Coupling of aryl chlorides by nickel and reducing metals

Colon, I.; Kelsey, Donald R.

doi:10.1021/jo00364a002

Cited by 404 publications

(283 citation statements)

References 6 publications

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“…These results give evidence for the electrophilic character of the nickel center, which is consistent with the previous studies of C-H bond activation of nickel center in solution [63][64][65].…”

Section: Fragmentation Of [Arni(pph 3 ) 2 ]supporting

confidence: 92%

Studies on gas-phase cyclometalations of [ArNi(PPh₃)n]⁺ (n = 1 or 2) by electrospray ionization tandem mass spectrometry

Zhou

Zhao

Chen

et al. 2010

J. Am. Soc. Mass Spectrom.

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Gas-phase cyclometalation of [ArNi(PPh 3 ) n ] ϩ (n ϭ 1, 2) complexes have been studied by ESI-MS/MS. The electron-donating substituents of aromatic iodides in the para position were found to inhibit the cyclometalation process of losing ArH, while the electron-withdrawing substituents in the para position were found to enhance it. These results indicate that the cyclometalation process of losing ArH is favored by electron-deficient aromatic groups. In addition, the detailed dissociation pathways of the cationic nickel complexes were studied, and among these pathways, the process of aryl-aryl interchange was also found to proceed in ESI-MS/MS. (J Am Soc Mass Spectrom 2010, 21, 1265-1274) © 2010 American Society for Mass Spectrometry C yclometalation occurs when a ligand on an organo-metal complex undergoes an intramolecular metalation with concomitant formation of a chelate ring containing a metal-carbon bond [1]. This kind of transformation has attracted significant attention over the past three decades [2][3][4][5][6][7]. On the one hand, cyclometalation can be detrimental to a desired reaction course and can be prevented by a variety of techniques to improve catalytic efficiency of the metal complex. As cyclometalation methodology has been developed, a number of cyclometalated complexes were employed successfully in organic synthesis [8,9], catalysis [10 -12], and photochemistry [13][14][15]. Mechanisms for the cyclometalation associated with C-H bond cleavage have been proposed [16 -21], and three related mechanisms for C-H bond cleavage are typically accepted: oxidative addition, electrophilic substitution, and multicentered pathways (such as -bond metathesis) [22][23][24][25][26]. The actual mechanisms that pertain for cyclometalation of a given metal complex are highly dependent on the exact nature of the metal complexes, identities of hydrocarbon substituents, solvents involved, and specific operating conditions [21]. As a result, a complete understanding and description of the general mechanism are still lacking, and more data are needed before we can fully describe critical reactivity patterns.The focus to date has been on the study of solutionphase cyclometalations, but gas-phase cyclometalations have recently received more attention [27][28][29]. Generally, gas-phase studies conducted with tandem mass spectrometry (MS/MS) on extremely small sample quantities can theoretically ascertain the propensity for a complex to undergo certain kinds of reactions. The energy conditions and dissociation pathways provide useful insights, with applicability to related solutionphase reactions [30 -40]. Based on the gas-phase methodologies, Henderson and coworkers published their investigation of the cyclometalation of palladium(II) and platinum(II) diphosphine complexes MCl 2 (Ph 2 P (CH 2 ) 5 PPh 2 ) in 2004 [28]. More recently, Schwarz and coworkers explored the whole process of cyclometalation of 2,2=-bipyridine platinum(II) complexes in gas phase by a combination of gas-phase methodologies and theoretical calcu...

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Section: Fragmentation Of [Arni(pph 3 ) 2 ]supporting

confidence: 92%

Studies on gas-phase cyclometalations of [ArNi(PPh₃)n]⁺ (n = 1 or 2) by electrospray ionization tandem mass spectrometry

Zhou

Zhao

Chen

et al. 2010

J. Am. Soc. Mass Spectrom.

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“…Even though zero-valent nickel reagents are generally sensitive, tris(triphenylphosphine)nickel(0) can be generated in situ using the Tiecco/Testaferri [21] modification of Kende's procedure [22]. The dimerization reaction of 10 was crucial and failed in DMF [23,24] or pyridine [25] as a solvent and gave only low yields of the dimer. In these solvents a fast de-bromination reaction took place; the main product was flupirtine (1).…”

Section: Resultsmentioning

confidence: 99%

Isolation, Structure, Synthesis and Cytotoxicity of an Unprecedented Flupirtine Dimer

Csuk

Sommerwerk

Wiese

et al. 2012

Zeitschrift Für Naturforschung B

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A previously unknown dimer of the well-established analgesic flupirtine has been found, and its structure was revealed by ESI-MS, NMR spectroscopy and an independent synthesis. Thus, starting from 2-amino-6-chloro-3-nitro-pyridine the target compound was obtained in a four-step synthesis. Key-step of this synthesis is a nickel-mediated aryl-aryl coupling. The dimer 4 did not show any cytotoxicity, and its IC 50 values were > 30 µm for all six human cancer cell lines and mouse fibroblasts used in this study.

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“…Employing a Ni(II) salt in the presence of zinc as a reducing agent overcomes this issue. 18 This procedure has been used to produce homo-coupling compounds of aryl halides in high yields when polar solvents such as DMF and DMAc are used. We prepared poly(fluorene)s by irradiating with microwaves from 9,9-dialkylated 2,7-dibromofluorene (1a-e), and the results are shown in Figure 1.…”

Section: Resultsmentioning

confidence: 99%

Microwave-Assisted Preparation of Poly(fluorene)s by Ni-Catalyzed Polymerization

et al. 2009

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A series of poly(fluorene)s was prepared from 9,9-dialkylated-2,7-dibromofluorenes by Ni-catalyzed polymerization (Yamamoto coupling reaction) under microwave irradiation. Compared to the oil heating bath method (24 h, M w 12800, yield 82%), microwave irradiation of 9,9-di-n-octyl-2,7-dibromofluorene produced poly[2,7-(9,9-di-n-octylfluorene)] with a high molecular weight (M w 24200) and yield (88%) in a short time (180 min). Hence, the microwave irradiation method effectively shortened the reaction time and increased the molecular weight of the prepared poly(fluorene)s.

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Coupling of aryl chlorides by nickel and reducing metals

Cited by 404 publications

References 6 publications

Studies on gas-phase cyclometalations of [ArNi(PPh₃)n]⁺ (n = 1 or 2) by electrospray ionization tandem mass spectrometry

Studies on gas-phase cyclometalations of [ArNi(PPh₃)n]⁺ (n = 1 or 2) by electrospray ionization tandem mass spectrometry

Isolation, Structure, Synthesis and Cytotoxicity of an Unprecedented Flupirtine Dimer

Microwave-Assisted Preparation of Poly(fluorene)s by Ni-Catalyzed Polymerization

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Coupling of aryl chlorides by nickel and reducing metals

Cited by 404 publications

References 6 publications

Studies on gas-phase cyclometalations of [ArNi(PPh3)n]+ (n = 1 or 2) by electrospray ionization tandem mass spectrometry

Studies on gas-phase cyclometalations of [ArNi(PPh3)n]+ (n = 1 or 2) by electrospray ionization tandem mass spectrometry

Isolation, Structure, Synthesis and Cytotoxicity of an Unprecedented Flupirtine Dimer

Microwave-Assisted Preparation of Poly(fluorene)s by Ni-Catalyzed Polymerization

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Studies on gas-phase cyclometalations of [ArNi(PPh₃)n]⁺ (n = 1 or 2) by electrospray ionization tandem mass spectrometry

Studies on gas-phase cyclometalations of [ArNi(PPh₃)n]⁺ (n = 1 or 2) by electrospray ionization tandem mass spectrometry