- Copper(0) nanoparticle catalyzed Z-Selective Transfer Semihydrogenation of Internal Alkynes
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The use of copper(0) nanoparticles in the transfer semihydrogenation of alkynes has been investigated as a lead-free alternative to Lindlar catalysts. A stereo-selective methodology for the hydrogenation of internal alkynes to the corresponding (Z)-alkenes in high isolated yields (86% average) has been developed. This green and sustainable transfer hydrogenation protocol relies on non-noble copper nanoparticles for reduction of both electron-rich and electron-deficient, aliphatic-substituted and aromatic- substituted internal alkynes. Polyols, such as ethylene glycol and glycerol, have been proven to act as hydrogen sources, and excellent stereo- and chemoselectivity have been observed. Enabling technologies, such as microwave and ultrasound irradiation are shown to enhance heat and mass transfer, whether used alone or in combination, resulting in a decrease in reaction time from hours to minutes. (Figure presented.).
- Moran, Maria Jesus,Martina, Katia,Bieliunas, Vidmantas,Baricco, Francesca,Tagliapietra, Silvia,Berlier, Gloria,De Borggraeve, Wim M.,Cravotto, Giancarlo
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supporting information
p. 2850 - 2860
(2021/05/06)
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- Dehydrative Cross-Coupling of 1-Phenylethanol Catalysed by Palladium Nanoparticles Formed in situ under Acidic Conditions
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A dehydrative cross-coupling of 1-phenylethanol catalysed by sugar derived, in situ formed palladium(0) nanoparticles under acidic conditions is realised. The acidic conditions allow for use of alcohols as a feedstock in metal-mediated coupling reactions via their in situ dehydration and subsequent cross-coupling. Extensive analysis of the size and morphology of the palladium nanoparticles formed in situ showed that the zero-valent metal was surrounded by hydrophilic hydroxyl groups. EDX-TEM imaging studies using a prototype silicon drift detector provided insight into the problematic role of molecular oxygen in the system. This increased understanding of the catalyst deactivation allowed for the development of the cross-coupling methodology. A 250-12,000 fold increase in molar efficiency was observed when compared to related two-step protocols that use alternative feedstocks for the palladium-mediated synthesis of stilbenes. This work opens up a new research area in which the active catalyst is formed, stabilised and regenerated by a renewable sugar.
- Camp, Jason E.,Bousfield, Thomas W.,Dunsford, Jay J.,Adams, James,Britton, Joshua,Fay, Michael W.,Angelis-Dimakis, Athanasios
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supporting information
p. 3862 - 3874
(2018/09/29)
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- In-situ-generated palladium nanoparticles in novel ionic liquid: an efficient catalytic system for Heck–Matsuda coupling
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Abstract: A green, convenient, ecological and recyclable method comprising dual functionalized, task-specific, ionic liquid (IL)-triggered, in situ-generated Pd nanoparticles (NPs) and their catalytic application for Heck–Matsuda coupling of olefins is described. Both arenediazonium tetrafluoroborate and silica sulphate salts are coupled with olefins under ligand-free and aerobic conditions at ambient temperature furnishing excellent yields of products. The Ionic liquid used acts as a reducing as well as stabilizing agent for in situ-generated Pd NPs. The formed NPs were characterized by transmission electron microscopy (TEM) analysis, having a size below 50?nm, and exhibited high catalytic activity. The catalytic system can be reused for eight times effectively without any significant loss of activity. The method was found to be highly stereo-specific, giving exclusively the ‘E’ isomer.
- Gaikwad,Undale,Patil,Pore,Korade,Kamble
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p. 4445 - 4458
(2017/07/22)
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- Cyclodextrin-Grafted Silica-Supported Pd Nanoparticles: An Efficient and Versatile Catalyst for Ligand-Free C-C Coupling and Hydrogenation
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Silica is an extremely versatile support, which is capable of hosting metal nanoparticles (NPs) and enhancing their stability and reactivity. In this study, a novel cyclodextrin/silica support for Pd NPs, which we have denoted Pd/Si-CD, has been prepared. The highly efficient and homogeneous impregnation of small palladium nanoparticles on this support has been carried out under conventional conditions, and ultrasound irradiation has been shown to have a beneficial effect on catalyst preparation. The catalyst exhibited excellent activity in ligand-free C-C Suzuki and Heck couplings with a large number of aryl iodide and bromides, in which microwave irradiation use cuts down reaction time. Pd/Si-CD have shown high activity and selectivity in the hydrogenation reaction, and the semihydrogenation of phenyl acetylene was also studied with excellent results.
- Martina, Katia,Baricco, Francesca,Caporaso, Marina,Berlier, Gloria,Cravotto, Giancarlo
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p. 1176 - 1184
(2016/04/05)
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- Controlling olefin isomerization in the heck reaction with neopentyl phosphine ligands
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The use of neopentyl phosphine ligands was examined in the coupling of aryl bromides with alkenes. Di-tert-butylneopentylphosphine (DTBNpP) was found to promote Heck couplings with aryl bromides at ambient temperature. In the Heck coupling of cyclic alkenes, the degree of alkene isomerization was found to be controlled by the choice of ligand with DTBNpP promoting isomerization to a much greater extent than trineopentylphosphine (TNpP). Under optimal conditions, DTBNpP provides high selectivity for 2-aryl-2,3-dihydrofuran in the arylation of 2,3-dihydrofuran, whereas TNpP provided high selectivity for the isomeric 2-aryl-2,5-dihydrofuran. A similar complementary product selectivity is seen in the Heck coupling of cyclopentene. Heck coupling of 2-bromophenols or 2-bromoanilides with 2,3-dihydrofurans affords 2,5-epoxybenzoxepin and 2,5-epoxybenzazepins, respectively.
- Lauer, Matthew G.,Thompson, Mallory K.,Shaughnessy, Kevin H.
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p. 10837 - 10848
(2015/01/08)
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- Investigation of sol-gel supported palladium catalysts for Heck coupling reactions in o/w-microemulsions
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Sol-gel supported palladium catalysts are investigated for the Heck coupling reaction between styrene and iodo-/bromobenzene to trans-stilbenes in o/w-microemulsions as alternative reaction medium. High conversions and selectivities are obtained with these catalysts and they show better catalytic performance than their commercial analogs Pd@SiO2 or Pd/C. The influence of the catalyst structure on the activity is investigated in detail showing mass transport limitations that can be optimized by the palladium loading. The catalyst is recyclable >6 times with negligible palladium leaching into the solution. Because of the good recyclability under retention of activity and selectivity, the influence of transport limitations is suppressed and the total catalyst efficiency is increased to more than 2.
- Volovych,Kasaka,Schwarze,Nairoukh,Blum,Fanun,Avnir,Schom?cker
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p. 210 - 221
(2014/07/22)
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- PALLADIUM CATALYST, METHOD FOR ITS PREPARATION AND ITS USE
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The invention relates to palladium(0)-tris{tri-[3,5-bis(trifluoromethyl)-phenyl]-phosphine} complex of formula (I), as well as to its preparation and use. This compound is outstandingly stable, and can be used as catalyst with excellent results.
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Page/Page column
(2013/11/05)
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- A NEW PALLADIUM CATALYST, METHOD FOR ITS PREPARATION AND ITS USE
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The invention relates to palladium(0)-tetrakis{tri-[3,5-bis(trifluoromethyl)- phenylj-phosphine} complex of formula (I), as well as to its preparation and use. This compound is outstandingly stable, and can be used as catalyst with excellent results.
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Page/Page column 22-23
(2012/07/27)
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- Oxime-palladacycle-catalyzed suzuki-miyaura arylation and alkenylation of aryl imidazolesulfonates under aqueous and phosphane-free conditions
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Aryl and hetaroaryl imidazole-1-sulfonates are efficiently arylated and alkenylated with aryl- and alkenylboronic acids and potassium trifluoroborates by using 0.5 mol-% palladacycles 1 or Pd(OAc)2 at 110 °C under aqueous and phosphane-free conditions. Reactions can be performed by using conventional or microwave heating, leading to biaryls, stilbenes, and alkenylarenes in good to high yields, and high regio- and diastereoselectivities. The optimized methodology allows in situ phenol sulfonylation and one-pot Suzuki arylation or alkenylation as well as orthogonal functionalization of halogen-containing aryl imidazolesulfonates.
- Civicos, Jose Francisco,Alonso, Diego A.,Najera, Carmen
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scheme or table
p. 3670 - 3676
(2012/07/31)
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- Palladium-nanoparticle-catalyzed Matsuda-Heck reaction in water
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An eco-friendly, simple method for Matsuda-Heck arylation of olefins catalyzed by in situ formed Pd nanoparticles is described in water operable at ambient temperature. A variety of arenediazonium salts were coupled with olefins under ligand-free and aerobic conditions in high yields and stereoselectivity.
- Gaikwad, Dipak S.,Pore, Dattaprasad M.
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supporting information
p. 2631 - 2634,4
(2012/12/12)
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- Straightforward synthesis of phenanthrenes from styrenes and arenes
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Semi-one-pot synthesis of phenanthrenes from styrenes and arenes was developed through cross-dehydrogenative coupling. A sequence of Heck-type coupling and photo-cyclization were involved and a variety of functionalities were tolerated. This method provides an effective and practical protocol towards the synthesis of substituted phenanthrenes. The Royal Society of Chemistry 2012.
- Li, Hu,He, Ke-Han,Liu, Jia,Wang, Bi-Qin,Zhao, Ke-Qing,Hu, Ping,Shi, Zhang-Jie
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supporting information; experimental part
p. 7028 - 7030
(2012/08/07)
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- Oxime palladacycle-catalyzed Suzuki-Miyaura alkenylation of aryl, heteroaryl, benzyl, and allyl chlorides under microwave irradiation conditions
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A simple new protocol for the palladium-catalyzed Suzuki-Miyaura cross-coupling of organic chlorides under microwave irradiation is presented. Deactivated aryl and heteroaryl chlorides are efficiently cross-coupled with alkenylboronic acids and potassium alkenyltrifluoroborates using the 4,4′-dichlorobenzophenone oxime-derived palladacycle 1b as precatalyst in 0.1 to 0.5 mol% palladium loading, tris(tert-butyl)phosphonium tetrafluoroborate {[HP(t-Bu)3]BF4} as ligand, tetra-n-butylammonium hydroxide as cocatalyst, and potassium carbonate as base in N,N- dimethylformamide at 130°C under microwave irradiation conditions. Under these conditions, styrenes, stilbenes, and alkenylarenes are obtained in good to high yields, and with high regio- and diastereoselectivities in only 20 min. The reported protocol is also very efficient for the regioselective alkenylation of benzyl and allyl chlorides to afford allylarenes and 1,4-dienes. Copyright
- Civicos, Jose F.,Alonso, Diego A.,Najera, Carmen
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supporting information; experimental part
p. 1683 - 1687
(2011/09/19)
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- Selective cine substitution of 1-arylethenyl acetates with arylboron reagents and a diene/rhodium catalyst
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When the crowd says Bo: A carbon-carbon bond is selectively formed at the β position of 1- arylethenyl acetate when the alkenyl substrate is reacted with arylboronic acids in the presence of a cycloocta-1,5-diene/rhodium catalyst. The choice of the ligand is crucial for the unusual cine substitution. Copyright
- Yu, Jung-Yi,Shimizu, Ryosuke,Kuwano, Ryoichi
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supporting information; experimental part
p. 6396 - 6399
(2010/11/17)
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- Aminophosphine palladium pincer complexes for Suzuki and Heck reactions
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The aminophosphine-based pincer complexes [C6H 3-2,6-{NHP(piperidinyl)2}2Pd(CI)] (2) and [C6H3-2,6-{OP(piperidinyl)2}2Pd(CI)] (3) are readily prepared from cheap starting materials by sequential addition of 1,1′,1 "-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to solutions of [Pd(cod)(CI)2] (cod = cyclooctadiene) in toluene under N2 in 'one pot'. Compounds 2 and 3 proved to be not only excellent catalysts for the Suzuki and the Heck cross-coupling reactions, but they are also very convenient to use: The toluene solutions of the 'one-pot' syntheses can be used directly for the catalytic reactions, thereby saving the time-consuming isolation of the catalysts. The Suzuki cross-coupling reaction catalyzed by 2 and 3 can be performed in air at 100 °C in toluene of technical quality: in the presence of only 0.001 mol% of catalyst, several electronically deactivated and sterically hindered aryl bromides are quantitatively coupled with phenylboronic acid within a few minutes of reaction time. Furthermore, complex 2 enables the use of activated and non-activated aryl chlorides as coupling partners in the Suzuki reaction. Compounds 2 and 3 have also been shown to be highly active and reliable Heck catalysts: Very low catalyst loadings and short reaction times are required for the quantitative coupling of several electronically deactivated and sterically hindered aryl bromides with various olefins at 140 °C. At increased temperatures, even electronically deactivated and sterically hindered aryl chlorides can be efficiently coupled with olefins in the presence of only 0.01 mol% of catalyst. Schweizerische Chemische Gesellschaft.
- Bolliger, Jeanne L.,Frech, Christian M.
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scheme or table
p. 23 - 28
(2010/04/24)
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- Rapid and efficient Pd-catalyzed sonogashira coupling of aryl chlorides
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(Chemical Equation Presented) An efficient and effective microwave-assisted cross-coupling of terminal alkynes with various aryl chlorides including sterically hindered, electron-rich, electron-neutral, and electron-deficient aryl chloride is developed. It proceeds faster and generally gives good to excellent yields and also can be extended successfully to the Suzuki coupling and Buchwald-Hartwig amination, as well as the Heck coupling with inert aryl chlorides. The short reaction times and simple reaction conditions coupling with a broad substrate scope render this method particularly attractive for the efficient preparation of biologically and medicinally interesting molecules.
- Huang, He,Liu, Hong,Jiang, Hualiang,Chen, Kaixian
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p. 6037 - 6040
(2008/12/21)
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- Palladium-catalyzed cross-coupling of aryl chlorides with alkenylboronic acids with low E/Z isomerization
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Using a bulky electron-rich monodentate benzoferrocenyl phosphine as supporting ligand, an efficient protocol for stereoselective palladium-catalyzed Suzuki-Miyaura cross-coupling of aryl chlorides with alkenylboronic acids was uncovered. Using this protocol, both trans- and cis-alkenylboronic acids can be coupled with high stereoselectivity giving the corresponding vinylarenes in good to quantitative yields. Electron-poor and -rich aryl chlorides including highly hindered ones are all suitable substrates for the reaction.
- Thimmaiah, Muralidhara,Zhang, Xiang,Fang, Shiyue
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p. 5605 - 5607
(2008/12/22)
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- Rapid room temperature buchwald-hartwig and suzuki-miyaura couplings of heteroaromatic compounds employing low catalyst loadings
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The use of second-generation [(NHC)Pd(R-allyl)Cl] complexes for Suzuki-Miyaura and Buchwald-Hartwig cross-coupling reactions involving heteroaromatic halides at room temperature is reported. The first examples of room temperature Suzuki-Miyaura cross-coupling of deactivated aryl chlorides with alkenyl boronic acids are also disclosed. Terminal substitution at the allyl moiety of the palladium complex facilitates its activation at room temperature leading to very active catalytic species enabling the present catalytic transformations to be performed rapidly using very mild reaction conditions. Catalyst loadings can be as low as 10 ppm for the Buchwald-Hartwig aryl amination and 50 ppm for the Suzuki-Miyaura reaction.
- Navarro, Oscar,Marion, Nicolas,Mei, Jianguo,Nolan, Steven P.
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p. 5142 - 5148
(2008/03/13)
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- Acyclic diaminocarbenes: Simple, versatile ligands for cross-coupling reactions
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Acyclic diaminocarbenes are found to be useful ligands for palladium catalyzed Suzuki-Miyaura, Sonogashira and Heck cross-coupling reactions of aryl/alkenyl bromides and chlorides. The Royal Society of Chemistry 2006.
- Dhudshia, Bhartesh,Thadani, Avinash N.
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p. 668 - 670
(2008/02/10)
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- Stereospecific palladium-catalyzed cross-coupling of (E)- and (Z)-alkenylsilanolates with aryl chlorides
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The cross-coupling of geometrically defined (E)- and (Z)-alkenyl- and styrylsilanolates with a wide variety of aromatic and heteroaromatic chlorides has been achieved. Under catalysis by bulky, biphenyl-derived phosphines and allylpalladium chloride, the (preformed, stable) potassium salts of di-, tri- and tetrasubstituted alkenyldimethylsilanols undergo high yielding and highly stereospecific coupling to aryl chlorides in THF or dioxane. A variety of functional groups are compatible with these reaction conditions including nitro, ester, ketone, and nitrile. Both (E)- and (Z)-alkenylsilanolates coupled with nearly identical rate and efficiency. Copyright
- Denmark, Scott E.,Kallemeyn, Jeffrey M.
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p. 15958 - 15959
(2007/10/03)
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- Generation of phosphoranes derived from phosphites. A new class of phosphorus ylides leading to high E selectivity with semi-stabilizing groups in Wittig Olefinations
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Tosylhydrazones derived from aryl aldehydes react with t-BuOK, ClFeTPP, (MeO)3P, and aldehydes to furnish olefins with high E selectivity. These reactions occur through a Wittig-type pathway via the corresponding diazo compounds, metal carbenes and phosphorous ylides, with the water-soluble trimethyl phosphate as the byproduct. Similar reactions can also be performed using ethyl diazoacetate; however, high E selectivity was only observed in the presence of LiBr. In this case, the reaction is believed to occur via the phosphonate anion, formed through an Arbuzov reaction. Thus this olefination reaction occurs through a Horner-Wadsworth-Emmons (HWE) reaction but the phosphonate anion is generated under completely base-free conditions. Copyright
- Aggarwal, Varinder K.,Fulton, J. Robin,Sheldon, Chris G.,De Vicente, Javier
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p. 6034 - 6035
(2007/10/03)
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