- How Inter- and Intramolecular Reactions Dominate the Formation of Products in Lignin Pyrolysis
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One of the key challenges in renewable chemical production is the conversion of lignin, especially by fast pyrolysis. The complexity of the lignin pyrolysis process has hindered the elucidation of the mechanism, inhibiting further industrial implementation. By combining pyrolysis of model compounds (4-phenoxyphenol and 2-methoxy-phenoxybenzene) with lignin bond characteristics both under vacuum and under realistic pressure conditions, the roles of inter- and intramolecular reactions were established. On the one hand, the stable 4-O-5 ether bond enables, without breaking, C?C bond formation and even directly forms naphthalene depending on the position and type of the substituent. p-Benzoquinone intermediates, on the other hand, are highly unstable at ambient pressure and directly decompose into coke and carbon monoxide. The system pressure (radical concentration) plays a crucial role in the dominant reaction mechanism by initiating intramolecular reactions, interfering with intramolecular reactions. H-transfer and recombination reactions suppress the decarbonylation of phenoxy radicals, thus yielding a very different product distribution.
- Custodis, Victoria B. F.,Hemberger, Patrick,van Bokhoven, Jeroen A.
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- Copper nanoparticle anchored biguanidine-modified Zr-UiO-66 MOFs: a competent heterogeneous and reusable nanocatalyst in Buchwald-Hartwig and Ullmann type coupling reactions
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We have designed a functionalized metal-organic framework (MOF) of UiO topology as a support, with an extremely high surface area, adjustable pore sizes and stable crystalline coordination polymeric structure and implanted copper (Cu) nanoparticles thereon. The core three dimensional Zr-derived MOF (UiO-66-NH2) was modified with a biguanidine moiety following a covalent post-functionalization approach. The morphological and physicochemical features of the material were determined using analytical methods such as FT-IR, SEM, TEM, EDX, atomic mapping, XRD and ICP-OES. The SEM and XRD results justified the unaffected morphology of Zr-MOF after structural modifications. The as-synthesized UiO-66-biguanidine/Cu nanocomposite was catalytically explored in the aryl and heteroaryl Buchwald-Hartwig C-N and Ullmann type C-O cross coupling reactions with excellent yields. A library of biaryl amine and biaryl ethers was synthesized over the catalyst under mild and green conditions. Furthermore, the catalyst was isolated by centrifugation and recycled 11 times with no significant copper leaching or change in its activity.
- Veisi, Hojat,Neyestani, Narges,Pirhayati, Mozhgan,Ahany Kamangar, Sheida,Lotfi, Shahram,Tamoradi, Taiebeh,Karmakar, Bikash
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p. 22278 - 22286
(2021/07/02)
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- Trimethoxyphenyl (TMP) as a Useful Auxiliary for in situ Formation and Reaction of Aryl(TMP)iodonium Salts: Synthesis of Diaryl Ethers
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Herein, we describe a synthetic approach for arylation that exploits the in situ formation and reaction of an unsymmetrical diaryliodonium salt. In this way, aryl iodides are used as reagents in a metal-free reaction with phenols, and a trimethoxyphenyl (TMP) group is used as a “dummy” group to facilitate transfer of a wide range of aryl moieties. The scope of aryl electrophiles and phenol nucleophiles is broad (>30 examples) and the yields are high (52–95%, 80% avg.). One-pot coupling reactions avoid the synthesis of diaryliodonium salts and provide opportunities for sequential reactions and novel chemoselectivity. (Figure presented.).
- Gallagher, Rory T.,Basu, Souradeep,Stuart, David R.
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supporting information
p. 320 - 325
(2019/12/11)
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- Catalytic Hydrogenolysis of Substituted Diaryl Ethers by Using Ruthenium Nanoparticles on an Acidic Supported Ionic Liquid Phase (Ru@SILP-SO3H)
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Catalytic hydrogenolysis of diaryl ethers is achieved by using ruthenium nanoparticles immobilized on an acidic supported ionic liquid phase (Ru@SILP-SO 3 H) as a multifunctional catalyst. The catalyst components are assembled through a molecular approach ensuring synergistic action of the metal and acid functions. The resulting catalyst is highly active for the hydrogenolysis of various diaryl ethers. For symmetric substrates such as diphenyl ether, hydrogenolysis is followed by full hydrodeoxygenation producing the corresponding cycloalkanes as the main products. For unsymmetric substrates, the cleavage of the C-O bond is regioselective and occurs adjacent to the unsubstituted phenyl ring. As hydrogenation of benzene is faster than hydrodeoxygenation over the Ru@SILP-SO 3 H catalyst, controlled mixtures of cyclohexane and substituted phenols are accessible with good selectivity. Application of Ru@SILP-SO 3 H catalyst in continuous-flow hydrogenolysis of 2-methoxy-4-methylphenoxybenzene is demonstrated with use of commercial equipment.
- Rengshausen, Simon,Etscheidt, Fabian,Gro?kurth, Johannes,Luska, Kylie L.,Bordet, Alexis,Leitner, Walter
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supporting information
p. 405 - 412
(2019/02/26)
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- URJC-1-MOF as New Heterogeneous Recyclable Catalyst for C-Heteroatom Coupling Reactions
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Guillermo Calleja and co-workers from @urjc describe URJC-1-MOF as a new heterogeneous recyclable catalyst for c-heteroatom coupling reactions. The capacity of copper-based URJC-1-MOF as a MOF catalyst in cross-coupling reactions has been evaluated, focusing on the Chan-Lam-Evans arylation-type reactions on amines and alcohols without extra additives or ligands. The extraordinary chemical and structural stability of URJC-1-MOF and its good specific surface, make this material a promising alternative to homogeneous Cu (II) catalysts for cross-coupling reactions. URJC-1-MOF showed a remarkable catalytic activity for cross-coupling C?N and C?O reactions, higher than other heterogeneous and homogeneous copper-based catalyst, such as CuO, HKUST-1, Cu?MOF-74, Cu(OAc)2 and CuSO4?5H2O. Moreover, its easy recovery by simple filtration and reusability in successive runs without any loss of activity and stability, demonstrates the potential of URJC-1-MOF as an alternative catalyst for this kind of reactions in different chemical media of industrial interest.
- Mu?oz, Antonio,Leo, Pedro,Orcajo, Gisela,Martínez, Fernando,Calleja, Guillermo
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p. 3376 - 3380
(2019/07/04)
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- CuCl heterogenized on metformine-modified multi walled carbon nanotubes as a recyclable nanocatalyst for Ullmann-type C-O and C-N coupling reactions
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Herein, a novel MWCNTs-Met/CuCl nanocatalyst synthesis method by metformine covalent grafting on the surface of carbon nanotubes and subsequent coordination with a CuCl catalyst is described. The nanocatalyst formation was analyzed by FTIR, energy dispersive spectroscopy (EDS), Raman spectroscopy and ICP analysis. The nanocatalyst morphology was examined by transmission and scanning electron microscopies (TEM and SEM). Moreover, in the N-arylation of anilines and indole, the nanocatalyst (MWCNTs-Met/CuCl) could be successfully used by formation of intermolecular C(aryl)-N bonds of the relevant aryl halides (Ar-I, Ar-Br, Ar-Cl) with amines by coupling reactions of Ullmann-type. The O-arylation of substituted phenols is also promoted by this heterogeneous copper catalyst with different aryl iodides and bromides. Additionally, without any considerable loss in activity, the novel catalyst was recovered and recycled several times.
- Akhavan, Elham,Hemmati, Saba,Hekmati, Malak,Veisi, Hojat
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p. 2782 - 2789
(2018/02/19)
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- Cellulose-supported N-heterocyclic carbene silver complex with pendant ferrocenyl group for diaryl ether synthesis
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A cellulose-supported N-heterocyclic carbene Ag(I) complex has been synthesized by covalent grafting of ferrocenyl ionic liquid in the matrix of cellulose followed by metallation with silver oxide. The complex was employed as a heterogeneous catalyst in the synthesis of diaryl ethers. Reactions of a variety of phenols with aryl halides afford corresponding diaryl ethers in moderate to good yields. Recyclability experiments were executed successfully for five consecutive runs.
- Jagadale, Megha,Salunkhe, Rajashri,Kumbhar, Arjun,Gajare, Shivanand,Rajmane, Mohan,Rashinkar, Gajanan
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- Synthesis of Violaceic Acid and Related Compounds through Aryl Triazene
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MPC1001 is a potent anticancer natural product that contains a violaceic acid moiety. Herein we report the total synthesis of the natural product violaceic acid and its derivative. In this approach, a triazene-directed Ullman coupling proved to be highly effective. We converted the triazene to a hydroxy group by means of a palladium-catalyzed reaction. Treatment of the triazene with trifluoroacetic acid generated an arenediazonium ion that produced an aryl radical, leading to the protodediazoniation and a tricyclic product.
- Ando, Shin,Burrows, James,Koide, Kazunori
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p. 1116 - 1119
(2017/03/14)
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- Ullmann diaryl ether synthesis catalyzed by copper (I)/pyridine-functionalized silane
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Ullmann-type diaryl ether synthesis was performed under mild conditions in DMF/K2CO3using a pyridinefunctionalized silane as a ligand. The productswere obtained in good yields. This method tolerates a variety of functional groups and is effective in the synthesis of hindered diaryl ethers and heteroaryl ethers.
- Zhang, Baohua,Shi, Lanxiang,Guo, Ruixia,Liu, Sijie
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p. 930 - 932
(2016/07/06)
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- CsF/clinoptilolite: An efficient solid base in SNAr and copper-catalyzed Ullmann reactions
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CsF/clinoptilolite was found to be an efficient solid base catalyst for both SNAr and Ullmann ether reactions. A general and efficient one-step procedure was developed for the synthesis of biaryl ethers via direct coupling of electron-deficient aryl halides to phenols using CsF/clinoptilolite. The protocol was also applied to electron-rich aryl halides by addition of a catalytic amount of copper oxide nanoparticles. Both SNAr and Ullmann reactions were rapid and provided good to excellent yields.
- Keipour, Hoda,Hosseini, Abolfazl,Afsari, Amir,Oladee, Razieh,Khalilzadeh, Mohammad A.,Ollevier, Thierry
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- Betti base as an efficient ligand for copper-catalyzed ullmann coupling of phenol with aryl halides
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GRAPHICAL ABSTRACT A simple, general, and highly efficient Betti base ligand has been developed for copper-catalyzed Ullmann coupling of phenol with aryl halides without the protection of an inert atmosphere. The reaction proceeds smoothly in the presence of K2CO3 as the base and dimethylsulfoxide as the solvent. The catalyst was reused several times with no evident loss of catalytic activity and is environmentally friendly.
- Yang, Li,Yang, Qichao,Shi, Jianxin,Wang, Yufang,Zhang, Mingjie
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supporting information
p. 2468 - 2477
(2014/08/05)
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- Copper-catalyzed Ullmann-type synthesis of diaryl ethers assisted by salicylaldimine ligands
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A series of salicylaldimine ligands were designed to promote the copper-catalyzed Ullmann cross-coupling reaction. After a screening process, 2-((2-isopropylphenylimino)methyl)phenol was found to serve as a good supporting ligand for this reaction. Employing this Schiff-base ligand as a new supporting ligand, the copper-catalyzed coupling reactions of aryl bromides and aryl iodides with various phenols successfully proceeded in good yields under mild conditions. Various diaryl ethers were obtained with excellent yields in dioxane in the presence of K3PO4 and a catalytic amount of copper(I) salt.
- Qian, Cun-Wei,Lv, Wen-Lin,Zong, Qian-Shou,Wang, Mao-Yuan,Fang, Dong
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p. 337 - 340
(2014/02/14)
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- KF/Clinoptilolite, an effective solid base in Ullmann ether synthesis catalyzed by CuO nanoparticles
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Employing KF/Clinoptilolite as an efficient base the cross-coupling reactions of various phenols with aryl iodides could be successfully carried out in the presence of copper oxide nanoparticles. The C-O coupling products were obtained in moderate to good yields (62-87%) for a variety of substrates. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014.
- Khalilzadeh, Mohammad A.,Keipour, Hoda,Hosseini, Abolfazl,Zareyee, Daryoush
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- A cyano-bridged copper(II)-copper(I) mixed-valence coordination polymer as a source of copper oxide nanoparticles with catalytic activity in C-N, C-O and C-S cross-coupling reactions
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A cyano-bridged copper(ii)-copper(i) mixed valence polymer, namely {[Cu4(CN)5(C5H5N)4]} n (1), was synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, differential scanning calorimetric analysis, and single crystal X-ray crystallography. Single crystal X-ray studies show that the coordination polymer 1 is linked by the cyanide anions with μ-1κN:2κC bridging modes to the copper centers, generating a two-dimensional (2D) layered network. The coordination polymer 1, upon pyrolyzing, yielded copper oxide nanoparticles, which have been characterized by TEM and powder X-ray diffraction. The catalytic properties of the resulting copper oxide nanoparticles have also been studied in C-N, C-O, and C-S cross-coupling reactions with aryl halides. The C-N, C-O and C-S coupling products were obtained in moderate to good yields (66-90%, 72-98%, and 50-86%), respectively. the Partner Organisations 2014.
- Trivedi, Manoj,Ujjain, Sanjeev Kumar,Sharma, Raj Kishore,Singh, Gurmeet,Kumar, Abhinav,Rath, Nigam P.
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p. 4267 - 4274
(2014/11/08)
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- An in situ generated CuI/metformin complex as a novel and efficient catalyst for C-N and C-O cross-coupling reactions
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An in situ generated complex of copper(I) and a biguanide, namely metformin, was found to be a highly efficient homogeneous catalyst in N/O-arylation reactions. The O-arylation of substituted phenols with various aryl iodides and bromides was also achieved using this copper catalyst to afford diaryl ethers in good to excellent yields in DMF. This heterogeneous copper catalyst also promotes the N-arylation of imidazole with a variety of aryl halides (Cl, Br, I) in acetonitrile.
- Ghorbani-Vaghei, Ramin,Hemmati, Saba,Veisi, Hojat
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p. 7095 - 7099
(2013/12/04)
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- Synthesis of diaryl ethers by CuI-catalyzed C-O bond formation via Ullman coupling: Assessing the reactivity of aryl halides
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Using cuprous iodide as the catalyst, aryl halides reacted with phenols to form diaryl ethers. The reaction conditions were optimized: aryl halides (1 equiv) reacted with phenol (1 equiv) at 130 °C in DMF for 16 h with cuprous iodide (10 mol %), cesium carbonate (2.5 equiv) as the base, and tetramethylenediamine (5 mol %) as the ligand. Under the optimum conditions, reaction conversion with time was summarized. The structural parameters of four types of aryl halides and the ionization energy of various C-X bond lengths in all aryl halides-CuI π-complexes were calculated at the B3LYP/LANL2MB level by using the Gaussian 03 program and the corresponding Ullman reaction conversion was determined by HPLC. Results suggested that different relationships existed between reactivity and the energy of the lowest unoccupied molecular orbital ELUMO, mean polarizability and dipole moment μ. Both experimental and theoretical results, all displayed Ullman coupling reactivity order of the four aryl halides: fluorobenzene ? chlorobenzene bromobenzene iodobenzene.
- Xuesheng Zhang,Liu, Fu,Wei, Zhongbo,Wang, Zunyao
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- A reusable polymer supported copper catalyst for the C-N and C-O bond cross-coupling reaction of aryl halides as well as arylboronic acids
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A simple and industrially viable protocol for C-N and C-O coupling was reported here. The polymer supported heterogeneous copper catalyst was prepared from chloromethyl polystyrene using a simple procedure. O-Arylation of substituted phenols with various aryl halides was achieved using this copper catalyst in DMSO medium. This heterogeneous copper catalyst, also efficiently works for the N-arylation of N-H heterocycles with aryboronic acids in methanol. This catalyst was also effective in amination reaction of primary amines with aryl halides as well as arylboronic acids in DMSO medium. The effects of solvent, base and temperature for the O-Arylation and amination reactions were reported. Further, the catalyst can be easily recovered quantitatively by simple filtration and reused up to several times without sufficient loss of its catalytic activity.
- Islam, Sk.Manirul,Mondal, Sanchita,Mondal, Paramita,Roy, Anupam Singha,Tuhina,Salam, Noor,Mobarak, Manir
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experimental part
p. 4264 - 4274
(2012/01/06)
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- Highly efficient copper catalytic system for the O-arylation of phenol with iodoarene
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An efficient Cu-catalyzed O-arylation was carried out by involving phenols with iodoarenes to afford various substituted diarylether derivatives with tiny loading of Cu2O and 1H-imidazole-4-carboxylic acid as catalytic system under mild conditions, which provided good to excellent yields with good tolerance of functional groups.
- Cheng, An-Yi,Hsieh, Jen-Chieh
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supporting information; experimental part
p. 71 - 75
(2012/01/31)
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- Methenamine as an efficient ligand for copper-catalyzed coupling of phenols with aryl halides
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Employing methenamine as a new supporting ligand, the copper-catalyzed coupling reactions of aryl bromides or aryl iodides with various phenols successfully proceeded in good yields under mild conditions. A series of diaryl ethers were obtained with excellent yields in the presence of K 3PO4 and copper(I) salt. Copyright
- Qian, Cunwei,Zong, Qianshou,Fang, Dong
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experimental part
p. 199 - 203
(2012/03/11)
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- Chemo-selective copper-catalyzed C-O coupling reactions of phenols with aryl/vinyl halides using enaminone as efficient ligand
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The copper-catalyzed Ullmann C-O coupling reactions between phenols and aryl/vinyl halides have been efficiently performed by employing (E)-3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one, an easily available enaminone, as ligand. This new ligand is advantageous for its easy availability, broad applicability and good efficiency. Copyright 2012 John Wiley & Sons, Ltd. Copyright
- Wan, Jie-Ping,Wang, Chunping,Liu, Yunyun
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experimental part
p. 445 - 447
(2012/09/25)
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- Copper(II) trans-bis-(glycinato): An efficient heterogeneous catalyst for cross coupling of phenols with aryl halides
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Copper(II) trans-bis-(glycinato) complex, easily prepared by the solid state reaction of copper(II) acetate and glycine (trans-[Cu(glyo) 2·H2O]) was found to be an efficient, recyclable, and high yielding catalyst for the Ullmann type synthesis of diaryl ethers via the cross coupling of phenols with aryl halides without using any additives at relatively low reaction temperature. The catalyst could easily be recovered by simple filtration and was reused for several runs with consistent catalytic activity.
- Verma, Sanny,Kumar, Neeraj,Jain, Suman L.
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experimental part
p. 4665 - 4668
(2012/09/05)
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- Efficient iron/copper-cocatalyzed o-arylation of phenols with bromoarenes
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Low catalytic amount CuI and Fe(acac)3 were found to effectively promote the C-O cross-coupling reaction in the presence of K2CO 3 as the base. A serious of diaryl ethers with different substitutents can be synthesized in good to excellent yields. This efficient and economic method is attractive for applications on an industrial scale. Georg Thieme Verlag Stuttgart New York.
- Liu, Xiaoyan,Zhang, Songlin
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supporting information; experimental part
p. 268 - 272
(2011/03/20)
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- Potassium fluoride supported on natural nanoporous zeolite: A new solid base for the synthesis of diaryl ethers
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An efficient and inexpensive synthesis of diaryl ethers has been developed. The process involves the nucleophilic aromatic substitution of electron-deficient aryl halides and phenols and is mediated by potassium fluoride/Clinoptilolite (KF/CP) in dimethyl sulfoxide (DMSO). The approach affords good to excellent yields of the arylated products without the need for additional cation capture. The solid base is also efficient in the Ullmann ether synthesis. A new, inexpensive solid base for the synthesis of diaryl ethers has been developed. Clinoptilolite, a natural zeolite with a high tendency for cation capture, combined with potassium fluoride, provides an efficientsolid base for the deprotonation of phenols in nucleophilic reactions. The same solid base acts as a reliable base for the copper-catalyzed synthesis of diaryl ethers. Copyright
- Khalilzadeh, Mohammad A.,Hosseini, Abolfazl,Pilevar, Afsaneh
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experimental part
p. 1587 - 1592
(2011/04/22)
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- Open air O-arylation reaction of phenols with aryl halides catalyzed by polymer-anchored copper(II) complexes
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Two copper complexes were synthesized from macroporous chloromethylated polystyrene beads. The first one was prepared by sequential attachment of imidazole and copper acetate with chloromethylated polystyrene-divinyl benzene copolymer, and the second one was prepared from 4-vinylpyridine and copper acetate with chloromethylated polystyrene-divinyl benzene copolymer. These catalysts showed excellent catalytic activity in O-arylation reaction of aryl halides with phenol in dimethylsulfoxide using potassium carbonate at 130 °C under open air conditions to give diaryl ethers in high yields. Less reactive aryl bromides and aryl chlorides have also been shown to react with phenols to give good yields of the diaryl ethers. The effects of various parameters such as solvent, catalyst from different copper salt and base on the reaction system were studied. The reaction is applicable to a wide variety of substituted aryl halides and phenols with different steric and electronic properties. These catalysts were recovered by simple filtration, and the reusability experiments showed that these catalysts can be used five times without much loss in the catalytic activity.
- Islam, Manirul,Mondal, Sanchita,Mondal, Paramita,Roy, Anupam Singha,Hossain, Dildar,Mobarak, Manir
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experimental part
p. 1 - 11
(2012/02/01)
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- Fe3O4@mesoporouspolyaniline: A highly efficient and magnetically separable catalyst for cross-coupling of aryl chlorides and phenols
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A high surface, magnetic Fe3O4@mesoporouspolyaniline core-shell nanocomposite was synthesized from magnetic iron oxide (Fe 3O4) nanoparticles and mesoporouspolyaniline (mPANI). The novel porous magnetic Fe3O4 was obtained by solvothermal method under sealed pressure reactor at high temperature to achieve high surface area. The mesoporouspolyaniline shell was synthesized by in situ surface polymerization onto porous magnetic Fe3O4 in the presence of polyvinylpyrrolidone (PVP) and sodium dodecylbenzenesulfonate (SDBS), as a linker and structure-directing agent, through 'blackberry nanostructures' assembly. The material composition, stoichiometric ratio and reaction conditions play vital roles in the synthesis of these nanostructures as confirmed by variety of characterization techniques. The role of the mesoporouspolyaniline shell is to stabilize the porous magnetic Fe3O4 nanoparticles, and provide direct access to the core Fe3O4 nanoparticles. The catalytic activity of magnetic Fe3O 4@mesoporousPANI nanocomposite was evaluated in the cross-coupling of aryl chlorides and phenols. Copyright
- Arundhathi,Damodara,Likhar, Pravin R.,Kantam, M. Lakshmi,Saravanan,Magdaleno, Travis,Kwon, Sun Hee
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supporting information; experimental part
p. 1591 - 1600
(2011/08/03)
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- Cu-catalyzed arylation of phenols: Synthesis of sterically hindered and heteroaryl diaryl ethers
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"Chemical Equation Presentation" Cu-catalyzed O-arylation of phenols with aryl iodides and bromides can be performed under mild condition in DMSO/K3PO4 with use of picolinic acid as the ligand for copper. This method tolerates a variety of functional groups and is effective in the synthesis of hindered diaryl ethers and heteroaryl ethers.
- Maiti, Debabrata,Buchwald, Stephen L.
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supporting information; experimental part
p. 1791 - 1794
(2010/05/01)
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- Glyoxal bis(phenylhydrazone) as promoter for CuI-catalyzed O-arylation of phenols with bromoarenes
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A very simple bishydrazone-type ligand, glyoxal bis(phenylhydrazone) (L1), was found to effectively promote the CuI-catalyzed O-arylation of phenols with aryl bromides. This cross-coupling reaction proceeded in acetonitrile at 60-80 °C in the presence of K3PO4 as base. A diverse array of phenols and bromoarenes was employed as substrates to afford diaryl ethers in good to excellent yields, and some base-sensitive groups, such as ester, aldehyde, and ketone groups, can survive under the mild reaction conditions.
- Liu, Yu-Hua,Li, Gang,Yang, Lian-Ming
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experimental part
p. 343 - 346
(2009/04/19)
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- CuO nanoparticles catalyzed C-N, C-O, and C-S cross-coupling reactions: Scope and mechanism
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CuO nanoparticles have been studied for C-N, C-O, and C-S bond formations via cross-coupling reactions of nitrogen, oxygen, and sulfur nucleophiles with aryl halides. Amides, amines, imidazoles, phenols, alcohols and thiols undergo reactions with aryl iodides in the presence of a base such as KOH, Cs 2CO3, and K2CO3 at moderate temperature. The procedure is simple, general, ligand-free, and efficient to afford the cross-coupled products in high yield.
- Jammi, Suribabu,Sakthivel, Sekarpandi,Rout, Laxmidhar,Mukherjee, Tathagata,Mandai, Santu,Mitra, Raja,Saha, Prasenjit,Punniyamurthy, Tharmalingam
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experimental part
p. 1971 - 1976
(2009/07/01)
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- General, mild, and intermolecular Ullmann-type synthesis of diaryl and alkyl aryl ethers catalyzed by diol-copper(I) complex
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(Chemical Equation Presented) A wide range of diaryl ethers and alkyl aryl ethers are synthesized through intermolecular C(aryl)-O bond formation from the corresponding aryl iodides/aryl bromides and phenols/alcohols through Ullmann-type coupling reaction in the presence of a catalytic amount of easily available (±)-diol L3-CuI complex under very mild reaction conditions. Less reactive aryl bromides can also be used for O-arylation of phenols under the same reaction conditions without increasing the reaction temperature, catalyst loading, and time. The catalytic system not only is capable of coupling hindered substrate but also tolerates a broad range of a series of functional groups.
- Naidu, Ajay B.,Jaseer,Sekar, Govindasamy
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supporting information; experimental part
p. 3675 - 3679
(2009/09/26)
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- CuI nanoparticles for C-N and C-O cross coupling of heterocyclic amines and phenols with chlorobenzenes
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(Chemical Equation Presented) Employing CuI nanoparticles as an efficient catalyst for the cross-coupling reactions of various N/O nucleophilic reagents with aryl chlorides could be successfully carried out under mild conditions in the absence of both the ligands and strong bases. A variety of products including N-arylimidazoles and aryl ethers were synthesized in good to excellent yields. 2009 American Chemical Society.
- Sreedhar,Arundhathi,Reddy, P. Linga,Kantam, M. Lakshmi
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supporting information; experimental part
p. 7951 - 7954
(2010/01/16)
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- Efficient palladium-catalyzed coupling reactions of aryl bromides and chlorides with phenols
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A convenient and general palladium-catalyzed coupling reaction of aryl bromides and chlorides with phenols was developed. Various functional groups such as nitriles, aldehydes, ketones and esters are well tolerated and the corresponding products are obtained in good to excellent yield.
- Hu, Tongjie,Schulz, Thomas,Torborg, Christian,Chen, Xiaorong,Wang, Jun,Beller, Matthias,Huang, Jun
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supporting information; scheme or table
p. 7330 - 7332
(2010/06/14)
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- An efficient BINAM-copper(II) catalyzed Ullmann-type synthesis of diaryl ethers
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A wide range of diaryl ethers are synthesized from the corresponding aryl iodides and phenols through Ullmann type coupling reactions in the presence of a catalytic amount of easily available BINAM-Cu(OTf)2 complex under mild reaction conditions. Less reactive aryl bromides have also been shown to react with phenols under identical reaction conditions to give good yields of the diaryl ethers without increasing the reaction temperature and time.
- Naidu, Ajay B.,Raghunath,Prasad,Sekar
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p. 1057 - 1061
(2008/09/18)
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- (Hetero)aryl-bicyclic heteroaryl derivatives, their preparation and their use as protease inhibitors
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The present invention provides novel compounds of the Formula (I): A-B, its prodrug forms, or pharmaceutically acceptable salts thereof, wherein A represents a saturated, unsaturated, or a partially unsaturated bicyclic heterocyclic ring structure, and B represents an aryl or a heteroaryl group. Preferred compounds of the present invention comprise a benzimidazole or indole nucleus. The compounds of this invention are inhibitors of serine proteases, Urokinase (uPA), Factor Xa (FXa), and/or Factor VIIa (FVIIa), and have utility as anti cancer agents and/or as anticoagulants for the treatment or prevention of thromboembolic disorders in mammals.
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Page/Page column 28
(2010/02/11)
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- Inhibition of the Bacterial Enoyl Reductase FabI by Triclosan: A Structure-Reactivity Analysis of FabI Inhibition by Triclosan Analogues
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To explore the molecular basis for the picomolar affinity of triclosan for FabI, the enoyl reductase enzyme from the type II fatty acid biosynthesis pathway in Escherichia coli, an SAR study has been conducted using a series of triclosan analogues. Triclosan (1) is a slow, tight-binding inhibitor of FabI, interacting specifically with the E·NAD+ form of the enzyme with a K1 value of 7 pM. In contrast, 2-phenoxyphenol (2) binds with equal affinity to the E·NAD+ (K1 = 0.5 μM) and E·NADH (K2 = 0.4 μM) forms of the enzyme and lacks the slow-binding step observed for triclosan. Thus, removal of the three triclosan chlorine atoms reduces the affinity of the inhibitor for FabI by 70 000-fold and removes the preference for the E·NAD+ FabI complex. 5-Chloro-2-phenoxyphenol (3) is a slow, tight-binding inhibitor of FabI and binds to the E· NAD+ form of the enzyme (K1 = 1.1 pM) 7-fold more tightly than triclosan. Thus, while the two ring B chlorine atoms are not required for FabI inhibition, replacement of the ring A chlorine increases binding affinity by 450 000-fold. Given this remarkable observation, the SAR study was extended to the 5-fluoro-2-phenoxyphenol (4) and 5-methyl-2-phenoxyphenol (5) analogues to further explore the role of the ring A substituent. While both 4 and 5 are slow, tight-binding inhibitors, they bind substantially less tightly to FabI than triclosan. Compound 4 binds to both E·NAD+ and E·NADH forms of the enzyme with K 1 and K2 values of 3.2 and 240 nM, respectively, whereas compound 5 binds exclusively to the E·NADH enzyme complex with a K 2 value of 7.2 nM. Thus, the ring A substituent is absolutely required for slow, tight-binding inhibition. In addition, pKa measurements coupled with simple electrostatic calculations suggest that the interaction of the ring A substituent with F203 is a major factor in governing the affinity of analogues 3-5 for the FabI complex containing the oxidized form of the cofactor.
- Sivaraman, Sharada,Sullivan, Todd J.,Johnson, Francis,Novichenok, Polina,Cui, Guanglei,Simmerling, Carlos,Tonge, Peter J.
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p. 509 - 518
(2007/10/03)
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- A general and efficient protocol for the synthesis of biaryl ethers from aryl silyl ethers using Cs2CO3
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A general and efficient one-step procedure has been developed for the synthesis of biaryl ethers via direct coupling of electron-deficient arylhalides or aryl triflates to aryl t-butyldimethylsilyl (TBS) ethers using Cs 2CO3. The protocol was also applied to electron-rich arylhalides by addition of a catalytic amount of copper(I) iodide. The reaction is rapid and provides good to excellent yields.
- Cui, Sun-Liang,Jiang, Zhi-Yong,Wang, Yan-Guang
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p. 1829 - 1831
(2007/10/03)
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- N,N-Dimethyl Glycine-Promoted Ullmann Coupling Reaction of Phenols and Aryl Halides
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(Matrix presented) Ullmann-type diaryl ether synthesis can be performed at 90°C using either aryl iodides or aryl bromides as the substrates under the assistance of N,N-dimethylglycine.
- Ma, Dawei,Cai, Qian
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p. 3799 - 3802
(2007/10/03)
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- Synthesis of psoralen analogues based on dibenzofuran
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The syntheses of four novel psoralen derivatives, 6a-d, of the benzofurocoumarin (=benzofuro[1]benzopyranone) type containing an ester group are described. These compounds might be of interest in PUVA (psoralen long-wave ultraviolet radiation) therapy. The overall efficiency of the synthetic procedure is greatly limited by the low yields for the penultimate step, i.e., formylation of the dibenzofuranols 3a,c or protected dibenzofuranol 4d to the carboxaldehydes 5 (Scheme 4). However, the final stage to form the pyranone ring from 5a - d proceeds smoothly (Scheme 5).
- Oliveira, Ana M. A. G.,Raposo, M. Manuela M.,Oliveira-Campos, Ana M. F.,Griffiths, John,Machado, Antonio E. H.
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p. 2900 - 2907
(2007/10/03)
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- Hydroxydiphenyl ether compounds
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The present invention relates to the use of hydroxydiphenyl ether compounds as antimicrobially active substances, to certain new compounds of this type and to processes for the preparation of these compounds.
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- Synthesis of diaryl ethers through the copper-promoted arylation of phenols with arylboronic acids. An expedient synthesis of thyroxine
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Diaryl ethers are readily synthesized in high yield at room temperature through the copper(II)-promoted coupling of arylboronic acids and phenols. The reaction is tolerant of a wide range of substituents on both coupling partners. These reaction condition
- Evans, David A.,Katz, Jeffrey L.,West, Theodore R.
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p. 2937 - 2940
(2007/10/03)
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- A Superior Synthesis of Diaryl Ethers by the Use of Ultrasound in the Ullmann Reaction
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The use of ultrasound in the reactions of phenols with bromoarenes, in the presence of potassium carbonate and copper(I) iodide but without added solvent, gives better yields of diaryl ethers (typically 70-90percent) at lower temperature (140 deg C) than is customary for traditional Ullmann reactions; the role of ultrasound is primarily to break up the particles of the inorganic solids.
- Smith, Keith,Jones, Dennis
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p. 407 - 408
(2007/10/02)
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- SYNTHESIS OF L,L-ISODITYROSINE
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A study of the development of reaction conditions for implementation of an activated Ullmann diaryl ether condensation reaction may be conducted without amino acid racemization and that has proven suitable for incorporation of a selectively-protected catechol is described and its application to the synthesis of L,L-isodityrosine (1) is detailed.
- Boger, Dale L.,Yohannes, Daniel
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p. 2053 - 2056
(2007/10/02)
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- IMPROVED ULLMANN SYNTHESIS OF DIARYL ETHERS
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Several diaryl ethers have been synthesized by using indefinitely stable and easily available copper(I) phenylacetylenide as condensing agent in Ullmann condensation reaction.
- Afzali, A.,Firouzabadi, H.,Khalafi-nejad, A.
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p. 335 - 340
(2007/10/02)
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- Oxidativ Coupling of Phenols. Part 6. A Study of the Role of Spin Density Factors on the Product Composition in the Oxidations of 3,5-Dimethylphenol and Phenol
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Oxidations of both 3,5-dimethyphenol and phenol with di-t-butyl peroxide at 140 degC gave as the major product the ortho-ortho-C-C coupled dimer, while oxidations with di-t-butyl peroxyoxalate at room temperature give much more of the ortho-para-C-C dimer.The results are not consistent either with the spin density distribution in the phenoxyl radical intermediates or with steric effects being the major factor which determines the product composition.It is proposed that the two phenoxyl radicals involved in coupling preferentially approach each other in a 'sandwich like' manner with the oxigens in a 1,3-relationship.
- Armstrong, David R.,Cameron, Colin,Nonhebel, Derek C.,Perkins, Peter G.
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p. 563 - 568
(2007/10/02)
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- POLYBROMINATED DIPHENYL ETHERS FROM DYSIDEA HERBACEA, DYSIDEA CHLOREA AND PHYLLOSPONGIA FOLIASCENS
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The marine sponges Dysidea herbacea, D. chlorea and Phyllospongia foliascens were differentiated with difficulty in the field.D. herbacea contained 2-(2',4'-dibromophenoxy)-3,4,5-tribromophenol (1), 2-(2',4'-dibromophenoxy)-4,5,6-tribromophenol (2) and 2-(2',4'-dibromophenoxy)-3,5-dibromophenol (6).D. chlorea contained only 2-(2',4'-dibromophenoxy)-4.6-dibromophenol (3), a compound previously reported as a metabolite of D. herbacea.Phyllospongia foliascens contained 2-(3',5'-dibromo-2'-methoxy-phenoxy)-3,5-dibromoanisole (7) and a 1:2 mixture of 2-(3',5'-dibromo-2'-hydroxyphenoxy)-3,5,6-tribromophenol (8) and 2-(3',5'-dibromo-2'-hydroxy phenoxy)-3,4,5,6-tetrabromophenol (9).
- Carte, Brad,Faulkner, D. John
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p. 2335 - 2340
(2007/10/02)
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- Aryloxenium Ions. Generation from N-(Aryloxy)pyridinium Tetrafluoroborates and Reaction with Anisole and Benzonitrile
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N-(Aryloxy)pyridinium tetrafluoroborates (4) decompose thermally at 180-200 deg C in anisole and benzonitrile to form products of intermolecular C-O-C and C-C bond formation.With anisole, diphenyl ethers (5) and hydroxybiphenyls (6) are formed; with benzonitrile, the main product is benzoxazole (14).A homolytic process was ruled out by showing that none of these products were formed when perbenzoyl p-nitrophenyl carbonate (18) was decomposed in these solvents.The main products in this case were those of homolytic phenylation (and benzoyloxylation with anisole).A concerted SN2-type heterolytic process was ruled out by showing that the nature of the substituent in the pyridine ring had no effect on the isomer ratios of 5 and 6 in the thermolysis of 4 (X = p-NO2) in anisole.The results are explained in terms of a unimolecular heterolysis of 4 to give the pyridine and aryloxenium ion 2 which now attacks solvent molecules.When an electron-withdrawing substituent is present in 2, more C-O-C than C-C products are formed in anisole.When it is absent only products of C-C bond formation are found.PhO+ is apparently electrophilic enough to attack anisole and give the four possible hydroxymethoxybiphenyls (10-13).
- Abramovitch, Rudolph A.,Alvernhe, Gerard,Bartnik, Romuald,Dassanayake, Nissanke L.,Inbasekaran, Mutiah N.,Kato, Shiego
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p. 4558 - 4565
(2007/10/02)
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