- Air-stable Pd(0) catalyst bearing dual phosphine ligands: a detailed evaluation of air stability and catalytic property in cross-coupling reactions
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We have synthesised an air-stable Pd(0) catalyst bearing donor and acceptor phosphine ligands (Complex1). This study revealed the long-term air stability and catalytic property of Complex1as a catalyst for cross-coupling reactions, where it was stable in air for eight months. DFT calculations revealed that the acceptor ligands in Complex1decreased the HOMO energy level, which provided the observed air stability. Complex1successfully served as a catalyst for direct C-H arylation reactions and Suzuki-Miyaura cross-coupling reactions, and catalysed the reaction of a relatively inactive substrate, 2-chrolopyridine, which could not be achieved by conventional, air-stable Pd(0) catalysts. Isolating the intermediates of the coupling reactions revealed that each intermediate possessed the donor ligand (PCy3), which was determined to be responsible for imparting the high catalytic activity exhibited by Complex1.
- Sato, Ryota,Kanbara, Takaki,Kuwabara, Junpei
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Read Online
- Synthesis of an Air-Stable Pd(0) Catalyst Bearing Donor and Acceptor Phosphine Ligands
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We synthesized a new Pd(0) complex bearing π-acceptor ligands and a σ-donor ligand and confirmed that it exhibits high air stability and catalytic activity in direct arylation reactions. Moreover, stoichiometric reactions of the complex revealed that the σ-donor ligand does not dissociate from the Pd center.
- Kanbara, Takaki,Kuwabara, Junpei,Sato, Ryota
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supporting information
(2020/02/04)
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- Potassium trimethylsilanolate enables rapid, homogeneous suzuki-miyaura cross-coupling of boronic esters
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Herein, a mild and operationally simple method for the Suzuki-Miyaura cross-coupling of boronic esters is described. Central to this advance is the use of the organic-soluble base, potassium trimethylsilanolate, which allows for a homogeneous, anhydrous cross-coupling. The coupling proceeds at a rapid rate, often furnishing products in quantitative yield in less than 5 min. By applying this method, a >10-fold decrease in reaction time was observed for three published reactions which required >48 h to reach satisfactory conversion.
- Delaney, Connor P.,Kassel, Vincent M.,Denmark, Scott E.
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- Analysis of the palladium-catalyzed (aromatic)C-H bond metalation- deprotonation mechanism spanning the entire spectrum of arenes
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A comprehensive understanding of the C-H bond cleavage step by the concerted metalation-deprotonation (CMD) pathway is important in further development of cross-coupling reactions using different catalysts. Distortion-interaction analysis of the C-H bond cleavage over a wide range of (hetero)aromatics has been performed in an attempt to quantify the various contributions to the CMD transition state (TS). The (hetero)aromatics evaluated were divided in different categories to allow an easier understanding of their reactivity and to quantify activation characteristics of different arene substituents. The CMD pathway to the C-H bond cleavage for different classes of arenes is also presented, including the formation of pre-CMD intermediates and the analysis of bonding interactions in TS structures. The effects of remote C2 substituents on the reactivity of thiophenes were evaluated computationally and were corroborated experimentally with competition studies. We show that nucleophilicity of thiophenes, evaluated by Hammett σp parameters, correlates with each of the distortion-interaction parameters. In the final part of this manuscript, we set the initial equations that can assist in the development of predictive guidelines for the functionalization of C-H bonds catalyzed by transition metal catalysts.
- Gorelsky, Serge I.,Lapointe, David,Fagnou, Keith
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experimental part
p. 658 - 668
(2012/03/11)
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- Synthesis and n-type field-effect transistor characteristics of dioxopyrrolopyrrole derivatives
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Dioxopyrrolopyrrole derivatives with electron-withdrawing groups have been synthesized and applied to organic field-effect transistors as n-channel semiconductors. A derivative with an intermolecular hydrogen-bonding network showed a good electron mobility up to 2.9 1012 cm2V 11 s11.
- Suna, Yuki,Nishida, Jun-Ichi,Fujisaki, Yoshihide,Yamashita, Yoshiro
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supporting information; experimental part
p. 822 - 824
(2011/09/14)
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- Ligand-less palladium-catalyzed direct 5-arylation of thiophenes at low catalyst loadings
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Ligand-less Pd(OAc)2 provides a very efficient catalyst for the direct 5-arylation of thiophene derivatives. With this catalyst, a low palladium concentration (0.1-0.001 mol%) should be employed in order to obtain high yields of coupling products. At higher concentrations a fast formation of inactive "Pd black" generally occurs. Substrates/catalysts ratios up to 100000 can be employed with the most reactive aryl bromides. A very wide variety of functional groups is tolerated on both coupling partners. The major waste of this reaction is HBr associated with KOAc. Therefore this procedure is more economically and environmentally attractive than the traditional cross-coupling procedures employing organometallic derivatives.
- Roger, Julien,Pozgan, Franc,Doucet, Henri
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experimental part
p. 425 - 432
(2010/04/22)
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- Direct arylation of thiophenes via palladium-catalysed C-H functionalisation at low catalyst loadings
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Palladium associated with cis,cis,cis-1,2,3,4- tetrakis(diphenylphosphinomethyl)cyclopentane (Tedicyp) was found to promote the direct 2-arylation of a variety of thiophene derivatives via C-H functionalisation in good yields using very low catalyst loadings. Electron-deficient, electron-excessive or sterically-congested aryl bromides are tolerated. Moreover, several substituents on the aryl bromide or thiophene derivatives such as acetyl, formyl, nitrile, nitro, ester, methoxy, fluoro or trifluoromethyl are tolerated. The most reactive aryl bromides were coupled with thiophenes derivatives using as little as 0.1-0.01 mol% catalyst.
- Battace, Ahmed,Lemhadri, Mhamed,Zair, Touriya,Doucet, Henri,Santelli, Maurice
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p. 2507 - 2516
(2008/09/19)
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- Direct release of nitriles from solid phase
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Cleavage conditions are described which allow resin bound secondary amides to be liberated from Sieber or Rink resin as nitriles. The method has been applied to the synthesis of a series of cyanobiaryls. Published by 2001 Elsevier Science Ltd.
- Hone, Neal D.,Payne, Lloyd J.,Tice, Colin M.
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p. 1115 - 1118
(2007/10/03)
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- Extension of the Heck reaction to the arylation of activated thiophenes
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The direct arylation of activated thiophenes was accomplished in moderate to good yields using a Heck-type reaction with the mixture of Pd(OAc)2 and n-Bu4NBr as a catalytic system. This new arylation method is applied to different derivatives and has proved to be compatible with sensitive functional groups. Furthermore, the substituent nature and position on the thiophene moiety influence the cross coupling. In particular the substitution is regiospecific when the heterocycle is substituted at position 2 with an electron withdrawing group.
- Lavenot,Gozzi,Ilg,Orlova,Penalva,Lemaire
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- Direct thiophene arylation catalysed by palladium
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Direct thiophene arylation using a Heck-type reaction with Pd(OAc)2/NBu4Br as catalytic system is reported. Reactions with 2- and 3-substituted thiophenes have shown that substituent nature and position influence the cross-coupling.
- Gozzi, Christel,Lavenot, Laurence,Ilg, Kerstin,Penalva, Vincent,Lemaire, Marc
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p. 8867 - 8870
(2007/10/03)
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