- Hydroboration Reaction and Mechanism of Carboxylic Acids using NaNH2(BH3)2, a Hydroboration Reagent with Reducing Capability between NaBH4and LiAlH4
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Hydroboration reactions of carboxylic acids using sodium aminodiboranate (NaNH2[BH3]2, NaADBH) to form primary alcohols were systematically investigated, and the reduction mechanism was elucidated experimentally and computationally. The transfer of hydride ions from B atoms to C atoms, the key step in the mechanism, was theoretically illustrated and supported by experimental results. The intermediates of NH2B2H5, PhCH= CHCOOBH2NH2BH3-, PhCH= CHCH2OBO, and the byproducts of BH4-, NH2BH2, and NH2BH3- were identified and characterized by 11B and 1H NMR. The reducing capacity of NaADBH was found between that of NaBH4 and LiAlH4. We have thus found that NaADBH is a promising reducing agent for hydroboration because of its stability and easy handling. These reactions exhibit excellent yields and good selectivity, therefore providing alternative synthetic approaches for the conversion of carboxylic acids to primary alcohols with a wide range of functional group tolerance.
- Wang, Jin,Ju, Ming-Yue,Wang, Xinghua,Ma, Yan-Na,Wei, Donghui,Chen, Xuenian
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p. 5305 - 5316
(2021/04/12)
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- A method of synthesis of alcohols
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The present invention belongs to the field of organic synthesis technology, specifically a synthesis method of an alcohol; the present invention is under the catalytic action of tert-butanol lithium, with ester compounds and pinacol borane as raw materials, tetrahydrofuran as a solvent, reacted at 100 ° C for 24h, followed by adding 2mol / LNaOH / MeOH solution, stirred at room temperature overnight to obtain alcohol compounds; the raw materials of the present invention are of extensive sources or easy to prepare, the reaction conditions are relatively mild and do not require a large number of / cumbersome additives, in addition to the tert-butanol lithium catalyst is simple, And the prepared alcohol compounds are of high quality and high separation yield.
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Paragraph 0043-0048
(2022/01/10)
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- Synthesis, Structure, and Catalytic Hydrogenation Activity of [NO]-Chelate Half-Sandwich Iridium Complexes with Schiff Base Ligands
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A series of N,O-coordinate iridium(III) complexes with a half-sandwich motif bearing Schiff base ligands for catalytic hydrogenation of nitro and carbonyl substrates have been synthesized. All iridium complexes showed efficient catalytic activity for the hydrogenation of ketones, aldehydes, and nitro-containing compounds using clean H2 as reducing reagent. The iridium catalyst displayed the highest TON values of 960 and 950 in the hydrogenation of carbonyl and nitro substrates, respectively. Various types of substrates with different substituted groups afforded corresponding products in excellent yields. All N,O-coordinate iridium(III) complexes 1-4 were well characterized by IR, NMR, HRMS, and elemental analysis. The molecular structure of complex 1 was further characterized by single-crystal X-ray determination.
- Lv, Wen-Rui,Li, Rong-Jian,Liu, Zhen-Jiang,Jin, Yan,Yao, Zi-Jian
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p. 8181 - 8188
(2021/05/26)
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- Visible Light Induced Reduction and Pinacol Coupling of Aldehydes and Ketones Catalyzed by Core/Shell Quantum Dots
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We present an efficient and versatile visible light-driven methodology to transform aryl aldehydes and ketones chemoselectively either to alcohols or to pinacol products with CdSe/CdS core/shell quantum dots as photocatalysts. Thiophenols were used as proton and hydrogen atom donors and as hole traps for the excited quantum dots (QDs) in these reactions. The two products can be switched from one to the other simply by changing the amount of thiophenol in the reaction system. The core/shell QD catalysts are highly efficient with a turn over number (TON) larger than 4 × 104 and 4 × 105 for the reduction to alcohol and pinacol formation, respectively, and are very stable so that they can be recycled for at least 10 times in the reactions without significant loss of catalytic activity. The additional advantages of this method include good functional group tolerance, mild reaction conditions, the allowance of selectively reducing aldehydes in the presence of ketones, and easiness for large scale reactions. Reaction mechanisms were studied by quenching experiments and a radical capture experiment, and the reasons for the switchover of the reaction pathways upon the change of reaction conditions are provided.
- Xi, Zi-Wei,Yang, Lei,Wang, Dan-Yan,Feng, Chuan-Wei,Qin, Yufeng,Shen, Yong-Miao,Pu, Chaodan,Peng, Xiaogang
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p. 2474 - 2488
(2021/02/05)
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- Selective aldehyde reductions in neutral water catalysed by encapsulation in a supramolecular cage
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The enhancement of reactivity inside supramolecular coordination cages has many analogies to the mode of action of enzymes, and continues to inspire the design of new catalysts for a range of reactions. However, despite being a near-ubiquitous class of reactions in organic chemistry, enhancement of the reduction of carbonyls to their corresponding alcohols remains very much underexplored in supramolecular coordination cages. Herein, we show that encapsulation of small aromatic aldehydes inside a supramolecular coordination cage allows the reduction of these aldehydes with the mild reducing agent sodium cyanoborohydride to proceed with high selectivity (ketones and esters are not reduced) and in good yields. In the absence of the cage, low pH conditions are essential for any appreciable conversion of the aldehydes to the alcohols. In contrast, the specific microenvironment inside the cage allows this reaction to proceed in bulk solution that is pH-neutral, or even basic. We propose that the cage acts to stabilise the protonated oxocarbenium ion reaction intermediates (enhancing aldehyde reactivity) whilst simultaneously favouring the encapsulation and reduction of smaller aldehydes (which fit more easily inside the cage). Such dual action (enhancement of reactivity and size-selectivity) is reminiscent of the mode of operation of natural enzymes and highlights the tremendous promise of cage architectures as selective catalysts.
- Paul, Avishek,Shipman, Michael A.,Onabule, Dolapo Y.,Sproules, Stephen,Symes, Mark D.
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p. 5082 - 5090
(2021/04/21)
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- Uranyl(VI) Triflate as Catalyst for the Meerwein-Ponndorf-Verley Reaction
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Catalytic transformation of oxygenated compounds is challenging in f-element chemistry due to the high oxophilicity of the f-block metals. We report here the first Meerwein-Ponndorf-Verley (MPV) reduction of carbonyl substrates with uranium-based catalysts, in particular from a series of uranyl(VI) compounds where [UO2(OTf)2] (1) displays the greatest efficiency (OTf = trifluoromethanesulfonate). [UO2(OTf)2] reduces a series of aromatic and aliphatic aldehydes and ketones into their corresponding alcohols with moderate to excellent yields, using iPrOH as a solvent and a reductant. The reaction proceeds under mild conditions (80 °C) with an optimized catalytic charge of 2.3 mol % and KOiPr as a cocatalyst. The reduction of aldehydes (1-10 h) is faster than that of ketones (>15 h). NMR investigations clearly evidence the formation of hemiacetal intermediates with aldehydes, while they are not formed with ketones.
- Kobylarski, Marie,Monsigny, Louis,Thuéry, Pierre,Berthet, Jean-Claude,Cantat, Thibault
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supporting information
p. 16140 - 16148
(2021/11/01)
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- Sodium Aminodiboranate, a New Reagent for Chemoselective Reduction of Aldehydes and Ketones to Alcohols
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Sodium aminodiboranate (NaNH 2(BH 3) 2, NaADBH) is a new member of the old borane family, which exhibits superior performance in chemoselective reduction. Experimental results show that NaADBH can rapidly reduce aldehydes and ketones to the corresponding alcohols in high efficiency and selectivity under mild conditions. There are little steric and electronic effects on this reduction.
- Wang, Jin,Guo, Yu,Li, Shouhu,Chen, Xuenian
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supporting information
p. 1104 - 1108
(2021/05/25)
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- N,N-Dimethylformamide-stabilised palladium nanoparticles combined with bathophenanthroline as catalyst for transfer vinylation of alcohols from vinyl ether
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We reportN,N-dimethylformamide-stabilised Pd nanoparticle (Pd NP)-catalysed transfer vinylation of alcohols from vinyl ether. Pd NPs combined with bathophenanthroline exhibited high catalytic activity. This reaction proceeded with low catalyst loading and the catalyst remained effective even after many rounds of recycling. The observation of the catalyst using transmission electron microscopy and dynamic light scattering implied no deleterious aggregation of Pd NPs.
- Tabaru, Kazuki,Nakatsuji, Masato,Itoh, Satoshi,Suzuki, Takeyuki,Obora, Yasushi
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supporting information
p. 3384 - 3388
(2021/05/03)
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- Discovery of Novel Azetidine Amides as Potent Small-Molecule STAT3 Inhibitors
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We optimized our previously reported proline-based STAT3 inhibitors into an exciting new series of (R)-azetidine-2-carboxamide analogues that have sub-micromolar potencies. 5a, 5o, and 8i have STAT3-inhibitory potencies (IC50) of 0.55, 0.38, and 0.34 μM, respectively, compared to potencies greater than 18 μM against STAT1 or STAT5 activity. Further modifications derived analogues, including 7e, 7f, 7g, and 9k, that addressed cell membrane permeability and other physicochemical issues. Isothermal titration calorimetry analysis confirmed high-affinity binding to STAT3, with KD of 880 nM (7g) and 960 nM (9k). 7g and 9k inhibited constitutive STAT3 phosphorylation and DNA-binding activity in human breast cancer, MDA-MB-231 or MDA-MB-468 cells. Furthermore, treatment of breast cancer cells with 7e, 7f, 7g, or 9k inhibited viable cells, with an EC50 of 0.9-1.9 μM, cell growth, and colony survival, and induced apoptosis while having relatively weaker effects on normal breast epithelial, MCF-10A or breast cancer, MCF-7 cells that do not harbor constitutively active STAT3.
- Brotherton-Pleiss, Christine,Yue, Peibin,Zhu, Yinsong,Nakamura, Kayo,Chen, Weiliang,Fu, Wenzhen,Kubota, Casie,Chen, Jasmine,Alonso-Valenteen, Felix,Mikhael, Simoun,Medina-Kauwe, Lali,Tius, Marcus A.,Lopez-Tapia, Francisco,Turkson, James
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supporting information
p. 695 - 710
(2021/01/14)
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- Cobalt-catalysed selective synthesis of aldehydes and alcohols from esters
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Efficient and selective reduction of esters to aldehydes and alcohols is reported in which a simple cobalt pincer catalyst catalyses both transformations using diethylsilane as a reductant. Remarkably, the reaction selectivity is controlled by the stoichiometry of diethylsilane. This journal is
- Pattanaik, Sandip,Gunanathan, Chidambaram
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supporting information
p. 7345 - 7348
(2020/07/14)
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- Continuous-Flow Amide and Ester Reductions Using Neat Borane Dimethylsulfide Complex
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Reductions of amides and esters are of critical importance in synthetic chemistry, and there are numerous protocols for executing these transformations employing traditional batch conditions. Notably, strategies based on flow chemistry, especially for amide reductions, are much less explored. Herein, a simple process was developed in which neat borane dimethylsulfide complex (BH3?DMS) was used to reduce various esters and amides under continuous-flow conditions. Taking advantage of the solvent-free nature of the commercially available borane reagent, high substrate concentrations were realized, allowing outstanding productivity and a significant reduction in E-factors. In addition, with carefully optimized short residence times, the corresponding alcohols and amines were obtained in high selectivity and high yields. The synthetic utility of the inexpensive and easily implemented flow protocol was further corroborated by multigram-scale syntheses of pharmaceutically relevant products. Owing to its beneficial features, including low solvent and reducing agent consumption, high selectivity, simplicity, and inherent scalability, the present process demonstrates fewer environmental concerns than most typical batch reductions using metal hydrides as reducing agents.
- ?tv?s, Sándor B.,Kappe, C. Oliver
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p. 1800 - 1807
(2020/02/27)
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- Bimetallic Bis-NHC-Ir(III) Complex Bearing 2-Arylbenzo[d]oxazolyl Ligand: Synthesis, Catalysis, and Bimetallic Effects
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Herein, an unprecedented bimetallic bis-NHC Cp*Ir complex 1 bearing 2-arylbenzo[d]oxazolyl and NHC ligands is reported. A significant increase in activity was observed for N-methylation of amines and reduction of aldehydes with MeOH catalyzed by 1 compared to the monometallic analogues (2-11). Under the optimal conditions, it showed to be highly effective in N-methylation of nitroarenes with MeOH as both C1 and H2 source. Substrates, including aromatic amines, ketones, and nitro compounds with various functional groups, can be well-tolerated. Mechanistic studies and DFT calculation highlight the significance of bimetallic centers cooperativity.
- Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhan, Bing,Li, Zhi-Ming,Hou, Xiu-Feng
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p. 3514 - 3523
(2020/10/09)
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- Thiourea-Catalyzed C?F Bond Activation: Amination of Benzylic Fluorides
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We describe the first thiourea-catalyzed C?F bond activation. The use of a thiourea catalyst and Ti(OiPr)4 as a fluoride scavenger allows the amination of benzylic fluorides to proceed in moderate to excellent yields. Preliminary results with S- and O-based nucleophiles are also presented. DFT calculations reveal the importance of hydrogen bonds between the catalyst and the fluorine atom of the substrate to lower the activation energy during the transition state.
- Houle, Camille,Savoie, Paul R.,Davies, Clotilde,Jardel, Damien,Champagne, Pier Alexandre,Bibal, Brigitte,Paquin, Jean-Fran?ois
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supporting information
p. 10620 - 10625
(2020/07/24)
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- Reduction of Aldehydes with Formic acid in Ethanol using Immobilized Iridium Nanoparticles on a Triazine-phosphanimine Polymeric Organic Support
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A novel triazine-phosphanimine polymeric organic support (TPA) was synthesized successfully by a controllable one-pot method using melamine (1,3,5-triazine-2,4,6-triamine) and trichlorophosphane (PCl3). The TPA substrate is a material incorporating P and N atoms which can coordinate with metals as a pincer ligand to stabilize them, providing an efficient heterogeneous support to prepare recyclable transition metal catalyst systems. In this study, TPA was used as support to immobilize iridium nanoparticles in the range of ~8 nm on its surface, resulting in the generation of a novel iridium nanocatalyst system (INP-TPA-POP). This catalyst system was characterized using different microscopic and spectroscopic techniques such as FT-IR, TEM, XPS, XRD, SEM, EDX, elemental analysis, ICP and BET analysis. The INP-TPA-POP nanocatalyst exhibited remarkable activity in reduction of aldehydes to alcohols using formic acids as reducing agent in ethanol as solvent.
- Panahi, Farhad,Haghighi, Fatemeh,Khalafi-Nezhad, Ali
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- Palladium nanoparticles stabilized by novel choline-based ionic liquids in glycerol applied in hydrogenation reactions
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Palladium nanoparticles stabilized by choline-based ionic liquids in glycerol were prepared from Pd(II) precursors by simply heating at 80 °C under argon; in this process, the water present in the ionic liquid was found to be responsible for the reduction of Pd(II) into zero-valent palladium species. Palladium nanoparticles were fully characterized in both liquid phase and solid state. The as-prepared metal nanoparticles exhibited remarkable catalytic activity in hydrogenation processes for a significant variety of functional groups (alkenes, alkynes, nitro derivatives, benzaldehydes, aromatic ketones).
- Garg, Garima,Foltran, Stéphanie,Favier, Isabelle,Pla, Daniel,Medina-González, Yaocihuatl,Gómez, Montserrat
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- Group 6 Metal Carbonyl Complexes Supported by a Bidentate PN Ligand: Syntheses, Characterization, and Catalytic Hydrogenation Activity
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We report on the preparation of a series of phosphorus-nitrogen donor ligand complexes [M(CO)4(PN)], where M = Cr, Mo, W and PN is 2-(diphenylphosphino)ethylamine. The organometallic compounds were readily obtained upon reacting the respective metal hexacarbonyls with equimolar amounts of the pertinent ligand in the presence of tetraethylammonium bromide. The PN-ligated metal carbonyls were fully characterized by standard spectroscopic techniques and X-ray crystallography. The ability of the title compounds to function as homogeneous hydrogenation catalysts was probed in the reduction of acetophenone and benzaldehyde derivatives to yield the corresponding alcohols. The reaction setup was easily assembled by simply combining the components in the autoclave on the bench outside an inert-gas-operated glovebox system.
- Faust, Kirill,Topf, Christoph,Vielhaber, Thomas
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p. 4535 - 4543
(2020/12/23)
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- Cerium(IV) Carboxylate Photocatalyst for Catalytic Radical Formation from Carboxylic Acids: Decarboxylative Oxygenation of Aliphatic Carboxylic Acids and Lactonization of Aromatic Carboxylic Acids
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We found that in situ generated cerium(IV) carboxylate generated by mixing the precursor Ce(OtBu)4 with the corresponding carboxylic acids served as efficient photocatalysts for the direct formation of carboxyl radicals from carboxylic acids under blue light-emitting diodes (blue LEDs) irradiation and air, resulting in catalytic decarboxylative oxygenation of aliphatic carboxylic acids to give C-O bond-forming products such as aldehydes and ketones. Control experiments revealed that hexanuclear Ce(IV) carboxylate clusters initially formed in the reaction mixture and the ligand-to-metal charge transfer nature of the Ce(IV) carboxylate clusters was responsible for the high catalytic performance to transform the carboxylate ligands to the carboxyl radical. In addition, the Ce(IV) carboxylate cluster catalyzed direct lactonization of 2-isopropylbenzoic acid to produce the corresponding peroxy lactone and ?3-lactone via intramolecular 1,5-hydrogen atom transfer (1,5-HAT).
- Hirosawa, Keishi,Mashima, Kazushi,Satoh, Tetsuya,Shinohara, Koichi,Shirase, Satoru,Tamaki, Sota,Tsurugi, Hayato
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supporting information
(2020/03/25)
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- Pd(OH)2/C, a Practical and Efficient Catalyst for the Carboxylation of Benzylic Bromides with Carbon Monoxide
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A simple, efficient, cheap, and broadly applicable system for the carboxylation of benzylic bromides with carbon monoxide and water is reported. Upon simple reaction with only 2.5 wt % of Pearlman's catalyst and 10 mol % of tetrabutylammonium bromide in tetrahydrofuran at 110 °C for 4 h, a range of benzylic bromides can be smoothly converted to the corresponding arylacetic acids in good to excellent yields after simple extraction and acid-base wash. The reaction was found to be broadly applicable, scalable, and could be successfully extended to the use of ex situ-generated carbon monoxide and applied to the synthesis of the nonsteroidal anti-inflammatory drug diclofenac.
- Wakuluk-Machado, Anne-Marie,Dewez, Damien F.,Baguia, Hajar,Imbratta, Miguel,Echeverria, Pierre-Georges,Evano, Gwilherm
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p. 713 - 723
(2020/02/04)
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- Selective Hydroboration of Carboxylic Acids with a Homogeneous Manganese Catalyst
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Catalytic reduction of carboxylic acid to the corresponding alcohol is a challenging task of great importance for the production of a variety of value-added chemicals. Herein, a manganese-catalyzed chemoselective hydroboration of carboxylic acids has been developed with a high turnover number (>99?000) and turnover frequency (>2000 h-1) at 25 °C. This method displayed tolerance of electronically and sterically differentiated substrates with high chemoselectivity. Importantly, aliphatic long-chain fatty acids, including biomass-derived compounds, can efficiently be reduced. Mechanistic studies revealed that the reaction occurs through the formation of active manganese-hydride species via an insertion and bond metathesis type mechanism.
- Barman, Milan K.,Das, Kuhali,Maji, Biplab
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p. 1570 - 1579
(2019/01/30)
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- Method for preparing alcoholic compound from anilino lithium compound as catalyst
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The invention relates to an application of an anilino lithium compound, in particular to a method for preparing an alcoholic compound from the anilino lithium compound as a catalyst. The catalyst, borane and carboxylic acid are stirred and mixed uniformly, subjected to a reaction and exposed to air to terminate the reaction, a reacted liquid is subjected to reduced-pressure treatment for solvent removal, silica gel and methanol are added, and the alcoholic compound is obtained by hydrolysis. The anilino lithium compound can perform high-activity catalysis on the reaction between carboxylic acid and borane at room temperature, dose of the catalyst is only 0.8mol% of the mole ratio of carboxylic acid, compared with the conventional catalysis system, the commercial reagent anilino lithium compound is used, reaction conditions are mild, and yield of borate with different substituents under limit conditions can reach 90% or higher.
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- Based on n-butyl aromatic carboxylic acid preparation of alcohol compound
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The present invention relates to n-butyl application, in particular to based on n-butyl aromatic carboxylic acid preparation of alcohol compound, the catalyst sequentially, borane and carboxylic acid uniformly stirred and mixed, exposed to the air after the reaction terminated in the reaction, the reaction solution under reduced pressure to remove the solvent, then adding silica gel methanol hydrolyzed to obtain the alcohol compound. The invention discloses a butyl lithium can be high activity under the room temperature condition of catalytic carboxylic acid and borane borohydride reaction, the catalyst levels are only the molar amount of carboxylic acid 0.5 μM %, compared with the prior catalytic system, using the commercial reagent is BuLi, mild reaction conditions, in under a limited condition of different substituents of the yield of the ester can reach 90% or more.
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- A is by aromatic carboxylic acid non-catalytic reaction of alcohol compound (by machine translation)
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The present invention discloses a non-catalytic reaction of the aromatic carboxylic acid preparation of alcohol compound. In an inert gas atmosphere, after dehydration and deoxidation treatment of the reaction bottle [...] borane and carboxylic acid stirring and mixing, reaction 6 - 12 hours to obtain borate, further hydrolyzed into alcohol; said carboxylic acid is benzoic acid, 4 - bromobenzoic acid, 4 - fluoro benzoic acid, 1 - naphthoic acid, 2 - methoxybenzene formic acid and the like. The invention for the first time in the absence of catalyst under the conditions of high-efficiently using carboxylic acid with borane generating borohydrite reaction, carbonyl compound with borane generating borohydrite reaction preparation borate, further hydrolysis alcohol, provides new programme. (by machine translation)
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Paragraph 0022
(2019/04/17)
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- Homogeneous Hydrogenation with a Cobalt/Tetraphosphine Catalyst: A Superior Hydride Donor for Polar Double Bonds and N-Heteroarenes
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The development of catalysts based on earth abundant metals in place of noble metals is becoming a central topic of catalysis. We herein report a cobalt/tetraphosphine complex-catalyzed homogeneous hydrogenation of polar unsaturated compounds using an air- and moisture-stable and scalable precatalyst. By activation with potassium hydroxide, this cobalt system shows both high efficiency (up to 24 000 TON and 12 000 h-1 TOF) and excellent chemoselectivities with various aldehydes, ketones, imines, and even N-heteroarenes. The preference for 1,2-reduction over 1,4-reduction makes this method an efficient way to prepare allylic alcohols and amines. Meanwhile, efficient hydrogenation of the challenging N-heteroarenes is also furnished with excellent functional group tolerance. Mechanistic studies and control experiments demonstrated that a CoIH complex functions as a strong hydride donor in the catalytic cycle. Each cobalt intermediate on the catalytic cycle was characterized, and a plausible outer-sphere mechanism was proposed. Noteworthy, external inorganic base plays multiple roles in this reaction and functions in almost every step of the catalytic cycle.
- Duan, Ya-Nan,Du, Xiaoyong,Cui, Zhikai,Zeng, Yiqun,Liu, Yufeng,Yang, Tilong,Wen, Jialin,Zhang, Xumu
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supporting information
p. 20424 - 20433
(2019/12/27)
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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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p. 373 - 384
(2019/01/28)
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- Deoxygenative cross-electrophile coupling of benzyl chloroformates with aryl iodides
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This work describes Ni-catalyzed cross-electrophile coupling of benzyl chloroformate derivatives with aryl iodides that generates a wide range of diaryl methane products. The mild reaction conditions merit the C-O bond radical fragmentation of benzyl chloroformates via halide abstraction or a single electron reduction by a Ni catalyst. This work offers a new substrate type for cross-electrophile couplings.
- Pan, Yingying,Gong, Yuxin,Song, Yanhong,Tong, Weiqi,Gong, Hegui
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supporting information
p. 4230 - 4233
(2019/05/06)
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- Nanoporous Na+-montmorillonite perchloric acid as an efficient and recyclable catalyst for the chemoselective protection of hydroxyl groups
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Nanoporous Na+-montmorillonite perchloric acid as a novel heterogeneous reusable solid acid catalyst was easily prepared by treatment of Na+-montmorillonite as a cheap and commercially available support with perchloric acid. The catalyst was characterized using a variety of techniques including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), pH analysis and determination of the Hammett acidity function. The prepared reagent showed excellent catalytic activity for the chemoselective conversion of alcohols and phenols to their corresponding trimethylsilyl ethers with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) at room temperature. Deprotection of the resulting trimethylsilyl ethers can also be carried out using the same catalyst in ethanol. All reactions were performed under mild and completely heterogeneous reaction conditions in good to excellent yields. The notable advantages of this protocol are: short reaction times, high yields, availability and low cost of the reagent, easy work-up procedure and the reusability of the catalyst during a simple filtration.
- Mashhadinezhad, Maryam,Shirini, Farhad,Mamaghani, Manouchehr
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p. 2099 - 2107
(2019/01/03)
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- DMSO-Triggered Complete Oxygen Transfer Leading to Accelerated Aqueous Hydrolysis of Organohalides under Mild Conditions
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Addition of DMSO is found to greatly accelerate the aqueous hydrolysis of organohalides to alcohols, providing a neutral, more efficient, milder and more economic process. Mechanistic studies using 18O-DMSO and 18O-H2O showed that, contrary to the opinion that DMSO works as a dipolar solvent to enhance water's nucleophilicity, the accelerating effect comes from a complete oxygen transfer from DMSO to organohalides through generation of ROS+Me2?X? salts through C?O bond formation, followed by O?S bond disassociative hydrolysis of ROS+Me2?X? with water. This method is applicable to a wide range of organohalides and thus may have potential for practical industrial application, owing to easy recovery of DMSO from the H2O/DMSO mixture by regular vacuum rectification.
- Liu, Haicheng,Liu, Jianping,Cheng, Xiaokai,Jia, Xiaojuan,Yu, Lei,Xu, Qing
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p. 2994 - 2998
(2019/01/04)
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- Selective Hydrogenations and Dechlorinations in Water Mediated by Anionic Surfactant-Stabilized Pd Nanoparticles
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We report a facile, inexpensive, and green method for the preparation of Pd nanoparticles in aqueous medium stabilized by anionic sulfonated surfactants sodium 1-dodecanesulfonate 1a, sodium dodecylbenzenesulfonate 1b, dioctyl sulfosuccinate sodium salt 1c, and poly(ethylene glycol) 4-nonylphenyl-3-sulfopropyl ether potassium salt 1d simply obtained by stirring aqueous solutions of Pd(OAc)2 with the commercial anionic surfactants further treated under hydrogen atmosphere for variable amounts of time. The aqueous Pd nanoparticle solutions were tested in the selective hydrogenation reactions of aryl-alcohols, -aldehydes, and -ketones, leading to complete conversion to the deoxygenated products even in the absence of strong Br?nsted acids in the reduction of aromatic aldehydes and ketones, in the controlled semihydrogenation of alkynes leading to alkenes, and in the efficient hydrodechlorination of aromatic substrates. In all cases, the micellar media were crucial for stabilizing the metal nanoparticles, dissolving substrates, steering product selectivity, and enabling recycling. What is interesting is also that a benchmark catalyst like Pd/C can often be surpassed in activity and/or selectivity in the reactions tested by simply switching to the appropriate commercially available surfactant, thereby providing an easy to use, flexible, and practical catalytic system capable of efficiently addressing a variety of synthetically significant hydrogenation reactions.
- La Sorella, Giorgio,Sperni, Laura,Canton, Patrizia,Coletti, Lisa,Fabris, Fabrizio,Strukul, Giorgio,Scarso, Alessandro
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supporting information
p. 7438 - 7446
(2018/05/29)
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- Nonenzymatic Dynamic Kinetic Resolution of in situ Generated Hemithioacetals: Access to 1,3-Disubstituted Phthalans
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The first nonenzymatic DKR reaction of hemithioacetals is developed. Hemithioacetals were formed in situ via thiol addition and subsequently underwent an intramolecular oxa-Michael reaction. The scope of the reaction was quite broad ranging from aliphatic to aromatic substituents and 1,3-disubstituted-1,3-dihyroisobenzofuran products were obtained in good yields with moderate diastereoselectivities and high enantioselectivities. (Figure presented.).
- Nath, Utpal,Chowdhury, Deepan,Pan, Subhas Chandra
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supporting information
p. 1628 - 1633
(2018/03/21)
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- Low-Valent Titanium-Mediated Radical Conjugate Addition Using Benzyl Alcohols as Benzyl Radical Sources
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A concise method to directly generate benzyl radicals from benzyl alcohol derivatives has been developed. The simple and inexpensive combination of TiCl4(collidine) (collidine = 2,4,6-collidine) and manganese powder afforded a low-valent titanium reagent, which facilitated homolytic cleavage of benzylic C-OH bonds. The application to radical conjugate addition reactions demonstrated the broad scope of this method. The reaction of various benzyl alcohol derivatives with electron-deficient alkenes furnished the corresponding radical adducts.
- Suga, Takuya,Shimazu, Shoma,Ukaji, Yutaka
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supporting information
p. 5389 - 5392
(2018/09/12)
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- Nickel-Catalyzed Cross-Electrophile Coupling between Benzyl Alcohols and Aryl Halides Assisted by Titanium Co-reductant
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A nickel-catalyzed cross-electrophile coupling reaction between benzyl alcohols and aryl halides has been developed using a homolytic C-O bond cleavage protocol that has recently been established. The treatment of a benzyl alcohol and aryl halide with a nickel catalyst and low-valent titanium reagent generated from TiCl4(lutidine) (lutidine = 2,6-lutidine) and manganese powder afforded the cross-coupled product in high yield. A mechanistic study indicated the intermediacy of the benzyl radicals that originate from the benzyl alcohols.
- Suga, Takuya,Ukaji, Yutaka
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supporting information
p. 7846 - 7850
(2019/01/14)
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- IRIDIUM-BASED CATALYSTS FOR HIGHLY EFFICIENT DEHYDROGENATION AND HYDROGENATION REACTIONS IN AQUEOUS SOLUTION AND APPLICATIONS THEREOF
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A series of iridium-based catalysts for dehydrogenation of formic acid, and hydrogenation using formic acid as the hydrogen source, and the process using the catalyst(s) to produce hydrogen gas from formic acid solution, or to reduce aldehydes using formic acid, are disclosed and claimed. More specifically, the present invention relates to a group of pentamethylcyclopentadienyl (Cp*) iridium complexes with different Ν,Ν-bidentate ligands that catalyze dehydrogenation from formic acid, and chemo-selective hydrogenation of aldehydes, in the aqueous solution system in a highly efficient, and long life-time manner.
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Page/Page column 13; 15
(2018/11/22)
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- A PROCESS FOR PREPARING FUNCTIONAL POLYMERS THROUGH ADDITION OF AMINO AND POLYMERYL GROUPS TO ALDEHYDE MOIETIES
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The present disclosure relates to a one-pot process for synthesizing functional compounds or functional polymers by reacting an aldehyde with an alkyl-zinc or polymeryl-zinc composition in the presence of a specific Lewis acid, wherein the reaction is rapid and facile at high temperatures.
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Paragraph 0062-0067
(2018/10/19)
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- Design, synthesis and structure-based optimization of novel isoxazole-containing benzamide derivatives as FtsZ modulators
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Antibiotic resistance among clinically significant bacterial pathogens is becoming a prevalent threat to public health, and new antibacterial agents with novel mechanisms of action hence are in an urgent need. Utilizing computational docking method and structure-based optimization strategy, we rationally designed and synthesized two series of isoxazol-3-yl- and isoxazol-5-yl-containing benzamide derivatives that targeted the bacterial cell division protein FtsZ. Evaluation of their activity against a panel of Gram-positive and -negative pathogens revealed that compounds B14 and B16 that possessed the isoxazol-5-yl group showed strong antibacterial activity against various testing strains, including methicillin-resistant Staphylococcus aureus and penicillin-resistant S. aureus. Further molecular biological studies and docking analyses proved that the compound functioned as an effective inhibitor to alter the dynamics of FtsZ self-polymerization via a stimulatory mechanism, which finally terminated the cell division and caused cell death. Taken together, these results could suggest a promising chemotype for development of new FtsZ-targeting bactericidal agent.
- Bi, Fangchao,Song, Di,Zhang, Nan,Liu, Zhiyang,Gu, Xinjie,Hu, Chaoyu,Cai, Xiaokang,Venter, Henrietta,Ma, Shutao
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- Direct allylation of benzyl alcohols, diarylmethanols, and triarylmethanols mediated by XtalFluor-E
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We report the direct allylation of benzyl alcohols, diarylmethanols and triarylmethanols mediated by XtalFluor-E using allyltrimethylsilane. The resulting allylated products are obtained in moderate to high yield.
- Lebleu, Thomas,Paquin, Jean-Fran?ois
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supporting information
p. 442 - 444
(2017/01/10)
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- Iridium-catalyzed highly efficient chemoselective reduction of aldehydes in water using formic acid as the hydrogen source
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A water-soluble highly efficient iridium catalyst is developed for the chemoselective reduction of aldehydes to alcohols in water. The reduction uses formic acid as the traceless reducing agent and water as a solvent. It can be carried out in air without the need for inert atmosphere protection. The products can be purified by simple extraction without any column chromatography. The catalyst loading can be as low as 0.005 mol% and the turn-over frequency (TOF) is as high as 73 800 mol mol-1 h-1. A wide variety of functional groups, such as electron-rich or deficient (hetero)arenes and alkenes, alkyloxy groups, halogens, phenols, ketones, esters, carboxylic acids, cyano, and nitro groups, are all well tolerated, indicating excellent chemoselectivity.
- Yang, Zhanhui,Zhu, Zhongpeng,Luo, Renshi,Qiu, Xiang,Liu, Ji-Tian,Yang, Jing-Kui,Tang, Weiping
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supporting information
p. 3296 - 3301
(2017/07/28)
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- SNAr catalysis enhanced by an aromatic donor-acceptor interaction; Facile access to chlorinated polyfluoroarenes
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Selective catalytic SNAr reaction of polyfluoroaryl C-F bonds with chloride is shown. Stoichiometric TMSCl makes the reaction exergonic and allows catalysis, which involves ground state elevation of chloride, aromatic donor-acceptor interactions, and stabilization of the Meisenheimer complex. Traditional cross-coupling of the products is now possible and demonstrates the utility.
- Senaweera, Sameera,Weaver, Jimmie D.
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supporting information
p. 7545 - 7548
(2017/07/12)
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- COMPOSITIONS AND METHODS FOR REDUCTION OF KETONES, ALDEHYDES AND IMINIUMS, AND PRODUCTS PRODUCED THEREBY
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A method of producing an alcohol, comprises reducing an aldehyde or a ketone with a hydridosilatrane. The reducing is carried out with an activator.
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Paragraph 0076-0077
(2018/01/20)
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- Chelating Bis(1,2,3-triazol-5-ylidene) Rhodium Complexes: Versatile Catalysts for Hydrosilylation Reactions
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NHC-rhodium complexes (NHC=N-heterocyclic carbenes) have been widely used as efficient catalysts for hydrosilylation reactions. However, the substrates were mostly limited to reactive carbonyl compounds (aldehydes and ketones) or carbon-carbon multiple bonds. Here, we describe the application of newly-developed chelating bis(tzNHC)-rhodium complexes (tz=1,2,3-triazol-5-ylidene) for several reductive transformations. With these catalysts, the formal reductive methylation of amines using carbon dioxide, the hydrosilylation of amides and carboxylic acids, and the reductive alkylation of amines using carboxylic acids have been achieved under mild reaction conditions.
- Nguyen, Thanh V. Q.,Yoo, Woo-Jin,Kobayashi, Shu
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supporting information
p. 452 - 458
(2016/02/12)
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- An Efficient, Stable and Reusable Palladium Nanocatalyst: Chemoselective Reduction of Aldehydes with Molecular Hydrogen in Water
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Palladium nanoparticles (Pd-BNP) stabilized by a binaphthyl-backbone can be efficiently used for the chemoselective reduction of aldehydes in the presence of hydrogen at room temperature in water. The Pd-BNP catalyst is easily recovered and reused for five catalytic cycles. (Figure presented.).
- Kotha, Surya Srinivas,Sharma, Nidhi,Sekar, Govindasamy
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supporting information
p. 1694 - 1698
(2016/10/13)
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- Silatrane as a Practical and Selective Reagent for the Reduction of Aryl Aldehydes to Benzylic Alcohols
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Hydrosilanes are cheap, readily available substrates, yet they do not see as extensive use for simple carbonyl reductions as borohydrides. Hydrosilane reducing agents broadly fall into one of two general categories: either a) they are easy to handle and require expensive and/or hazardous additives, or b) they are difficult and/or dangerous to handle. This work details the discovery of mild and functional group compatible conditions utilizing hydrosilatrane for the selective reduction of aryl aldehydes to benzylic alcohols without unwanted formation of ethers or deoxygenated products. This method offers significant advances in silane reductions as silatrane is an air- and moisture-stable yet relatively reactive reducing agent that can be used in benchtop open air reactions.
- Skrypai, Vladislav,Hurley, Joseph J. M.,Adler, Marc J.
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supporting information
p. 2207 - 2211
(2016/05/09)
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- Selective acetylation of primary alcohols by ethyl acetate
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A KOtBu and ethyl acetate mediated efficient methodology has been developed for the acetylation of primary and secondary alcohols where ethyl acetate is the source of acetyl group. The reaction is fast, mild, efficient, and highly selective towards the primary alcohols.
- Singha, Raju,Ray, Jayanta K.
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supporting information
p. 5395 - 5398
(2016/11/11)
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- Indium(III) Isopropoxide as a Hydrogen Transfer Catalyst for Conversion of Benzylic Alcohols into Aldehydes or Ketones via Oppenauer Oxidation
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Indium(III) isopropoxide [In(Oi-Pr)3] was applicable as an Oppenauer oxidation catalyst, and the conversion of primary or secondary alcohols into the corresponding aldehydes or ketones was promoted at room temperature using pivalaldehyde as an oxidant.
- Ogiwara, Yohei,Ono, Yuji,Sakai, Norio
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p. 4143 - 4148
(2016/11/26)
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- Introduction of PEG-SANM nanocomposite as a new and highly efficient reagent for the promotion of the silylation of alcohols and phenols and deprotection of the silyl ethers
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Poly (ethylene glycol)-sulfonated sodium montmorillonite (PEG-SANM) nanocomposite was prepared by a simple method and characterized using XRD, TGA, SEM, TEM, and FT-IR techniques. After preparation and characterization, this reagent was used as a highly efficient and reusable solid acid catalyst for the chemoselective silylation of alcohols and phenols and deprotection of the obtained silyl ethers. Themethod offers several advantages including high to excellent yields of the products, short reaction times, easy preparation of the catalyst and easy work-up procedure. In addition, the catalyst can be recycled and reused at least for five times without significant decrease in the catalytic activity.
- Shirini, Farhad,Shojaei, Abdollah Fallah,Heirati, Seyedeh Zahra Dalil
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p. 944 - 951
(2016/07/06)
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- In situ activation of benzyl alcohols with XtalFluor-E: Formation of 1,1-diarylmethanes and 1,1,1-triarylmethanes through Friedel-Crafts benzylation
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The Friedel-Crafts benzylation of arenes using benzyl alcohols activated in situ with XtalFluor-E is described. A wide range of 1,1-diarylmethanes and 1,1,1-triarylmethanes were prepared under experimentally simple and mild conditions, without the need for a transition metal or a strong Lewis acid. Notably, the reactivity observed demonstrates the potential of XtalFluor-E to induce C-OH bond ionization and SN1 reactivity of benzylic alcohols. This journal is
- Desroches, Justine,Champagne, Pier Alexandre,Benhassine, Yasmine,Paquin, Jean-Franois
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supporting information
p. 2243 - 2246
(2015/03/04)
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- Iron-catalyzed reduction of aromatic aldehydes with paraformaldehyde and H2O as the hydrogen source
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In this Letter, we report a novel, general, convenient, and inexpensive method for the reduction of aromatic aldehydes to the corresponding benzylic alcohols. Various aromatic aldehydes were reduced in good to excellent yields by using well-defined iron-complex as the catalyst precursor and using paraformaldehyde and water as the hydrogen source.
- Natte, Kishore,Li, Wanfang,Zhou, Shaolin,Neumann, Helfried,Wu, Xiao-Feng
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supporting information
p. 1118 - 1121
(2015/02/19)
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- Friedel-crafts reaction of benzyl fluorides: Selective activation of C-f bonds as enabled by hydrogen bonding
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A Friedel-Crafts benzylation of arenes with benzyl fluorides has been developed. The reaction produces 1,1-diaryl alkanes in good yield under mild conditions without the need for a transition metal or a strong Lewis acid. A mechanism involving activation of the C-F bond through hydrogen bonding is proposed. This mode of activation enables the selective reaction of benzylic C-F bonds in the presence of other benzylic leaving groups.
- Champagne, Pier Alexandre,Benhassine, Yasmine,Desroches, Justine,Paquin, Jean-Franois
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supporting information
p. 13835 - 13839
(2015/02/05)
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- Ru nanoparticles entrapped in ordered mesoporous carbons: An efficient and reusable catalyst for liquid-phase hydrogenation
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Ru nanoparticles entrapped in ordered mesoporous carbons (CMK-3) served as an efficient and reusable catalyst for liquid-phase hydrogenation of benzaldehyde and its derivatives under our tested conditions (medium hydrogen pressure, room temperature, water as solvent). The Ru nanoparticles can be well stabilized by CMK-3 ordered mesoporous carbons so that the Ru leaching was below the detection limit of ICP-AES. Therefore, the Ru/CMK-3 catalyst can be used for at least five times without distinct loss in activity or selectivity for the hydrogenation of benzaldehyde. It is worthy of note that the Ru/CMK-3 catalyst was more efficient than the commercial Ru/C and homemade Ru/AC catalyst for the liquid-phase hydrogenation of benzaldehyde. The Ru/ CMK-3 catalyst can also catalyze the liquid-phase hydrogenation of nitrobenzene and its derivatives with high conversions and excellent selectivities under optimal conditions. Springer Science+Business Media New York 2013.
- Ding, Yue,Li, Xiaohong,Pan, Huiyan,Wu, Peng
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p. 268 - 277
(2014/05/06)
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- Experimental and computational studies of borohydride catalyzed hydrosilylation of a variety of C=O and C=N functionalities including esters, amides and heteroarenes
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Sodium borohydride and a series of related borohydrides catalyze a transition metal-free hydrosilylation of a variety of C=O and C=N functionalities under mild conditions. Importantly, many of these reactions are possible using the cheap and environmentally benign hydrosilane polymethylhydrosiloxane. A mechanism is proposed based on experimental and computational results.
- Manas, Michael G.,Sharninghausen, Liam S.,Balcells, David,Crabtree, Robert H.
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supporting information
p. 1694 - 1700
(2014/05/06)
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- Metal-free, visible-light photoredox catalysis: Transformation of arylmethyl bromides to alcohols and aldehydes
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A mild, simple, and controllable metal-free photocatalytic system for the transformation of arylmethyl bromides to corresponding alcohols and aldehydes in high yields with visible-light irradiation has been achieved. Eosin Y was found to be an efficient promoter for this oxidative dehalogenation reaction under photo irradiation conditions.
- Li, Jian,Wang, Hongni,Liu, Li,Sun, Jiangtao
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p. 49974 - 49978
(2014/12/10)
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