- Palladium-mediated radical homocoupling reactions: A surface catalytic insight
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In this contribution, we report a palladium nanoparticle-promoted reductive homocoupling of haloarenes that proceeds efficiently to produce corresponding bis-aryls in moderate to excellent yields using relatively low catalyst loading (1 mol%), and exhibits broad functional group tolerance. This work sheds light on how the surface state of Pd(0) nanoparticles plays a crucial role in the reactivity of catalytic systems. Notably, the appropriate choice of palladium salts for the preparation of the preformed nanocatalysts was a key parameter having a major impact on the catalytic activity; thus, the effect of halide anions on the reactivity of the as-prepared palladium nanoparticles could be assessed, with iodide anions being capable of inhibiting the corresponding homocoupling reaction. The homocoupling reaction mechanism has been further studied by means of radical trap and electron paramagnetic resonance (EPR) experiments, revealing that the reaction proceeds via radical intermediates. Taking into account these data, a plausible reaction mechanism based on single-electron transfer processes on the palladium nanoparticle surface is discussed.
- Favier, Isabelle,Toro, Marie-Lou,Lecante, Pierre,Pla, Daniel,Gómez, Montserrat
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p. 4766 - 4773
(2018/09/29)
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- Optimizing the Mizoroki–Heck reaction of cyclic allyl amines: Gram-scale synthesis of preclamol without protecting groups
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Though a widely used metal-catalyzed cross-coupling process, the Mizoroki–Heck (MH) reaction can be a capricious transformation. This is particularly true for oxidation-prone alkene substrates containing ligating heteroatoms, as in the case of N-alkyl tetrahydropyridines, whose MH reactions have been underexplored due to the many side reactions that hamper the process. Since the products of tetrahydropyridine Heck reactions are direct precursors to potent pharmacophores, and therefore of commercial value, this is a significant drawback. We report here the results of our study designed to deliver an optimized, scalable MH procedure for N-alkyltetrahydropyridines and its exemplification in a gram-scale synthesis of the drug substance preclamol.
- Sweeney, Joseph B.,Adams, Kirsty,Doulcet, Julien,Thapa, Bimod,Tran, Fanny,Crook, Robert
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- Iron-catalyzed homocoupling of aryl halides and derivatives in the presence of alkyllithiums
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Direct synthesis of biaryl derivatives from aryl halides takes place under very mild temperature conditions by using a ligand-free iron catalytic system. The procedure, which proceeds via an in situ quantitative aryl halide exchange with alkyllithiums, allows for excellent control of the reactivity and is in line with the sustainable development. The method is also applicable to styryl and benzyl halides and to phenylacetylene.
- Toummini, Dounia,Ouazzani, Fouad,Taillefer, Marc
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supporting information
p. 4690 - 4693
(2013/10/08)
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- Palladium(II)-catalyzed coupling of electron-deficient arenes via C-H activation
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Homocoupling and cross-coupling of electron-deficient arenes, including nitrobenzene, (trifluoromethyl)benzene, ethyl benzoate, etc., have been developed to afford biaryls using a catalytic system of Pd(OAc) 2/trifluoroacetic acid (TFA)/O2 or K2S 2O8. The crucial step is to tune the concentrations of arenes and the loading of TFA carefully to enhance the reaction rates and the selectivity of these couplings involving dual C-H activation.
- Zhou, Lihong,Lu, Wenjun
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scheme or table
p. 2124 - 2127
(2012/06/01)
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- Cobalt-xantphos-catalyzed, LiCl-mediated preparation of arylzinc reagents from aryl iodides, bromides, and chlorides
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A cobalt-Xantphos-catalyzed, LiCl-mediated system has been developed for the direct and expedient preparation of arylzinc reagents in THF from the corresponding aryl iodides, bromides, and chlorides. Owing to the use of THF as a versatile solvent, the thus-formed arylzinc reagents displayed a high degree of compatibility with a variety of conventional as well as newly emerging metal-catalyzed cross-coupling reactions.
- Jin, Meng-Yi,Yoshikai, Naohiko
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experimental part
p. 1972 - 1978
(2011/05/19)
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- Synthesis of functionalized 2-arylthiophenes with triarylbismuths as atom-efficient multicoupling organometallic nucleophiles under palladium catalysis
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Atom-efficient cross-coupling reactions of functionalized 2-bromo- and 2-iodothiophenes have been demonstrated using triarylbismuths as atom-efficient multicoupling organometallic nucleophiles under palladium-catalyzed conditions. These couplings with various functionalized triarylbismuths proceeded smoothly to afford the corresponding functionalized 2-arylthiophenes in high yields. Georg Thieme Verlag Stuttgart · New York.
- Rao, Maddali L. N.,Banerjee, Debasis,Dhanorkar, Ritesh J.
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supporting information; experimental part
p. 1324 - 1330
(2011/07/07)
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- Pd-catalyzed synthesis of α-aryl ketones through couplings of α-arylacetyl chlorides with triarylbismuths as multi-coupling nucleophiles
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The cross-coupling reaction of α-arylacetyl chlorides with triarylbismuths was studied under Pd-catalyzed conditions. The reaction was found to be facile under the established protocol and furnished high yields of α-aryl ketones in short reaction times. T
- Rao, Maddali L.N.,Giri, Somnath,Jadhav, Deepak N.
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experimental part
p. 6133 - 6138
(2010/02/27)
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- Preparation of functionalized aryl- and heteroarylpyridazines by nickel-catalyzed electrochemical cross-coupling reactions
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(Chemical Equation Presented) A general efficient electrochemical method for the preparation of aryl- and heteroarylpyridazines in a nickel-catalyzed cross-coupling reaction of 3-chloro-6-methoxypyridazine and 3-chloro-6- methylpyridazine with a range of functionalized aryl or heteroaryl halides is reported.
- Sengmany, Stephane,Leonel, Eric,Polissaint, Frantz,Nedelec, Jean-Yves,Pipelier, Muriel,Thobie-Gautier, Christine,Dubreuil, Didier
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p. 5631 - 5636
(2008/02/09)
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- Efficient palladium-catalyzed nucleophilic addition of triorganoindium reagents to carbocyclic derivatives
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Palladium (0)-catalyzed allylic substitution reactions employing triorganoindium reagents have been investigated. In situ generated vinyl- and arylindiums react with substituted and unsubstituted cyclohex-2-enyl esters in the presence of 1-3 mol % Pd2(dba)3 to produce vinyl- or arylcyclohexenes in moderate to excellent yields. The stereoselectivity of this process was also examined, and evidence is presented that the reaction proceeds with inversion of stereochemical configuration.
- Baker, Lucas,Minehan, Thomas
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p. 3957 - 3960
(2007/10/03)
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- Convenient Processes for the Synthesis of Aromatic Ketones from Aryl Bromides and Carboxylic Anhydrides Using a Cobalt Catalysis
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The cross-coupling of various para- and meta-substituted aromatic bromides, mostly bearing sensitive moieties, with several carboxylic acid anhydrides is reported. This reaction can be carried out in two steps, by forming an aromatic organozinc reagent via cobalt catalysis in the first step, or even more interestingly in a single step, also by using a cobalt-based catalyst. The aromatic ketones are obtained by these new, mild, and convenient methods in 30-79% yields versus starting aryl bromide. Results are also disclosed that suggest the role played by cobalt species in the coupling of organozinc reagents with electrophiles could be similar to those of more commonplace transition metal complexes.
- Kazmierski, Igor,Bastienne, Mylene,Gosmini, Corinne,Paris, Jean-Marc,Perichon, Jacques
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p. 936 - 942
(2007/10/03)
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- Process of heterocoupling by electrolytic microbattery, use of cobalt for implementing said coupling and composition for doing so
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This invention has as its object a process for preparation of vinyl aryl derivatives by an electrochemical path. This process is defined in that it consists in subjecting a composition that comprises a cobalt salt, an aromatic halide and a vinyl ester to the action of a metal that is at least as reducing as zinc. Application to organic synthesis.
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- New chemical synthesis of functionalized arylzinc compounds from aromatic or thienyl bromides under mild conditions using a simple cobalt catalyst and zinc dust
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A new chemical method for the preparation of arylzinc intermediates is described in acetonitrile, on the basis of the activation of aryl bromides by low-valent cobalt species arising from the reduction of cobalt halide by zinc dust. This procedure allows for the synthesis of a variety of functionalized aryl- and thienylzinc species in good to excellent yields. The versatility and the simplicity of that original method represent an alternative to most known procedures.
- Fillon, Hyacinthe,Gosmini, Corinne,Perichon, Jacques
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p. 3867 - 3870
(2007/10/03)
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- New chemical cross-coupling between aryl halides and allylic acetates using a cobalt catalyst
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(Figure presented) The cobalt-catalyzed coupling reaction of aromatic halides and allylic acetates proceeds readily under mild conditions in the presence of the appropriate reducing agent to produce allylaromatic derivatives either in pure acetonitrile (aryl bromides) or in an acetonitrile/pyridine mixture (aryl chlorides).
- Gomes, Paulo,Gosmini, Corinne,Perichon, Jacques
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p. 1043 - 1045
(2007/10/03)
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- Synthesis of unsymmetrical biaryls by electroreductive cobalt-catalyzed cross-coupling of aryl halides
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The consumable anode process allows the electrochemical cross-coupling reaction between various functionalized aromatic halides (iodides, bromides and chlorides) in the presence of cobalt halides as catalyst in a mixed solvent acetonitrile/pyridine (9:1). A great variety of unsymmetrical biaryls are obtained in moderate to excellent yields.
- Gomes, Paulo,Fillon, Hyacinthe,Gosmini, Corinne,Labbé, Eric,Périchon, Jacques
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p. 8417 - 8424
(2007/10/03)
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- Homocoupling of aryl iodides and bromides promoted by sulfur-containing palladacycles
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Sulfur-containing palladacycles, in particular those derived from the orthometalation of benzylthioethers, effectively promote the homocoupling of aryl iodides and bromides, under relatively mild reaction conditions to furnish symmetrical biphenyls in good yields.
- Silveira, Priscila B.,Lando, Vanusa R.,Dupont, Jairton,Monteiro, Adriano L.
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p. 2327 - 2329
(2007/10/03)
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