- A Key Intermediate in Copper-Mediated Arene Trifluoromethylation, [nBu4N][Cu(Ar)(CF3)3]: Synthesis, Characterization, and C(sp2)?CF3 Reductive Elimination
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The synthesis, characterization, and C(sp2)?CF3 reductive elimination of stable aryl[tris(trifluoromethyl)]cuprate(III) complexes [nBu4N][Cu(Ar)(CF3)3] are described. Mechanistic investigations, including kinetic studies, studies of the effect of temperature, solvent, and the para substituent of the aryl group, as well as DFT calculations, suggest that the C(sp2)?CF3 reductive elimination proceeds through a concerted carbon–carbon bond-forming pathway.
- Lu, Zehai,Liu, He,Liu, Shihan,Leng, Xuebing,Lan, Yu,Shen, Qilong
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supporting information
p. 8510 - 8514
(2019/05/22)
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- NHC Nickel Catalyzed Hiyama- and Negishi-Type Cross-Coupling of Aryl Fluorides and Investigations on the Stability of Nickel(II) Fluoroaryl Alkyl Complexes
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The reactivity of [Ni(iPr2Im)4(μ-COD)] 1 (iPr2Im = 1,3-diisopropyl-imidazolin-2-ylidene, COD = 1,4-cyclooctadiene) in Hiyama- and Negishi-type cross-coupling reactions as well as the synthesis of several novel nickel fluoroaryl alkyl complexes is reported. Hiyama coupling of 1.1 equiv. perfluoroaromatics and 1 equiv. PhSi(OR)3 (R = Me, Et) with 5 mol-% of 1 as catalyst leads to the C–C coupling product ArF–Ph in good to fair yields. In presence of the additive NMe4F alkoxy transfer from PhSi(OR)3 to the perfluoroarene occurs to yield ArF–OR and PhSiF(OR)2. Negishi cross-coupling between C6F6 or C7F8 (1 equiv.), diorganozinc reagents [ZnR2] (R = Me, Et) (2.1 equiv.) and 5 mol-% 1 as the catalyst in toluene at 115 °C leads to ArF–R only in traces. However, NMR experiments revealed that nickel alkyl complexes are readily formed from the reaction of trans-[Ni(iPr2Im)2(F)(ArF)] with [ZnR2] (R = Me, Et). In course of these investigations, a series of novel nickel alkyl complexes trans-[Ni(iPr2Im)2(R)(ArF)] (R = Me, ArF = C6F5 2, C7F7 3, C12F9 4; R = Et, ArF = C6F5 5, C7F7 6, C12F9 7) have been synthesized in stoichiometric reactions starting from trans-[Ni(iPr2Im)2(F)(ArF)] (ArF = C6F5, C7F7, C12F9) and [ZnR2] (R = Me, Et) in thf at –78 °C. As these nickel alkyl complexes 2–7 are stable at room temperature in solution for several days with respect to reductive elimination, their thermal stability was investigated. Heating trans-[Ni(iPr2Im)2(Me)(C6F5)] 2 for 24 hours at 100 °C leads to 91 % unreacted complex 2 and only traces of reductive elimination product, i.e. C6F5Me, are formed. Furthermore, the nickel ethyl complex trans-[Ni(iPr2Im)2(Et)(C6F5)] 5 is also very stable, even with respect to β-hydride elimination. After heating this complex to 100 °C for 24 hours there is still 26 % unreacted 5 left.
- Kuntze-Fechner, Maximilian W.,Kerpen, Christoph,Schmidt, David,H?ring, Mathias,Radius, Udo
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supporting information
p. 1767 - 1775
(2019/03/11)
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- Transformations of perfluoroxylenes and perfluoro-p-cymene under the action of Zn(Cu)-DMF-H2O
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Perfluorinated xylenes and perfluoro-para-cymene undergo hydrodefluorination under the action of Zn(Cu)-DMF-H2O. Hydrogen enters mainly at the benzyl position of para-dialkylbenzenes and at the para position to perfluoroalkyl groups of perfluor
- Krasnov, Vyacheslav I.,Platonov, Vyacheslav E.,Beregovaya, Irina V.,Shchegoleva, Lyudmila N.
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p. 1797 - 1812
(2007/10/03)
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- Reactions of perfluoroaromatic compounds with ethereal solutions of methylmagnesium iodide in the presence of silver(I) and copper(I) salts
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The reactions of hexafluorobenzene, octafluorotoluene, decafluorodiphenyl, and octafluoronaphthalene with ethereal solutions of methylmagnesium iodide in the presence of AgCl or CuI gave the products of the methylation and 1-ethoxy-ethylation of the perfluorinated substrates, whose formation has been suggested to occur with participation of free radicals. Substitution of fluorine atoms by the 1-ethoxyethyl radicals in C6F5CF3 and C6F5C6F5 proceeds with predominant para-orientation; in C10F8, 1- and 2-orientations take place to an equal extent, whereas the methyl radicals attack mainly the 1-position of octafluoronaphthalene and show a low selectivity in the reaction with octafluorotoluene.
- Bogachev,Kobrina,Yakobson
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