Au → M bonds promote catalytic alkyne hydrofunctionalisation

Eltester, M. Alexander; Gildenast, Hans; Rabatinová, Kristína; Pütz, Christopher; Cremer, Christopher; Lanzerath, Patrick; Schroers, Julian P.; Tauchert, Michael E.

doi:10.1039/d3cc01008b

Cited by 1 publication

(3 citation statements)

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“…Yet weakly coordinating anions (X = OTf, NTf 2 ) or chloride scavengers are required (X = Cl). 39 The ligand scaffold suggests an electron-deficient Tshaped tricoordinate gold(I) center as the catalytically active site. Peris et al reported a ferrocenyl imidazolylidene gold(I) complex, which becomes active in the hydroamination of phenylacetylene with arylamines and in the cyclization of 2,5dimethylfuran after oxidation with acetylferrocenium tetrafluoroborate.…”

Section: ■ Introductionmentioning

confidence: 99%

“…An alternative method to inter- or intramolecular halide abstraction employs positively charged ligands (Chart b). − The charge seems to form highly electrophilic gold centers, while the halide remains coordinated to the gold(I) ion. Sarkar et al developed chlorido gold(I) precatalysts with ferrocenyl-substituted mesoionic carbene ligands ( F Ar ; Chart b). − Oxidation of F Ar with acetylferrocenium tetrafluoroborate to the ferrocenium complex [F Ar ] •+ yields the catalytically active species for the cyclization of N (2-propyn-1-yl)benzamide to 2-phenyl-5-vinylidene-2-oxazoline.…”

Section: Introductionmentioning

confidence: 99%

“…Placing positively charged Lewis acids (M = Zn 2+ , Cu + , or Ag + ) close to a di(phosphane) gold(I) fragment [K M ] n + (Chart b), Tauchert observed high activity in the cycloisomerization of N (2-propyn-1-yl)benzamide. Yet weakly coordinating anions (X = OTf, NTf 2 ) or chloride scavengers are required (X = Cl) . The ligand scaffold suggests an electron-deficient T-shaped tricoordinate gold(I) center as the catalytically active site.…”

Section: Introductionmentioning

confidence: 99%

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Redox Activation of Acyclic (Aryl)(amino)carbene Gold(I) Complexes

Schrick,

Ramollo,

Hirschbiegel

et al. 2024

Organometallics

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Activation of halido gold(I) precatalysts Au(L)X to a cationic species [Au(L)] + with a vacant coordination site for substrate binding typically requires abstraction of the halide X − . The Fischer-type carbene gold(I) precatalysts 2−4 feature redoxactive dimethylanilinyl, 2-furyl, and ferrocenyl substituents without (2a−4a) and with (2b−4b), a dangling dimethylamino substituent. After single-electron oxidation, 2−4 catalyze the cyclization of N(2-propyn-1-yl)benzamide to 2-phenyl-5-vinylidene-2-oxazoline without the presence of a halide scavenger. While all dimethylanilinyl and 2-furyl substituted precatalysts likely form catalytically active nanoparticles after oxidation, the ferrocenyl substituted gold(I) complexes 4a and 4b operate in a homogeneous fashion. The dimethylamino substituted ferrocenyl precatalyst 4b is the most active one. The formation of the catalytically active molecular species after oxidation was probed by stopped-flow experiments, quantitative EPR spectroscopy, and quantum chemical calculations to arrive at a consistent mechanistic picture that involves one-electron oxidation of the ferrocene, valence isomerization to a gold(II) species and anion coordination to the gold(II) center. This oxidation/isomerization/coordination activation mechanism is fundamentally different from the typical activation of gold(I) precatalysts by halide abstraction and opens new avenues in gold catalysis beyond gold(I) and gold(III) catalyses.

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Section: ■ Introductionmentioning

confidence: 99%