- Developing benign syntheses using ion pairsviasolvent-free mechanochemistry
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Solvent-free mechanochemical conditions have been developed to investigate the significance of ion pairing and the use of weak bases for driving forward nucleophilic substitution reactions. This approach takes advantage of the lack of solvent shells to in
- Crain, Jazmine,Mack, James,Ortiz-Trankina, Lianna N.,Williams, Carl
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- CoII Immobilized on Aminated Magnetic-Based Metal–Organic Framework: An Efficient Heterogeneous Nanostructured Catalyst for the C–O Cross-Coupling Reaction in Solvent-Free Conditions
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Abstract: In this paper, we report the synthesis of Fe3O4?AMCA-MIL53(Al)-NH2-CoII NPs based on the metal–organic framework structures as a magnetically separable and environmentally friendly heterogeneous nanocatalyst. The prepared nanostructured catalyst efficiently promotes the C–O cross-coupling reaction in solvent-free conditions without the need for using toxic solvents and/or expensive palladium catalyst. Graphic Abstract: [Figure not available: see fulltext.].
- Mohammadinezhad, Arezou,Akhlaghinia, Batool
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p. 332 - 352
(2020/01/11)
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- Base-Mediated O-Arylation of Alcohols and Phenols by Triarylsulfonium Triflates
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A mild and efficient protocol for O-arylation of alcohols and phenols (ROH) by triarylsulfonium triflates was developed under transition-metal-free conditions. Various alcohols, including primary, secondary and tertiary, and phenols bearing either electron-donating or electron-withdrawing groups on the aryl rings were smoothly converted to form the corresponding aromatic ethers in moderate to excellent yields. The reactions were conducted at 50 or 80 °C for 24 h in the presence of a certain base and showed good functional group tolerance. The base-mediated arylation with asymmetric triarylsulfonium salts could selectively transfer the aryl groups of sulfoniums to ROH, depending on their inherent electronic nature. The mechanistic studies revealed that the reaction might proceed through the nucleophilic attack of the in situ formed alkoxy or phenoxy anions at the aromatic carbon atoms of the C?S bonds of triarylsulfonium cations to furnish the target products.
- Ming, Xiao-Xia,Tian, Ze-Yu,Zhang, Cheng-Pan
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supporting information
p. 3370 - 3379
(2019/11/03)
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- Palladium nanoparticles supported on cysteine-functionalized MNPs as robust recyclable catalysts for fast O- and N-arylation reactions in green media
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A magnetically robust recyclable nanocatalyst was fabricated by immobilizing of Pd onto the surface of cysteine-functionalized magnetic nanoparticles (MNPs?Cys-Pd). This nanocatalyst was characterized using various techniques such as FT-IR, XRD, TEM, SEM, EDX, VSM, and ICP. The application of catalyst (MNPs?Cys-Pd) was investigated for O-arylation and N-arylation reactions. This phosphine-free complex was found as highly efficient heterogeneous catalyst in green media and mild reaction conditions. In addition, it gave excellent recyclability without significant deactivation after ten cycles.
- Hajipour, Abdol R.,Khorsandi, Zahra,Fatemeh Mohammadi Metkazini
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- From insertion to multicomponent coupling: Temperature dependent reactions of arynes with aliphatic alcohols
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The temperature dependent selectivity switch in the reaction of arynes with aliphatic alcohols in THF has been reported. At -20°C, arynes smoothly insert into the O-H bond of alcohols to form alkyl aryl ethers. Interestingly, at 60°C, a highly selective multicomponent coupling occurs with the solvent THF acting as the nucleophilic trigger affording (4-(alkoxy)butoxy)arenes.
- Thangaraj, Manikandan,Bhojgude, Sachin Suresh,Mane, Manoj V.,Biju, Akkattu T.
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supporting information
p. 1665 - 1668
(2016/01/30)
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- α-Lithiated Aryl Benzyl Ethers: Inhibition of [1,2]-Wittig Rearrangement and Application to the Synthesis of Benzo[b]furan Derivatives
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The use of t-BuLi at low temperature selectively leads to α-lithiation of benzyl phenyl ether generating a stable organolithium, which can be efficiently trapped with a variety of selected electrophiles prior to suffering the expected [1,2]-Wittig rearrangement. In the case of (o-alkynyl)phenyl benzyl ethers, the intermediate α-aryloxyorganolithium undergoes an unexpected anti intramolecular carbolithiation reaction leading to functionalized benzo[b]furan derivatives.
- Velasco, Rocío,Feberero, Claudia,Sanz, Roberto
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supporting information
p. 4416 - 4419
(2015/09/28)
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- Choline chloride based deep eutectic solvent as an efficient solvent for the benzylation of phenols
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Deep eutectic solvents (such as the combination of urea and choline chloride) are found to be promising solvent and phase-transfer-media for benzylation of phenol. These methods avoided the complexity of multiple alkylations giving selectively O-alkylated aromatic products. Good to excellent yields of the corresponding benzyl phenyl ether were obtained. The non-toxic, biodegradable, inexpensive, and recyclable nature of DES make this protocol green and cost-effective.
- Singh, Abhilash S.,Shendage, Suresh S.,Nagarkar, Jayashree M.
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p. 7243 - 7246
(2015/02/02)
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- Tetrabutyl ammonium bromide-mediated benzylation of phenols in water under mild condition
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Benzylation of phenol was successfully achieved in water under room temperature mediated by tetrabutylammonium bromide (TBAB) for only 2 h affording the corresponding benzyl phenyl ether with good to excellent yields. This protocol is very efficient, simple, avoiding catalysts, easy to work-up after reaction, and especially 'green'.
- Wang, Hailei,Ma, Yuping,Tian, Heng,Yu, Ajuan,Chang, Junbiao,Wu, Yangjie
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p. 2669 - 2673
(2014/04/03)
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- Benzyl protection of phenols under neutral conditions: Palladium-catalyzed benzylations of phenols
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Benzyl protection of phenols under neutral conditions was achieved by using a Pd(n3-C3H5)Cp-DPEphos catalyst. The palladium catalyst efficiently converted aryl benzyl carbonates into benzyl-protected phenols through the decarboxylative etherification. Alternatively, the nucleophilic substitution of benzyl methyl carbonates with phenols proceeded In the presence of the catalyst, yielding aryl benzyl ethers.
- Kuwano, Ryoichi,Kusano, Hiroki
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supporting information; experimental part
p. 1979 - 1982
(2009/04/10)
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- Ionic liquids as reagent and reaction medium: Preparation of alkyl aryl ethers
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Room temperature ionic liquid, [bmIm]OH, is used as a green recyclable reaction medium and reagent for the alkylation of phenols in excellent yields. The recovered ionic liquid was reused five to six times with consistent activity.
- Mohanazadeh, Farajollah,Aghvami, Majid
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Benzyl and phenyl ethers can be easily obtained, with excellent yields, by the setting of Williamson's reaction in a heterogeneous medium: solid/liquid or liquid/liquid, or even with the use of microwaves, since the last two techniques do not need the use of a solvent.
- Brǎtulescu, George,Bigot, Yves L.E.,Delmas, Michel,Pogany, Iuliu
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p. 321 - 326
(2007/10/03)
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- Isotope effects in nucleophilic substitution reactions X. The effect of changing the nucleophilic atom on ion-pairing in an S(N)2 reaction
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The effect of ion-pairing in an S(N)2 reaction is very different when the nucleophilic atom is changed from sulfur to oxygen, i.e., changing the nucleophile from thiophenoxide ion to phenoxide ion. When the nucleophile is sodium thiophenoxide, ion-pairing markedly alters the secondary α-deuterium kinetic isotope effect (transition state structure) and the substituent effect found by changing the para substituent on the nucleophile. When the nucleophile is sodium phenoxide, ion-pairing does not significantly affect the secondary α-deuterium or the chlorine leaving group kinetic isotope effects (transition state structure) or the substituent effects found by changing a para substituent on the nucleophile or the substrate. The different effects of ion-pairing may occur because the electron density on the hard oxygen atom of the sodium phenoxide is not affected significantly by ion-pairing.
- Fang, Yao-Ren,Lai, Zhu-Gen,Westaway, Kenneth Charles
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p. 758 - 764
(2007/10/03)
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- Substituent Dependence of the ?-Acceptor Induced Bond Cleavage Reactions of Benzyl Phenyl Ethers
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The relative C-O bond cleavage reaction rates (krel) of eight substituted benzyl phenyl ethers (BPE's) have been measured.These C-O bond cleavage reactions were thermally initiated by 2,3-dichloro-5,6-dicyanoquinone (DDQ).The equilibrium constants (K) for charge-transfer complex formation of these BPE's with the electron acceptors DDQ and TCNE in the solvent methylene chloride have also been determined at room temperature.The best correlation of log krel for DDQ reactions has been observed in these reactions.From this data, hydride transfer to DDQ is the rate-determining step of the reaction.
- Penn, John H.,Lin, Zhe
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p. 1554 - 1559
(2007/10/02)
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