Efficient Electrochemical Process for the Oxidation of Saturated Hydrocarbons: the Gif-Orsay System
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The selective oxidation of saturated hydrocarbons can be carried out using triplet oxygen, pyridine, trifluoroacetic acid, and an iron catalyst in an unicellular electrochemical cell (Gif-Orsay system), cyclododecane, adamantane, and cyclo-octane being oxidised in 17-30 mmolar amounts with improved coulombic yields of up to ca. 30percent being attainable; oxidation of cyclohexane in 48 mmolar amounts gave cyclohexanone with some cyclohexanol in ca. 40percent coulombic yield, and similar yields were obtained on a 140-167 mmolar scale (saturated solution of hydrocarbon) with addition of electron transfer reagents and enough water to give two layers (good stirring) and satisfactory conductivity.
- Balavoine, Gilbert,Barton, Derek H. R.,Boivin, Jean,Gref, Aurore,Ozbalik, Nubar,Riviere, Henriette
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- The functionalization of saturated hydrocarbons. Part XIX. Oxidation of alkanes by H2O2 in pyridine catalyzed by copper(II) complexes. A Gif-type reaction
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The Cu(II)-catalyzed oxidation of saturated hydrocarbons by hydrogen peroxide proceeds in pyridine-acetic acid solutions affording mainly ketones as the reaction product. The conversion of hydrocarbon is about 20-30%. This system (called GoChAgg) shares with the Fe(III)-catalyzed system (GoAgg(II)) its unusual chemical characteristics.
- Barton,Csuhai,Doller,Geletii
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- Catalytic hydrogenation of aldehydes and ketones using cinchona–bipyridyl-based palladium catalyst
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Understanding the need for simple, robust and low effluents, in chemical processes, we have developed an elegant protocol for the catalytic reduction of aldehydes and ketones to corresponding alcohols which are used in synthetic fragrance applications using cinchona alkaloid-derived palladium catalyst. This system holds good for very low catalyst loading surfaces with the formation of fewer impurities and negligible decomposition under moderate pressure. The conversions and yields range from moderate to good (60–80%).
- Chidambaram, Ramasamy R.,Sadhasivam, Velu,Mariyappan, Mathappan,Siva, Ayyanar
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- FUNCTIONALISATION OF SATURATED HYDROCARBONS. PART XVI. CHEMOSELECTIVE OXIDATION
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Cyclododecane is efficiently oxidised under GifIV and GoAggII conditions to give over 25percent of cyclododecanone with some cyclododecanol.The addition in equimolar amounts of ethanol, isopropanol, ethylene glycol, diisopropyl ether, biphenyl, anisole, diphenyl sulfide, methyl benzoate and dimethylacetamide have little effect on the oxidation.Thiophenols have a minor effect, but t-butyl thiol and dimethylaniline reduce oxidation to a major extent.In all cases, the mass balances are satisfactory.Overoxidation of cyclododecanone affords cyclododecane-1,3-, 1,4-, 1,5- and 1,6-diones.The major dione is 1,4- followed by 1,6-.
- Barton, Derek H. R.,Csuhai, Eva,Ozbalik, Nubar
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- Hierarchically porous BEA stannosilicates as unique catalysts for bulky ketone conversion and continuous operation
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Pore size limitations typically limit the applicability of Lewis acidic zeolites, such as titano- and stanno-silicates, to catalytic processes based on small-to-mid sized substrates, and increase their rates of deactivation, prohibiting further exploitation. Herein, we demonstrate that tin-containing zeolites possessing modified hierarchical BEA matrices can be prepared. These hierarchical stannosilicates are able to mediate the catalytic conversion of bulky ketone substrates, a pertaining challenge in the field that purely microporous analogues are unable to mediate. Deactivation studies in the continuous regime also demonstrate the exceptional stability of hierarchical Sn-Beta compared to purely microporous Sn-Beta, with 20% loss of activity observed over 700 h on stream. In contrast, the purely microporous analogue lost ±70% activity in only 200 h. To the best of our knowledge, this is the first time a stannosilicate with a beneficial hierarchical BEA framework has been prepared, and the first evidence of cyclododecanone valorisation with stannosilicate catalysts.
- Al-Nayili, Abbas,Yakabi, Keiko,Hammond, Ceri
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- A NOVEL PHOTOOXIDATION OF HYDROCARBONS SENSITIZED BY 2,7-DIAZAPYRENIUM DICATION IN THE PRESENCE OF IRON CATALYST
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A novel photooxidation of hydrocarbons sensitized by N,N'-dimethyl-2,7-diazapyrenium dication in the presence of iron catalyst has been described.Formation of free hydroxyl radical from molecular oxygen has been demonstrated.
- Saito, Isao,Takayama, Masami,Matsuura, Teruo
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- Pincerlike molybdenum complex and preparation method thereof, catalytic composition and application thereof, and alcohol preparation method
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The invention discloses a clamp-type molybdenum complex, a preparation method, a corresponding catalyst composition and application. The method comprises the steps: obtaining 9 molybdenum complexes with different structures through coordination reaction of 2-(substituent ethyl)-(5, 6, 7, 8-tetrahydroquinolyl) amine and a corresponding carbonyl molybdenum metal precursor; and catalyzing a ketone compound transfer hydrogenation reaction through a molybdenum complex to generate 40 alcohol compounds. The preparation method of the molybdenum complex is simple, high in yield and good in stability. For a transfer hydrogenation reaction of ketone, the molybdenum-based catalytic system has high catalytic activity and small molybdenum loading capacity, is used for production of aromatic and aliphatic alcohols, and has the advantages of simple method, small environmental pollution and high yield.
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Paragraph 0134-0140
(2021/08/11)
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- Efficient oxidation of cycloalkanes with simultaneously increased conversion and selectivity using O2 catalyzed by metalloporphyrins and boosted by Zn(AcO)2: A practical strategy to inhibit the formation of aliphatic diacids
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The direct sources of aliphatic acids in cycloalkanes oxidation were investigated, and a strategy to suppress the formation of aliphatic acids was adopted through enhancing the catalytic transformation of oxidation intermediates cycloalkyl hydroperoxides to cycloalkanols by Zn(II) and delaying the emergence of cycloalkanones. Benefitted from the delayed formation of cycloalkanones and suppressed non-selective thermal decomposition of cycloalkyl hydroperoxides, the conversion of cycloalkanes and selectivity towards cycloalkanols and cycloalkanones were increased simultaneously with satisfying tolerance to both of metalloporphyrins and substrates. For cyclohexane, the selectivity towards KA-oil was increased from 80.1% to 96.9% meanwhile the conversion was increased from 3.83 % to 6.53 %, a very competitive conversion level with higher selectivity compared with current industrial process. This protocol is not only a valuable strategy to overcome the problems of low conversion and low selectivity lying in front of current cyclohexane oxidation in industry, but also an important reference to other alkanes oxidation.
- Shen, Hai-Min,Wang, Xiong,Ning, Lei,Guo, A-Bing,Deng, Jin-Hui,She, Yuan-Bin
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- Three metal centers (Co _AOMARKENCODEAMPX0AOA) Cu _AOMARKENCODEAMPX0AOA Method using Zn) 2D MOFs/ultraviolet light to catalyze oxidation of cycloalkane
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The invention relates to a three-metal center (Co _AOMARKENCODEAMPX0AOA). Cu _AOMARKENCODEAMPX0AOA The method comprises Zn) 2D MOFs/ultraviolet light catalytic oxidation of cycloalkane to synthesize cycloalkyl alcohol and cycloalkanone, and belongs to the field of industrial catalysis and fine organic synthesis. To the application method, metalloporphyrin three-metal center (Co _AOMARKENCODEAMPX0AOA) is used. Cu _AOMARKENCODEAMPX0AOA Zn) 2D MOFs dispersed in cycloalkane, wherein metalloporphyrin three-metal center (Co _AOMARKENCODEAMPX0AOA) Cu _AOMARKENCODEAMPX0AOA Zn) 2D MOFs mass is 0.01% - 20%, g / mol of the substance of the cycloalkane, and the reaction system is sealed. An oxidant is introduced, the ultraviolet lamp is a light source, and the reaction liquid of the stirring reaction 2.0-24 . 0h. is subjected to post-treatment to obtain the product cycloalkyl alcohol and cycloalkyl ketone. The method provided by the invention has the advantages of low reaction temperature, mild reaction conditions, high reaction efficiency, high selectivity of cycloalkyl alcohol and cycloalkyl ketone, less byproducts and small environmental impact. The invention provides a high efficiency. Available, safe cycloalkanes selectively catalyze the oxidative synthesis of cycloalkyl alcohols and cycloalkyl ketones.
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Paragraph 0028; 0081-0082
(2021/11/06)
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- Fe-Catalyzed Anaerobic Mukaiyama-Type Hydration of Alkenes using Nitroarenes
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Hydration of alkenes using first row transition metals (Fe, Co, Mn) under oxygen atmosphere (Mukaiyama-type hydration) is highly practical for alkene functionalization in complex synthesis. Different hydration protocols have been developed, however, control of the stereoselectivity remains a challenge. Herein, highly diastereoselective Fe-catalyzed anaerobic Markovnikov-selective hydration of alkenes using nitroarenes as oxygenation reagents is reported. The nitro moiety is not well explored in radical chemistry and nitroarenes are known to suppress free radical processes. Our findings show the potential of cheap nitroarenes as oxygen donors in radical transformations. Secondary and tertiary alcohols were prepared with excellent Markovnikov-selectivity. The method features large functional group tolerance and is also applicable for late-stage chemical functionalization. The anaerobic protocol outperforms existing hydration methodology in terms of reaction efficiency and selectivity.
- Bhunia, Anup,Bergander, Klaus,Daniliuc, Constantin Gabriel,Studer, Armido
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supporting information
p. 8313 - 8320
(2021/03/08)
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- Hydrogen-Catalyzed Acid Transformation for the Hydration of Alkenes and Epoxy Alkanes over Co-N Frustrated Lewis Pair Surfaces
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Hydrogen (H2) is widely used as a reductant for many hydrogenation reactions; however, it has not been recognized as a catalyst for the acid transformation of active sites on solid surface. Here, we report the H2-promoted hydration of alkenes (such as styrenes and cyclic alkenes) and epoxy alkanes over single-atom Co-dispersed nitrogen-doped carbon (Co-NC) via a transformation mechanism of acid-base sites. Specifically, the specific catalytic activity and selectivity of Co-NC are superior to those of classical solid acids (acidic zeolites and resins) per micromole of acid, whereas the hydration catalysis does not take place under a nitrogen atmosphere. Detailed investigations indicate that H2 can be heterolyzed on the Co-N bond to form Hδ-Co-N-Hδ+ and then be converted into OHδ-Co-N-Hδ+ accompanied by H2 generation via a H2O-mediated path, which significantly reduces the activation energy for hydration reactions. This work not only provides a novel catalytic method for hydration reactions but also removes the conceptual barriers between hydrogenation and acid catalysis.
- Deng, Qiang,Deng, Shuguang,Gao, Ruijie,Li, Xiang,Tsang, Shik Chi Edman,Wang, Jun,Zeng, Zheling,Zou, Ji-Jun
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p. 21294 - 21301
(2021/12/17)
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- Synthesis and characterization of silica-coated magnetite nanoparticles modified with bis(pyrazolyl) triazine ruthenium(II) complex and the application of these nanoparticles as a highly efficient catalyst for the hydrogen transfer reduction of ketones
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We present a facile and efficient method for modifying the surface of silica-coated Fe3O4 magnetic nanoparticles (MNPs) with bis(pyrazolyl) triazine ruthenium(II) complex [MNPs@BPT–Ru (II)]. Field emission-scanning electron microscopy, thermogravimetric/derivative thermogravimetry analysis, X-ray powder diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, and energy-dispersive X-ray spectrometry analyses were employed for characterizing the structure of these nanoparticles. MNPs@BPT–Ru(II) nanoparticles proved to be a magnetic, reusable, and heterogeneous catalyst for the hydrogen transfer reduction of ketone derivatives. In addition, highly pure products were obtained with excellent yields in relatively short times in the presence of this catalyst. A comparison of this catalyst with those previously used for the hydrogen transfer reactions proved the uniqueness of MNPs@BPT–Ru(II) nanoparticle which is due to its inherent magnetic properties and large surface area. The presented method also had other advantages such as simple reaction conditions, eco-friendliness, high recovery ability, easy work-up, and low cost.
- Mobinikhaledi, Akbar,Moghanian, Hassan,Ajerloo, Bahram,Dousti, Fatemeh
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- Method for catalytic oxidation of cycloalkane by confinement porphyrin Co (II)
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The invention relates to a method for catalytic oxidation of cycloalkane by confinement porphyrin Co (II). The method comprises the following steps: dispersing confinement cobalt porphyrin (II) in cycloalkane, sealing the reaction system, heating to 100-130 DEG C while stirring, introducing oxygen to 0.2-3.0 MPa, keeping the set temperature and oxygen pressure, stirring to react for 3.0-24.0 h, and carrying out post-treatment on a reaction solution to obtain products naphthenic alcohol and naphthenic ketone. The method achieves high selectivity of naphthenic alcohol and naphthenic ketone, andeffectively inhibits the generation of aliphatic diacid. The aliphatic diacid is low in selectivity, so that the continuity of the cycloalkane oxidation process and the separation of the products arefacilitated; the method has the potential of solving the problem that naphthenic alcohol and naphthenic ketone are easily and deeply oxidized to generate aliphatic diacid in the industrial cycloalkanecatalytic oxidation process; and the method is a novel efficient and feasible method for selective catalytic oxidation of cycloalkane.
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Paragraph 0073; 0074
(2020/05/01)
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- Confinement porphyrin Co (II), and preparation method and application thereof
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Confinement porphyrin Co (II). A preparation method includes: under acidic condition, performing condensation on aromatic aldehyde and pyrrole in equal molar ratio to obtain a phenylporphyrin compound, and carrying out metallization in a chloroform-methanol solution to obtain porphyrin Cu (II), performing bromination and demetalization by perchloric acid to obtain confinement porphyrin, performingstirring reflux on the confinement porphyrin in a methanol solution for 12.0-24.0 h to obtain confinement porphyrin Co (II). An application includes: dissolving the confinement porphyrin Co (II) in naphthenic hydrocarbon and sealing the reaction system, stirring and heating the reaction system to 100-130 DEG C and feeding oxygen to 0.2-3.0 MPa; maintaining the set temperature and oxygen pressureand performing a stirring reaction for 3.0-24.0 h; performing after treatment on the reaction liquid to prepare the product. In the invention, generation of fatty diacid is effectively inhibited, andcontinuity of a naphthenic hydrocarbon oxidization process and product separation is facilitated. The invention has the potential of solving the problem that naphthene alcohols and naphthene ketones are liable to undergo deep oxidization and form the fatty diacid in an industrial naphthenic hydrocarbon catalytic oxidation process.
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Paragraph 0105-0106
(2020/04/17)
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- Method for synergistically catalyzing and oxidizing cycloparaffin through confined metalloporphyrin cobalt (II)/Cu (II) salt
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The invention discloses a method for synergistically catalyzing and oxidizing cycloparaffin through confined metalloporphyrin cobalt (II)/Cu (II) salt. The preparation method comprises the following steps: dispersing confined metalloporphyrin cobalt (II) (0.001%-5%, g/mol) and Cu (II) salt (0.01%-10%, mol/mol) into cycloparaffin; and sealing the reaction system, heating the temperature to 90-150 DEG C while stirring, introducing an oxidant, keeping the set temperature and pressure, carrying out stirring and reacting for 2.0-24.0 hours, and carrying out after-treatment on the reaction solutionto obtain the products cycloalkyl alcohol and cycloalkyl ketone. The method disclosed by the invention has the advantages of high cycloalkyl alcohol and cycloalkyl ketone selectivity, low reaction temperature, few byproducts, small environmental influence and the like. In addition, the content of cycloalkyl hydroperoxide is low, and the safety coefficient is high. The invention provides an efficient, feasible and safe method for synthesizing cycloalkyl alcohol and cycloalkyl ketone through selective catalytic oxidation of cycloparaffin.
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Paragraph 0047-0048
(2020/12/10)
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- Erbium-Catalyzed Regioselective Isomerization-Cobalt-Catalyzed Transfer Hydrogenation Sequence for the Synthesis of Anti-Markovnikov Alcohols from Epoxides under Mild Conditions
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Herein, we report an efficient isomerization-transfer hydrogenation reaction sequence based on a cobalt pincer catalyst (1 mol %), which allows the synthesis of a series of anti-Markovnikov alcohols from terminal and internal epoxides under mild reaction conditions (≤55 °C, 8 h) at low catalyst loading. The reaction proceeds by Lewis acid (3 mol % Er(OTf)3)-catalyzed epoxide isomerization and subsequent cobalt-catalyzed transfer hydrogenation using ammonia borane as the hydrogen source. The general applicability of this methodology is highlighted by the synthesis of 43 alcohols from epoxides. A variety of terminal (23 examples) and 1,2-disubstituted internal epoxides (14 examples) bearing different functional groups are converted to the desired anti-Markovnikov alcohols in excellent selectivity and yields of up to 98%. For selected examples, it is shown that the reaction can be performed on a preparative scale up to 50 mmol. Notably, the isomerization step proceeds via the most stable carbocation. Thus, the regiochemistry is controlled by stereoelectronic effects. As a result, in some cases, rearrangement of the carbon framework is observed when tri-and tetra-substituted epoxides (6 examples) are converted. A variety of functional groups are tolerated under the reaction conditions even though aldehydes and ketones are also reduced to the respective alcohols under the reaction conditions. Mechanistic studies and control experiments were used to investigate the role of the Lewis acid in the reaction. Besides acting as the catalyst for the epoxide isomerization, the Lewis acid was found to facilitate the dehydrogenation of the hydrogen donor, which enhances the rate of the transfer hydrogenation step. These experiments additionally indicate the direct transfer of hydrogen from the amine borane in the reduction step.
- Liu, Xin,Longwitz, Lars,Spiegelberg, Brian,T?njes, Jan,Beweries, Torsten,Werner, Thomas
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p. 13659 - 13667
(2020/11/30)
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- Borinic Acid Mediated Hydrosilylations: Reductions of Carbonyl Derivatives
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4-Fluoro-2-chlorophenylborinic acid acts as a precatalyst in the presence of phenylsilane for the facile reduction of ketones, aldehydes and imines. Notably, synergistic mediation of a tertiary amine was found essential to trigger silicon to boron hydride transfer to generate a key amine–diarylhydroborane Lewis complex.
- Chardon, Aurélien,Rouden, Jacques,Blanchet, Jér?me
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supporting information
p. 995 - 998
(2018/12/13)
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- Copper-Catalyzed and Indium-Mediated Methoxycarbonylation of Unactivated Alkyl Iodides with Balloon CO
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This work emphasizes the synthesis of alkyl esters via Cu-catalyzed and In-mediated alkoxycarbonylation of unactivated alkyl iodides in the presence of In or InI. The reactions were suitable for the preparation of primary, secondary, and even tertiary alkyl esters, representing an exceptionally rare example for the creation of quaternary carbon centers upon formation of esters. The preliminary mechanistic studies indicated that alkyl radicals were involved, and Cu/In/CO played a cooperative role in the carbonylation event.
- Chen, Yanchi,Su, Lei,Gong, Hegui
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supporting information
p. 4689 - 4693
(2019/06/27)
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- Selective biocatalytic hydroxylation of unactivated methylene C-H bonds in cyclic alkyl substrates
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The cytochrome P450 monooxygenase CYP101B1 from Novosphingobium aromaticivorans selectively hydroxylated methylene C-H bonds in cycloalkyl rings. Cycloketones and cycloalkyl esters containing C6, C8, C10 and C12 rings were oxidised with high selectively on the opposite side of the ring to the carbonyl substituent. Cyclodecanone was oxidised to oxabicycloundecanol derivatives in equilibrium with the hydroxycyclodecanones.
- Sarkar, Md Raihan,Dasgupta, Samrat,Pyke, Simon M.,Bell, Stephen G.
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supporting information
p. 5029 - 5032
(2019/05/21)
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- Oxidative Deprotection of p-Methoxybenzyl Ethers via Metal-Free Photoredox Catalysis
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An efficient and greener deprotection method for p-methoxybenzyl (PMB) ethers using a metal-free visible light photoredox catalyst and air and ammonium persulfate as the terminal oxidants is presented. Various functional groups and protecting groups were tolerated in the developed method to achieve good to excellent yields in short reaction times. Significantly, the developed method was compatible with PMB ethers derived from primary, secondary, and tertiary alcohols and a gram-scale reaction. Mechanistic studies support a proposed reaction mechanism that involves single electron oxidation of the PMB ether.
- Ahn, Deok Kyun,Kang, Young Woo,Woo, Sang Kook
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p. 3612 - 3623
(2019/03/11)
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- Highly efficient hydroboration of carbonyl compounds catalyzed by tris(methylcyclopentadienyl)lanthanide complexes
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Homoleptic lanthanide complexes coordinated by a Me-substituted Cp ligand [(MeCp)3Ln] demonstrate unprecedentedly high efficiency in catalyzing the hydroboration of aldehydes and ketones with pinacolborane. This protocol is also applicable for the hydroboration of aryl-substituted imines. In addition, broad functional group compatibility and excellent chemoselectivity is also achieved. DFT calculations are employed to shed light on the reaction mechanism.
- Yan, Dandan,Dai, Ping,Chen, Sufang,Xue, Mingqiang,Yao, Yingming,Shen, Qi,Bao, Xiaoguang
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p. 2787 - 2791
(2018/04/27)
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- An air and moisture tolerant iminotrihydroquinoline-ruthenium(ii) catalyst for the transfer hydrogenation of ketones
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Reaction of 8-amino-5,6,7,8-tetrahydroquinoline with RuCl2(PPh3)3 at room temperature affords the ruthenium(ii) chelate (8-NH2-C9H10N)RuCl2(PPh3)2 (E), in which the two triphenylphosphine ligands are disposed mutually cis. By contrast, when the reaction is performed at reflux ligand oxidation/dehydrogenation occurs along with cis-trans reorganization of the triphenylphosphines to form the 8-imino-5,6,7-trihydroquinoline-ruthenium(ii) complex, (8-NH-C9H9N)RuCl2(PPh3)2 (F). Complex F can also be obtained in higher yield by heating a solution of E alone to reflux. Comparison of their molecular structures highlights the superior binding properties of the bidentate imine ligand in F over its amine-containing counterpart in E. Both complexes are highly effective in the transfer hydrogenation of a wide range of alkyl-, aryl- and cycloalkyl-containing ketones affording their corresponding secondary alcohols with loadings of as low as 0.1 mol%. Significantly, F can deliver excellent conversions even in bench quality 2-propanol in reaction vessels open to the air, whereas the catalytic efficiency of E is diminished by the presence of air but only operates efficiently under inert conditions.
- Li, Jiaoyan,Ma, Yingmiao,Wang, Zheng,Liu, Qingbin,Solan, Gregory A.,Ma, Yanping,Sun, Wen-Hua
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p. 8738 - 8745
(2018/07/13)
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- Reliably Regioselective Dialkyl Ether Cleavage with Mixed Boron Trihalides
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A protocol for the regioselective cleavage of unsymmetrical alkyl ethers to generate alkyl alcohol and alkyl bromide products is described. A mixture of trihaloboranes triggers this conversion and exhibits improved reactivity profiles (regioselectivity and yield) compared with BBr3 alone. Additionally, this procedure allows the efficient synthesis of (B-Cl) dialkyl boronate esters. There are limited methods to generate acyclic dialkoxyboryl chlorides, and these intermediates constitute important synthons in main-group chemistry.
- Atienza, Bren Jordan P.,Truong, Nam,Williams, Florence J.
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p. 6332 - 6335
(2018/10/09)
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- Selection of microbial biocatalysts for the reduction of cyclic and heterocyclic ketones
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The reduction of carbonyl compounds plays an important role in the synthesis of complex chiral molecules. In particular, enantiopure substituted cyclic and heterocyclic compounds are useful intermediates for the synthesis of several antiviral, antitumor, and antibiotic agents, and recently, they have also been used as organocatalysts for C-C addition. Alcohol dehydrogenases (ADH) are enzymes involved in the transformation of prochiral ketones to chiral hydroxyl compounds. While significant scientific effort has been paid to the use of aliphatic and exocyclic ketones as ADH substrates, reports on (hetero)cyclic carbonyl compounds as substrates of these enzymes are scarce. In the present study, 109 bacteria and 36 fungi were screened, resulting in 10 organisms belonging to both kingdoms capable of transforming cyclic and heterocyclic ketones into the corresponding alcohols. Among them, Erwinia chrysanthemi could quantitatively reduce cyclododecanone and Geotrichum candidum could stereoselectively reduce N-Boc-3-piperidone and N-Boc-3-pyrrolidinone to their corresponding (S)-alcohols; however, the anti-Prelog isomer was obtained when acetophenone was the substrate.
- Bianchi, Paola,Varela, Romina Fernández,Bianchi, Dario A.,Kemppainen, Minna,Iribarren, Adolfo M.,Lewkowicz, Elizabeth
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p. 137 - 144
(2017/06/21)
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- Visible-Light-Mediated Anti-Markovnikov Hydration of Olefins
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Considering that stoichiometric borane and oxidant are required in the classical alkene anti-Markovnikov hydration process, it remains appealing to achieve the transformation in a catalytic protocol. Herein, a visible-light-mediated anti-Markovnikov addition of water to alkenes by using an organic photoredox catalyst in conjunction with a redox-active hydrogen atom donor was developed, which avoided the need for a transition-metal catalyst, stoichiometric borane, as well as oxidant. Both terminal and internal olefins are readily accommodated in this transformation to obtain corresponding primary and secondary alcohols in good yields with single regioselectivity. This procedure can be scaled up to gram scale with a 230 turnover number based on photocatalyst.
- Hu, Xia,Zhang, Guoting,Bu, Faxiang,Lei, Aiwen
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p. 1432 - 1437
(2017/08/09)
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- CATALYST SYSTEM FOR PRODUCING KETONES FROM EPOXIDES
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A catalyst composition is useful for producing a ketone from a compound containing at least one epoxide group, and the catalyst composition contains at least one precious metal; and at least one mixed oxide; wherein the mixed oxide contains zirconium dioxide and silicon dioxide; wherein the precious metal is supported and the support is not entirely made of the mixed oxide; and wherein a mass ratio of zirconium dioxide to silicon dioxide in the mixed oxide is 86:14 to 99.9:0.1.
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Paragraph 0138; 0139
(2016/05/02)
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- Highly Active and Selective Manganese C=O Bond Hydrogenation Catalysts: The Importance of the Multidentate Ligand, the Ancillary Ligands, and the Oxidation State
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The replacement of expensive noble metals by earth-abundant transition metals is a central topic in catalysis. Herein, we introduce a highly active and selective homogeneous manganese-based C=O bond hydrogenation catalyst. Our catalyst has a broad substrate scope, it is able to hydrogenate aryl–alkyl, diaryl, dialkyl, and cycloalkyl ketones as well as aldehydes. A very good functional group tolerance including the quantitative and selective hydrogenation of a ketone in the presence of a non-shielded olefin is observed. In Mn hydrogenation catalysis, the combination of the multidentate ligand, the oxidation state of the metal, and the choice of the right ancillary ligand is crucial for high activity. This observation emphasizes an advantage and the importance of homogeneous catalysts in 3d-metal catalysis. For coordination compounds, fine-tuning of a complex coordination environment is easily accomplished in comparison to enzyme and/or heterogeneous catalysts.
- Kallmeier, Fabian,Irrgang, Torsten,Dietel, Thomas,Kempe, Rhett
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supporting information
p. 11806 - 11809
(2016/11/16)
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- Ruthenium Catalyzed Selective Hydroboration of Carbonyl Compounds
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Using the [Ru(p-cymene)Cl2]2 (1) complex, catalytic hydroboration of aldehydes and ketones with pinacolborane under neat and mild conditions is reported. At rt, chemoselective hydroboration of aldehydes over the ketones is also attained. Mechanistic studies confirmed the immediate formation of monohydride bridged dinuclear complex [{(μ6-p-cymene)RuCl}2(μ-H-μ-Cl)] (1b) from the reaction of 1 with pinacolborane, which catalyzed the highly efficient hydroboration reactions. The catalytic cycle containing mononuclear Ru-H species and intramolecular 1,3-hydride transfer is postulated.
- Kaithal, Akash,Chatterjee, Basujit,Gunanathan, Chidambaram
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p. 4790 - 4793
(2015/10/12)
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- Selective transformations of carbonyl functions in the presence of α,β-unsaturated ketones: Concise asymmetric total synthesis of decytospolides A and B
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Enones selectively react with a combination of PPh3 and TMSOTf to produce phosphonium silyl enol ethers, which work as protective groups of enones during the reduction of other carbonyl functions and can be easily deprotected to regenerate parent enones at workup. Furthermore, the first ketone selective alkylations in the presence of enones were also accomplished. This in situ protection method was applied to concise asymmetric total syntheses of decytospolides A and B.
- Yahata, Kenzo,Minami, Masaki,Watanabe, Kei,Fujioka, Hiromichi
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supporting information
p. 3680 - 3683
(2014/08/05)
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- Nanostructured RuO2 on MWCNTs: Efficient catalyst for transfer hydrogenation of carbonyl compounds and aerial oxidation of alcohols
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Multiwall carbon nanotubes (MWCNTs)/ruthenium dioxide nanoparticles (RuO2NPs) composite was prepared by a straightforward 'dry synthesis' method. After being well characterized, the prepared composite was used as a nanocatalyst (RuO2/MWCNT) for the transfer hydrogenation of carbonyl compounds. The excellent adhesion of RuO2NPs on the anchoring sites of MWCNTs was confirmed by TEM and Raman analyses. The weight percentage (7.97 wt%) and the chemical state (+4) of Ru in RuO2/MWCNT was confirmed by EDS and XPS analyses, respectively. It was found that the RuO2/MWCNT has a higher specific surface area of 189.3 m2 g-1. Initially the reaction conditions were optimized and then the scope of the catalytic system was extended with a wide range of carbonyl compounds. The influence of the size of RuO2NPs on the transfer hydrogenation of carbonyl compounds was also studied. The RuO2/MWCNT is highly chemoselective, heterogeneous in nature, reusable and highly stable. Owing to the high stability of the used catalyst (u-RuO2/MWCNT), it was further calcinated at high temperature to obtain RuO2 nanorods (NRs) hybrid MWCNTs. Then the hybrid material was used as a catalyst (r-RuO 2/MWCNT) for the aerial oxidation of alcohols and the result was found to be good.
- Gopiraman,Babu, S. Ganesh,Karvembu,Kim
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- Oxidative debenzylation of N-benzyl amides and O-benzyl ethers using alkali metal bromide
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The oxidative debenzylation of N-benzyl amides and O-benzyl ethers was promoted with high efficiency by a bromo radical formed through the oxidation of bromide from alkali metal bromide under mild conditions. This reaction provided the corresponding amides from N-benzyl amides and carbonyl compounds from O-benzyl ethers in high yields.
- Moriyama, Katsuhiko,Nakamura, Yu,Togo, Hideo
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supporting information
p. 3812 - 3815
(2014/08/05)
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- General and highly efficient iron-catalyzed hydrogenation of aldehydes, ketones, and α,β-unsaturated aldehydes
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EnvIRONmentally friendly: The title hydrogenation of aldehydes, ketones, and α,β-unsaturated aldehydes is reported. In the presence of the catalyst 1, primary, secondary, and allylic alcohols were obtained in good to excellent yields under mild reaction conditions. The catalyst is easily and inexpensively prepared, and is also stable to air, water, and column chromatography. Copyright
- Fleischer, Steffen,Zhou, Shaolin,Junge, Kathrin,Beller, Matthias
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p. 5120 - 5124
(2013/06/27)
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- Reductions of aldehydes and ketones with a readily available N-heterocyclic carbene borane and acetic acid
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Acetic acid promotes the reduction of aldehydes and ketones by the readily available N-heterocyclic carbene borane, 1,3-dimethylimidazol-2-ylidene borane. Aldehydes are reduced over 1-24 h at room temperature with 1 equiv of acetic acid and 0.5 equiv of the NHC-borane. Ketone reductions are slower but can be accelerated by using 5 equiv of acetic acid. Aldehydes can be selectively reduced in the presence of ketones. On a small scale, products are isolated by evaporation of the reaction mixture and direct chromatography.
- Lamm, Vladimir,Pan, Xiangcheng,Taniguchi, Tsuyoshi,Curran, Dennis P.
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p. 675 - 680
(2013/05/21)
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- Aniline-terephthalaldehyde resin p-toluenesulfonic acid (ATRT) salt as efficient mild polymeric solid acid catalyst
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Aniline-terephthalaldehyde resin p-toluenesulfonic acid (ATRT) salt was easily prepared by the reaction of aniline with 1.25 equiv of terephthalaldehyde in the presence of 1.0 equiv of p-toluenesulfonic acid at 75 C for 24 h in EtOH. ATRT efficiently catalyzed the tetrahydropyranylation of alcohols and deprotection of tetrahydropyranyl (THP), triethylsilyl (TES), and tert-butyldimethylsilyl (TBDMS) ethers. Deprotection of dodecyl THP ether and dodecyl TBDMS ether catalyzed by ATRT proceeded faster than those by pyridinium p-toluenesulfonate (PPTS). ATRT was reused without significant loss of activities.
- Tanemura, Kiyoshi,Suzuki, Tsuneo
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supporting information
p. 6740 - 6743
(2013/11/19)
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- Heterogeneous catalytic epoxidation of olefin over a hydrothermally synthesized 3D phosphate bridged copper(II) framework
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A 3D copper phosphate, [Cu2(PO4)(OH)] n (1), has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction analysis. In [Cu2(PO4)(OH)] n, there are two types of copper centers having distorted trigonal bipyramidal geometry and distorted octahedral geometry that are connected by the μ2-bridging of each phosphate oxygen ultimately forming a η8-PO4 bridged 3D network. The compound exhibited excellent catalytic performance in olefin epoxidation. Epoxidation of styrene and substituted styrenes, as well as bulky olefins like cycloalkenes and long-chain alkenes, is efficiently catalyzed by [Cu2(PO 4)(OH)] n using tert-butylhydroperoxide in acetonitrile. The results obtained in the heterogeneous catalytic reactions show that the olefins are converted to the respective epoxides in good yield with high selectivity. [Cu2(PO4)(OH)] n was catalytically more active and selective in comparison to simple copper(II) phosphate salt in heterogeneous medium. The catalyst can be recycled and reused several times without significant loss of activity.
- Saha, Debraj,Maity, Tanmoy,Sen, Rupam
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p. 2444 - 2454
(2013/08/23)
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- Silica gel promotes reductions of aldehydes and ketones by N-heterocyclic carbene boranes
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N-Heterocyclic carbene boranes (NHC-boranes) such as 1,3-dimethylimidazol- 2-ylidine trihydridoborane (diMe-Imd-BH3) serve as practical hydride donors for the reduction of aldehydes and ketones in the presence of silica gel. Primary and secondary alcohols are formed in good yields under ambient conditions. Aldehydes are selectively reduced in the presence of ketones. One, two, or even all three of the boron hydrides can be transferred. The process is attractive because all the components are stable and easy to handle and because both the reaction and isolation procedures are convenient.
- Taniguchi, Tsuyoshi,Curran, Dennis P.
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p. 4540 - 4543
(2012/10/29)
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- Lanthanide carboxylate frameworks: Efficient heterogeneous catalytic system for epoxidation of olefins
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Two lanthanide-based three dimensional metal-organic frameworks (MOF) viz. [Nd(HCOO)3]n (1) and [Pr(HCOO)3]n (2) have been synthesized and characterized. Both the compounds have similar structure. In this study we have demonstrated that the compounds are highly efficient in catalyzing epoxidation of various cyclic and linear olefinic substrates. MOF compounds are stable and recyclable under the reaction conditions. Notably, MOF systems are remarkably more active and selective than the corresponding lanthanide oxide in epoxidation reaction of olefins.
- Sen, Rupam,Saha, Debraj,Koner, Subratanath
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experimental part
p. 124 - 130
(2012/04/10)
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- Oxidative functional group transformations with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate
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A divanadium-substituted phosphotungstate TBA4[γ-PW 10O38V2(μ-OH)(μ-O)] (I, TBA = tetra-n-butylammonium) reacts with one equivalent H+ to form a bis-μ-hydroxo species [γ-PW10O38V 2(μ-OH)2]3- (I′) in organic media. The strong electrophilic oxidants such as [γ-PW10O 38V2(μ-OH)(μ-OOH)]3- (II) and [γ-PW10O38V2(μ-η2: η2-O2)]3- (III) are formed by the reaction of the bis-μ-hydroxo species with H2O2. In the presence of I and H+, H2O2-based oxidations such as (i) epoxidation of alkenes (17 examples including electron-deficient ones), (ii) hydroxylation of alkanes (11 examples), and (iii) oxidative bromination of alkenes, alkynes, and aromatics with Br- as a bromo source (12 examples including chlorination) chemo-, diastereo-, and regioselectively proceed to give the corresponding oxidized products in moderate to high yields with high efficiencies of H2O2 utilization.
- Mizuno, Noritaka,Kamata, Keigo,Yamaguchi, Kazuya
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scheme or table
p. 157 - 161
(2012/06/18)
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- Screening of a minimal enriched P450 BM3 mutant library for hydroxylation of cyclic and acyclic alkanes
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A minimal enriched P450 BM3 library was screened for the ability to oxidize inert cyclic and acyclic alkanes. The F87A/A328V mutant was found to effectively hydroxylate cyclooctane, cyclodecane and cyclododecane. F87V/A328F with high activity towards cyclooctane hydroxylated acyclic n-octane to 2-(R)-octanol (46% ee) with high regioselectivity (92%).
- Weber, Evelyne,Seifert, Alexander,Antonovici, Mihaela,Geinitz, Christopher,Pleiss, Juergen,Urlacher, Vlada B.
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scheme or table
p. 944 - 946
(2011/02/25)
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- Highly selective synthesis of cyclododecanone over mesostructured VSBA-15 catalysts
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Highly ordered VSBA-15 mesoporous catalysts have been synthesized under pH-adjusting direct hydrothermal (pH-aDH) method using vanadyl sulphate hydrate and Pluronic P123 as the sources of vanadium and template, respectively. The mesoporous catalysts characterized by sophisticated instrumental techniques, viz. ICP-AES, XRD, N2 adsorption, ESR, UV-vis DRS, 51V MAS NMR, 29Si MAS NMR and TEM show their two-dimensional mesostructures with tetrahedral vanadium species on the silica surface. The well ordered VSBA-15 catalysts have been used in the oxidation of cyclododecane (CDD) with hydrogen peroxide (H2O2, 30%) to find their catalytic activities. The regenerated VSBA-15 catalysts have been examined to find their catalytic stabilities. VSBA-15(5) catalyst has been washed with ammonium acetate solution to investigate the leaching of vanadium species in the framework of silica network of SBA-15, and the catalytic activity of washed VSBA-15(5) has also been examined in the catalytic reactions. Moreover, the hydrothermally stable VSBA-15(5) catalyst has also been examined in the catalytic reaction to find the effect of its catalytic activity. Additionally, the influences of various reaction parameters such as temperature, time, ratios of reactant and solvents on the oxidation of CDD have been investigated. Based on the catalytic results, VSBA-15(5) catalyst is found to be a highly active, recyclable and promising heterogeneous catalyst for selective synthesis of cyclododecanone (CDDO).
- Selvaraj,Park
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experimental part
p. 22 - 30
(2011/01/12)
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- Manganese-catalyzed direct oxidation of methyl ethers to ketones
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Direct C-H oxidation of alkyl ethers into ketones was achieved using 0.1 mol % of MnCl2 and 4, 4′, 4″-tri(tert-butyl)-2, 2′:6′, 2″-terpyridine (tBu-terpy) in the presence of mCPBA. Conversion of methyl ethers into ketones was particularly efficient and chemoselective. Electron-deficient oxygen functionalities survived under the reaction conditions. The present method broadens the utility of methyl ethers as stable protective groups for hydroxy functionalities and as precursors to carbonyl compounds. (Chemical equation presented).
- Kamijo, Shin,Amaoka, Yuuki,Inoue, Masayuki
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supporting information; experimental part
p. 486 - 489
(2010/09/04)
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- Unified oxidation protocol for the synthesis of carbonyl compounds using a manganese catalyst
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We have developed a unified protocol for the oxidation of ethers, benzylic compounds, and alcohols to carbonyl compounds. The protocol uses catalytic amounts of manganese(II) chloride tetrahydrate and tri(t-butyl)-2,2':6',2Prime;- terpyridine in combination with a stoichiometric amount of either m-chloroperbenzoic acid (MCPBA) or potassium hydrogen peroxysulfate (KHSO 5). A reagent system consisting of the Mn catalyst and MCPBA permitted the chemoselective sp3 C-H oxidation of alkyl ethers and benzylic compounds to generate the corresponding ketones. Alternatively, the water-soluble inorganic salt KHSO5 in combination with the Mn catalyst was used to oxidize alcohols to ketones or carboxylic acids. Importantly, the Mn catalyst/KHSO5 system eliminates technical difficulties associated with the isolation of carboxylic acid products. All the oxidations presented in this feature article proceed at sup-ambient temperature in an aerobic atmosphere, and can therefore be used in practical syntheses of complex organic molecules. Georg Thieme Verlag Stuttgart · New York.
- Kamijo, Shin,Amaoka, Yuuki,Inoue, Masayuki
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experimental part
p. 2475 - 2489
(2010/09/06)
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- PROCESS FOR PREPARING PURE CYCLODODECANONE
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The present invention relates to a process for preparing at least one cyclic compound with Z cycles and 7 to 16 carbon atoms with a keto group, at least comprising the stages: (a1) oxidation of a composition (A), at least comprising one cyclic olefin with Z cycles and 7 to 16 carbon atoms and at least two C—C double bonds, by means of dinitrogen monoxide to give a composition (A1),(a2) separating off the at least one cyclic olefin with Z cycles and 7 to 16 carbon atoms with at least two C—C double bonds from the composition (A1) in order to obtain a composition (A2), and(b) distillative treatment of the composition (A2) from step (a2) in order to obtain a composition (B), comprising the at least one cyclic compound with Z cycles and 7 to 16 carbon atoms with a keto group andless than 1.0% by weight of the at least one compound with Z?1 cycles and 7 to 16 carbon atoms with at least one aldehyde group, where Z can be 1, 2, 3 or 4.
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Page/Page column 18-19
(2010/08/07)
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- Green and efficient procedure for the trimethylsilylation of hydroxy groups and their regeneration using sulfamic acid as recyclable catalyst
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Structurally diverse alcohols and phenols were efficiently transformed into their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) in the presence of catalytic amounts of sulfamic acid (SA) at room temperature under both acetonitrile and solvent-free conditions. Deprotection of these trimethylsilyl ethers to their parent alcohols and phenols was also achieved using this catalyst in water at room temperature. Copyright Taylor & Francis Group, LLC.
- Rostami, Amin,Ahmad-Jangi, Firoz,Zarebin, Mohammad Rezgar,Akradi, Jamal
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experimental part
p. 1500 - 1507
(2010/07/15)
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- Efficient stereo- and regioselective hydroxylation of alkanes catalysed by a bulky polyoxometalate
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Direct functionalization of alkanes by oxidation of C-H bonds to form alcohols under mild conditions is a challenge for synthetic chemistry. Most alkanes contain a large number of C-H bonds that present difficulties for selectivity, and the oxidants employed often result in overoxidation. Here we describe a divanadium-substituted phosphotungstate that catalyses the stereo- and regioselective hydroxylation of alkanes with hydrogen peroxide as the sole oxidant. Both cyclic and acyclic alkanes were oxidized to form alcohols with greater than 96% selectivity. The bulky polyoxometalate framework of the catalyst results in an unusual selectivity that can lead to the oxidation of secondary rather than the weaker tertiary C-H bonds. The catalyst also avoids wasteful decomposition of the stoichiometric oxidant, which can result in the production of hydroxyl radicals and lead to non-selective oxidation and overoxidation of the desired products.
- Kamata, Keigo,Yonehara, Kazuhiro,Nakagawa, Yoshinao,Uehara, Kazuhiro,Mizuno, Noritaka
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scheme or table
p. 478 - 483
(2010/09/17)
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- METHODS OF MAKING CYCLODODECATRIENE AND METHODS OF MAKING LAUROLACTONE
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The present disclosure provides processes for the preparation of dodecanedioic acid (DDDA).
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Page/Page column 6
(2009/10/01)
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- Catalytic transfer hydrogenation of cycloalkanones on MgO. Vapour and liquid phase modes of reaction
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The reactivity of a series of cycloalkanones of the general formula (CH2)nCO, where n = 4, 5, 6, 7, 11 and 14 in the transfer hydrogenation reaction over magnesium oxide as the catalyst, either in vapour or liquid phase (VP or LP) has been studied. In the VP mode of reaction the activity of MgO treated with triethylamine, water, phenol or benzoic acid in the reduction of cyclopentanone by propan-2-ol has been determined. A strongly diminished or residual activity of MgO has been observed after the catalyst's treatment with phenol or benzoic acid, respectively. The occurrence of side reactions of cyclopentanone in the LP mode of reaction resulted in high conversions of the ketone (up to 91%), very low yields of cyclopentanol (I) (below 6%) and very high yields of 2-cyclopentyli- dene-cyclopentanone (II) (>80%).
- Glinski
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experimental part
p. 187 - 194
(2009/10/23)
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- Photoinduced reversible structural transformation and selective oxidation catalysis of unsaturated ruthenium complexes supported on SiO2
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(Chemical Equation Presented) Ru experienced? Two novel coordinatively unsaturated SiO2-supported Ru complexes were prepared by photoinduced ligand elimination, accompanied by dissociative coordination of a surface OH group to the unsaturated Ru center by photoirradiation. Wavelength- and atmosphere-dependent photoinduced reversible interconversion occurs between the two Ru complexes. One of the complexes is catalytically active for the photooxidation of cycloalkanes with O2.
- Tada, Mizuki,Akatsuka, Yusaku,Yang, Yong,Sasaki, Takehiko,Kinoshita, Mutsuo,Motokura, Ken,Iwasawa, Yasuhiro
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experimental part
p. 9252 - 9255
(2009/05/16)
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- A new insight into the oxidation of cyclododecane with hydrogen peroxide in the presence of iron-substituted polyoxotungstates
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The catalytic homogeneous oxidation of cyclododecane with hydrogen peroxide in the presence of tetrabutylammonium salts of iron-substituted Keggin-type polyoxotungstates of general formula (TBA)4HzXW 11Fe(H2O)O39-nH2O (where X = P, Si, B, and z = 0-2) is described. In the reaction conditions reported, the corresponding alcohol, ketone, and hydroperoxide are obtained as the main reaction products. The catalytic activity of the anions with phosphorous, silicon, and boron is compared in different reaction conditions. These catalytic oxidation reactions seem to be radical processes, since they are totally inhibited in the presence of I2, a well-known radical scavenger. Thieme Stuttgart.
- Santos, Isabel C. M. S.,Sim?es, Mário M. Q.,Balula, M. Salete S.,Neves, M. Gra?a P. M. S.,Cavaleiro, José A. S.,Cavaleiro, Ana M. V.
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experimental part
p. 1623 - 1626
(2009/05/07)
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- Selective oxidation of alkanes with molecular oxygen and acetaldehyde in compressed (supercritical) carbon dioxide as reaction medium
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The oxidation of cycloalkanes or alkylarenes with molecular oxygen and acetaldehyde as sacrificial co-reductant occurs efficiently in compressed (supercritical) carbon dioxide (scCO2) under mild multiphase conditions. No catalyst is required and high-pressure ATR-FTIR online measurements show that a radical reaction pathway is heterogeneously initiated by the stainless steel of the reactor walls. For secondary carbon atoms, high ketone to alcohol ratios are observed (3.5-7.9), most probably due to fast consecutive oxidation of alcoholic intermediates. Since C - C scission reactions are detected only to a very small extent, tertiary carbon atoms are transformed into the corresponding alcohols with high selectivity. Detailed analysis of the product distributions and other mechanistic evidence suggest that acetaldehyde acts not only as the sacrificial oxygen acceptor, but also as an efficient H-atom donor for peroxo and oxo radicals and as a crucial reductant for hydroperoxo intermediates. In comparison to other inert gases such as compressed N, or Ar, the use of carbon dioxide was shown to increase the yields of alkane oxygenates under identical reaction conditions.
- Theyssen, Nils,Hou, Zhenshan,Leitner, Walter
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p. 3401 - 3409
(2008/09/19)
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- Water: The ideal hydrogen-atom source in free-radical chemistry mediated by TiIII and other single-electron-transfer metals?
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(Chemical Equation Presented) Hydrogen-atom transfer from water to free radicals can be mediated by aqua complexes of titanium(III) (see scheme). Asymmetric epoxidation in combination with [Cp2TiCl]/H 2O-mediated reductive epoxide opening can be viewed as an alternative with complementary stereoselectivity to the hydroboration-epoxidation method for the enantioselective synthesis of anti-Markovnikov alcohols from alkenes.
- Cuerva, Juan M.,Campa?a, Araceli G.,Justicia, José,Rosales, Antonio,Oller-López, Juan L.,Robles, Rafael,Cárdenas, Diego J.,Bu?uel, Elena,Oltra, J. Enrique
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p. 5522 - 5526
(2007/10/03)
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