- Dual-mesoporous ZSM-5 zeolite with highly b-axis-oriented large mesopore channels for the production of benzoin ethyl ether
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Dual-mesoporous ZSM-5 zeolite with highly b axis oriented large mesopores was synthesized by using nonionic copolymer F127 and cationic surfactant CTAB as co-templates. The product contains two types of mesopores - smaller wormlike ones of 3.3 nm in size
- Zhou, Xiaoxia,Chen, Hangrong,Zhu, Yan,Song, Yudian,Chen, Yu,Wang, Yongxia,Gong, Yun,Zhang, Guobin,Shu, Zhu,Cui, Xiangzhi,Zhao, Jinjin,Shi, Jianlin
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Read Online
- Dehydrogenative ester synthesis from enol ethers and water with a ruthenium complex catalyzing two reactions in synergy
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We report the dehydrogenative synthesis of esters from enol ethers using water as the formal oxidant, catalyzed by a newly developed ruthenium acridine-based PNP(Ph)-type complex. Mechanistic experiments and density functional theory (DFT) studies suggest that an inner-sphere stepwise coupled reaction pathway is operational instead of a more intuitive outer-sphere tandem hydration-dehydrogenation pathway.
- Ben-David, Yehoshoa,Diskin-Posner, Yael,Kar, Sayan,Luo, Jie,Milstein, David,Rauch, Michael
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supporting information
p. 1481 - 1487
(2022/03/07)
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- Comparing Separation vs. Fresh Start to Assess Reusability of Pd/C Catalyst in Liquid-Phase Hydrogenation
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The reusability of metal catalysts is a key issue for the potential application of new catalysts in research and industrial practice. The most common procedure for testing catalyst reusability in liquid-phase heterogeneous reactions is based on separating a catalyst from a reaction mixture followed by the next run. An alternative procedure called “fresh start” consists of the addition of a new portion of reagents to the reaction mixture without any isolation operation. In this work, we compare both procedures in a model Pd/C-catalyzed hydrogenation with different heteroatoms, e. g., O-, S-, and N-vinyl derivatives. It was shown that regardless of whether the catalyst is stable or potentially poisoned during the reaction, both procedures lead to comparable results. It appears that a much easier implementation of a fresh start procedure may be an option of choice. The possibilities of using both procedures to rationalize the experimental protocol for assessing Pd/C catalyst reusability in liquid-phase hydrogenations are discussed.
- Mironenko, Roman M.,Saybulina, Elina R.,Trenikhin, Mikhail V.,Izmailov, Rinat R.,Lotsman, Kristina A.,Rodygin, Konstantin S.,Ananikov, Valentine P.
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p. 3656 - 3661
(2021/07/02)
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- Synergistic catalysis of hybrid nano-structure Pd catalyst for highly efficient catalytic selective hydrogenation of benzaldehyde
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Selective hydrogenation of benzaldehyde is a green and sustainable technology to produce benzyl alcohol. Herein, we report a hybrid nano-structure catalyst(Pd/@-ZrO2/AC) by photochemical route for selective hydrogenation of benzaldehyde under m
- Zhang, Yanji,Zhou, Jicheng,Li, Kai,Lv, Mengdie
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p. 129 - 137
(2020/01/28)
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- Hydrosilylation of carbonyl and carboxyl groups catalysed by Mn(i) complexes bearing triazole ligands
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Manganese(i) complexes bearing triazole ligands are reported as catalysts for the hydrosilylation of carbonyl and carboxyl compounds. The desired reaction proceeds readily at 80 °C within 3 hours at catalyst loadings as low as 0.25 to 1 mol%. Hence, good to excellent yields of alcohols could be obtained for a wide range of substrates including ketones, esters, and carboxylic acids illustrating the versatility of the metal/ligand combination.
- Martínez-Ferraté, Oriol,Chatterjee, Basujit,Werlé, Christophe,Leitner, Walter
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p. 6370 - 6378
(2019/11/20)
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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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- Alcohol-based Michaelis-Arbuzov reaction: An efficient and environmentally-benign method for C-P(O) bond formation
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The famous Michaelis-Arbuzov reaction is extensively used both in the laboratory and industry to manufacture tons of widely-used organophosphoryl compounds every year. However, this method and the modified Michaelis-Arbuzov reactions developed recently still have some limitations. We now report a new alcohol-version of the Michaelis-Arbuzov reaction that can provide an efficient and environmentally-benign method to address the problems of the known Michaelis-Arbuzov reactions. That is, a wide range of alcohols can readily react with phosphites, phosphonites, and phosphinites to give all the three kinds of phosphoryl compounds (phosphonates, phosphinates, and phosphine oxides) using an n-Bu4NI-catalyzed efficient C-P(O) bond formation reaction. This general method can also be easily scaled up and used for further synthetic transformations in one pot.
- Ma, Xiantao,Xu, Qing,Li, Huan,Su, Chenliang,Yu, Lei,Zhang, Xu,Cao, Hongen,Han, Li-Biao
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supporting information
p. 3408 - 3413
(2018/08/06)
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- Singlet vs Triplet Reactivity of Photogenerated α,n-Didehydrotoluenes
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The reactivity of α,n-didehydrotoluenes (DHTs) in protic media (organic/aqueous mixtures) was explored by means of a combined computational and experimental approach. These intermediates were generated via a photoinduced double elimination process occurring in (chlorobenzyl)trimethylsilanes and led to the formation of a varied products distribution, depending on the isomer tested. Irradiation of ortho- and para-derivatives resulted, respectively, in the formation of triplet α,2- and α,4-DHTs, whose diradical reactivity led to both radical and polar products. On the other hand, irradiation of the meta-precursor led to the singlet α,3-DHT isomer. The latter showed a marked preference for the formation of polar products and this was rationalized, as supported by computational evidence, via the involvement of a zwitterionic species arising through interaction of the nucleophilic solvent with the benzylic position of the DHT.
- Pedroli, Chiara,Ravelli, Davide,Protti, Stefano,Albini, Angelo,Fagnoni, Maurizio
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supporting information
p. 6592 - 6603
(2017/07/15)
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- Auto-Tandem Catalysis with Frustrated Lewis Pairs for Reductive Etherification of Aldehydes and Ketones
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Herein we report that a single frustrated Lewis pair (FLP) catalyst can promote the reductive etherification of aldehydes and ketones. The reaction does not require an exogenous acid catalyst, but the combined action of FLP on H2, R-OH or H2O generates the required Br?nsted acid in a reversible, “turn on” manner. The method is not only a complementary metal-free reductive etherification, but also a niche procedure for ethers that would be either synthetically inconvenient or even intractable to access by alternative synthetic protocols.
- Bakos, Mária,Gy?m?re, ádám,Domján, Attila,Soós, Tibor
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supporting information
p. 5217 - 5221
(2017/04/27)
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- A Versatile Iridium(III) Metallacycle Catalyst for the Effective Hydrosilylation of Carbonyl and Carboxylic Acid Derivatives
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A versatile iridium(III) metallacycle catalysed rapidly and selectively the reduction of a large array of challenging esters and carboxylic acids as well as various ketones and aldehydes. The reactions proceeded in high yields at room temperature by hydrosilylation followed by desilylation. Although the reactions of various aldehydes and ketones resulted exclusively in alcohols, the hydrosilylation of esters led to alcohols or ethers, depending on the type of substrate. Regarding the carboxylic acids, again the nature of the reagent controlled the outcome of the hydrosilylation reaction, either alcohols or aldehydes being formed.
- Corre, Yann,Rysak, Vincent,Trivelli, Xavier,Agbossou-Niedercorn, Francine,Michon, Christophe
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supporting information
p. 4820 - 4826
(2017/09/07)
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- Selective Hydrosilylation of Esters to Aldehydes Catalysed by Iridium(III) Metallacycles through Trapping of Transient Silyl Cations
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The combination of an iridium(III) metallacycle and 1,3,5-trimethoxybenzene catalyses rapidly and selectively the reduction of esters to aldehydes at room temperature with high yields through hydrosilylation followed by hydrolysis. The ester reduction involves the trapping of transient silyl cations by the 1,3,5-trimethoxybenzene co-catalyst, supposedly by formation of an arenium intermediate whose role was addressed by DFT calculations.
- Corre, Yann,Rysak, Vincent,Capet, Frédéric,Djukic, Jean-Pierre,Agbossou-Niedercorn, Francine,Michon, Christophe
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supporting information
p. 14036 - 14041
(2016/09/21)
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- Hydrochloric acid as an efficient catalyst for intermolecular condensation of alcohols. A simple and highly efficient synthesis of unsymmetrical ethers from benzylic alcohols and alkanols
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Benzylic alcohols and diarylmethanols with electron-donating substituents in the aromatic ring reacted with aliphatic alcohols in the presence of a catalytic amount of HCl to give the corresponding alkyl arylmethyl ethers. The reactivity of diarylmethanols in the intermolecular dehydration depended on the nature of substituents in the aromatic rings and structure of aliphatic alcohol.
- Mochalov,Fedotov,Trofimova,Zefirov
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p. 1217 - 1231
(2015/11/09)
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- Lewis acid promoted ruthenium(II)-catalyzed etherifications by selective hydrogenation of carboxylic acids/esters
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Ethers are of fundamental importance in organic chemistry and they are an integral part of valuable flavors, fragrances, and numerous bioactive compounds. In general, the reduction of esters constitutes the most straightforward preparation of ethers. Unfortunately, this transformation requires large amounts of metal hydrides. Presented herein is a bifunctional catalyst system, consisting of Ru/phosphine complex and aluminum triflate, which allows selective synthesis of ethers by hydrogenation of esters or carboxylic acids. Different lactones were reduced in good yields to the desired products. Even challenging aromatic and aliphatic esters were reduced to the desired products. Notably, the in situ formed catalyst can be reused several times without any significant loss of activity. An assist from Al: A bifunctional catalyst system consisting of a Ru/phosphine complex and aluminum triflate allows selective hydrogenation of esters to ethers. A variety of lactones were reduced to the desired products in good yields. The catalyst further provides a general method for the reduction of linear esters and reductive etherification of carboxylic acids with alcohols.
- Li, Yuehui,Topf, Christoph,Cui, Xinjiang,Junge, Kathrin,Beller, Matthias
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supporting information
p. 5196 - 5200
(2015/04/27)
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- Effects of the carbon support nature and ruthenium content on the performances of Ru/C catalysts in the liquid-phase hydrogenation of benzaldehyde to benzyl alcohol
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Abstract The hydrogenation of benzaldehyde in ethanol medium in the presence of Ru/C catalysts was shown to proceed with the preferential formation of benzyl alcohol without subsequent hydrodeoxygenation into toluene. An increase in ruthenium content of t
- Mironenko, Roman M.,Belskaya, Olga B.,Zaikovskii, Vladimir I.,Likholobov, Vladimir A.
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p. 923 - 930
(2015/08/06)
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- Selective catalytic synthesis of unsymmetrical ethers from the dehydrative etherification of two different alcohols
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The cationic ruthenium-hydride complex [(C6H6)(PCy3)(CO)RuH]+BF4- catalyzes selective etherification of two different alcohols to form unsymmetrically substituted ethers. The catalytic method exhibits a broad substrate scope while tolerating a range of heteroatom functional groups in forming unsymmetrical ethers, and it is successfully used to directly synthesize a number of highly functionalized chiral nonracemic ethers.
- Kim, Junghwa,Lee, Dong-Hwan,Kalutharage, Nishantha,Yi, Chae S.
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p. 3881 - 3885
(2015/01/16)
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- SNAAP sulfonimidate alkylating agent for acids, alcohols, and phenols 1
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Stable, crystalline ethyl N-tert-butyl-4-nitrobenzenesulfonimidate has been prepared in high yield by direct O-ethylation of N-tert-butyl-4- nitrobenzenesulfonamide with iodoethane and silver(I) oxide in dichloromethane. This sulfonimidate directly ethylates various acids to esters; the stronger the acid, the faster it alkylates and in higher yield. It readily ethylates alcohols and phenols to ethers at room temperature in the presence of tetrafluoroboric acid catalyst without molecular rearrangements or racemization. We have defined these reactions as SNAAP alkylations: [substitution, nucleophilic of acids, alcohols and phenols]. The hard sulfonimidate alkylating agent is chemoselective, preferring oxygen > nitrogen > sulfur. The sulfonamide byproduct of alkylation is readily recycled to the sulfonimidate. Georg Thieme Verlag Stuttgart . New York.
- Maricich, Tom J.,Allan, Matthew J.,Kislin, Brett S.,Chen, Andrea I-T.,Meng, Fan-Chun,Bradford, Christine,Kuan, Nai-Chia,Wood, Jeremy,Aisagbonhi, Omonigho,Poste, Alethea,Wride, Dustin,Kim, Sylvia,Santos, Therese,Fimbres, Michael,Choi, Dianne,Elia, Haydi,Kaladjian, Joseph,Abou-Zahr, Ali,Mejia, Arturo
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p. 3361 - 3368
(2014/01/06)
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- Practical metal- and additive-free methods for radical-mediated reduction and cyclization reactions
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Two facile, metal- and additive-free protocols for radical dehalogenation, deoxygenation and cyclization reactions are reported. Irradiation by household fluorescent light bulbs or the presence of an air atmosphere is shown to initiate the desired reactions, thus providing highly practical reaction setups for radical-mediated reductions and cyclizations.
- Jiang, Hao,Bak, Jesper R.,Lopez-Delgado, Francisco Javier,Jorgensen, Karl Anker
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supporting information
p. 3355 - 3359
(2013/12/04)
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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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- Ionic liquid/PPh3 promoted cleavage of diphenyl disulfide and diselenide: A straight-forward metal-free one-pot route to the synthesis of unsymmetrical sulfides and selenides
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A metal-free cleavage of diphenyl disulfide and diphenyl diselenide has been achieved using ionic liquid/triphenyl phosphine (PPh3) and a convenient protocol for the one-pot synthesis of unsymmetrical sulfides and selenides by condensing 'in situ' generated thiolate or selenate anion with alkyl halides has been developed. In addition, 1,4-conjugate addition of the generated thiolate anions to activated alkenes has also been demonstrated. The ionic liquid, 1-methyl-3-pentyl imidazolium bromide, [pmIm]Br plays a crucial role in promoting the course of the reactions and shows superior activity and selectivity compared to other solvents. The [pmIm]Br has been reused for at least five times without appreciable loss of activity.
- Banerjee, Subhash,Adak, Laksmikanta,Ranu, Brindaban C.
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scheme or table
p. 2149 - 2152
(2012/05/05)
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- Pt nanoparticles entrapped in ordered mesoporous carbons for liquid-phase hydrogenation of unsaturated compounds
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Pt nanoparticles entrapped in ordered mesoporous carbons were proved effective for liquid-phase hydrogenation of benzaldehyde and its derivatives in water. Due to higher hydrophobicity, Pt/CMK-3 catalyst was slightly superior to Pt/CMK-8 catalyst towards benzaldehyde hydrogenation. Nevertheless, the larger pore volume of Pt/CMK-8 catalyst is more beneficial for mass transfer of benzaldehyde derivatives. In addition, the surface electronic state of Pt particles deposited on CMK-8 is helpful for the activation of carbonyl compounds. Therefore, the Pt/CMK-8 and Pt/CMK-3 catalysts showed tiny differences in most cases. The Pt catalysts can also catalyze the hydrogenation of olefins and other carbonyl compounds.
- Ding, Yue,Li, Xiaohong,Li, Bo,Wang, Haihong,Wu, Peng
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p. 147 - 151
(2013/01/14)
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- Reductive etherification of aldehydes photocatalyzed by dicarbonyl pentamethylcyclopentadienyl iron complexes
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The reductive etherification of aldehydes can be performed by the reaction with dialkylmethylsilanes in the presence of new iron(II) piano-stool catalysts of general formula Cp*Fe(CO)2Ar (Cp * = η5-C5Me5; Ar = Ph, 4-C6H4OCH3, 4-C6H4CH 3, Fc). This transformation is promoted by UV light and affords a simple route for the preparation of unsymmetrical alkyl ethers.
- Argouarch, Gilles,Grelaud, Guillaume,Roisnel, Thierry,Humphrey, Mark G.,Paul, Frédéric
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supporting information
p. 5015 - 5018
(2012/11/07)
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- α,n-didehydrotoluenes by photoactivation of (chlorobenzyl) trimethylsilanes: An alternative to enyne-allenes cyclization
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Doubly radical: A novel entry to ?,n-didehydrotoluene (DHT) diradicals is disclosed and proceeds through the photochemical activation of (chlorobenzyl)trimethylsilanes with chloride loss and elimination of the SiMe3+ group (see scheme). The products formed in solution are indicative of the intermediacy of the three isomers of the ?,n-DHT
- Protti, Stefano,Ravelli, Davide,Mannucci, Barbara,Albini, Angelo,Fagnoni, Maurizio
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supporting information; experimental part
p. 8577 - 8580
(2012/09/22)
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- New method for the synthesis of benzyl alkyl ethers mediated by FeSO 4
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The synthesis of benzyl alkyl ethers from benzyl bromides and alcohols using FeSO4 as a recoverable and reusable mediator has been described without use of base and cosolvent under mild conditions.
- Joshi, Girdhar,Adimurthy, Subbarayappa
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experimental part
p. 720 - 728
(2011/03/22)
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- A clean, palladium-catalyzed oxidative esterification of aldehydes using benzyl chloride
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A highly efficient, mild, simple and clean procedure is presented for the one-pot oxidation of aromatic and aliphatic aldehydes to their corresponding ethyl esters using benzyl chloride as the oxidant under palladium-catalyzed conditions. The reaction is complete in just 30 min under microwave irradiation and inert conditions are not required to obtain good to excellent yields (65-93%) of isolated products.
- Heropoulos, Georgios A.,Villalonga-Barber, Carolina
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scheme or table
p. 5319 - 5322
(2011/10/31)
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- Triflic acid catalyzed reductive coupling reactions of carbonyl compounds with O-, S-, and N-nucleophiles
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Highly efficient metal-free reductive coupling reactions of aldehydes and ketones with a range of nucleophiles in the presence of triflic acid (1-5 mol %) as the catalyst are presented. The reactions can be performed at ambient temperature without exclusion of moisture or air. A range of symmetrical and unsymmetrical ethers were obtained by this method in high yields and short reaction times. For the first time, the influence of additional functionalization has been studied. Furthermore, the formation of thioethers from ketones (by addition of unmodified thiols) and of sulfonamides from either aldehydes or ketones has been achieved under catalytic conditions.
- Gellert, Beate A.,Kahlcke, Nils,Feurer, Markus,Roth, Stefanie
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supporting information; experimental part
p. 12203 - 12209
(2011/11/07)
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- A simple access to metallic or onium bistrifluoromethanesulfonimide salts
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Numerous salts of the (CF3SO2)2N- anion, called TFSI, were prepared according to an original one-pot procedure. First, N-benzyl trifluoromethanesulfonimide (N-benzyl triflimide) was treated with ethanol to form
- Arvai, Roman,Toulgoat, Fabien,Langlois, Bernard R.,Sanchez, Jean-Yves,Médebielle, Maurice
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experimental part
p. 5361 - 5368
(2009/12/01)
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- Direct reduction of esters to ethers with an indium(III) bromide/triethylsilane catalytic system
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An indium(III) bromide-triethylsilane reagent system promotes direct reduction of esters to produce the corresponding unsymmetrical ethers. This simple catalytic system accommodated other carbonyl compounds, such as a tertiary amide and a carboxylic acid. Georg Thieme Verlag Stuttgart.
- Sakai, Norio,Moriya, Toshimitsu,Fujii, Kohji,Konakahara, Takeo
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experimental part
p. 3533 - 3536
(2009/05/07)
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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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- Efficient preparation of new fluorinated lithium and ammonium sulfonimides
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(Chemical Equation Presented) An efficient preparation of new fluorinated lithium and ammonium sulfonimides, from the corresponding sulfonyl fluorides, is reported. These sulfonyl fluorides are reacted with benzylamine, then triflated. Due to the high lea
- Toulgoat, Fabien,Langlois, Bernard R.,Medebielle, Maurice,Sanchez, Jean-Yves
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p. 5613 - 5616
(2008/12/21)
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- Highly efficient indium-catalyzed chemoselective allylation-etherification and reductive etherification of aromatic aldehydes with functional silanes
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Indium(III) chloride is an effective Lewis acid catalyst for one-pot allylation-etherification and reductive etherification of aromatic aldehydes with functional silanes, allyltriethoxysilane, and triethoxysilane, at room temperature to afford corresponding ethers in excellent yields. Additionally, the InCl3-catalyzed reactions in the presence of TMSCl offer significant advantages in its ease of working-up for the preparation of unsymmetrical ethers under mild conditions.
- Yang, Ming-Song,Xu, Li-Wen,Qiu, Hua-Yu,Lai, Guo-Qiao,Jiang, Jian-Xiong
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p. 253 - 256
(2008/03/30)
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- A kinetic model for water reactivity (avoiding activities) for hydrolyses in aqueous mixtures - Selectivities for solvolyses of 4-substituted benzyl derivatives in alcohol-water mixtures
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For solvolyses of various benzyl substrates in ethanol-water (EW) and methanol-water (MW) mixtures, product selectivities (S) are reported for chlorides at 75°C defined as follows using molar concentrations: S= ([ether product]/[alcohol product]) × ([water]/[alcohol solvent]). The results support earlier evidence that solvolyses of 4-nitrobenzyl substrates are S N2 processes, which are not susceptible to mechanistic changes over the whole range of solvents from water to alcohol. S values at 25 and/or 45°C in EW and MW, and additional kinetic data including kinetic solvent isotope effects (KSIE) are reported for solvolyses of 4-nitrobenzyl mesylate and tosylate. A kinetic model, explaining both rates and product, is proposed; a general medium effect due to solvent polarity is combined in one parameter with solvent effects on the nucleophilicity of the water and alcohol molecules acting as nucleophiles in SN2 reactions. According to this model, as alcohol is added to water the rate of reaction decreases due to a decrease in solvent polarity, but the nucleophilicity of water increases relative to alcohol. The availability of experimental rate and product data over the whole range of solvent compositions from alcohol to water, reveals limitations of alternative approaches using activities. Copyright
- Bentley, T. William,Koo, In Sun,Choi, Hojune,Llewellyn, Gareth
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p. 251 - 256
(2008/09/20)
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- An efficient one-pot synthesis of unsymmetrical ethers: A directly reductive deoxygenation of esters using an InBr3/Et3SiH catalytic system
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(Chemical Equation Presented) This study describes a novel one-pot procedure for a directly reductive conversion of the carbonyl function of esters to the corresponding ethers by Et3SiH in the presence of a catalytic amount of InBr3.
- Sakai, Norio,Moriya, Toshimitsu,Konakahara, Takeo
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p. 5920 - 5922
(2008/02/09)
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- Iodine catalyzed selective O-alkylation of alcohols with orthoesters
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In the present communication O-alkylation of a number of allylic and benzylic alcohols has been described.
- Kumar,Anjaneyulu,Joyasawal, Sipak,Pawan Chakravarthy,Naveen Kumar,Yadav
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p. 189 - 192
(2008/02/13)
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- Reaction of orthoesters with alcohols in the presence of acidic catalysts: A study
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Allylic and benzylic alcohols are converted into corresponding unsymmetrical ethers when reacted with various orthoesters in the presence of montmorillonite KSF at ambient temperature. A detailed study has been undertaken to examine the mechanism and generality of these reactions with regard to various acidic catalysts, which reveal interesting competitive reactions mainly O-acetylation, together with trace amount of dimerized product. The type of the side product and their relative quantity depends upon the nature of the catalyst employed. Furthermore, the low yields of the Claisen rearrangement product obtained from allylic alcohols under heating is rationalized due to the formation of some of these products.
- Sampath Kumar,Joyasawal, Sipak,Reddy,Pawan Chakravarthy,Krishna,Yadav
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p. 1686 - 1692
(2007/10/03)
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- Bismuth trichloride catalyzed efficient reductive etherification of carbonyl compounds with alcohols: A novel method for preparation of symmetrical and unsymmetrical ethers
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The reductive homocoupling of a carbonyl compound and heterocoupling of a carbonyl compound with a non-protected alcohol were both effected smoothly at room temperature with triethylsilane in the presence of a catalytic amount of bismuth trichloride to afford the corresponding ethers in good yields.
- Wada, Makoto,Nagayama, Sonoe,Mizutani, Kaori,Hiroi, Ryoichi,Miyoshi, Norikazu
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p. 248 - 249
(2007/10/03)
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- Self-decomposition of K-, K+(15-crown-5)2 tetrahydrofuran solution via organometallic intermediates
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Self-decomposition of K-, K+(15-crown-5)2 tetrahydrofuran solution results in dipotassium tetraethylene glycoxide and ethylene as the main reaction products. Dipotassium triethylene glycoxide, potassium tetraethylene glyco
- Grobelny, Zbigniew,Stolarzewicz, Andrzej,Maercker, Adalbert
-
-
- Rate and product studies with benzyl and p-nitrobenzyl chloroformates under solvolytic conditions
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The specific rates of solvolysis of p-nitrobenzyl chloroformate are well correlated using the extended Grunwald-Winstein equation, with a high sensitivity (l) to changes in solvent nucleophilicity (N(T)) and a moderate sensitivity (m) to changes in solvent ionizing power (Y(Cl)). The values are consistent with a rate-determining association within an association-dissociation pathway. The selectivity values (S) for the attack at the acyl carbon show a modest preference for ethanol over water and a relatively high preference for ethanol over 2,2,2-trifluoroethanol (TFE). The solvolyses of benzyl chloroformate show similar characteristics in solvents of relatively high nucleophilicity and/or low ionizing power. In solvents with considerable fluoro alcohol content, an ionization mechanism, accompanied by loss of carbon dioxide, leads to benzyl chloride, benzyl alcohol, and benzyl alkyl ether. A new correlation now applies, with a much lower l value and somewhat higher m value. The S values for this pathway are close to unity, even in TFE-ethanol mixtures, consistent with the components of the binary solvent capturing a highly reactive carbocation.
- Kyong,Park,Kim,Kevill
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p. 8051 - 8058
(2007/10/03)
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- Reductive etherification of aromatic aldehydes with decaborane
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Aromatic aldehydes were easily convened to the corresponding ethers in methanol or ethanol using decaborane at r.t. under nitrogen in high yields.
- Lee, Seung Hwan,Park, Yong June,Yoon, Cheol Min
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p. 6049 - 6050
(2007/10/03)
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- Correlation of the rates of solvolysis of (arylmethyl)methylphenyl-sulfonium ions
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The specific rates of solvolysis of the benzylmethylphenylsulfonium ion (prepared as the trifluoromethanesulfonate salt) and five benzylic ring-substituted derivatives can be satisfactorily correlated using NT solvent nucleophilicity values. Addition of a secondary term, governed by the aromatic ring parameter (I), shows the sensitivities towards changes in this parameter to fall and those towards changes in NT to rise with increasing electron-withdrawing ability of the substituent. The Hammett ρ values with electron-withdrawing substituents (based on ρ+ values) vary from -0.9 in 95% acetone to -1.8 in 97% 2,2,2-trifluoroethanol. These Grunwald-Winstein and Hammett analyses are compared to those previously reported, with essentially the same solvents and substituents, for solvolyses of arylmethyl p-toluenesulfonates.
- Kevill, Dennis N.,Ismail, Norsaadah H.J.
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p. 1865 - 1868
(2007/10/03)
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- The carbonylation of allylic halides and prop-2-en-1-ol catalysed by triethylphosphine complexes of rhodium
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In ethanol, [RhX(CO)(PEt3)2] added directly or formed in situ from [Rh2(OAc)4]·2MeOH (OAc = O2CMe) and PEt3 or [Rh(OAc)(CO)(PEt3)2] catalysed the carbonylation of CH2=CHCH2X (X = Cl, Br or I) to ethyl but-3-enoate with CH2=CHCH2OEt as a side product. Small amounts of the isomerisation product, ethyl but-2-enoate were produced but no base was required for the reaction. The selectivity of the reaction is in the order Cl > Br > I and prop-2-en-1-ol can be successfully carbonylated to prop-2-enyl but-3-enoate by the same system using 3-chloroprop-1-ene as a promoter. 3-Fluoropropene was not carbonylated, but in the presence of H2 underwent hydroformylation to produce acetals. 3-Chlorobut-1-ene and 1-chlorobut-2-ene both produced ethyl pent-3-enoate and 3-ethoxybut-1-ene. In situ and ex situ NMR and IR spectroscopic studies have been used to show that the first step of the reaction is oxidative addition to give [Rh(CH2CH=CH2)Cl2(CO)(PEt3) 2] for which thermodynamic parameters have been obtained. Both 3-chlorobut-1-ene and 1-chlorobut-2-ene give [Rh(CH2CH=CHMe)Cl2-(CO)(PEt3)2] but with different E:Z ratios. The detailed mechanism of the oxidative addition is discussed. The CO inserts into the Rh-C bond to give [Rh(COCH2CH=CH2)Cl2(CO)(PEt3) 2], from which but-3-enoyl chloride reductively eliminates to react with ethanol to give the observed products. High-pressure IR and high-pressure NMR studies reveal that [RhX(CO)(PEt3)2] (X = Cl or Br) reacts with CO to give [RhX(CO)2(PEt3)2], which exists as two isomeric forms. The compound [Rh(OAc)(CO)(PEt3)2] catalyses the formation of prop-2-enyl ethanoate from 1-chloroprop-2-ene and sodium ethanoate. A mechanism is proposed.
- Payne, Marc J.,Cole-Hamilton, David J.
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p. 3167 - 3175
(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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- 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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- Preparation of zirconium (benzyldiethylammoniomethylphosphonate chloride) and PTC reactions
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Zirconium (benzyldiethylammoniomethylphosphonate chloride)phosphate Zr(HPO4)2-x (O2PCH2N+Et2CH2ph·Cl-)x·H2O, (0.25 x 0.75, ZBEPC-ZP) were prepared for the first time and characterized by IR and elemental analyses. ZBEPC-ZP catalyzed some typical PTC reactions in L/S/L phases were carried out to give good results. ZBEPC-ZP can be easily separated from the reaction mixture and recovered about 70-100%, and can be reused and did not show any change in activity after 10 cycles.
- Fu,Wen
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p. 2435 - 2442
(2007/10/02)
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- Carbonylation of Organic Halides catalysed by Rhodium Triethylphosphine Complexes
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Allyl and benzyl halides but not phenyl or propyl halides have been carbonylated in ethanol in the presence of rhodium triethylphosphine complexes to their respective butenoic or benzylic esters; no added base was required.
- Simpson, Michael C.,Payne, Marc J.,Cole-Hamilton, David J.
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p. 2899 - 2900
(2007/10/02)
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- Selective Cross Coupling via Oxovanadium(V)-Induced Oxidative Desilylation of Benzylic Silanes
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Benzylic silanes bearing an electron-donating group at the ortho- or para-position underwent the oxovanadium(V)-induced one-electron oxidative desilylation due to low ionization potential, which was applied to the intermolecular regioselective coupling with allylic silanes or silyl enol ether.
- Hirao, Toshikazu,Fujii, Takashi,Ohshiro, Yoshiki
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p. 8005 - 8008
(2007/10/02)
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- Pulse radiolysis of benzyl chloride and -bromide; the UV-visible absorption spectrum of the benzyl cation
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Pulse radiolysis study of liquid benzyl chloride has been carried out at room temperature. In order to identify transient species that absorb in the UV-vis region, various scavengers were used including oxygen, ethanol, pyrrole, biphenyl, and mesitylene (1,3,5-trimethylbenzene). The spectrum of the benzyl cation was obtained by subtracting the transient spectrum for the 0.6 M solutions of ethanol in O2-saturated benzyl chloride from that for O2-saturated benzyl chloride. The difference spectrum obtained has a strong absorption band at 303 ± 2 nm and a weak broad band near 500 nm. The analyses of end products formed in the γ radiolysis of benzyl chloride were done in the presence and absence of scavengers. The formation of benzyl ethyl ether with a G value of 0.9 from a 0.6 M solution of ethanol in O2-saturated benzyl chloride was taken as evidence that added ethanol reacts with benzyl cations to give benzyl ethyl ether. Some pulse radiolysis experiments were performed with benzyl bromide. Transient spectra observed in benzyl bromide are similar to those observed in benzyl chloride. It is, however, inferred from the product analysis that the radiolytic mechanisms of benzyl bromide appreciably differ from those of benzyl chloride.
- Fujisaki,Comte,Gaumann
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p. 1256 - 1262
(2007/10/02)
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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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- Generation and Trapping of Benzyl Radicals from Benzyl Iodides by Cobaloxime-mediated Iodine Atom Abstractions
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Ethylcobaloxime has been demonstrated to function as a convenient source of ethyl radicals on white light photolysis in ethanol.The ethyl radicals so generated take part in iodine abstractions with benzyl iodides giving benzyl radicals which may be trapped with 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) or lepidinium camphor-10-sulfonate.
- Brown, Trevor M.,Cooksey, Christopher J.,Crich, David,Dronsfield, Alan T.,Ellis, Robert
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p. 2131 - 2136
(2007/10/02)
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- Triazene Drug Metabolites. Part 10. Metal-ion Catalysed Decomposition of Monoalkyltriazenes in Ethanol Solutions
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The metal ions Fe(2+), Zn(2+) and Cu(2+) bring about the rapid decomposition of 1-aryl-3-alkyltriazenes to the corresponding anilines.For Fe(2+), a linear dependence of the pseudo-first-order rate constant, k0, on was observed, while for Zn(2+) and Cu(2+) plots of k0 versus were curved and indicative of complex formation.For Fe(2+), second-order rate constants k2Fe(2+) for substituted 1-aryl-3-methyltriazenes follow a Hammett relationship giving rise to a ρ value of -3.0.For Zn(2+) and Cu(2+), the data were analysed in terms of an equilibrium konstant, KM(2+), for the dissociation of a metal-ion-triazene complex and the first-order rate constant, for the collapse of this complex to products, k2M(2+).Hammett ρ values of 1.0 for both KZn(2+) and KCu(2+) are found, and the corresponding ρ values for k2Zn(2+) and k2Cu(2+) are -1.3 and -1.9.There is reasonable correlation between the Taft Eg parameter for the alkyl group and KCu(2+), giving a δ value of -1.6.The dependence of k2Cu(2+) on the alkyl group is not simple: k2Cu(2+) decreases in the order Pr > Et * PhCH2 ca. 4-MeOC6H4CH2 > CD3 ca.Me.The reactions catalysed by Cu(2+) are inhibited by added nucleophiles e.g.Br(1-) and N-methylimidazole. A mechanism is proposed in which the triazene complexes to the metal ion via the N(1) nitrogen atom of the E-cis conformer, then undergoes a fast proton transfer to form a complex involving the unconjugated tautomer which subsequently decomposes via unimolecular scission of the N(2)-N(3) bond to form an alkyldiazonium ion and an aniline-metal complex.The observed products then arise from rapid solvolysis of the metal-aniline complex and the alkyl diazonium ion.
- Iley, Jim,Moreira, Rui,Rosa, Eduarda
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- TRANSITION METAL COMPLEX CATALYZED CARBONYLATION OF ORGANIC HALIDES IN THE PRESENCE OF MOLECULAR SIEVES INSTEAD OF BASE
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In the presence of molecular sieves under base free conditions organic halides are successfully carbonylated under carbon monoxide pressure with water or alcohols catalyzed by Co or Pd complex to generate the corresponding carboxylic acids or esters, respectively, in good yields.
- Urata, Hisao,Hu, Nan-Xing,Maekawa, Hisayuki,Fuchikami, Takamasa
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p. 4733 - 4736
(2007/10/02)
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