A Cu(II)-catalyzed oxidative substitution of pyrazole C–H bonds afforded the first halogenated pyrazolecarboxylato-based copper(II) coordination complexes

Chen, Lan-Fen; Cao, Xiaoshu; Li, Zhaoji; Cheng, Jianchun; Lin, Qipu; Yao, Yuan‐Gen

doi:10.1016/j.inoche.2008.05.011

Cited by 13 publications

(4 citation statements)

References 44 publications

(15 reference statements)

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“…That the centrosymmetric pairs of halogen bonds present a robust motif can also be seen in the crystal structures of the two isostructural complexes presented by Yao and co‐workers 83. These are copper(II) complexes formed with 4‐bromopyrazole‐3,5‐dicarboxylic (KOGMOJ) and 4‐iodopyrazole‐3,5‐dicarboxylic acid (KOGMUP); both complexes engage in extensive hydrogen bonding but also form centrosymmetric pairs of C–Br/I ··· O halogen bonds (Br ··· O 2.97 Å, 11 % reduction and I ··· O 3.00 Å, 14 % reduction).…”

Section: Halogen Bonding Involving Metal Complexessupporting

confidence: 58%

Alternative Motifs for Halogen Bonding

et al. 2013

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The halogen‐bonding interaction is one of the rising stars in supramolecular chemistry. Although other weak interactions and their influence on the structure and chemistry of various molecules, complexes and materials have been investigated thoroughly, the field of halogen bonding is still quite unexplored and its impact on chemistry in general is yet to be fully revealed. In principle, every Y–X bond (Y = electron‐withdrawing atom or moiety, X = halogen atom) can act as a halogen‐bond donor when the halogen is polarized enough by Y. Perfluorohalocarbons are iconic halogen‐bond donor molecules in which Y is a perfluorinated aryl or alkyl moiety and X is either iodine or bromine. In this article, alternative halogen‐bond motifs such as X2···A and Ar–X···A [A = Lewis basic halogen‐bond‐accepting atom of a molecule or ion; Ar = neutral or charged (hetero)aromatic system] are reviewed. In addition, haloalkenes, haloalkynes, N‐haloamides and other non‐metallic halogen‐bond donors and their respective halogen‐bonded structures will also be described. Although purely organic halogen‐bonding motifs are very prominent, the role of metal complexes in halogen bonding is becoming increasingly evident as well, which is also reflected in this review. Finally, halogen bonding in solution is briefly highlighted. Contemporary research is proving that halogen bonding is more than a solid‐state phenomenon and is now a well‐recognized weak interaction in chemistry.

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Section: Halogen Bonding Involving Metal Complexessupporting

confidence: 58%

Alternative Motifs for Halogen Bonding

et al. 2013

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“…[86] Yao and co-workers reported an oxidative C À H halogenation of pyrazole-3,5-dicarboxylic acid using stoichiometric CuCl 2 , KOH, and halide salts. [87] After 3 days at 160 8C, halogenated pyrazoles were isolated as Cu II coordination complexes; halogenation is proposed to benefit from a directing effect by pendant carboxylates. [88] These reactions qualitatively resemble Pd-catalyzed chelate-directed C À H functionalization reactions, [4c] but preliminary mechanistic insights suggest the reactions proceed by a different mechanism.…”

Section: Chelate-directed Càh Oxidation Reactionsmentioning

confidence: 99%

Copper‐Catalyzed Aerobic Oxidative CH Functionalizations: Trends and Mechanistic Insights

2011

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The selective oxidation of C-H bonds and the use of O(2) as a stoichiometric oxidant represent two prominent challenges in organic chemistry. Copper(II) is a versatile oxidant, capable of promoting a wide range of oxidative coupling reactions initiated by single-electron transfer (SET) from electron-rich organic molecules. Many of these reactions can be rendered catalytic in Cu by employing molecular oxygen as a stoichiometric oxidant to regenerate the active copper(II) catalyst. Meanwhile, numerous other recently reported Cu-catalyzed C-H oxidation reactions feature substrates that are electron-deficient or appear unlikely to undergo single-electron transfer to copper(II). In some of these cases, evidence has been obtained for the involvement of organocopper(III) intermediates in the reaction mechanism. Organometallic C-H oxidation reactions of this type represent important new opportunities for the field of Cu-catalyzed aerobic oxidations.

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“…[75] [86] Yao et al berichteten über eine oxidative C-H-Halogenierung von Pyrazol-3,5-dicarbonsäure unter Verwendung von stçchiometrischem CuCl 2 , KOH und Halogenidsalzen. [87] Nach 3 Tagen bei 160 8C wurden die halogenierten Pyrazole als Cu II -Koordinationskomplexe isoliert. Es wird angenommen, dass die Halogenierung durch einen dirigierenden Effekt der anhängenden Carboxylate begünstigt wird.…”

Section: Chelatgesteuerte C-h-oxidationenunclassified

Kupferkatalysierte aerobe oxidative C‐H‐Funktionalisierungen: Trends und Erkenntnisse zum Mechanismus

2011

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Die selektive Oxidation von C‐H‐Bindungen und der Einsatz von O2 als stöchiometrisches Oxidationsmittel stellen zwei wesentliche Herausforderungen in der organischen Chemie dar. Kupfer(II) ist ein vielseitiges Oxidationsmittel für verschiedene oxidative Kupplungen, die durch Einelektronen‐Transfer (SET) von elektronenreichen organischen Molekülen ausgelöst werden. Viele dieser Reaktionen können mit Kupfer katalytisch durchgeführt werden, wenn molekularer Sauerstoff als Oxidationsmittel eingesetzt wird, um den aktiven Kupfer(II)‐Katalysator zu regenerieren. Daneben wurden auch zahlreiche neue Cu‐katalysierte C‐H‐Oxidationen mit elektronenarmen Substraten beschrieben, von denen ein SET zum Kupfer(II) unwahrscheinlich scheint. In einigen dieser Fälle konnte die Beteiligung von Organokupfer(III)‐Intermediaten im Reaktionsmechanismus nachgewiesen werden. Metallorganische C‐H‐Oxidationen dieser Art eröffnen neue bedeutende Möglichkeiten für das Gebiet der Cu‐katalysierten aeroben Oxidationen.

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A Cu(II)-catalyzed oxidative substitution of pyrazole C–H bonds afforded the first halogenated pyrazolecarboxylato-based copper(II) coordination complexes

Cited by 13 publications

References 44 publications

Alternative Motifs for Halogen Bonding

Alternative Motifs for Halogen Bonding

Copper‐Catalyzed Aerobic Oxidative CH Functionalizations: Trends and Mechanistic Insights

Kupferkatalysierte aerobe oxidative C‐H‐Funktionalisierungen: Trends und Erkenntnisse zum Mechanismus

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