Gold‐Catalyzed C(sp<sup>2</sup>)−C(sp) Coupling by Alkynylation through Oxidative Addition of Bromoalkynes

Yang, Yangyang; Schießl, Jasmin; Zallouz, Sirine; Göker, Verena; Gross, Jürgen H.; Rudolph, Matthias; Röminger, Frank; Hashmi, A. Stephen K.

doi:10.1002/chem.201902213

“…Pioneering work by Hashmi and co-workers demonstrated visible light gold(I)-catalyzed C-C cross coupling using aryldiazonium salts without a photosensitizer and the proof of oxidative addition of diazonium salts at gold(I) centers to access organogold(III) complexes. [42][43][44] Importantly, this photosensitizer-free gold catalysis does not use external oxidants and has been used to synthesize biaryls under mild conditions using substrates with halogen or boronic acid functionality. [45][46][47] Bourissou and Toste stimulated the pursuit of oxidative addition at gold(I) centers.…”

Section: (F)mentioning

confidence: 99%

Stable Au(I) catalysts for oxidant-free C-H functionalization with iodoarenes

Mertens

¹

,

Greif

²

,

Coogle

³

et al. 2022

Journal of Catalysis

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“…ChemSusChem 2020, 13,1986 -1990 www.chemsuschem.org In conclusion, an operationally simple, visible light-mediated [34] oxidative addition [35] of diazonium salts to DMSAu I Cl, DMSAu I C 6 F 5 or NHCAu I Cl for the synthesis of [C^N^C]gold(III) complexes,n ot dependent on additional photosensitizers, was developed. This technology allows the first mercury-free synthesis of well-defined gold complexes, openingn ew gates especially for medicalu se.…”

Section: Scheme3proposed Reaction Mechanismmentioning

confidence: 99%

“…[32] .Scheme2.Different applications of the oxidativeadditions trategy and further reaction.Scheme3.Proposed reaction mechanism. the aryl ring to generate Whelandc omplex III.R earomatization under liberation of ap roton then delivers the desired [C^N^C]AuCl complex (IV).In conclusion, an operationally simple, visible light-mediated [34] oxidative addition [35] of diazonium salts to DMSAu I Cl, DMSAu I C 6 F 5 or NHCAu I Cl for the synthesis of [C^N^C]gold(III) complexes,n ot dependent on additional photosensitizers, was developed. This technology allows the first mercury-free synthesis of well-defined gold complexes, openingn ew gates especially for medicalu se.…”

mentioning

confidence: 96%

Mercury‐Free Synthesis of Pincer [C^N^C]Au^III Complexes by an Oxidative Addition/CH Activation Cascade

Eppel

¹

,

Rudolph

²

,

Röminger

³

et al. 2020

Self Cite

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Startingf rom the commercially available dimethyl sulfidegold(I) chloride complex (DMSAuCl) and diazonium salts in the presenceo f2 ,6-di-tert-butyl-4-methylpyridine as base, symmetric and unsymmetric [C^N^C]Au III Cl complexesw ere synthesized in as elective, photosensitizer-free, photochemical reaction using blue LED light. This new protocol providest he first mercury-free synthesis of these types of pincer-complexes in moderate-to-excellent yields, startingf rom ar eadily available gold(I) precursor.O wing to the extraordinary properties of the target compounds, like excellent luminescence and high anticancer activities, the synthesis of such complexes is ah ighly active field of research, which might make its way to an industrial application.O wing to the disadvantages of the known protocols, especially the toxicitya nd the selectivity issues in the case of unsymmetric complexes,a voidingt he use of mercury,should further accelerate this ongoing development.With the first synthesis of a[ C^N^C]Au III Cl complex by Che and co-workersi n1 998, af ast rise of research concerning this privileged motif in gold(III) chemistrys tarted. [1] Complexesw ith these tridentate ligands represent the most actively explored structure in the field of goldp incer complexes. [2] By displacement of the chloride ligand with different phosphines, [1] N-heterocyclic carbenes (NHCs), [1,3] thiolates, [1,4] alkyl-groups, [5] or acetylides [6][7][8][9][10] compounds with interesting photo-physical properties, such as intense photoluminescence, weres ynthesized. Aryl-substituted [C^N^C]Au III complexes were already applieda sp hosphorescentd opantsi nt he fabrication of solution-processable and vacuum-deposited organicl ight-emitting devices( OLEDs). [11][12][13][14] Complexes bearingatriazine scaffold in combination with an aryl-substitution showed thermally stimulated delayed phosphorescence, which makes them promising candidates for phosphorescent dopants for OLEDs (PHO-LEDs). [15] Moreover, the cytotoxicity of various complexes towards different tumor cells proved to be very efficient. Especially,p ositivelyc harged [C^N^C]Au III (NHC) complexes were tested as anticancer agents with potentially low drug resistance for multiple molecular targets. [4,[16][17][18][19][20][21] Even thoughm ore than 50 publications on [C^N^C]gold(III) complexes exist, so far alwayst he same synthetic accesst ot he complexes is applied,aprocess which uses highlyt oxic mercury(II) acetate as reactant. In this approach, 2,6-diaryl pyridines are directly metalated with mercury(II)a cetate. At ransmetallation reaction from the organo mercury compound to potassium tetrachloroaurate in refluxing acetonitrile then leads to the corresponding [C^N^C]Au III Cl complex, followed by aC H-activation step of the second arene moiety( Scheme 1a). [11] The product is accompanied by stoichiometric amountso ft he undesired mercury(II) chloride, ah ighly toxic waste. In addition, because of their excellent lipid solubility,u nreacted organic mercury compounds can cause acut...

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“…The formation of C–C bonds from (NHC)Au I –R (NHC = N -heterocyclic carbene; R = Ph, Me, or p -tolyl) occurs upon addition of electrophiles (R′X), such as PhI, MeI, and MeOTf, to form R–R′ as well as homocoupled products R–R and R′–R′ (Scheme b). − The proposed mechanism involves formal trans oxidative addition of the electrophile (R′X) to form an (NHC)Au III (R′)(X)(R) intermediate, followed by competitive (a) C–C reductive elimination to form R′–R and (b) intermolecular transfer of RX from a Au(III) intermediate to (NHC)Au I –R to yield (NHC)Au III (R) 2 (X) followed by C–C reductive elimination to give the homocoupled product R–R. Related to these processes, the addition of F + -donors to Au(I) hydrocarbyl compounds also promotes C–C coupling reactions. − …”

Section: Introductionmentioning

confidence: 99%

Reductive C–C Coupling from Molecular Au(I) Hydrocarbyl Complexes: A Mechanistic Study

Miranda-Pizarro

¹

,

Luo

²

,

Moreno

³

et al. 2021

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Organometallic gold complexes are used in a range of catalytic reactions, and they often serve as catalyst precursors that mediate C–C bond formation. In this study, we investigate C–C coupling to form ethane from various phosphine-ligated gem-digold(I) methyl complexes including [Au 2 (μ-CH 3 )(PMe 2 Ar′) 2 ][NTf 2 ], [Au 2 (μ-CH 3 )(XPhos) 2 ][NTf 2 ], and [Au 2 (μ-CH 3 )( t BuXPhos) 2 ][NTf 2 ] {Ar′ = C 6 H 3 -2,6-(C 6 H 3 -2,6-Me) 2 , C 6 H 3 -2,6-(C 6 H 2 -2,4,6-Me) 2 , C 6 H 3 -2,6-(C 6 H 3 -2,6- i Pr) 2 , or C 6 H 3 -2,6-(C 6 H 2 -2,4,6- i Pr) 2 ; XPhos = 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl; t BuXPhos = 2-di- tert -butylphosphino-2′,4′,6′-triisopropylbiphenyl; NTf 2 = bis(trifluoromethyl sulfonylimide)}. The gem-digold methyl complexes are synthesized through reaction between Au(CH 3 )L and Au(L)(NTf 2 ) {L = phosphines listed above}. For [Au 2 (μ-CH 3 )(XPhos) 2 ][NTf 2 ] and [Au 2 (μ-CH 3 )( t BuXPhos) 2 ][NTf 2 ], solid-state X-ray structures have been elucidated. The rate of ethane formation from [Au 2 (μ-CH 3 )(PMe 2 Ar′) 2 ][NTf 2 ] increases as the steric bulk of the phosphine substituent Ar′ decreases. Monitoring the rate of ethane elimination reactions by multinuclear NMR spectroscopy provides evidence for a second-order dependence on the gem-digold methyl complexes. Using experimental and computational evidence, it is proposed that the mechanism of C–C coupling likely involves (1) cleavage of [Au 2 (μ-CH 3 )(PMe 2 Ar′) 2 ][NTf 2 ] to form Au(PR 2 Ar′)(NTf 2 ) and Au(CH 3 )(PMe 2 Ar′), (2) phosphine migratio...

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Gold‐Catalyzed C(sp²)−C(sp) Coupling by Alkynylation through Oxidative Addition of Bromoalkynes

Cited by 50 publications

References 50 publications

Stable Au(I) catalysts for oxidant-free C-H functionalization with iodoarenes

Stable Au(I) catalysts for oxidant-free C-H functionalization with iodoarenes

Mercury‐Free Synthesis of Pincer [C^N^C]Au^III Complexes by an Oxidative Addition/CH Activation Cascade

Reductive C–C Coupling from Molecular Au(I) Hydrocarbyl Complexes: A Mechanistic Study

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Gold‐Catalyzed C(sp2)−C(sp) Coupling by Alkynylation through Oxidative Addition of Bromoalkynes

Cited by 50 publications

References 50 publications

Stable Au(I) catalysts for oxidant-free C-H functionalization with iodoarenes

Stable Au(I) catalysts for oxidant-free C-H functionalization with iodoarenes

Mercury‐Free Synthesis of Pincer [C^N^C]AuIII Complexes by an Oxidative Addition/CH Activation Cascade

Reductive C–C Coupling from Molecular Au(I) Hydrocarbyl Complexes: A Mechanistic Study

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Product

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Gold‐Catalyzed C(sp²)−C(sp) Coupling by Alkynylation through Oxidative Addition of Bromoalkynes

Mercury‐Free Synthesis of Pincer [C^N^C]Au^III Complexes by an Oxidative Addition/CH Activation Cascade