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Mechanistic Aspects of the Kharasch Addition Reaction Catalyzed by Organonickel(II)

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Organometallics 1997, 16, 4985-4994 4985 Mechanistic Aspects of the Kharasch Addition Reaction Catalyzed by Organonickel(II) Complexes Containing the Monoanionic Terdentate Aryldiamine Ligand System -† [C6H2(CH2NMe2)2-2,6-R-4] Lucia A. van de Kuil,‡,§ David M. Grove,‡ Robert A. Gossage,‡ Jan W. Zwikker,§ Leonardus W. Jenneskens,§ Wiendelt Drenth,§ and Gerard van Koten*,‡ Debye Institute, Departments of Metal-Mediated Synthesis and Physical Organic Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands Received January 28, 1997X The addition reaction of polyhalogenated alkanes to alkenes (Kharasch addition reaction) is homogeneously catalyzed in the absence of O2 under mild reaction conditions (25 °C) by II the arylnickel complexes [Ni {C6H2(CH2NMe2)2-2,6-R-4}Br] (R ) H, MeC(O), Cl, MeO, NH2) and shows a high selectivity for the 1:1 adduct. Kinetic data on the catalytic system with [Ni{C6H3(CH2NMe2)2-2,6}Br] (R ) H; abbreviated as [Ni(NCN)Br]), methyl methacrylate, and CCl4 reveal a rate of reaction that is first order in nickel complex and in alkene. In our series of para-substituted arylnickel catalysts, the rate of catalysis increases with the electron donating character of the para substituents on the aryl ligand and this rate correlates directly with the NiII/NiIII redox potential. These data, together with separate spectroscopic studies and results from individual experiments employing other solvents, other polyhalogenated alkanes such as CBr4 and CF3CCl3 and other alkene substrates such as styrene, 1-octene, and cyclohexene, lead to the proposal of a catalytic cycle based on a nonchain mechanism with a mononuclear nickel species. Before or in the rate-determining step oxidation of the Ni(II) center to a d7 arylnickel(III) species occurs by a single electron transfer and halide transfer from the polyhalogenated alkane in an inner-sphere activated complex [Ni(NCN)- (µ-Cl)CCl4]. This step generates an organic radical intermediate which is proposed to stay in the coordination sphere of the metal where it reacts with the alkene. The reaction rate decreases with an increase in the steric congestion at the N-donor centers in derivatives of the [Ni(NCN)Br] catalyst (i.e., NMe2 > NEt2 > NMe(i-Pr) > NMe(t-Bu)). This behavior is consistent with the characteristics for an inner-sphere electron-transfer process. Selective 1:1 Kharasch product formation then results from a chain transfer in the Ni(III) coordination sphere by the reverse process, i.e., single electron transfer with concomitant halide transfer. Important conclusions of this study are that the initially active site of the catalyst is the Ni-X unit (X ) halide) and that activation of CCl4 occurs in the absence of a free coordination site. Introduction substituents are introduced at the same time. The application of such 1:1 adducts as synthetic intermedi- The generation of carbon carbon bonds is an impor- - ates has been reviewed.2 The Kharasch addition reac- tant reaction step in organic synthesis. One way to form tion requires either a free radical precursor as the such a bond and, thus, extend a carbon chain is by the promotor or a metal complex as the catalyst. The addition of a polyhalogenated alkane to an alkene reaction has been extensively investigated both for substrate to form a 1:1 adduct, as shown in eq 1. This synthetic purposes and for mechanistic information. The ′ classical free radical chain mechanism is operative not ′ RH R H only with initiators such as light, heat, and peroxides,1 CX3Y + C C XCCCX2Y (1) but also with a variety of metal complexes.3 With RH RH certain substrates, it can be difficult to select for the X = halogen; Y = H, halogen, CF3, or other electronegative group (1) (a) Kharasch, M. S.; Engelmann, H.; Mayo, F. R. J. Org. Chem. 1938, 2, 288. (b) Kharasch, M. S.; Jensen, E. V.; Urry, W. H. Science type of reaction is generally known as the Kharasch 1945, 102, 169. (c) Kharasch, M. S.; Elwood, E. V.; Urry, W. H. J. Am. addition reaction,1 and in addition to the formation of Chem. Soc. 1947, 69, 1100. (d) Kharasch, M. S.; Friedlander, H. N. J. Org. Chem. 1949, 14, 239. (e) Kharasch, M. S.; Sage, M. Ibid. 1949, a new carbon-carbon σ-bond, synthetically useful halide 14, 537. (f) Kharasch, M. S.; Simon, E.; Nudenberg, W. Ibid. 1953, 18, 328. (g) Walling, C.; Huyser, E. S. Org. React. 1963, 13, 91. (h) Walling, * To whom correspondence should be addressed. E-mail: C. Free Radicals in Solution; Wiley: New York, 1963. [email protected]. (2) Bellus, D. Pure Appl. Chem. 1985, 57, 1827. † Presented in part at the 6th IUPAC Symposium on Organometallic (3) (a) Ha´jek, M.; Silhavy, P.; Ma´lek, J. Collect. Czech. Chem. Chemistry Directed Towards Organic Synthesis, Utrecht, The Neth- Commun. 1980, 45, 3488. (b) Maruoka, K.; Sano, H.; Fukutani, Y.; erlands, 1991. Yamamoto, H. Chem. Lett. 1985, 1689. (c) Grigg, R.; Devlin, J.; ‡ Department of Metal-Mediated Synthesis. Ramasubbu, A.; Scott, R. M.; Stevenson, P. J. Chem. Soc., Perkin § Department of Physical Organic Chemistry. Trans. 1 1987, 1515. (d) Friedlina, R. Kh.; Velichko, F. K. Synthesis X Abstract published in Advance ACS Abstracts, October 1, 1997. 1977, 145. S0276-7333(97)00061-7 CCC: $14.00 © 1997 American Chemical Society 4986 Organometallics, Vol. 16, No. 23, 1997 van de Kuil et al. Scheme 1 Figure 1. Square-planar arylnickel complexes II [Ni {C6H2(CH2NMe2)2-2,6-R-4}Br], 1-5. Complex 1 is ab- breviated as [Ni(NCN)Br]. Kharasch addition because of radical stability or activity which leads to chain propagation and, thus, the forma- Scheme 2 tion of 1:2 adducts, telomers and/or polymers. The pre- requisite for selective 1:1 addition is, thus, controlled chain termination. For metal-complex-catalyzed reac- tions, the two principal types of mechanisms are pri- marily discriminated by the role of the metal species. The first type of mechanism (Scheme 1) involves the inclusion of a redox system into the propagation steps such a mechanism for Kharasch catalysis with com- of the conventional free radical chain addition. The plexes of the general formula [MCl2(PPh3)x](M)Ru, x metal complex then participates both in the initiation ) 3; M ) Ni, x ) 2). Recent studies into applications and in the chain propagation as a halogen transfer and mechanisms of the complex-catalyzed Kharasch agent, in its oxidized form being a much more reactive addition reaction with a variety of metal species9 have halogen donor than the polyhalogenated alkane.4 This included a suggestion of another type of mechanism reaction sequence is commonly encountered in the so- involving oxidative addition of a polyhalogenated alkane called atom transfer radical addition (ATRA) reactions to a rhodium(I) complex.9g 5,6 for C-C bond formation in organic synthesis, as well Earlier studies in this laboratory10 have shown that as in controlled living radical polymerization by atom the arylnickel(II) complex [Ni{C6H2(CH2NMe2)2-2,6-R- 7 transfer polymerization (ATRAP). This redox chain 4}Br] (R ) H; 1), depicted in Figure 1, is an active mechanism has been postulated for copper and iron homogeneous catalyst for the Kharasch addition reac- halides as catalysts.4a-i tion with a range of polyhalogenated alkanes (e.g., CCl4, In the second type of Kharasch addition, the mecha- CBr4, and CF3CCl3) and a variety of terminal alkenes nism proceeds via a non-chain pathway as depicted in (e.g., methyl methacrylate, styrene, and 1-octene) under 8 Scheme 2. The organic radicals that result from a mild reaction conditions.10,11 Furthermore, we have single electron transfer (SET) between the metal com- used the substituent R to graft the arylnickel moiety plex and a polyhalogenated alkane are more-or-less not only to polysiloxane polymers12a and silica12b but ‘caged’ in the coordination sphere of the metal species. also on to carbosilane dendrimers13 and have shown that 8a-e 8g Matsumoto et al. and Davis et al. have proposed some of these new (water and organic solvent) soluble materials possess good catalytic activity.12a,13 (4) (a) Asscher, M.; Vofsi, D. J. Chem. Soc. 1961, 2261. (b) Asscher, M.; Vofsi, D. Ibid. 1963, 1887. (c) Asscher, M.; Vofsi, D. Ibid. 1963, Recently, as an extension of the metal-catalyzed 3921. (d) Asscher, M.; Vofsi, D. J. Chem. Soc. B 1968, 947. (e) Orochov, Kharasch addition reaction, Sawamoto et al reported A.; Asscher, M.; Vofsi, D. J. Chem. Soc., Perkin Trans. 2 1973, 1000. (f) Kochi, J. K. Organometallic Mechanisms and Catalysis; Academic that certain metal complexes can homogeneously poly- Press: New York, 1978. (g) Minisci, F. Acc. Chem. Res. 1975, 8, 165. merize methyl methacrylate (MMA) in the presence of (h) Ha´jek, M.; Silhavy, P. Collect. Czech. Chem. Commun. 1983, 48, low concentrations of XCCl (X ) Cl, Br) in aromatic 1710. (i) Vit, Z.; Ha´jek, M. Ibid. 1987, 52, 1280. (j) Davis, R.; Groves, 3 I. F. J. Chem. Soc., Dalton Trans. 1982, 2281. (k) Tsuji, J.; Sato, K.; media. This process is catalyzed by either [RuCl2- 7b,c 7j Nagashima, H. Chem. Lett. 1981, 1169. (l) Tsuji, J.; Sato, K.; Na- (PPh3)3] or [NiX2(PR3)2] in the presence of a Lewis gashima, H. Tetrahedron 1985, 26, 393; Ibid. 1985, 26, 5003. (5) Reviews: (a) Curran, D. P. Synthesis 1988, 489. (b) Curran, D. P. I. Free Radicals in Organic Synthesis and Biology; Minisci, F., Ed.; (8) (a) Matsumoto, H.; Nakano, T.; Nagai, Y. Tetrahedron Lett. 1973, Kluwer: Dordrecht, The Netherlands, 1989; p 37. (c) Curran D. P. In 5147. (b) Matsumoto, H.; Nakano, T.; Nagai, Y.
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    catalysts Review Decomposition of Ruthenium OlefinOlefin Metathesis CatalystMetathesis Catalyst Magdalena Jawiczuk 1,, Anna Anna Marczyk Marczyk 1,21,2 andand Bartosz Bartosz Trzaskowski Trzaskowski 1,* 1,* 1 1 CentreCentre of of New New Technologies, Technologies, University University of of Warsaw, Warsaw, Banacha Banacha 2c, 2c, 02-097 02-097 Warsaw, Warsaw, Poland; [email protected]@cent.uw.edu.pl (M.J.); (M.J.); [email protected] [email protected] (A.M.) (A.M.) 2 Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland 2 Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland * Correspondence: [email protected] * Correspondence: [email protected] Received: 28 28 June 2020; Accepted: 02 2 AugustAugust 2020;2020; Published:Published: 5date August 2020 Abstract: RutheniumRuthenium olefin olefin metathesis metathesis catalysts catalysts are are one one of of the most commonly used class of catalysts. There There are are multiple multiple reviews reviews on on their their us useses in in various branches of chemistry and other sciences but a detailed review of their decomposition is missing, despite a large number of recent and important advances advances in in this this field. field. In In particular, particular, in in the the last last five five years years several several new new mechanism mechanism of decomposition,of decomposition, both both olefin-driven olefin-driven as well as well as induc as induceded by external by external agents, agents, have have been been suggested suggested and usedand usedto explain to explain differences differences in the decomposition in the decomposition rates and rates the metathesis and the metathesis activities activitiesof both standard, of both N-heterocyclicstandard, N-heterocyclic carbene-based carbene-based systems and systems the recently and the developed recently developed cyclic alkyl cyclic amino alkyl carbene- amino containingcarbene-containing complexes.
  • X International Conference “Mechanisms of Catalytic Reactions”

    X International Conference “Mechanisms of Catalytic Reactions”

    Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia Zelinsky Institute of Organic Chemistry RAS, Moscow, Russia Lomonosov Moscow State University, Moscow, Russia 2016 X International Conference “Mechanisms of Catalytic Reactions” Svetlogorsk, Kaliningrad Region, Russia October 2 - 6, 2016 ABSTRACTS Novosibirsk-2016 Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia Zelinsky Institute of Organic Chemistry RAS, Moscow, Russia Lomonosov Moscow State University, Moscow, Russia X International Conference “Mechanisms of Catalytic Reactions” Svetlogorsk, Kaliningrad Region, Russia October 2 - 6, 2016 ABSTRACTS Novosibirsk-2016 УДК 544.47+66.09 ББК Г544 M45 Mechanisms of Catalytic Reactions. X International Conference (MCR-X). (October 2 - 6, 2016, Svetlogorsk, Kaliningrad Region, Russia) [Electronic resourse]: Book of abstracts / Boreskov Institute of Catalysis SB RAS ed.: prof. V.I. Bukhtiyarov, - Novosibirsk: BIC, 2016. p.328, – 1 electronic optical disc (CD-R). ISBN 978-5-906376-15-2 В надзаг.: Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia Zelinsky Institute of Organic Chemistry RAS, Moscow, Russia Lomonosov Moscow State University, Moscow, Russia Topics of book: – First-principles approach, theory and simulation in catalysis; – Advanced methods for studies of mechanisms of catalyzed reactions; – In-situ and operando studies of model and real catalysts; – Kinetics and reaction intermediates of catalyzed processes; – From mechanistic studies to design of advanced catalyst systems. The Conference is accompanied