389-40-2Relevant articles and documents
NHC Nickel Catalyzed Hiyama- and Negishi-Type Cross-Coupling of Aryl Fluorides and Investigations on the Stability of Nickel(II) Fluoroaryl Alkyl Complexes
Kuntze-Fechner, Maximilian W.,Kerpen, Christoph,Schmidt, David,H?ring, Mathias,Radius, Udo
, p. 1767 - 1775 (2019/03/11)
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.
Quantitative estimation of the reactivity of perfluorinated methylbenzenes and benzocycloalkenes in nucleophilic substitution reactions
Rodionov, Peter P.,Osina, Ol'Ga I.,Platonov, Vyacheslav E.,Yakobson, Georg G.
, p. 986 - 993 (2007/10/02)
The kinetics of the reactions of perfluorinated xylenes, mesitylene, p-cymene, benzocycloalkenes (benzocyclobutene, indane, tetralin) and octafluoronaphthalene with sodium methoxide and piperidine have been studied.Rate constants of the reactions of perfluorinated aromatic compounds with sodium methoxide (taking into account one reaction centre) are shown to incease in the order: hexafluorobenzene perfluoro-p-xylene ca.= perfluoro-p-cymene octafluorotoluene ca.= perfluoro-m-xylene perfluoromesitylene ca.= perfluoro-o-xylene.In the reactions with piperidine, a different sequence was observed: hexafluorobenzene perfluoro-p-xylene perfluoro-p-cymene perfluoromesitylene perfluoro-m-xylene octafluorotoluene perfluoro-o-xylene.In the reactions of perfluorobenzocycloalkenes with sodium methoxide and piperidine, the reactivity grows by about a factor of 2 with increase of the perfluoroalicyclic ring size by one CF2-group, in the following order: perfluorobenzocyclobutene perfluoroindan perfluorotetralin.
REACTION OF AROMATIC COMPOUNDS WITH NUCLEOPHILIC REAGENTS IN LIQUID AMMONIA. II. NUCLEOPHILIC SUBSTITUTION IN NITROHALOGENO AND POLYFLUORINATED AROMATIC COMPOUNDS
Shtark, A. V.,Kizner, T. A.,Shteingarts, V. D.
, p. 2051 - 2056 (2007/10/02)
The possibility of aromatic nucleophilic substitution in liquid ammonia was investigated for the case of the reaction of p-nitrochlorobenzene, 2,4-dinitrochlorobenzene, hexafluorobenzene, bromopentafluorobenzene, pentafluorobenzene, and octafluoronaphthalene with a series of charged nucleophiles (potassium hydroxide and sulphite, alcoholates, sodium azide, thiophenolate, phenolate, and sulfide) at -70 to -33 deg C.It was shown that alkyl ethers of p-nitrophenol, phenyl p-nitrophenyl sulfide, 2,4-dinitrophenyl azide, polyfluorinaqted phenols, and their ethers can be obtained with good yields.Comparisons of the results with published data on the rate of the same reactions in other solvents shows that liquid ammonia is highly effective as a solvent for aromatic nucleophilic substitution reactions and in some cases makes it possible to avoid side processes.
