Copper-Catalyzed Aerobic Oxidative Functionalization of an Arene C−H Bond: Evidence for an Aryl-Copper(III) Intermediate

King, Amanda E.; Huffman, Lauren M.; Casitas, Alicia; Costas, Miguel; Ribas, Xavi; Stahl, Shannon S.

doi:10.1021/ja1045378

Cited by 428 publications

(186 citation statements)

References 71 publications

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“…An alternative, putative mechanism via an adatom-related dehydrogenation (Fig. 4b) similar to the one proposed by King et al 32 seems even more unlikely as it is associated with a reaction barrier of 1.9 eV. Moreover, there is no evidence for atomic steps playing a relevant role in the potential dehydrogenation according to the STM observations.…”

Section: Resultsmentioning

confidence: 55%

“…The hierarchic steps in which the reaction proceeds demonstrate how sensitive the alkyne C À H activation and reactivity responds to subtle changes of the local environment. Moreover, with the reaction pathway being established via a tautomerized intermediate, there is no need to a priori invoke an organometallic reaction intermediate, that is, there is a formal similarity with the envisioned mechanism in silver acetylide formation in the presence of a base 23 , being at variance with related processes mediated by transient attachment of copper ions at the ethynyl group 32 . It is also interesting to note that it was impossible to induce covalent bonding of acetylene molecules on an oxide surface by the presence of single silver atoms 39 .…”

Section: Discussionmentioning

confidence: 99%

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Homo-coupling of terminal alkynes on a noble metal surface

et al. 2012

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The covalent linking of acetylenes presents an important route for the fabrication of novel carbon-based scaffolds and two-dimensional materials distinct from graphene. To date few attempts have been reported to implement this strategy at well-defined interfaces or monolayer templates. Here we demonstrate through real space direct visualization and manipulation in combination with X-ray photoelectron spectroscopy and density functional theory calculations the Ag surface-mediated terminal alkyne C sp À H bond activation and concomitant homo-coupling in a process formally reminiscent of the classical Glaser-Hay type reaction. The alkyne homo-coupling takes place on the Ag(111) noble metal surface in ultrahigh vacuum under soft conditions in the absence of conventionally used transition metal catalysts and with volatile H 2 as the only by-product. With the employed multitopic ethynyl species, we demonstrate a hierarchic reaction pathway that affords discrete compounds or polymeric networks featuring a conjugated backbone. This presents a new approach towards on-surface covalent chemistry and the realization of two-dimensional carbon-rich or allcarbon polymers.

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Section: Resultsmentioning

confidence: 55%

Section: Discussionmentioning

confidence: 99%

Homo-coupling of terminal alkynes on a noble metal surface

et al. 2012

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“…If acetonitrile is replaced with methanol as the solvent, complex 2 reacts quantitatively to afford the corresponding aryl methyl ether, as described previously. [25] The dependence of the reaction rate on the [phenol] was investigated with several para-substituted phenols. The reactions of complex 2 with p-methoxy-and p-fluorophenol The effect of phenol pK a was evaluated by comparing the reaction rates obtained when the reaction was carried out in the presence of 10 equivalents of nucleophile.…”

Section: Summary Of Previous Work With Nitrogen Nucleophilesmentioning

confidence: 99%

Observation and Mechanistic Study of Facile CO Bond Formation between a Well‐Defined Aryl–Copper(III) Complex and Oxygen Nucleophiles

Huffman

Casitas

Font

et al. 2011

Chemistry A European J

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125

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A well-defined macrocyclic aryl–Cu(III) complex (2) reacts readily with a variety of oxygen nucleophiles, including carboxylic acids, phenols and alcohols, under mild conditions to form the corresponding aryl esters, biaryl ethers and alkyl aryl ethers. The relationship between these reactions and catalytic C-O coupling methods is demonstrated by the reaction of the macrocyclic aryl–Br species with acetic acid and p-fluorophenol in the presence of 10 mol% Cu(I). An aryl-Cu(III)-Br species 2(Br) was observed as an intermediate in the catalytic reaction. Investigation of the stoichiometric C-O bond-forming reactions revealed nucleophile-dependent changes in the mechanism. The reaction of 2 with carboxylic acids revealed a positive correlation between the log(k(obs)) and the pK(a) of the nucleophile (less-acidic nucleophiles react more rapidly), whereas a negative correlation was observed with most phenols (more-acidic phenols react more rapidly). The latter trend resembles previous observations with nitrogen nucleophiles. With carboxylic acids and acidic phenols, UV-visible spectroscopic data support the formation of a ground-state adduct between 2 and the oxygen nucleophile. Collectively, kinetic and spectroscopic data support a unified mechanism for aryl-O coupling from the Cu(III) complex, consisting of nucleophile coordination to the Cu(III) center, deprotonation of the coordinated nucleophile, and C-O (or C-N) reductive elimination from Cu(III).

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“…[146] Huffman und Stahl berichteten 2008 über die Reaktion einiger verschiedener Stickstoffnucleophile mit dem triazamakrocyclischen Aryl-Cu III -Komplex 18, der den hochvalenten Cu-Intermediaten der oxidativen [147] und nicht-oxidativen [120] [140] Stahl und Ribas führten kürzlich mit dem makrocyclischen Aren 17 eine katalytische C-H-Oxidation unter 1 atm O 2 mit 10 Mol-% Cu(ClO 4 ) 2 oder CuBr 2 durch (Schema 64). [146] …”

Section: Hochvalente Organokupfer-komplexe In Nicht-oxidativen Reaktiunclassified

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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Copper-Catalyzed Aerobic Oxidative Functionalization of an Arene C−H Bond: Evidence for an Aryl-Copper(III) Intermediate

Cited by 428 publications

References 71 publications

Homo-coupling of terminal alkynes on a noble metal surface

Homo-coupling of terminal alkynes on a noble metal surface

Observation and Mechanistic Study of Facile CO Bond Formation between a Well‐Defined Aryl–Copper(III) Complex and Oxygen Nucleophiles

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

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