- Electrochemical Study of Phase-Transfer Catalysis Reactions: The Williamson Ether Synthesis
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The transfer properties of the ionic species involved in the Williamson ether synthesis by phase-transfer catalysis were investigated using electrochemical techniques developed for the study of polarised liquid-liquid interfaces.This approach allows the measurement of the apparent partition coefficients of the transferring species.From these data, it is proposed that the role of the phase-transfer catalyst salt in the reaction mechanism is to establish a Galvani distribution potential difference between the two phases which in turn acts as the driving force for transferring the reactive aqueous ions to the organic phase.
- Tan, S. N.,Dryfe, R. A.,Girault, Hubert H.
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- A Catalyst System Based on Copper(II) Bromide Supported on Zeolite HY with a Hierarchical Pore Structure in Benzyl Butyl Ether Synthesis
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Abstract: Novel catalyst systems based on CuBr2 supported on zeolite HY with a hierarchical pore structure have been proposed for benzyl butyl ether synthesis by the intermolecular dehydration of benzyl and butyl alcohols. It has been shown that catalyst systems with a CuBr2 content of ~10 wt percent provide a benzyl butyl ether yield of ~95percent at 150°C.
- Agliullin, M. R.,Bayguzina, A. R.,Gallyamova, L. I.,Khusnutdinov, R. I.
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p. 937 - 941
(2020/09/02)
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- Catalytic reductive deoxygenation of esters to ethers driven by hydrosilane activation through non-covalent interactions with a fluorinated borate salt
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We report the catalytic and transition metal-free reductive deoxygenation of esters to ethers through the use of a hydrosilane and a fluorinated borate BArF salt as a catalyst. Experimental and theoretical studies support the role of noncovalent interactions between the fluorinated catalyst, the hydrosilane and the ester substrate in the reaction mechanism.
- Agbossou-Niedercorn, Francine,Dixit, Ruchi,Merle, Nicolas,Michon, Christophe,Rysak, Vincent,Trivelli, Xavier,Vanka, Kumar
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p. 4586 - 4592
(2020/08/14)
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- Method for hydrogenolysis of halides
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The invention discloses a method for hydrogenolysis of halides. The invention discloses a preparation method of a compound represented by a formula I. The preparation method comprises the following step: in a polar aprotic solvent, zinc, H2O and a compound represented by a formula II are subjected to a reaction as shown in the specification, wherein X is halogen; Y is -CHRR or R; hydrogenin H2O exists in the form of natural abundance or non-natural abundance. According to the preparation method, halide hydrogenolysis can be simply, conveniently and efficiently achieved through a simple and mild reaction system, and good functional group compatibility and substrate universality are achieved.
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- Kinetics and Mechanism of the Synthesis of Benzylbutyl Ether in the Presence of Copper-Containing Catalysts
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Abstract: The reaction of the synthesis of benzylbutyl ether via the intermolecular dehydration of benzyl and n-butyl alcohols under the action of copper-containing catalysts is studied by mathematical means. The mechanism of the reaction was proposed, and the values of kinetic parameters are determined. A comparative analysis of the activation energies of possible stages of chemical conversions is performed, and possible routes of the reactions and the catalytic cycles of reactions are determined. Variations in stage rates and the concentrations of all substances participating in the reaction are analyzed.
- Koledina,Gubaidullin,Koledin,Baiguzina,Gallyamova,Khusnutdinov
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p. 2146 - 2151
(2019/11/11)
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- Dehalogenative Deuteration of Unactivated Alkyl Halides Using D2O as the Deuterium Source
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The general dehalogenation of alkyl halides with zinc using D2O or H2O as a deuterium or hydrogen donor has been developed. The method provides an efficient and economic protocol for deuterium-labeled derivatives with a wide substrate scope under mild reaction conditions. Mechanistic studies indicated that a radical process is involved for the formation of organozinc intermediates. The facile hydrolysis of the organozinc intermediates provides the driving force for this transformation.
- Xia, Aiyou,Xie, Xin,Hu, Xiaoping,Xu, Wei,Liu, Yuanhong
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p. 13841 - 13857
(2019/10/17)
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- Reductive C-O, C-N, and C-S Cleavage by a Zirconium Catalyzed Hydrometalation/β-Elimination Approach
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A zirconium catalyzed reductive cleavage of Csp3 and Csp2 carbon-heteroatom bonds is reported that makes use of a tethered alkene functionality as a traceless directing group. The reaction is successfully demonstrated on C-O, C-N, and C-S bonds and proposed to proceed via a hydrozirconation/β-heteroatom elimination sequence of an in situ formed zirconium hydride catalyst. The positional isomerization of the catalyst further enables the cleavage of homoallylic ethers and the removal of terminal allyl and propargyl groups.
- Matt, Christof,K?lblin, Frederic,Streuff, Jan
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supporting information
p. 6983 - 6988
(2019/09/09)
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- The Guanidine-Promoted Direct Synthesis of Open-Chained Carbonates
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In order to reduce CO2 accumulation in the atmosphere, chemical fixation methodologies were developed and proved to be promising. In general, CO2 was turned into cyclic carbonates by cycloaddition with epoxides. However, the cyclic carbonates need to be converted into open-chained carbonates by transesterification for industrial usage, which results in wasted energy and materials. Herein, we report a process catalyzed by tetramethylguanidine (TMG) to afford linear carbonates directly. This process is greener and shows potential for industrial applications.
- Shang, Yuhan,Zheng, Mai,Zhang, Haibo,Zhou, Xiaohai
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p. 933 - 938
(2019/09/30)
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- Introduction of Cyclopropyl and Cyclobutyl Ring on Alkyl Iodides through Cobalt-Catalyzed Cross-Coupling
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A cobalt-catalyzed cross-coupling between alkyl iodides and cyclopropyl, cyclobutyl, and alkenyl Grignard reagents is disclosed. The reaction allows the introduction of strained rings on a large panel of primary and secondary alkyl iodides. The catalytic system is simple and nonexpensive, and the reaction is general, chemoselective, and diastereoconvergent. The alkene resulting from the cross-coupling can be transformed to substituted cyclopropanes using a Simmons-Smith reaction. The formation of radical intermediates during the coupling is hypothesized.
- Andersen, Claire,Ferey, Vincent,Daumas, Marc,Bernardelli, Patrick,Guérinot, Amandine,Cossy, Janine
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p. 2285 - 2289
(2019/03/29)
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- Synthesis of Benzyl Alkyl Ethers by Intermolecular Dehydration of Benzyl Alcohol with Aliphatic Alcohols under the Effect of Copper Containing Catalysts
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Synthesis of benzyl alkyl ethers was performed in high yields by intermolecular dehydration of benzyl and primary, secondary, tertiary alcohols under the effect of copper containing catalysts. The formation of benzyl alkyl ethers occurs with participation of benzyl cation.
- Bayguzina,Gimaletdinova,Khusnutdinov
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p. 1148 - 1155
(2018/10/24)
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- Remote sp3 C–H Amination of Alkenes with Nitroarenes
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Direct installation of a functional group at remote, unfunctionalized sites in an alkyl chain is a synthetically valuable but rarely reported process. The remote relay hydroarylamination of distal and proximal olefins, and of olefin isomeric mixtures, has been achieved through NiH-catalyzed alkene isomerization and sequential reductive hydroarylamination with nitroarenes. This provides an attractive approach to the direct installation of a distal arylamino group within alkyl chains. The single-step conversion of simple olefins and nitro(hetero)arenes to value-added arylamines is a practical strategy for amine synthesis as well as the remote activation of sp3 C–H bonds. The value of this transformation is further supported by the regioconvergent arylamination of isomeric mixtures of olefins. Modern organic synthesis requires more efficient strategies, such as C–H functionalization, with which to construct complex molecules from readily available chemicals. Undirected functionalization of remote aliphatic C–H bonds is a synthetically valuable but largely unknown process. Synergistic combination of metal-catalyzed chainwalking (migration of a double bond along the hydrocarbon chain, a process involving repeated migratory insertions and β-hydride eliminations) and cross-coupling chemistry offers a general approach to the remote functionalization of easily accessed unsaturated hydrocarbon substrates. In this paper, we demonstrate that direct installation of a distal arylamino group can be achieved from two common feedstock chemicals (olefins and nitroarenes) via nickel hydride chemistry. It is anticipated that the strategy could inspire the development of other remote functionalizations with different regioselectivity as well as asymmetric transformations. Zhu and colleagues describe the remote hydroamination of alkenes with nitro(hetero)arenes through nickel-catalyzed alkene isomerization and sequential reductive relay hydroamination process. Using two common feedstock chemicals, olefins and nitroaromatics, in an operationally simple procedure, this attractive protocol provides efficient and practical access to a wide range of arylamines under mild conditions.
- Xiao, Jichao,He, Yuli,Ye, Feng,Zhu, Shaolin
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supporting information
p. 1645 - 1657
(2018/05/16)
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- Palladium on Carbon-Catalyzed Benzylic Methoxylation for Synthesis of Mixed Acetals and Orthoesters
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The palladium on carbon (Pd/C)-catalyzed direct methoxylation of the benzylic positions of linear benzyl and cyclic ether substrates proceeded in the presence of i-Pr2NEt under an oxygen atmosphere to give the corresponding mixed acetals. Cyclic acetal derivatives could also be converted into orthoesters. The present direct methoxylation via a carbon-hydrogen (C?H) functionalization can be accomplished using the easily-removed Pd/C and molecular oxygen as a green oxidant. The obtained mixed acetals were transformed into the corresponding ether products by chemoselective substitution of the methoxy group using a silyltriflate, 2,4,6-collidine, and a nucleophile. The orthoester derivative could also be transformed into the cyclic ketal under similar reaction conditions.
- Yasukawa, Naoki,Kanie, Takafumi,Kuwata, Marina,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
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supporting information
p. 10974 - 10977
(2017/08/22)
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- Direct and efficient synthesis of unsymmetrical ethers from alcohols catalyzed by Fe(HSO4)3 under solvent-free conditions
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Highly efficient Fe(HSO4)3 catalyzed etherification of primary, secondary and tertiary benzylic alcohols with primary and secondary aliphatic alcohols is reported. The reaction affords unsymmetrical benzyl ethers in good to excellent yields under solvent-free conditions.
- Moghadam, Bashir Nazari,Akhlaghinia, Batool,Rezazadeh, Soodabeh
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p. 1487 - 1501
(2016/04/26)
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- Sulfated tungstate as hydroxyl group activator for preparation of benzyl, including p-methoxybenzyl ethers of alcohols and phenols
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Sulfated tungstate was found to be an effective heterogeneous and reusable catalyst for hydroxy group activation–mediated preparation of benzylic ethers including p-methoxybenzylic ethers of a wide range of alcohols and phenols under mild reaction conditions.
- Katkar, Kamlesh V.,Veer, Sachin D.,Akamanchi, Krishnacharya G.
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supporting information
p. 1893 - 1901
(2016/11/25)
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- Direct C-H bond activation of ethers and successive C-C bond formation with benzene by a bifunctional palladium-titania photocatalyst
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Palladium-loaded titanium oxide was found to work as a bifunctional photocatalyst for functionalization of benzene with ether upon photoirradiation, without using any special reagents. The metal-loaded TiO2 photocatalyst activated a C-H bond of ethers and the heterogeneous Pd metal nanoparticle catalyst promoted the successive C-C bond formation between benzene and the radical species. In this reaction, benzene reacted very selectively with the α-carbon of various ethers at least in the initial stage of the reaction. Kinetic and ESR studies revealed a detailed mechanism for the reaction.
- Tyagi, Akanksha,Matsumoto, Tomoya,Kato, Tatsuhisa,Yoshida, Hisao
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p. 4577 - 4583
(2016/07/06)
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- Gold(I)-catalyzed synthesis of unsymmetrical ethers using alcohols as alkylating reagents
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A microwave-irradiated alcohol-protecting strategy based on gold catalysis utilizing benzyl alcohol, tert-butyl alcohol and triphenylmethanol as alkylating reagents has been developed. This protecting strategy has wide functional group tolerance with satisfactory yields for the majority of the selected alcohols. The mechanism of this transformation was probed with oxygen-18 isotope labelled alcohols assisted by GC-MS techniques and chemical kinetic experiments. This strategy provides an efficient, straightforward and alternative approach to the preparation of benzyl, tert-butyl and trityl ethers in organic synthesis.
- Liu, Yongxiang,Wang, Xiaoyu,Wang, Yanshi,Du, Chuan,Shi, Hui,Jin, Shengfei,Jiang, Chongguo,Xiao, Jianyong,Cheng, Maosheng
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p. 1029 - 1036
(2015/03/30)
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- Tandem ring-closing metathesis/transfer hydrogenation: Practical chemoselective hydrogenation of alkenes
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An operationally simple chemoselective transfer hydrogenation of alkenes using ruthenium metathesis catalysts is presented. Of great practicality, the transfer hydrogenation reagents can be added directly to a metathesis reaction and effect hydrogenation of the product alkene in a single pot at ambient temperature without the need to seal the vessel to prevent hydrogen gas escape. The reduction is applicable to a range of alkenes and can be performed in the presence of aryl halides and benzyl groups, a notable weakness of Pd-catalyzed hydrogenations. Scope and mechanistic considerations are presented.
- Connolly, Timothy,Wang, Zhongyu,Walker, Michael A.,McDonald, Ivar M.,Peese, Kevin M.
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p. 4444 - 4447
(2015/01/09)
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- Cyclohexanones by Rh-mediated intramolecular C-H insertion
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Some long chain α-aryl α-diazo ketones under Rh catalysis cyclize efficiently to the corresponding cyclohexanones. This is in marked contrast to the cyclizations of α-diazo β-ketoesters, which consistently deliver cyclopentanone products.
- Taber, Douglass F.,Paquette, Craig M.,Gu, Peiming,Tian, Weiwei
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p. 9772 - 9780
(2013/10/22)
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- A novel method for synthesis of benzyl alkyl ethers using Vanadium-based metal complex catalysts
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A novel method has been developed for the synthesis of benzyl alkyl ethers in 25-85% yields via the reaction of toluene with alcohols in a CCl4 medium catalyzed by Et3N-activated VO(acac)2.
- Khusnutdinov,Bayguzina,Gallyamova,Dzhemilev
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p. 261 - 266
(2012/10/29)
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- Direct synthesis of unsymmetrical ethers from alcohols catalyzed by titanium cation-exchanged montmorillonite
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Titanium-exchanged montmorillonite (Ti4+-mont) was found to act as an efficient heterogeneous catalyst for the etherification of a wide range of alcohols under mild reaction conditions. Ti4+-mont was reusable with retention of high efficiency and applicable to scale-up reaction conditions. The Royal Society of Chemistry 2012.
- Mitsudome, Takato,Matsuno, Tsuyoshi,Sueoka, Shoichiro,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information; experimental part
p. 610 - 613
(2012/04/23)
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- [IrCl2Cp*(NHC)] complexes as highly versatile efficient catalysts for the cross-coupling of alcohols and amines
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A comparative study on the catalytic activity of a series of [IrCl 2Cp*(NHC)] complexes in several C-O and C-N coupling processes implying hydrogen-borrowing mechanisms has been performed. The compound [IrCl2Cp*(InBu)] (Cp* = pentamethyl cyclopentadiene; InBu = 1,3-di-n-butylimidazolylidene) showed to be highly effective in the cross-coupling reactions of amines and alcohols, providing high yields in the production of unsymmetrical ethers and N-alkylated amines. A remarkable feature is that the processes were carried out in the absence of base, phosphine, or any other external additive. A comparative study with other known catalysts, such as Shvo's catalyst, is also reported.
- Prades, Amparo,Corberan, Rosa,Poyatos, Macarena,Peris, Eduardo
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scheme or table
p. 11474 - 11479
(2009/12/03)
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- Partial hydrogenation of alkynes to cis-olefins by using a novel Pd 0-polyethyleneimine catalyst
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The creation and application of a new Pd0-polyethyleneimine complex catalyst (Pd0-PEI) was investigated. The 55 Pd 0-PEI catalyst was prepared by introduction of Pd(OAc)2 directly in the MeOH solution of deaerated PEI under Ar atmosphere. Reactions were carried out using 10 weight % versus substrate of 5% Pd0-PEI in 2mL solvent under H2 atmosphere at room temperature. The generality of the process was shown by disubstituting alkynes. Even for the substrate bearing a conjugated ketone on the alkyne, the serious over-reduction was not observed while significant cistrans isomerization of methyl styryl ketone accompanied the partial hydrogenation on the basis of keto-enol tautomerism. Pd0-PEI catalyst is also applicable to the partial hydrogenation of monosubstituted alkynes to monosubstituted olefins.
- Sajiki, Hironao,Mori, Shigeki,Ohkubo, Tomoyuki,Ikawa, Takashi,Kume, Akira,Maegawa, Tomohiro,Monguchi, Yasunari
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supporting information; experimental part
p. 5109 - 5111
(2009/05/07)
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- Hydrogenation versus hydrogenolysis with a safe, selective and reusable catalyst: Palladium black on Teflon
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Palladium black deposit is obtained by reduction and metallization of the Teflon polymer surface of magnetic stirring bars. These stirring bars can be used to perform selective hydrogenation of olefins and acetylenic compounds whilst hydrogenolysis is not observed. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.
- Belotti, Damien,Cantagrel, Guillaume,Combellas, Catherine,Cossy, Janine,Kanoufi, Frederic,Nunige, Sandra
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p. 761 - 764
(2007/10/03)
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- Alkylation on graphite in the absence of Lewis acids
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Graphite is introduced as a convenient catalyst for alkylation of aromatic compounds and alcohols by benzyl, tertiary alkyl, and secondary alkyl halides in the absence of strong Lewis acids. Primary alkyl halides are not active under the reaction conditions.
- Sereda, Grigoriy A.
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p. 7265 - 7267
(2007/10/03)
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- Decomposition of vinyl ethers by alkalide K- K+ (15-crown-5)2 via organopotassium intermediates
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The structure of vinyl ethers determines the direction of the C-O bond cleavage by alkalide K-, K+(15-crown-5)2 1. Highly reactive organopotassium compounds are intermediate products formed in the system containing phenyl vinyl ether, butyl vinyl ether, ethylene glycol butyl vinyl ether or triethylene glycol methyl vinyl ether. Vinylpotassium and butylpotassium react with 15-crown-5. The oxacyclic ring of the latter is opened in this case. Organopotassium ethers possessing CH2CH2O units eliminate ethylene. It results in various potassium alkoxides. The reaction of 1 with butyl vinyl ether occurs very slow as compared to other vinyl ethers and most of other reagents used till now.
- Grobelny, Zbigniew,Stolarzewicz, Andrzej,Maercker, Adalbert,Krompiec, Stanis,Kasperczyk, Janusz,Rzepa, Józef
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p. 1580 - 1585
(2007/10/03)
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- Lewis acid-catalyzed reductive etherification of carbonyl compounds with alkoxyhydrosilanes
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The TMSI-catalyzed reaction of aldehydes and ketones with alkoxydimethylsilanes gave unsymmetrical ethers in good to high yields. This reductive etherification is superior to the conventional method using two kinds of silicon reagents in terms of atom eff
- Miura, Katsukiyo,Ootsuka, Kazunori,Suda, Shuntaro,Nishikori, Hisashi,Hosomi, Akira
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p. 313 - 315
(2007/10/03)
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- Reduction of acetals with samarium diiodide in acetonitrile in the presence of Lewis acids
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Transformation of acetals into ethers by partial reduction using a samarium diiodide-Lewis acids-acetonitrile system is described. The reaction with aromatic acetals occurred in good yields in the presence of aluminum chloride (2 eq) whereas the corresponding aliphatic, vinylic, and alkynyl derivatives did not afford ethers under the same conditions, β-Elimination to give an enol ether becomes predominant when aliphatic acetals that possess a hydrogen at the 2-position are treated with iodotrimethylsilane in the presence of SmI2 or SmI3.
- Kunishima,Nakata,Sakuma,Kono,Sato,Tani
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- Reduction of monothioacetals with SmI2: Application to [2,3]-Wittig rearrangement
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Simple reduction of O,S-acetals with SmI2 yielding ethers with selective liberation of the sulfenyl group can be accomplished using benzene-HMPA with t-BuOH. When O,S-acetals possess an O-allyl group, the [2,3]-Wittig rearrangement yielding homoallyl alcohols follows the elimination of a sulfenyl group. For chemoselective elimination of an alkoxy group to give sulfides, MeOTf serves as a moderately effective additive.
- Nakata, Daisuke,Kusaka, Chie,Tani, Shohei,Kunishima, Munetaka
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p. 415 - 418
(2007/10/03)
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- BiBr3, an efficient catalyst for the benzylation of alcohols: 2-Phenyl- 2-propyl, a new benzyl-type protecting group
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The benzylation of aliphatic alcohols with various benzylic alcohols has been achieved in the presence of BiBr3 under mild conditions. 2- Phenylpropan-2-ol proved to be the most efficient and can be considered as a novel protecting group. (C) 2000 Elsevier Science Ltd.
- Boyer, Bernard,Keramane, El-Mehdi,Roque, Jean-Pierre,Pavia, André A.
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p. 2891 - 2894
(2007/10/03)
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- Auxiliary accelerated reactions: Towards the use of catalytic chiral auxiliaries
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In competition experiments, the acceleration of reactivity of alkenes tethered to pyridyl groups compared with the corresponding alkenes tethered to phenyl groups in the presence of transition metals was demonstrated for two reaction types: Diels-Alder cycloaddition of enoate esters and catalytic hydrogenation of allylic and homoallylic ethers. The rate accelerations observed are of crucial importance in the development of a new concept for asymmetric catalysis: chiral auxiliaries which can function in a catalytic manner.
- Westwell, Andrew D.,Williams, Jonathan M. J.
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p. 13063 - 13078
(2007/10/03)
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- Synthesis of benzyl/allyl alkyl ethers from corresponding magnesium alkoxides
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In the presence of iodine, alcohols react with magnesium to produce magnesium alkoxides which are then treated with benzyl chloride or allyl bromide to produce benzyl alkyl ethers or allyl alkyl ethers.
- Lin, Ji-Mao,Li, Hui-Hui,Zhou, Ai-Min
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p. 5159 - 5160
(2007/10/03)
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- Syntheses of long-chain quaternary ammonium salts from fatty alcohols by microwave irradiation
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The phase-transfer catalysts, long-chain quaternary ammonium salts, were rapidly synthesized from fatty alcohols by the reactions with hydrogen halides in the presence of trialkyl amines under microwave irradiation. The catalysts could be widely applied in a variety of quick and new organic reactions, whether by conventional heating or under microwave irradiation. The reaction efficiencies under microwave irradiation were higher than those obtained with conventional heating.
- Jiang,Hu,Pang,Yuan
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p. 847 - 850
(2007/10/03)
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- Hypervalent (tert-butylperoxy)iodanes generate iodine-centered radicals at room temperature in solution: Oxidation and deprotection of benzyl and allyl ethers, and evidence for generation of α-oxy carbon radicals
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1-(tert-Butylperoxy)-1,2-benziodoxol-3(1H)-one (1a) oxidizes benzyl and allyl ethers to the esters at room temperature in benzene or cyclohexane in the presence of alkali metal carbonates. Since this reaction is compatible with other protecting groups such as MOM, THP, and TBDMS ethers, and acetoxy groups, and because esters are readily hydrolyzed under basic conditions, this new method provides a convenient and effective alternative to the usual reductive deprotection. Oxidation with 1a occurs readily with C-H bonds activated by both enthalpic effects (benzylic, allylic, and propargylic C-H bonds) and/or polar effects (α-oxy C-H bonds), generating α-oxy carbon-centered radicals, which can be detected by nitroxyl radical trapping. Measurement of the relative rates of oxidation for a series of ring-substituted benzyl n-butyl ethers 2d and 2p-s indicated that electron-releasing groups such as p-MeO and p-Me groups increase the rate of oxidation, and Hammett correlation of the relative rate factors with the σ+ constants of substituents afforded the reaction constant ρ+ = -0.30. The large value of the isotope effect obtained for the oxidation of benzyl n-butyl ether 2d (k(H)/k(D) = 12-14) indicates that the rate-determining step of the reactions probably involves a high degree of benzylic C-H bond breaking. The effects of molecular dioxygen were examined, and the mechanism involving the intermediacy of the tert-butylperoxy acetal 5 and/or the hydroperoxy acetal 32 is proposed. Particularly noteworthy is the finding that (tert-butylperoxy)iodane 1a can generate the tert-butylperoxy radical and the iodine-centered radical 33a, even at room temperature in solution, via homolytic bond cleavage of the hypervalent iodine(III)-peroxy bond.
- Ochiai, Masahito,Ito, Takao,Takahashi, Hideo,Nakanishi, Akinobu,Toyonari, Mika,Sueda, Takuya,Goto, Satoru,Shiro, Motoo
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p. 7716 - 7730
(2007/10/03)
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- DIRECT SYNTHESES OF ETHERS IN THE PRESENCE OF QUATERNARY AMMONIUM SLATS UNDER MICROWAVE IRRADIATION
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Several ethers have been synthesized directly from alcohols and alkyl halides without an additional base, in the presence of a quaternary ammonium salt, under microwave irradiation, within a few minutes.
- Yuncheng, Yuan,Yulin, Jiang,Jun, Pang,Xiaohui, Zhang,Conggui, Yang
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p. 519 - 520
(2007/10/02)
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- Use of Polyoxetane Resin-Supported Quaternary Onium Salts as a Polymeric Phase-Transfer Catalyst for Preparing Ethers from Hydroxy Compounds and Alkyl Halides
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As a polymer support for preparing polymeric phase-transfer catalysts (PTC), soft, moderately polar polyoxetane resins were employed which were synthesized by a cationic ring-opening copolymerization of oxetanes Br(CH2)nOCH2-X with bisoxetanes X-CH2O(CH2)nOCH2-X, where X=3-methyl-3-oxetanyl and n=4 or 6.In a few cases of those polymerizations, 3-(2-oxadecyl)-3-methyloxetane was used as a comonomer with a lipophilic pendant.The terminal bromine of the pendant groups of such polyoxetane resins was quaternized with tributylamine or tributylphosphine in DMF in order to examine the phase-transfer catalyzing ability of the resultant quaternary onium bromides in the etherification reaction between alkyl halides and alcohols or phenols.These reactions gave the desired products in fairly good yields within reaction periods of 1-3 h, indicating that the catalytic activities of those PTCs are comparable to that of tetrabutylammonium bromide.A fairly high catalytic activity of the polymeric PTC was observed at each of ten stages in a process using the polymeric PTC repeatedly for the etherification reaction of 3-hydroxymethyl-3-methyloxethane with 1,4-dibromobutane.
- Motoi, Masatoshi,Shimamura, Katsuhiko,Shimamura, Chikako,Muramoto, Satoru,Kanoh, Shigeyoshi,Suda, Hiroshi
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p. 2553 - 2561
(2007/10/02)
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- Substituents Effect on the Reaction of Aromatic Acetals Over Aluminium Phosphate and Aluminium Sulphate Catalyst
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Aromatic acetals in the presence of aluminium phosphate (AP) catalyst at elevated temperatures yield the corresponding esters (b), ethers (c) and the parent aldehydes (d).These substrates over aluminium sulphate (AS) catalyst give only the esters (b) and aldehydes (d).The products distribution varies with temperature.Substituents in the ring also play a part in the reaction.
- Xavier, N.,Arulraj, S. J.
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p. 775 - 777
(2007/10/02)
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- Fluorodestannylation. A Powerful Technique to Liberate Anions of Oxygen, Sulfur, Selenium, and Carbon
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Fluoride ions smoothly destannylate organotin chalcogenides to liberate nucleophilic chalcogenide ions; hence the first nucleophilic oxide (O2-) and selenide (Se2-) transfer agents are reported where the tin atom serves as "group 16 (VIB) transfer agent".In the presence of crown ethers or ammonium salts, this process results in a new way to generate "naked" nucleophiles.Ethers and selenides are formed in good to excellent yield.In addition, a useful C-C bond-forming reaction has been developed by using alkyltins with aldehydes and acid chlorides in the presence of fluroide ion.Aspects concerning reactivity and mechanism are presented.Finally, the generality of the fluorodestannylation procedure and the differences with parallel silicon chemistry are detailed.
- Harpp, David N.,Gingras, Marc
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p. 7737 - 7745
(2007/10/02)
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- Action of Lewis Acids on Aromatic Acetals
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Acetals of the type X.C6H4CH(OR)2, where R = Et, n-Bu and isoamyl, and X = H and CH3, react with antimony perchloride and ferric chloride in anhydrous 1,2-dichloroethane to give benzyl alkyl ether, alkyl benzoate, benzyl ester, α,β-unsaturated aldehyde, benzaldehyde and a small quantity of benzyl alcohol. p-Nitrobenzaldehyde di-n-butyl acetal gave only p-nitrobenzaldehyde and a trace of p-nitrobenzyl alcohol.The mechanism of the formation of benzyl alkyl ether is explained by a hydride ion transfer and that of α,β-unsaturated aldehyde by an aldol type of condensation.The aliphatic and aromatic aldehydes produced in the reaction could undergo Tischenko reaction in the presence of antimony or iron alkoxides to give the esters.
- Alphonse, I.,Arulraj, S. J.
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p. 820 - 822
(2007/10/02)
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- REARRANGEMENT OF SUBSTITUTED AROMATIC ACETALS CATALYSED BY γ-ALUMINA
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Aromatic acetals over γ-alumina undergo rearrangement to give the corresponding esters (b) and ethers (c) in good yield.The product distribution varied unusually over the range of reaction temperatures.The effect of substituents has also been felt much in the study.Probable mechanisms have been suggested for the reaction.The catalyst has been characterized by various studies and the specific poisoning of the catalyst has been done with NH3, CO2 and H2S.
- Xavier, N.,Arulraj, S. J.
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p. 2875 - 2878
(2007/10/02)
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- Kinetic Studies on an Improved Williamson Ether Synthesis Using a Polymer-Supported Phase-Transfer Catalyst
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An improved Williamson ether synthesis was conducted under phase-transfer conditions by using a polymer-supported quaternary salt.Benzyl butyl ether was produced from benzyl alcohol and butyl bromide, and it was shown that the rate of reaction was influenced by the concentrations of benzyl alcohol and butyl bromide in the organic phase and the concentration of KOH in the aqueous phase.Based on kinetic studies, the rate-determining step was found to depend on the concentrations of the reactants.The content of water in the organic phase, which increased with the concentration of benzyl alcohol, was found to be closely related to the decrease in the rate of raction. Keywords --- triphase catalysis; phase-transfer catalysis; polymer-supported quaternary salt; Williamson ether synthesis; kinetics; benzyl butyl ether
- Takeuchi, Hirofumi,Miwa, Yoshihisa,Morita, Shushi,Okada, Jutaro
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p. 3101 - 3106
(2007/10/02)
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- Action of Boron Trifluoride on Aromatic Acetals
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Acetals of the type X-C6H4CH(OR)2 (where R = Et, n-Bu and isoamyl and X = H, CH3) react with boron trifluoride in anhyd. 1,2-dichloroethane to give benzyl alkyl ethers, α,β-unsaturated aldehydes and benzaldehyde.However, p-nitrobenzaldehyde di-n-butyl acetal gives only p-nitrobenzaldehyde.The formation of benzyl alkyl ethers is explained by a hydride ion transfer mechanism and that of α,β-unsaturated aldehyde by an aldol-type of condensation.
- Alphonse, I.,Arulraj, S. J.
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p. 199 - 200
(2007/10/02)
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- Rearrangement of Aromatic Acetals Over Solid Acid Catalysts
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The reactions of aromatic acetals (1a-6a) catalysed by aluminium phosphate (AP) yield the corresponding esters (b), ethers (c) and the parent aldehydes (d).Similar reactions over aluminium sulphate (AS) give only esters (b) and the aldehydes (d).Probable mechanisms have been suggested for the reactions.The catalysts have been characterized by various studies.The specific poisoning of the catalysts have been done with NH3 and CO2 and the product formation on the poisoned catalyst provides support to the suggested mechanisms.
- Xavier, N.,Arulraj, S. J.
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p. 519 - 522
(2007/10/02)
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- Reactions in Microemulsion Media. Nucleophilic Substitution Reactions of Benzyl and p-Alkylbenzyl Chlorides
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A kinetic and synthetic study of nucleophilic displacement reaction of bromide ion with benzyl chloride (1a) and its p-ethyl-substituted (1b) and p-n-dodecyl-substituted (1c) analogues has been performed in microemulsions prepared from combinations of a 1.23:1 (w/w) mixture (S) of cetyltrimethylammonium bromide (CTABr) and 1-butanol, a 1:5 (w/w) KBr-H2O solution (W), and hexane (O).The rates of reaction decreased differentially with increasing hexane content at a constant ratio of S:W to indicate that the interphase was the microemulsion reactive site.For microemulsion with respect to aqueous micellar and aqueous ethanol reaction media, solubilization of substrate was higher, initial reaction rates were comparable or slightly less, and overall conversions were greater.
- Martin, Craig A.,McCrann, Patrick M.,Ward, Mary Darlene,Angelos, George H.,Jaeger, David A.
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p. 4392 - 4396
(2007/10/02)
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- CONJUGATED THREE-COMPONENT FRIEDEL-CRAFTS REACTIONS. VI. REACTION OF CHLOROMETHYL BUTYL ETHER WITH PROPYLENE AND BENZENE IN THE PRESENCE OF ALUMINUM CHLORIDE
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The reaction of chloromethyl butyl ether with propylene in benzene in the presence of aluminum chloride at low temperatures leads predominantly to the products from addition of the α-chloro ether to the olefin, i.e. γ-chlorodibutyl and γ-phenyldibutyl ethers.
- Grebenyuk, A. D.,Zavizion, E. M.,Rusin, A. N.,Bengard, Z. V.
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p. 811 - 814
(2007/10/02)
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- REACTIONS IN MICROEMULSION MEDIA. NUCLEOPHILIC DISPLACEMENT REACTION OF BENZYL CHLORIDE WITH BROMIDE ION
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A kinetic and synthetic study of the reaction of benzyl chloride with bromide ion has been performed in microemulsions composed of cetyltrimethylammonium bromide, 1-butanol, water, potassium bromide, and hexane; rates and yields of benzyl bromide formatio
- Martin, Craig A.,McCrann, Patrick M.,Angelos, George H.,Jaeger, David A.
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p. 4651 - 4654
(2007/10/02)
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- FLUORIDE SALTS ON ALUMINA AS REAGENTS FOR ALKYLATION OF PHENOLS AND ALCOHOLS.
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THE EFFECTIVENESS OF ALKALI METAL FLUORIDES IMPREGNATED ON ALUMINA AS A REAGENT FOR PROMOTING ALKYLATION WAS OPTIMIZED WITH RESPECT TO THE METAL CATION, THE AMOUNT OF IMPREGNATION, AND THE REACTION SOLVENT. POTASSIUM OR CAESIUM FLUORIDE ONALUMINA IN ACETONITRILE OR 1,2-DIMETHOXYETHANE WAS CONCLUDED TO BE THE BEST REACTION SYSTEM FOR GENERAL USE. O-ALKYLATION OF SUBSTITUTED PHENOLS, PRIMARY AND SECONDARY ALCOHOLS, AND A GLYCOL WAS CARRIED OUT MOSTLY IN GOOD YIELDS UNDER MILDCONDITIONS WITH SIMPLE EXPERIMENTAL PROCEDURES.
- ANDO,YAMAWAKI,KAWATE,SUMI,HANAFUSA
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p. 2504 - 2507
(2007/10/02)
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