- Palladium(II) thiosemicarbazone complex: Synthesis, structure and application to carbon-oxygen cross-coupling reaction
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A simple route for the synthesis of square-planar palladium(II) 3-methyl-thiophene-2-aldehyde thiosemicarbazone complex is described. The composition of the complex has been established by elemental analysis and spectral methods. The molecular structure was confirmed by single crystal X-ray diffraction study. Further, the complex was used as a potential catalyst for the carbon-oxygen cross-coupling reaction of activating, non-activating and deactivating aryl iodides or aryl bromides with p-cresol.
- Suganthy, Pandimuni Kalpaga,Prabhu, Rupesh Narayana,Sridevi, Venugopal Shanmugham
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- Tripodal N-heterocyclic carbene complexes of palladium and copper: Syntheses, characterization, and catalytic activity
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The tris-palladium tripodal N-heterocyclic carbene (NHC) complexes (timtebtBu){Pd(ICy)I2}3 (4a), (timteb tBu){Pd(PPh3)I2}3 (5a), and (timtebdipp){Pd(PPh3)I2}3 (5b) (timtebtBu = 1,3,5-{tris(tert-butylimidazol-2-ylidene)methyl}-2,4,6- triethylbenzene, 3a; ICy = 1,3-dicyclohexylimidazol-2-ylidene; timteb dipp = 1,3,5-{tris({2,6-diisopropylphenyl}imidazol-2-ylidene)methyl}- 2,4,6-triethylbenzene, 3b) were prepared by reaction of Pd(II) precursors with either the free carbenes or imidazolium salts. Treatment of [Cu(NCMe) 4]X (X = PF6, BF4) with 3a or 3b produced the tris-copper(I) bridged complexes [(timtebR) Cu3(μ3-O)]X (R = tBu, X = PF6, 6a; R = dipp, X = BF4, 6b). Complexes 4a, 5a, and 6a were structurally characterized. The palladium complexes were tested as catalysts for Suzuki-Miyaura and Sonogashira coupling reactions and the copper species also employed for the Sonogashira reaction, as well as for the Ullmann-type arylation of imidazoles and phenols.
- Ellul, Charles E.,Reed, Graham,Mahon, Mary F.,Pascu, Sofia I.,Whittlesey, Michael K.
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- Synthesis of diaryl ethers using an easy-to-prepare, air-stable, soluble copper(I) catalyst
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We have found that bromo(triphenylphosphine)copper(I), an air-stable and soluble copper(I) complex, can be used as a catalyst in the synthesis of diaryl ethers. Using this catalyst, we have synthesized diaryl ethers from electron-rich aryl bromides and electron-rich phenols in the presence of cesium carbonate, in 17-24 h, in NMP. We also found that electron-deficient aryl bromides couple with phenols in the presence of cesium carbonate, in 6 h in NMP at 70°C, without the catalyst.
- Gujadhur,Venkataraman
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- Synthesis and characterization of nano-cellulose immobilized phenanthroline-copper (I) complex as a recyclable and efficient catalyst for preparation of diaryl ethers, N-aryl amides and N-aryl heterocycles
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Functionalized nanocellulose was prepared and employed for immobilization of phenanthroline-copper(I) complex to afford cellulose nanofibril grafted heterogeneous copper catalyst [CNF-phen-Cu(I)]. This nanocatalyst was well characterized using FT-IR, NMR, XRD, CHNS, AAS, TGA, EDX and SEM. The activities of the synthesized catalyst were examined in the synthesis of diaryl ethers via C-O cross-coupling of phenols and aryl iodides, as well as, the preparation of N-aryl amides and N-aryl heterocycles through C-N cross-coupling of amides and N-H heterocycle compounds with aryl halides. In this trend, various substrates containing electron-donating and electron-withdrawing groups were exploited to evaluate the generality of this catalytic protocol. Accordingly, the catalyst demonstrated remarkable catalytic efficiency for both C-N and C-O cross-coupling reactions, thereby resulting in good to excellent yields of the desired products. Furthermore, the recoverability experiments of the catalyst showed that it can be readily retrieved by simple filtration and successfully reused several times with negligible loss of its catalytic activity.
- Aghili, Nora,Hosseinzadeh, Rahman,Mavvaji, Mohammad
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- Pd-Catalyzed Etherification of Nitroarenes
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The Pd-catalyzed etherification of nitroarenes with arenols has been achieved using a new rationally designed ligand. Mechanistic insights were used to design the ligand so that both the oxidative addition and reductive elimination steps of a plausible catalytic cycle were facilitated. The catalytic system established here provides direct access to a range of unsymmetrical diaryl ethers from nitroarenes.
- Matsushita, Naoki,Kashihara, Myuto,Formica, Michele,Nakao, Yoshiaki
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supporting information
p. 2209 - 2214
(2021/07/20)
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- Oxalohydrazide Ligands for Copper-Catalyzed C?O Coupling Reactions with High Turnover Numbers
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Here, we report a class of ligands based on oxalohydrazide cores and N-amino pyrrole and N-amino indole units that generates long-lived copper catalysts for couplings that form the C?O bonds in biaryl ethers. These Cu-catalyzed coupling of phenols with aryl bromides occurred with turnovers up to 8000, a value which is nearly two orders of magnitude higher than those of prior couplings to form biaryl ethers and nearly an order of magnitude higher than those of any prior copper-catalyzed coupling of aryl bromides and chlorides. This ligand also led to copper systems that catalyze the coupling of aryl chlorides with phenols and the coupling of aryl bromides and iodides with primary benzylic and aliphatic alcohols. A wide variety of functional groups including nitriles, halides, ethers, ketones, amines, esters, amides, vinylarenes, alcohols and boronic acid esters were tolerated, and reactions occurred with aryl bromides in pharmaceutically related structures.
- Ray, Ritwika,Hartwig, John F.
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supporting information
p. 8203 - 8211
(2021/03/08)
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- A novel magnetic polyacrylonotrile-based palladium Core?Shell complex: A highly efficientcatalyst for Synthesis of Diaryl ethers
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The present article describes the synthesis of a new magnetic polyacrylonitrile-based Pd catalyst involving polyacrylonitrile modified via 2-aminopyridine as an efficient support to immobilize Pd nanoparticles. The simple reusability, easy separation and high stability of this Pd complex make it an excellent candidate to generate a C–O bond via Ph-X activation which is a really important subject in achieving biologically active compounds. It is worth to note access to good and high yields as well as broad substrate scope have resulted from superior reactivity of this catalyst complex. Furthermore, the structure of the magnetic polyacrylonitrile-based heterogeneous catalyst was characterized by fourier transmission infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD). Also, its thermal properties were studied by thermogravimetric analysis (TGA).
- Eslami, Mohammad,Jarahiyan, Atefeh,Moghaddam, Firouz Matloubi,Pourjavadi, Ali
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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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- Oxalic amide ligands, and uses thereof in copper-catalyzed coupling reaction of aryl halides
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The present invention provides oxalic amide ligands and uses thereof in copper-catalyzed coupling reaction of aryl halides. Specifically, the present invention provides a use of a compound represented by formula I, wherein definitions of each group are described in the specification. The compound represented by formula I can be used as a ligand in copper-catalyzed coupling reaction of aryl halides for the formation of C—N, C—O and C—S bonds.
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Page/Page column 98
(2020/01/09)
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- Immobilized palladium nanoparticles on MNPs@A-N-AEB as an efficient catalyst for C-O bond formation in water as a green Solvent
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Palladium nanoparticles immobilized on the magnetic nanoparticles@2-amino-N-(2-aminoethyl) benzamide (MNPs@A-N-AEB.Pd0) have been presented as an efficient, and reusable magnetically heterogeneous catalyst for the C-O coupling reaction, namely Ullmann condensation reactions in an aqueous medium. This heterogeneous catalyst shows superior reactivity for the C-O arylation of different aryl halide (chloride, bromide, and iodide) with phenol derivatives to afford the desired products in good to excellent yields within short reaction time. Moreover, the catalyst can be easily recovered and reused for seven runs without loss of catalytic activity. The catalyst was characterized by several techniques, such as FT-IR, SEM, TEM, EDS, XRD, TGA and ICP-OES.
- Moghaddam, Firouz Matloubi,Eslami, Mohammad
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- Palladium-Catalyzed Formal Cross-Coupling of Diaryl Ethers with Amines: Slicing the 4-O-5 Linkage in Lignin Models
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Lignin is the second most abundant organic matter on Earth, and is an underutilized renewable source for valuable aromatic chemicals. For future sustainable production of aromatic compounds, it is highly desirable to convert lignin into value-added platform chemicals instead of using fossil-based resources. Lignins are aromatic polymers linked by three types of ether bonds (α-O-4, β-O-4, and 4-O-5 linkages) and other C?C bonds. Among the ether bonds, the bond dissociation energy of the 4-O-5 linkage is the highest and the most challenging to cleave. To date, 4-O-5 ether linkage model compounds have been cleaved to obtain phenol, cyclohexane, cyclohexanone, and cyclohexanol. The first example of direct formal cross-coupling of diaryl ether 4-O-5 linkage models with amines is reported, in which dual C(Ar)?O bond cleavages form valuable nitrogen-containing derivatives.
- Zeng, Huiying,Cao, Dawei,Qiu, Zihang,Li, Chao-Jun
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supporting information
p. 3752 - 3757
(2018/03/13)
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- Competing Pathways in O-Arylations with Diaryliodonium Salts: Mechanistic Insights
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A mechanistic study of arylations of aliphatic alcohols and hydroxide with diaryliodonium salts, to give alkyl aryl ethers and diaryl ethers, has been performed using experimental techniques and DFT calculations. Aryne intermediates have been trapped, and additives to avoid by-product formation originating from arynes have been found. An alcohol oxidation pathway was observed in parallel to arylation; this is suggested to proceed by an intramolecular mechanism. Product formation pathways via ligand coupling and arynes have been compared, and 4-coordinated transition states were found to be favored in reactions with alcohols. Furthermore, a novel, direct nucleophilic substitution pathway has been identified in reactions with electron-deficient diaryliodonium salts.
- Stridfeldt, Elin,Lindstedt, Erik,Reitti, Marcus,Blid, Jan,Norrby, Per-Ola,Olofsson, Berit
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p. 13249 - 13258
(2017/09/12)
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- Synthesis of copper nanoparticles supported on a microporous covalent triazine polymer: An efficient and reusable catalyst for O-arylation reaction
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Copper nanoparticles were supported on a microporous covalent triazine polymer prepared by the Friedel-Crafts reaction (Cu@MCTP-1). The resulting material was characterized by powder X-ray diffraction, thermogravimetric analysis, N2 adsorption-desorption isotherms at 77 K, transmission electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectroscopy, and Cu particles with an average size of 3.0 nm and a BET total surface area of ca. 1002 m2 g-1 were obtained. Cu@MCTP-1 was evaluated as a heterogeneous catalyst for the Ullmann coupling of O-arylation over a series of aryl halides and phenols without employing expensive ligands or inert atmosphere, which produced an excellent yield of the corresponding diaryl ethers. The catalyst could be recovered by simple centrifugation and was reusable at least five times with only a slight decrease in catalytic activity.
- Puthiaraj, Pillaiyar,Ahn, Wha-Seung
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p. 1701 - 1709
(2016/04/05)
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- Maghemite-Copper Nanocomposites: Applications for Ligand-Free Cross-Coupling (C-O, C-S, and C-N) Reactions
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A magnetically retrievable, efficient, and benign maghemite-Cu nanocatalyst was synthesized from inexpensive precursors and applied for C-O, C-N, and C-S bond-formation reactions. The obtained maghemite-Cu nanocatalyst was characterized by various techniques such as XRD, X-ray photoelectron spectroscopy, field-emission gun SEM with energy-dispersive spectroscopy, atomic absorption spectroscopy, TEM, high-angle annular dark-field scanning transmission electron microscopy, FTIR spectroscopy, and M?ssbauer spectroscopy. Excellent catalytic activity, ease of recovery, and reusability without a significant loss of yield make the present protocol highly sustainable to deal with industrial and environmental concerns. Magnetic attraction: A magnetically retrievable, efficient, and benign maghemite-Cu nanocatalyst is synthesized from inexpensive precursors and applied for C-O, C-N, and C-S bond-formation reactions. Excellent catalytic activity, ease of recovery, and reusability without significant loss of yield make the present protocol highly sustainable to deal with industrial and environmental concerns.
- Sharma, Rakesh K.,Gaur, Rashmi,Yadav, Manavi,Rathi, Anuj K.,Pechousek, Jiri,Petr, Martin,Zboril, Radek,Gawande, Manoj B.
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p. 3495 - 3502
(2015/11/10)
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- Copper-catalyzed C-N bond cross-coupling of aryl halides and amines in water in the presence of ligand derived from oxalyl dihydrazide: Scope and limitation
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An efficient and convenient method has been developed for the copper-catalyzed C-N bond cross-coupling of aryl bromides with electron-donor substituents and aliphatic amines in water. The new ligand system N-phenyloxalyl bishydrazide/hexane-2,5-dione has been shown to be considerably more efficient in the copper-catalyzed C-N bond cross-coupling reaction as compared to the ligands described in the literature and allowed decreasing of the catalyst amount (up to 2 mol %) to achieve acceptable yields of isolated products (46-84%). Acceptor substituted aryl bromides, aryl bromides with substituents in the ortho-position, and some aryl dichlorides can undergo the C-N cross-coupling under the developed conditions, but their reactivity is lower.
- Kurandina,Eliseenkov,Khaibulova,Petrov,Boyarskiy
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p. 7931 - 7937
(2015/09/15)
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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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- Chemoselective and ligand-free synthesis of diaryl ethers in aqueous medium using recyclable alumina-supported nickel nanoparticles
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An economical and eco-compatible ligand-free protocol for the synthesis of diaryl ethers has been developed using easily accessible alumina-supported nickel nanoparticles as a stable recyclable heterogeneous catalyst in aqueous medium along with a surfactant (SDS) and a mild base (K2CO3). Various sensitive functional groups like allyl, alkoxycarbonyl, formyl, oxo, chloro, bromo, amine and nitro were tolerated in the aforesaid method. Excellent chemoselectivity was demonstrated through competition experiments.
- Ghatak, Avishek,Khan, Sagar,Roy, Rimi,Bhar, Sanjay
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supporting information
p. 7082 - 7088
(2015/02/02)
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- Facile preparation of unsymmetrical diaryl ethers from unsymmetrical diaryliodonium tosylates and phenols with high regioselectivity
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Unsymmetrical diaryl ethers were efficiently obtained in good yields by the reactions of aryl(4-methoxyphenyl)iodonium tosylates with phenols, and aryl(2,4-dimethoxyphenyl)iodonium tosylates with phenols, in the presence of potassium carbonate in acetonitrile, respectively. The latter iodonium tosylates provided the corresponding unsymmetrical diaryl ethers in good yields with high regioselectivities, together with the quantitative formation of 1-iodo-2,4-dimethoxybenzene. Georg Thieme Verlag Stuttgart New York.
- Kakinuma, Yohji,Moriyama, Katsuhiko,Togo, Hideo
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p. 183 - 188
(2013/02/23)
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- A heterogeneous nickel catalyst for the hydrogenolysis of aryl ethers without arene hydrogenation
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A heterogeneous nickel catalyst for the selective hydrogenolysis of aryl ethers to arenes and alcohols generated without an added dative ligand is described. The catalyst is formed in situ from the well-defined soluble nickel precursor Ni(COD)2 or Ni(CH2TMS)2(TMEDA) in the presence of a base additive, such as tBuONa. The catalyst selectively cleaves CAr-O bonds in aryl ether models of lignin without hydrogenation of aromatic rings, and it operates at loadings down to 0.25 mol % at 1 bar of H2 pressure. The selectivity of this catalyst for electronically varied aryl ethers differs from that of the homogeneous catalyst reported previously, implying that the two catalysts are distinct from each other.
- Sergeev, Alexey G.,Webb, Jonathan D.,Hartwig, John F.
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supporting information
p. 20226 - 20229
(2013/02/25)
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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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- Bis(μ-iodo)bis[(-)-sparteine]-dicopper: A versatile catalyst for direct O-Arylation and O-Alkylation of phenols and aliphatic alcohols with haloarenes
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The easy to prepare dimeric bis(μ-iodo)bis[(-)-sparteine]- dicopper ([CuI{(-)-spa}]2 complex) is shown to be versatile catalyst for O-arylation and O-alkylation with various aryl halides with phenols and aliphatic alcohols respectively, including less reactive aryl chlorides, such as chlorobenzene under mild conditions.
- Satyanarayana, Ponnam,Maheswaran, Hariharasarma,Kantam, Mannepalli Lakshmi,Bhargava, Suresh
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supporting information; experimental part
p. 788 - 790
(2011/08/22)
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- Selective one-pot access to symmetrical or unsymmetrical diaryl ethers by copper-catalyzed double arylation of a simple oxygen source
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Great CO-mbination: A novel method is reported for the controlled one-pot synthesis of various symmetrical or unsymmetrical diaryl ethers by double arylation of a simple inorganic oxygen source (see scheme). This versatile and highly selective process is based on the use of a cheap and low toxicity copper catalytic system.
- Tlili, Anis,Monnier, Florian,Taillefer, Marc
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supporting information; experimental part
p. 12299 - 12302
(2011/02/16)
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- Copper(I)-catalyzed C-C and C-O coupling reactions using hydrazone ligands
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Copper-catalyzed C-C coupling reaction of aryl iodides with diethylmalonate in toluene at 90C gave arylated malonates using 5 mol% of CuI with hydrazone 1a as a ligand in good yields under an aerobic atmosphere. We also found CuI/hydrazone 1b in toluene to be an efficient catalytic system for C-O coupling reactions of aryl bromides with phenols to give aryl ethers in good yields at 110C under an aerobic atmosphere.
- Mino, Takashi,Yagishita, Fumitoshi,Shibuya, Masanori,Kajiwara, Kenji,Shindo, Hiroaki,Sakamoto, Masami,Fujita, Tsutomu
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experimental part
p. 2457 - 2460
(2010/01/07)
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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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- 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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- Synthesis of diaryl ethers through the copper-catalyzed arylation of phenols with aryl iodides using KF/Al2O3
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An efficient synthesis of diaryl ethers by the copper-catalyzed arylation of phenols with a variety of aryl iodide susing KF/Al2O3 as a suitable base and CuI and 1,3 diphenyl-1,3 propandione as the catalyst is described. Copyright Taylor & Francis Group, LLC.
- Hosseinzadeh, Rahman,Tajbakhsh, Mahmood,Mohadjerani, Maryam,Rezaei, Parizad,Alikarami, Mohammad
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p. 3023 - 3031
(2008/12/23)
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- Copper-catalyzed Ullmann coupling under ligand- and additive- free conditions. Part 1: O-Arylation of phenols with aryl halides
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O-Arylation of a wide variety of substituted phenols and aliphatic alcohols with aryl halides catalyzed by copper iodide under mild ligand and additive free conditions (nBu4NBr, DMF, K3PO4, reflux, 22 h) is accomplished in good to excellent product yields (up to 95%).
- Chang, Joyce Wei Wei,Chee, Sheena,Mak, Shiya,Buranaprasertsuk, Pongchart,Chavasiri, Warinthorn,Chan, Philip Wai Hong
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p. 2018 - 2022
(2008/09/19)
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- Palladium-catalyzed C-O bond formation: direct synthesis of phenols and aryl/alkyl ethers from activated aryl halides
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A simple and efficient palladium-catalyzed carbon-oxygen bond formation is reported. The palladium-tri-tert-butylphosphine complex was found to be effective in converting haloarenes to corresponding substituted phenols. This methodology offers a direct transformation of aryl halides to phenols, as well as the straightforward application to generate a wide variety of diaryl or alkyl/aryl ethers.
- Chen, Guoshu,Chan, Albert S.C.,Kwong, Fuk Yee
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p. 473 - 476
(2008/02/03)
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- Steps towards a practical synthesis of macrocyclic bisbenzylisoquinolines
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There are more than 400-reported bisbenzylisoquinoline alkaloids, many with interesting biological activity, but the reported syntheses are long and low yielding. As a result, there have been no systematic attempts at exploitation of the potential therapeutic applications. The concept of a sulfur 'stitch', restricting the conformational freedom of intermediates in the synthesis, will potentially allow analogues of the natural products to be prepared using relatively efficient routes. The synthesis of intermediate sulfur heterocycles is reported, based on 2,8-dimethylphenoxathiin, leading via 2,8-bis(bromomethyl) phenoxathiin-10,10-dioxide to a synthesis of 3,4,8,9-tetrahydro-13-oxa-6-thia-2, 10-diazapentacene, a key potential intermediate on the route to a variety of macrocyclic bisbenzylisoquinolines.
- Al-Hiari, Yusuf M.,Bennett, Stephen J.,Cox, Brian,Davies, Robert J.,Khalaf, Abedawn I.,Waigh, Roger D.,Worsley, Alan J.
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p. 647 - 659
(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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- Organophosphorus and Nitro-Substituted Sulfonate Esters of 1-Hydroxy-7-azabenzotriazole as Highly Efficient Fast-Acting Peptide Coupling Reagents
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Organophosphorus esters 9, 10, 14, and 15 prepared via reaction of diethyl- and diphenylphosphoryl chloride, di(o-tolyl)phosphinyl chloride, and 2,8-dimethylphenoxaphosphinyl chloride with HOAt are excellent coupling reagents for peptide synthesis which are generally superior to their uronium/guanidinium analogues and HOBt- or HODhbt-derived phosphate ester counterparts in minimizing loss of configuration during segment coupling. The phosphinyl analogues are more shelf-stable than the phosphoryl systems. The new reagents have been tested in segment couplings leading to two tripeptides (20, 21) and a hexapeptide 22. Outstanding utility is also shown for the solid-phase assembly of the ACP decapeptide. Similar results were obtained with the 2- and 4-nitro- and 2,4-dinitrophenylsulfonyl esters derived from HOAt.
- Carpino, Louis A.,Xia, Jusong,Zhang, Chongwu,El-Faham, Ayman
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- Synthesis of symmetrical diaryl ethers from arylboronic acids mediated by copper(II) acetate
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Copper promoted generation of phenols in situ through arylation of water and their subsequent arylation with arylboronic acids affords a wide range of symmetrical diaryl ethers in good to high yield. The reaction is rapid, mild, convenient and tolerant of a wide range of functionalities on the arylboronic acid.
- Sagar,Tale,Adude
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p. 7061 - 7063
(2007/10/03)
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- Synthesis of polymeric diaryliodonium salts and its use in preparation of diaryl sulfides and diaryl ethers
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Polymeric diaryliodonium salts were synthesized and applied to the preparation of diaryl ethers and diaryl sulfides under mild conditions. The byproduct, polyiodostyrene, could be recycled and reused.
- Huang,Zhu,Xu
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p. 2823 - 2828
(2007/10/03)
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- Formation of aryl-nitrogen, aryl-oxygen, and aryl-carbon bonds using well-defined copper(I)-based catalysts
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(Matrix Presented) We report mild synthetic protocols for the formation of aryl-carbon, aryl-nitrogen, and aryl-oxygen bonds based on soluble, well-defined copper(I) catalysts. These protocols do not require the use of palladium and/or expensive ligands.
- Gujadhur, Rattan K.,Bates, Craig G.,Venkataraman
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p. 4315 - 4317
(2007/10/03)
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- Reaction of triaryloxonium salts with bases via dehydroarenes
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Tri-p-tolyloxonium tetrafluoroborate reacts with NaOH in water yielding a mixture of m- and p-cresls (1:1) use of MeOH as solvent rsults in a mixture of m- and p-crescols (1:1), use of MeOH as solvent results in a mixture of m- and p-methoxytoluenes (1:5:1). This result proves this reaction to proceed via 3,4-dehydrotoluene.
- Tolstaya, Tatiana P.,Tsariev, Dmitry A.,Luzikov, Yury N.
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p. 4457 - 4458
(2007/10/03)
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- New Synthetic Applications of Aryllead Triacetates. N-Arylation of Azoles
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Treatment of a variety of azoles or their anions with p-tolyllead triacetate in the presence of copper(II) acetate afforded the corresponding N-aryl derivatives, normally in excellent yields.Room temperature arylation of an aminobenzimidazole derivative was chemoselectively directed to the amino group.
- Lopez-Alvarado, Pilar,Avendano, Carmen,Menendez, J. Carlos
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p. 5678 - 5682
(2007/10/03)
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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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- Reactions of Triarylsulphonium Salt with Alkoxide Nucleophiles: Involvement of Radical Intermediates
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Tri-p-tolylsulphonium bromide reacts with sodium isopropoxide or potassium hydroxide to give toluene; solvent isotope labelling experiments clearly show involvement of the p-tolyl radical species rather than the corresponding anion in this reaction.
- Chung, Sung-Kee,Sasamoto, Kazumi
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p. 346 - 347
(2007/10/02)
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- Copper-catalyzed synthesis of phenol and diaryl ether derivatives: Via hydroxylation of diaryliodoniums
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A copper-catalysed hydroxylation of diaryliodoniums to generate phenols and diaryl ethers is reported. This method allows the synthesis of diversely functionalized phenols under mild reaction conditions without the need for a strong inorganic base or an expensive noble-metal catalyst. Significantly, convenient application of diaryliodoniums is demonstrated in the preparation of diaryl ethers in a one-pot operation.
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