- Synthesis of Hf(IV) complex from cyclam (1,4,8,11-tetraazacyclotetradecane) -containing amino-amido groups
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The reactivity of cyclam (1,4,8,11-tetraazacyclcotetradecane)-containing amino-amido groups with hafnium(IV) chloride was described. Taylor & Francis Group, LLC.
- Thirumavalavan, Munusamy,Lee, Jiunn-Fwu
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- Redox-active alkylsulfones as precursors for alkyl radicals under photoredox catalysis
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A method for generating alkyl radicals using visible-light photoredox catalysis is described. This procedure was found to present an efficient means to access a diverse collection of 1°, 2°, and 3° alkyl radicals through the single-electron transfer of sulfones under mild reaction conditions. These alkyl radicals generated via the reductive desulfonylation of readily synthesized and stable alkylsulfones were engaged to forge C-C bonds. A detailed study was also carried out to shed light on the mechanism.
- Patel, Sandeep,Paul, Biprajit,Paul, Hrishikesh,Shankhdhar, Rajat,Chatterjee, Indranil
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p. 4857 - 4860
(2022/04/19)
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- Electrochemical Tandem Olefination and Hydrogenation Reaction with Ammonia
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An electrochemical Horner-Wadsworth-Emmons/hydrogenation tandem reaction was achieved using ammonia as electron and proton donors. The reaction could give two-carbon-elongated ester and nitrile from aldehyde or ketones directly. This reaction could proceed with a catalytic amount of base or even without a base. The ammonia provides both the electron and proton for this tandem reaction and enables the catalyst-free hydrogenation of an α,β-unsaturated HWE intermediate. More than 40 examples were reported, and functional groups, including heterocycles and hydroxyl, were tolerated.
- Zhang, Xiaofeng,Jiang, Runze,Cheng, Xu
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p. 16016 - 16025
(2021/08/24)
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- Visible-light induced metal-free cascade Wittig/hydroalkylation reactions
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Cascade reactions are green and powerful transformations for building multiple carbon-carbon bonds in one step. Through a relay olefination and radical addition process, we were able to develop the cascade Wittig/hydroalkylation reactions induced by visible light. This metal-free radical approach features mild conditions, robustness, and excellent functionality compatibility. It allows access to saturated C3 homologation products directly from aldehydes or ketones. The synthetic utility of this method is demonstrated by a two-step synthesis ofindolizidine 209D.
- Miao, Pannan,Li, Ruining,Lin, Xianfeng,Rao, Liangming,Sun, Zhankui
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supporting information
p. 1638 - 1641
(2021/03/09)
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- ZWITTERIONIC CATALYSTS FOR (TRANS)ESTERIFICATION: APPLICATION IN FLUOROINDOLE-DERIVATIVES AND BIODIESEL SYNTHESIS
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An amide/iminium zwitterion catalyst has a catalyst pocket size that promotes transesterification and dehydrative esterification. The amide/iminium zwitterions are easily prepared by reacting aziridines with aminopyridines. The reaction can be applied a wide variety of esterification processes including the large-scale synthesis of biodiesel. The amide/iminium zwitterions allow the avoidance of strongly basic or acidic condition and avoidance of metal contamination in the products. Reactions are carried out at ambient or only modestly elevated temperatures. The amide/iminium zwitterion catalyst is easily recycled and reactions proceed in high to quantitative yields.
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Paragraph 0019; 0031
(2021/01/29)
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- Radical-Mediated Strategies for the Functionalization of Alkenes with Diazo Compounds
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One of the most common reactions of diazo compounds with alkenes is cyclopropanation, which occurs through metal carbene or free carbene intermediates. Alternative functionalization of alkenes with diazo compounds is limited, and a methodology for the addition of the elements of Z-CHR2 (with Z = H or heteroatom, and CHR2 originates from N2 CR2) across a carbon-carbon double bond has not been reported. Here we report a novel reaction of diazo compounds utilizing a radical-mediated addition strategy to achieve difunctionalization of diverse alkenes. Diazo compounds are transformed to carbon radicals with a photocatalyst or an iron catalyst through PCET processes. The carbon radical selectively adds to diverse alkenes, delivering new carbon radical species, and then forms products through hydroalkylation by thiol-assisted hydrogen atom transfer (HAT), or forms azidoalkylation products through an iron catalytic cycle. These two processes are highly complementary, proceed under mild reaction conditions, and show high functional group tolerance. Furthermore, both transformations are successfully performed on a gram-scale, and diverse γ-amino esters, γ-amino alcohols, and complex spirolactams are easily prepared with commercially available reagents. Mechanistic studies reveal the plausible pathways that link the two processes and explain the unique advantages of each.
- Su, Yong-Liang,Liu, Geng-Xin,Liu, Jun-Wen,Tram, Linh,Qiu, Huang,Doyle, Michael P.
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supporting information
p. 13846 - 13855
(2020/09/21)
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- Oxo-Rhenium-Catalyzed Radical Addition of Benzylic Alcohols to Olefins
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Although carbon radicals generated from a variety of alcohol derivatives have proven valuable in coupling and addition reactions, the direct use of alcohols as synthetically useful radical sources is less known. In this report, benzylic alcohols are shown to be effective radical precursors for addition reactions to alkenes when treated with triphenylphosphine or piperidine with the catalyst ReIO2(PPh3)2 (I).
- Bandari, Chandrasekhar,Nicholas, Kenneth M.
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p. 3320 - 3327
(2020/03/23)
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- A metal-free iodine-mediated conversion of hydroxamates to esters
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A metal-, oxidant-, and additive-free conversion of hydroxamates to esters have been achieved using molecular iodine as the reagent using a novel but not-so-explored heron-type rearrangement. The reaction proceeds with almost equal facility with substrates having either electron-donating or electron-withdrawing substituent. Similarly, α,?-unsaturated, and sterically hindered ortho-substituted hydroxamates also undergo the desired transformation smoothly.
- Ghosh, Subhankar,Banerjee, Jeet,Ghosh, Rajat,Chattopadhyay, Shital K.
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p. 1353 - 1360
(2020/03/30)
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- Visible-light-initiated manganese-catalyzed Giese addition of unactivated alkyl iodides to electron-poor olefins
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Herein, we report a mild protocol for direct visible-light-initiated Giese addition of unactivated alkyl iodides to electron-poor olefins (Michael acceptors) with catalysis by decacarbonyl dimanganese, Mn2(CO)10, an inexpensive earth-abundant-metal catalyst. This protocol is compatible with a wide array of sensitive functional groups and has a broad substrate scope with regard to both the alkyl iodide and the Michael acceptor.
- Dong, Jianyang,Wang, Xiaochen,Wang, Zhen,Song, Hongjian,Liu, Yuxiu,Wang, Qingmin
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supporting information
p. 11707 - 11710
(2019/10/02)
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- Catalyst-Free Deaminative Functionalizations of Primary Amines by Photoinduced Single-Electron Transfer
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The use of pyridinium-activated primary amines as photoactive functional groups for deaminative generation of alkyl radicals under catalyst-free conditions is described. By taking advantage of the visible light absorptivity of electron donor–acceptor complexes between Katritzky pyridinium salts and either Hantzsch ester or Et3N, photoinduced single-electron transfer could be initiated in the absence of a photocatalyst. This general reactivity platform has been applied to deaminative alkylation (Giese), allylation, vinylation, alkynylation, thioetherification, and hydrodeamination reactions. The mild conditions are amenable to a diverse range of primary and secondary alkyl pyridiniums and demonstrate broad functional group tolerance.
- Wu, Jingjing,Grant, Phillip S.,Li, Xiabing,Noble, Adam,Aggarwal, Varinder K.
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supporting information
p. 5697 - 5701
(2019/03/21)
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- Metal-free visible light photoredox enables generation of carbyne equivalents via phosphonium ylide C-H activation
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Carbyne, an interesting synthetic intermediate, has recently been generated from hypervalent iodine precursors via photoredox catalysis. Given the underexplored chemistry of carbyne, due to the paucity of carbyne sources, we are intrigued to discover a new source for this reactive species from classical reagents-phosphonium ylides. Our novel strategy employing phosphonium ylides in an olefin hydrocarbonation reaction features a facile approach for constructing carbon-carbon bonds through metal-free and benign reaction conditions. Moreover, the hydrocarbonation products were delivered in a highly regioselective manner.
- Das, Mrinmoy,Vu, Minh Duy,Zhang, Qi,Liu, Xue-Wei
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p. 1687 - 1691
(2019/02/14)
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- Amide/Iminium Zwitterionic Catalysts for (Trans)esterification: Application in Biodiesel Synthesis
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A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair has been developed. The zwitterions are easily prepared by reacting aziridines with aminopyridines. They are catalytically applicable to transesterifications and dehydrative esterifications. Mechanistic studies reveal that the amide anion and iminium cation work synergistically in activating the reaction partners, with the iminium cationic moiety interacting with the carbonyl substrates through nonclassical hydrogen bonding. The reaction can be applied to large-scale synthesis of biodiesel under mild conditions.
- Lam, Ying-Pong,Ng, Wing-Hin,Tan, Fei,Tse, Ying-Lung Steve,Wang, Xinyan,Yeung, Ying-Yeung
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p. 8083 - 8092
(2019/08/26)
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- Esterification of the Primary Benzylic C-H Bonds with Carboxylic Acids Catalyzed by Ionic Iron(III) Complexes Containing an Imidazolinium Cation
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The first iron-catalyzed esterification of the primary benzylic C-H bonds with carboxylic acids using di-tert-butyl peroxide as an oxidant is achieved by novel ionic iron(III) complexes containing an imidazolinium cation. The use of well-defined, air-stable, and available iron(III) complex in a 5 mol % loading and readily available starting materials with a broad generality and outstanding sterically hindered tolerance renders this methodology a useful alternative to other protocols that are typically employed for the synthesis of benzyl esters.
- Lu, Bing,Zhu, Fan,Sun, Hong-Mei,Shen, Qi
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supporting information
p. 1132 - 1135
(2017/03/14)
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- Imidazole derivatives as accelerators for ruthenium-catalyzed hydroesterification and hydrocarbamoylation of alkenes: Extensive ligand screening and mechanistic study
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Imidazole derivatives are effective ligands for promoting the [Ru3(CO)12]-catalyzed hydroesterification of alkenes using formates. Extensive ligand screening was performed to identify 2-hydroxymethylated imidazole as the optimal ligand. Neither carbon monoxide gas nor a directing group was required, and the reaction also showed a wide substrate generality. The Ru-imidazole catalyst system also promoted intramolecular hydrocarbamoylation to afford lactams. A Ru-imidazole complex was unambiguously analyzed by X-ray crystallography, and it had a trinuclear structure derived from one [Ru3(CO)12] and two ligands. This complex was also successfully used for hydroesterification. The mechanism was examined in detail by using D- and 13C-labeled formates, indicating that the hydroesterification reaction proceeds by a decarbonylation-recarbonylation pathway. Effective imidazole assistant: [Ru3(CO)12]-catalyzed hydroesterification of alkenes by using formates is drastically accelerated by imidazole derivatives and exhibits a broad substrate scope for both alkenes and formates. The Ru-imidazole complex also catalyzes the intramolecular hydrocarbamoylation of alkenes.
- Konishi, Hideyuki,Muto, Takashi,Ueda, Tsuyoshi,Yamada, Yayoi,Yamaguchi, Miyuki,Manabe, Kei
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p. 836 - 845
(2015/03/14)
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- Novel ruthenium-catalyst for hydroesterification of olefins with formates
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An alternative ruthenium-based catalyst for the hydroesterification of olefins with formates is reported. The good activity of our system is ensured by the use of a bidentate P,N-ligand and ruthenium dodecacarbonyl. A range of formates can be used for selective alkoxycarbonylation of aromatic olefins. In addition, the synthesis of selected aliphatic esters is realized. The proposed active ruthenium complex has been isolated and characterized. This journal is the Partner Organisations 2014.
- Profir, Irina,Beller, Matthias,Fleischer, Ivana
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supporting information
p. 6972 - 6976
(2014/10/15)
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- N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate as a highly active and selective esterification catalyst
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N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate (1) was found to be a very active esterification catalyst that promotes condensation of equal mole amount of carboxylic acids and alcohols under mild conditions. This catalyst is also highly selective towards carboxylic acid and alcohol substrates at ambient temperature.
- Sattenapally, Narsimha,Wang, Wei,Liu, Huimin,Gao, Yong
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p. 6665 - 6668
(2013/11/19)
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- Sulfonated polypyrene (S-PPR) as efficient catalyst for esterification of carboxylic acids with equimolar amounts of alcohols without removing water
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Sulfonated polypyrene (S-PPR) efficiently catalyzed the reactions between carboxylic acids and equimolar amounts of alcohols with and without heptane to give the corresponding esters in good to excellent yields. Esterification was carried out at 110 °C without removing water. Transesterification of carboxylic esters with a slight excess of alcohols smoothly proceeded without heptane to give the corresponding esters in good yields. For these reactions, S-PPR was recycled without significant loss of activities.
- Tanemura, Kiyoshi,Suzuki, Tsuneo
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p. 1972 - 1975
(2013/04/23)
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- Esterification catalysis by pyridinium p -toluenesulfonate revisited - Modification with a lipid chain for improved activities and selectivities
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The lipid analogs of pyridinium p-toluenesulfonate (PPTS) were examined for catalysis of the condensation of an equimolar mixture of carboxylic acids and alcohols under mild conditions without removal of water. Although PPTS is a poor catalyst, the introduction of a lipid chain and nitro group significantly improved the activity of PPTS and led to selectivity at suppressing the elimination side reactions of alcohols. 2-Oleamido-5-nitro-pyridinium p-toluenesulfonate (6) is a lead catalyst that promoted various esterification reactions with yields up to 99%.
- Wang, Wei,Liu, Huimin,Xu, Shaoyi,Gao, Yong
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p. 2906 - 2912
(2013/09/02)
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- Remarkable improvement achieved by imidazole derivatives in ruthenium-catalyzed hydroesterification of alkenes using formates
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Imidazole derivatives are revealed to be effective ligands in the Ru-catalyzed hydroesterification of alkenes using formates, affording one-carbonelongated esters in high yields. Further, intramolecular hydroesterification was successfully performed to give lactones for the first time. Imidazole derivatives can contribute to promote the reaction as well as to suppress the undesired decarbonylation of formate. Toxic CO gas, a directing group, and large excess alkenes are not required.
- Konishi, Hideyuki,Muto, Takashi,Manabe, Kei,Ueda, Tsuyoshi
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supporting information
p. 4722 - 4725,4
(2012/12/12)
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- CATALYST COMPOSITION INCLUDING ZIRCONIUM COMPOUNDS FOR ESTERFICATION REACTION AND METHOD FOR PREPARING ESTER COMPOUNDS
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The present invention relates to an esterification catalyst composition that includes a zirconium compound and a method for producing an ester compound, which includes the steps of esterifying alcohol and carboxylic acid compounds by using the same, and i
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Page/Page column 6
(2010/12/26)
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- METHOD FOR PRODUCING ESTER CONDENSED PRODUCT
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The present invention is to provide a method for preparing an ester condensate and a catalyst therefor; wherein the method enables synthesis of enormous amounts of ester condensates comprising a specific structure in good yield, by a reaction of carboxylic acid and alcohol in equimolar amounts, while generation of by-products is prevented; wherein the catalyst exhibits good catalytic efficiency as a catalyst for use, the use of the catalyst in small amount is sufficient, and the catalyst is reusable and can be used repeatedly; therefore, the method for preparing an ester condensate of the present invention and the catalyst therefor can be applied to industrial methods which are preferable in view of green chemistry. Esterification reaction is performed by using a catalyst comprising a zirconium(IV) compound and/or a hafnium(IV) compound and an iron compound and a gallium compound. It is preferable that the zirconium(IV) compound is a compound represented by Zr(OH)a(OR1)b, (wherein, R1 represents an acyl group or an alkyl group, and each of a and b is 0 or any one of integers of 1 to 4 and the relationship of a + b = 4 is satisfied), and a zirconium(IV) halide.
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Page/Page column 11-12
(2008/06/13)
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- Bulky diarylammonium arenesulfonates as mild and extremely active dehydrative ester condensation catalysts
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More environmentally benign alternatives to current chemical processes, especially large-scale, fundamental reactions like ester condensations, are highly desirable for many reactions. Bulky diarylammonium pentafluorobenzenesulfonates and tosylates serve as extremely active dehydration catalysts for the ester condensation reaction of carboxylic acids with equimolar amounts of sterically demanding alcohols and acid-sensitive alcohols. Typically, the esterification reaction is performed in heptane by heating at 80°C in the presence of 1 mol% of the catalyst without removing water. Esterification with primary alcohols proceeds without solvents even at room temperature. Furthermore, 4-(N-mesitylamino)polystyrene resin-bound pentafluorobenzenesulfonate can be recycled more than 10 times without a loss of activity.
- Sakakura, Akira,Nakagawa, Shoko,Ishihara, Kazuaki
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p. 422 - 433
(2007/10/03)
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- METHOD FOR PRODUCING ESTER AND ESTERIFICATION CATALYST
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A process for producing an ester includes the step of allowing a carboxylic acid to react with an alcohol, wherein an ammonium sulfonate is used as an esterification catalyst, the ammonium sulfonate being composed of an ammonium cation having a basic skeleton represented by formula (1) (wherein n represents 1 or 2) in which hydrogen atoms in the benzene rings and hydrogen atoms bonded to bridge carbon may be substituted), and a sulfonic acid anion represented by RSO 3 - (wherein R represents an arene, a perfluoroalkane having 1 to 8 carbon atoms, or a bulky alkane).
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Page/Page column 21
(2008/06/13)
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- Iron(III)-zirconium(IV) combined salt immobilized on N-(polystyrylbutyl) pyridinium triflylimide as a reusable catalyst for a dehydrative esterification reaction
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N-(Polystyrylbutyl)pyridinium triflylimide is prepared by a coupling reaction of commercially available 4-bromobutyl-polystyrene with pyridine and a subsequent anion exchange reaction with lithium triflylimide. This new polystyrene-bound pyridinium salt is useful as a solid support to immobilize a zirconium(IV)-iron(III) binary metal complex, which is a homogeneous catalyst for the dehydrative ester condensation of an equimolar mixture of carboxylic acids and alcohols. The immobilized zirconium(IV)-iron(III) complex is easily recovered by filtration after complete esterification, and is reusable without any loss of activity.
- Nakamura, Yuka,Maki, Toshikatsu,Wang, Xiaowei,Ishihara, Kazuaki,Yamamoto, Hisashi
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p. 1505 - 1510
(2007/10/03)
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- Zr(IV)-Fe(III), -Ga(III), and -Sn(IV) binary metal complexes as synergistic and reusable esterification catalysts
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Synergism in catalytic activity with the combined use of Hf(O-i-Pr) 4 or Zr(O-i-Pr)4 and Fe(O-i-Pr)3 for direct esterification and a very simple method for their extraction with ionic liquids for their recovery and reuse are described. This Zr(IV)-Fe(III) complex is an environmentally benign catalyst due to its high turnover number, extremely mild Lewis acidity, low toxicity, reusability, and commercial availability at low cost.
- Sato, Atsushi,Nakamura, Yuka,Maki, Toshikatsu,Ishihara, Kazuaki,Yamamoto, Hisashi
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p. 1337 - 1340
(2007/10/03)
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- Bulky diarylammonium arenesulfonates as selective esterification catalysts
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More environmentally benign alternatives to current chemical processes, especially large-scale, fundamental reactions such as ester condensations, are highly desirable for many reactions. Bulky diarylammonium pentafluorobenzenesulfonates and tosylates serve as extremely active dehydration catalysts for the ester condensation reaction of carboxylic acids with equimolar amounts of sterically demanding alcohols and acid-sensitive alcohols. Typically, the esterification reaction is performed in heptane by heating at 80 °C in the presence of 1 mol % of the catalyst without removing water. Esterification with primary alcohols proceeds without solvents even at room temperature. Furthermore, 4-(N-mesitylamino)polystyrene resin-bound pentafluorobenzenesulfonate can be recycled more than 10 times without activity loss. Copyright
- Ishihara, Kazuaki,Nakagawa, Shoko,Sakakura, Akira
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p. 4168 - 4169
(2007/10/03)
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- Water-tolerant and reusable catalysts for direct ester condensation between equimolar amounts of carboxylic acids and alcohols
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ZrOCl2 · 8 H2O and HfOCl2 · 8 H2O are highly effective, water-tolerant, and reusable homogeneous catalysts for direct ester condensation be-tween equimolar amounts of carboxylic acids and alcohols. Notably, zirconium(IV) salts such as ZrOCl2 · 8 H2O and Zr(OAc)x(OH)y are potential green catalysts due to their low toxicity, commercial availability at low cost, ease of handling, high catalytic activity, and reusability.
- Nakayama, Masaya,Sato, Atsushi,Ishihara, Kazuaki,Yamamoto, Hisashi
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p. 1275 - 1279
(2007/10/03)
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- Process for producing esterificated condensate
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The present invention provides a method for preparing ester or thioester that can conduct catalytic esterification reaction with an equimolar amount of carboxylic acid and alcohol, or catalytic thioesterification reaction with carboxylic acid and an equimolar amount or small amount of thiol, and can be expected as an industrial method that needs an enormous amount of synthesis in the light of green chemistry. By using hafnium chloride (IV), especially tetravalent hafnium compounds represented by hafnium chloride (IV)?(THF)2 or hafnium (IV)t-butoxide as a (poly) condensation catalyst, direct condensation reaction is conducted from carboxylic acid and an equimolar amount of alcohol or a little smaller amount of thiol, in the nonpolar solvent such as toluene and the like, in a deoxidization atmosphere and under heating reflux, and the reaction synthesizes ester monomer or thioester monomer, polyester or polythioester. When heating reflux is conducted by using a nonpolar solvent, it is preferable to remove azeotropic water from the reaction system.
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- Fluorous biphasic esterification directed towards ultimate atom efficiency
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Aperfectly selective esterification that discriminates between primary and sterically hindered or aromatic carboxylic acids occurs in the presence of the fluoroalkyldistannoxane [{Cl(C6F13CH2 CH2)2SnOSn(CH2CH2 -C6F13)2Cl}2] (1). The reaction gives 100% yield with a strict 1:1 ratio of the carboxylic acid and alcohol reactants, and the catalyst can be recycled without any loss of activity.
- Xiang, Jiannan,Orita, Akihiro,Otera, Junzo
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p. 4117 - 4119
(2007/10/03)
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- Direct ester condensation from a 1:1 mixture of carboxylic acids and alcohols catalyzed by hafnium(IV) or zirconium(IV) salts
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To promote atom efficiency in synthesis and to avoid the generation of environmental waste, the use of stoichiometric amounts of condensing reagents or excess substrates should be avoided. In esterification, excess amounts of either carboxylic acids or alcohols are normally needed. We found that the direct condensation of equimolar amounts of carboxylic acids and alcohols could be achieved using hafnium(IV) or zirconium(IV) salts. These metal salts are highly effective as catalysts for the selective esterification of primary alcohols with carboxylic acids in the presence of secondary alcohols or aromatic alcohols. The present methods can be applied to direct polyesterification and may be suitable for large-scale operations.
- Ishihara, Kazuaki,Nakayama, Masaya,Ohara, Suguru,Yamamoto, Hisashi
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p. 8179 - 8188
(2007/10/03)
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- NEW METHODS AND REAGENTS IN ORGANIC SYNTHESIS, 8. TRIMETHYLSILYLDIAZOMETHANE, A NEW, STABLE, AND SAFE REAGENT FOR THE CLASSICAL ARNDT-EISTERT SYNTHESIS
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Stable and safe trimethylsilyldiazomethane (TMSCHN2) can be used efficiently for the Arndt-Eistert synthesis in place of highly toxic and explosive diazomethane.
- Aoyama, Toyohiko,Shioiri, Takayuki
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p. 4461 - 4462
(2007/10/02)
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