Gold-mediated C–H bond functionalisation

Boorman, Tanya C.; Larrosa, Igor

doi:10.1039/c0cs00098a

Cited by 453 publications

(143 citation statements)

References 70 publications

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“…Another possible alternative would be nucleophilic activation of indole (6) by auration on the three position. [30] The formed Au-complex would then act as nucleophile instead of indole (6) in the described catalytic cycles.…”

Section: Mechanistic Investigationsmentioning

confidence: 99%

Ethynyl Benziodoxolones for the Direct Alkynylation of Heterocycles: Structural Requirement, Improved Procedure for Pyrroles, and Insights into the Mechanism

Brand

Chevalley

Scopelliti

et al. 2012

Chemistry A European J

171

121

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This report describes a full study of the gold‐catalyzed direct alkynylation of indoles, pyrroles, and thiophenes using alkynyl hypervalent iodine reagents, especially the study of the structural requirements of alkynyl benziodoxolones for an efficient acetylene transfer to heterocycles. An improved procedure for the alkynylation of pyrroles using pyridine as additive is also reported. Nineteen alkynyl benziodoxol(on)es were synthesized and evaluated in the direct alkynylation of indoles and/or thiophenes. Bulky silyl groups as acetylene substituents were optimal. Nevertheless, transfer of aromatic acetylenes to thiophene was achieved for the first time. An accelerating effect of a methyl substituent in both the 3‐ and 6‐position of triisopropylsilylethynyl‐1,2‐benziodoxol‐3(1H)‐one (TIPS‐EBX) on the reaction rate was observed. Competitive experiments between substrates of different nucleophilicity, deuterium labeling experiments, as well as the regioselectivity observed are all in agreement with electrophilic aromatic substitution. Gold(III) 2‐pyridinecarboxylate dichloride was also an efficient catalyst for the reaction. Investigations indicated that gold(III) could be eventually reduced to gold(I) during the process. As a result of these investigations, a π activation or an oxidative mechanism are most probable for the alkynylation reaction.

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Section: Mechanistic Investigationsmentioning

confidence: 99%

Ethynyl Benziodoxolones for the Direct Alkynylation of Heterocycles: Structural Requirement, Improved Procedure for Pyrroles, and Insights into the Mechanism

Brand

Chevalley

Scopelliti

et al. 2012

Chemistry A European J

171

121

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“…Emission spectra in dichloromethane solutions were recorded upon excitation of the samples at 330 nm (4)(5)(6)(7)(8) and 290 nm (9)(10)(11)(12)(13) (Fig. 3) and a dual emission was observed in all cases with maxima at ca.…”

Section: Photophysical Characterizationmentioning

confidence: 99%

Polypyridyl-functionalizated alkynyl gold(i) metallaligands supported by tri- and tetradentate phosphanes

et al. 2017

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A series of alkynyl gold(I) tri and tetratopic metallaligands of the type [Au 3 (CuC-R) 3 (μ 3 -triphosphane)] (R = 2,2'-bipyridin-5-yl or C 10 H 7 N 2 , 2,2':6',2''-terpyridin-4-yl or C 15 H 10 N 3 ; triphosphane = 1,1,1-tris(diphenylphosphanyl)ethane or triphos, 1,3,5-tris(diphenylphosphanyl)benzene or triphosph) and [Au 4 (CuC-R) 4 (μ 4 -tetraphosphane)] (R = C 10 H 7 N 2 , C 15 H 10 N 3 ; tetraphosphane = tetrakis(diphenylphosphanylmethyl)methane or tetraphos, 1,2,3,5-tetrakis(diphenylphosphanyl)benzene or tpbz, tetrakis(diphenylphosphaneylmethyl)-1,2-ethylenediamine or dppeda) were obtained in moderate to good yields. All complexes could be prepared by a reaction between the alkynyl gold(I) polymeric species [Au(CuC-R)] n and the appropriate polyphosphane. An alternative strategy that required the previous synthesis of the appropriate acetylacetonate precursors [Au n (acac) n (μ n -polyphosphane)] ("acac method") was assayed, nevertheless only the polyacac derivatives The photophysical properties of the synthesized compounds were carefully studied and used as a probe of their possible use as multidentate ligands for Cu(I) and Zn(II). The UV-Vis speciation studies of the complexation reactions were conducted via metal titration and, in most cases the dangling units of the ligand were found to behave in a fairy independent manner. While in the case of Cu(I) multiple equilibria exist in solution a single complex is detected for Zn(II) under the conditions studied.

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“…Copper and gold have been directly implicated in M(I)/M(III) oxidative addition and reductive elimination processes [18][19][20][21][22][23][24][25] , whereas such chemistry has never been considered for silver. Nevertheless, silver has been reported as an effective catalyst in cross-coupling reactions such as Agcatalysed Sonogashira couplings 26 and Ag-catalysed Ullmanntype C-heteroatom bond-forming reactions 27 .…”

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confidence: 99%

Direct observation of two-electron Ag(I)/Ag(III) redox cycles in coupling catalysis

et al. 2014

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Silver is extensively used in homogeneous catalysis for organic synthesis owing to its Lewis acidity, and as a powerful one-electron oxidant. However, two-electron redox catalytic cycles, which are most common in noble metal organometallic reactivity, have never been considered. Here we show that a Ag(I)/Ag(III) catalytic cycle is operative in model C–O and C–C cross-coupling reactions. An aryl-Ag(III) species is unequivocally identified as an intermediate in the catalytic cycle and we provide direct evidence of aryl halide oxidative addition and C–N, C–O, C–S, C–C and C–halide bond-forming reductive elimination steps at monometallic silver centres. We anticipate our study as the starting point for expanding Ag(I)/ Ag(III) redox chemistry into new methodologies for organic synthesis, resembling well-known copper or palladium cross-coupling catalysis. Furthermore, findings described herein provide unique fundamental mechanistic understanding on Ag-catalysed cross-coupling reactions and dismiss the generally accepted conception that silver redox chemistry can only arise from one-electron processesThis work was supported by grants from the European Research Council (Starting Grant Project ERC-2011-StG-277801), the Spanish MINECO (CTQ2012-37420-C02-01/BQU, CTQ2012-32436, Consolider-Ingenio CSD2010-00065, INNPLANTA project INP-2011-0059-PCT-420000-ACT1) and the Catalan DIUE of the Generalitat de Catalunya (2009SGR637

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Gold-mediated C–H bond functionalisation

Cited by 453 publications

References 70 publications

Ethynyl Benziodoxolones for the Direct Alkynylation of Heterocycles: Structural Requirement, Improved Procedure for Pyrroles, and Insights into the Mechanism

Ethynyl Benziodoxolones for the Direct Alkynylation of Heterocycles: Structural Requirement, Improved Procedure for Pyrroles, and Insights into the Mechanism

Polypyridyl-functionalizated alkynyl gold(i) metallaligands supported by tri- and tetradentate phosphanes

Direct observation of two-electron Ag(I)/Ag(III) redox cycles in coupling catalysis

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