- 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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- The aminocyclodextrin/Pd(OAc)2 complex as an efficient catalyst for the Mizoroki-Heck cross-coupling reaction
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An aminocyclodextrin/Pd(OAc)2 complex is used as an efficient, reusable catalyst in the Mizoroki-Heck reaction of aryl halides/triflates with olefins to give carbon-carbon-coupled products in good to excellent yields. This simple, efficient catalytic system is applicable to a wide range of aryl and heteroaryl halides/triflates and olefins. This environmentally benign procedure is less hazardous, milder, uses a catalytic amount of ligand and Pd(OAc) 2, avoids an inert atmosphere, and catalyst recovery and reusability are achieved. Copyright
- Kanagaraj, Kuppusamy,Pitchumani, Kasi
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supporting information
p. 14425 - 14431
(2013/11/06)
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- Palladium/tris(tert-butyl)phosphine-catalyzed Suzuki cross-couplings in the presence of water
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Dipalladiumtris(dibenzylideneacetone)/tris(tert-butyl)phosphonium tetrafluoroborate/potassium fluoride dihydrate [Pd2(dba) 3/[HP(t-Bu)3]BF4/KF·2H2O] serves as a mild, robust, and user-friendly method for the efficient Suzuki cross-coupling of a diverse array of aryl and heteroaryl halides with aryl- and heteroarylboronic acids.
- Lou, Sha,Fu, Gregory C.
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supporting information; experimental part
p. 2081 - 2084
(2010/10/20)
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- Transition metal complexes of N-heterocyclic carbenes, method of preparation and use in transition metal catalyzed organic transformations
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The present invention relates to catalysts of transition metal complexes of N-heterocyclic carbenes, their methods of preparation and their use in chemical synthesis. The synthesis, ease-of-use, and activity of the compounds of the present invention are substantial improvements over in situ catalyst generation. Further, the transition metal complexes of N-heterocyclic carbenes of the present invention may be used as precatalysts in metal-catalyzed cross-coupling reactions.
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Page/Page column 11; 16
(2010/11/26)
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- Easily prepared air- and moisture-stable Pd-NHC (NHC = N-heterocyclic carbene) complexes: A reliable, user-friendly, highly active palladium precatalyst for the Suzuki-Miyaura reaction
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The synthesis of NHC-PdCl2-3-chloropyridine (NHC = N-heterocyclic carbene) complexes from readily available starting materials in air is described. The 2,6-diisopropylphenyl derivative was found to be highly catalytically active in alkyl-alkyl Suzuki and Negishi cross-coupling reactions. The synthesis, ease-of-use, and activity of this complex are substantial improvements over in situ catalyst generation and all current Pd-NHC complexes. The utilization of complex 4 led to the development of a reliable, easily employed Suzuki-Miyama protocol. Employing various reaction conditions allowed a large array of hindered biaryl and drug-like heteroaromatic compounds to be synthesized without difficulty.
- O'Brien, Christopher J.,Kantchev, Eric Assen B.,Valente, Cory,Hadei, Niloufar,Chass, Gregory A.,Lough, Alan,Hopkinson, Alan C.,Organ, Michael G.
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p. 4743 - 4748
(2008/02/08)
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- Suzuki-Miyaura cross-coupling reactions of potassium alkenyltrifluoroborates
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We have previously reported that the palladium-catalyzed cross-coupling reaction of air-stable potassium alkenyltrifluoroborates with aryl halides and triflates proceeds readily with good yields. Recent progress in outlining the scope and limitations of s
- Molander, Gary A.,Bernardi, Carmem R.
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p. 8424 - 8429
(2007/10/03)
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- Photochemical Reactivity of Halofuran and Halothiophene Derivatives in the Presence of Arylalkenes and Arylalkynes
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The photochemical reactions of 5-iodothiophene-2-carbaldehyde (4a), 2-acetyl-5-iodothiophene (4b), 5-bromofuran-2-carbaldehyde (3b) with arylalkenes 5 (styrene), 7 (2-vinylthiophene), 10 (2-vinylfuran), 12 (4-methyl-5-vinylthiazole), and 16 (benzofuran) are reported.All of the reactions give the corresponding substitution products as a cis-trans mixture.The photochemical reaction of 4a and 4c (methyl 5-iodothiophene-2-carboxylate) with arylalkynes is also reported: in this case the reaction of 4a and 4c with phenylacetylene (18) furnishes the substitution products (19 and 26, respectively) deriving from an attack on the alkyne moiety, while the reaction with 2-ethynylthiophene (20) and 2-ethynylfuran (23) furnishes a mixture deriving from the attack both on the alkyne and on the heterocyclic ring.The ratio between these two products can be modified by changing the concentrations of the reagents.The mechanism of these reactions is discussed on the basis of photochemical and electrochemical properties of the reagents in terms of an electron-transfer process.The experimental results are explained in terms of ΔG values, and they are in agreement with the formation of both a solvent-separated pair and a contact radical ion pair.
- D'Auria, Maurizio,Piancatelli, Giovanni,Ferri, Tommaso
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p. 4019 - 4025
(2007/10/02)
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