- 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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- 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(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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- Mechanism of the Non-Aryne Hydroxydehalogenation of Unactivated Aryl Halides
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The hydroxydehalogenation of aryl halides upon reaction with aqueous alkali at temperatures up to 333 deg C was examined to determine the nature of an ipso hydroxydehalogenation process reported in 1957 to compete with the aryne mechanism.The reactions of p-iodo-, p-bromo-, and p-chlorotoluene with aqueous solutions of sodium or potassium hydroxide or carbonate, carried out in Pyrex glass tubes with exclusion of traces of transition metals, led in all cases to the same product distribution. m-Cresol and p-cresol, the two main products, formed with a para/meta ratio of0.82+/-0.03, consistent with the occurence of the aryne mechanism only.Addition of traces of copper salts or conducting the reaction in a Monel bomb, as done by other investigators, caused the occurence of a non-aryne ipso hydroxydehalogenation.This effect was not produced by nickel, iron, manganese, or cadmium.The ipso hydroxydehalogenation observed in previous studies is identified as a copper-catalyzed process.
- Zoratti, Mario,Bunnett, J. F.
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p. 1769 - 1776
(2007/10/02)
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