- 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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- Synthesis of highly functionalized diaryl ethers by copper-mediated O-arylation of phenols using trivalent arylbismuth reagents
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Highly functionalized diaryl ethers were prepared by copper(II) acetate mediated O-arylation reaction of phenols using trivalent organobismuthanes. The reaction is performed under simple conditions and tolerates a wide diversity of functional groups on the phenol and on the organobismuth reagent. Substoichiometric amounts of catalyst can be used by performing the reaction under an oxygen atmosphere. The N-arylation of pyridones is also reported. Highly functionalized diaryl ethers were prepared by a copper(II) acetate mediated O-arylation reaction of phenols using trivalent organobismuthanes (see scheme). The reaction is performed under simple conditions and tolerates a wide diversity of functional groups on the phenol and on the organobismuth reagent. Substoichiometric amounts of catalyst can be used by performing the reaction under an oxygen atmosphere. The N-arylation of pyridones is also reported. FG=functional group.
- Crifar, Cynthia,Petiot, Pauline,Ahmad, Tabinda,Gagnon, Alexandre
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supporting information
p. 2755 - 2760
(2014/03/21)
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- A new biarylphosphine ligand for the Pd-catalyzed synthesis of diaryl ethers under mild conditions
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A new bulky biarylphosphine ligand (L8) has been developed that allows the Pd-catalyzed C-O cross-coupling of a wide range of aryl halides and phenols under milder conditions than previously possible. A direct correlation between the size of the ligand substituents in the 2′, 4′, and 6′ positions of the nonphosphine containing ring and the reactivity of the derived catalyst system was observed. Specifically, the rate of coupling increased with the size of these substituents.
- Salvi, Luca,Davis, Nicole R.,Ali, Siraj Z.,Buchwald, Stephen L.
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supporting information; experimental part
p. 170 - 173
(2012/03/08)
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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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- Iodonium Cyclophanes for SECURE Arene Functionalization
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This disclosure relates to compounds, reagents, and methods useful in the synthesis of aryl fluorides, for example, in the preparation of 18F labeled radiotracers. For example, this disclosure provides universal “locked” aryl substituents that result in StereoElectronic Control of Unidirectional Reductive Elimination (SECURE) from diaryliodonium salts. The reagents and methods provided herein may be used to access a broad range of compounds, including aromatic compounds, heteroaromatic compounds, amino acids, nucleotides, and synthetic compounds.
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Page/Page column 26
(2011/08/08)
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- Regiospecific reductive elimination from diaryliodonium salts
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(Figure Presented) Out-of-plane steric bulk furnished by a cyclophane substituent on iodine(III) strongly destabilizes the transition state in the reductive elimination from diaryliodonium salts and leads to regiochemical control (dubbed SECURE), as is demonstrated by computational and experimental studies. This approach should be general for high-valent maingroup and transition metal ions. X=N3, OAc, PhO, CF3CH2O, SCN, PhS.
- Wang, Bijia,Graskemper, Joseph W.,Qin, Linlin,DiMagno, Stephen G.
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supporting information; experimental part
p. 4079 - 4083
(2010/08/07)
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- Significantly improved method for the pd-catalyzed coupling of phenols with aryl halides: Understanding ligand effects
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(Chemical Equation Presented) A variety of diaryl ethers were synthesized by the Pd-catalyzed reaction of (hetero)-aryl halides and phenols. These reactions were achieved through the use of two new di-tert-butylphosphino biaryl ligands that overcome several limitations of previously described methods.
- Burgos, Carlos H.,Barder, Timothy E.,Huang, Xiaohua,Buchwald, Stephen L.
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p. 4321 - 4326
(2007/10/03)
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- Novel electron-rich bulky phosphine ligands facilitate the palladium-catalyzed preparation of diaryl ethers
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A general method for the palladium-catalyzed formation of diaryl ethers is described. Electron-rich, bulky aryldialkylphosphine ligands, in which the two alkyl groups are either tert-butyl or 1-adamantyl, are the key to the success of the transformation. A wide range of electron-deficient, electronically neutral and electron-rich aryl bromides, chlorides, and triflates can be combined with a variety of phenols with the use of sodium hydride or potassium phosphate as base in toluene at 100 °C. The bulky yet basic nature of the phosphine ligand is thought to be responsible for increasing the rate of reductive elimination of the diaryl ether from palladium.
- Aranyos, Attila,Old, David W.,Kiyomori, Ayumu,Wolfe, John P.,Sadighi, Joseph P.,Buchwald, Stephen L.
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p. 4369 - 4378
(2007/10/03)
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