Catalytically Relevant Organocopper(III) Complexes Formed through Aryl-Radical-Enabled Oxidative Addition

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(22), С. 15176 - 15185

Опубликована: Май 21, 2024

Stepwise oxidative addition of copper(I) complexes to form copper(III) species via single electron transfer (SET) events has been widely proposed in copper catalysis. However, direct observation and detailed investigation these fundamental steps remain elusive owing largely the typically slow rate instability species. We report herein a novel aryl-radical-enabled stepwise pathway that allows for formation well-defined alkyl–CuIII from CuI complexes. The process is enabled by SET an aryl diazonium salt CuII radical. Subsequent iodine abstraction alkyl iodide radical affords radical, which then reacts with complex. structure resultant [(bpy)CuIII(CF3)2(alkyl)] characterized NMR spectroscopy X-ray crystallography. Competition experiments have revealed at different iodides undergo consistent carbon-centered radicals. intermediate formed during identified as four-coordinate complex, [CuII(CH3CN)2(CF3)2], through electronic paramagnetic resonance (EPR) studies. catalytic relevance high-valent organo-CuIII demonstrated C–C bond-forming reductive elimination reactivity. Finally, localized orbital bonding analysis formal CuIII indicates inverted ligand fields σ(Cu–CH2) bonds. These results demonstrate catalysis provide general strategy investigate

Язык: Английский

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Copper-Mediated Enantioselective C–H Thiolation of Ferrocenes Enabled by the BINOL Ligand

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Янв. 30, 2025

Transition-metal-catalyzed enantioselective C-H activation has transformed the landscape of asymmetric synthesis, enabling efficient conversion bonds into C-C and carbon-heteroatom (C-X) bonds. However, formation C-S through thiolation remains underdeveloped due to challenges such as catalyst deactivation competitive coordination sulfur-containing compounds with chiral ligands. Herein, we report an unprecedented approach constructing sulfur-substituted planar ferrocenes (PCFs) copper-mediated enabled by only a 2.5 mol % 1,1'-bi-2,2'-naphthol (BINOL) ligand. A variety PCFs were obtained in good yields (up 83%) excellent enantioselectivity >99% ee). Mechanistic studies reveal that irreversible serves both stereo- rate-determining step can be achieved catalytic amounts Cu species. Furthermore, utility this protocol is illustrated gram-scale removal directing group, synthesis N,S-chiral ligands well rotaxanes. This significant advancement not expands tool kit for organosulfur but also highlights potential synthesis.

Язык: Английский

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Copper–Carbon Homolysis Competes with Reductive Elimination in Well-Defined Copper(III) Complexes

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(48), С. 26152 - 26159

Опубликована: Ноя. 22, 2023

Despite the recent advancements of Cu catalysis for cross-coupling alkyl electrophiles and frequently proposed involvement alkyl-Cu(III) complexes in such reactions, little is known about reactivity these high-valent complexes. Specifically, although reversible interconversion between an alkyl-CuIII complex radical/CuII pair has been catalysis, direct observation steps well-defined CuIII remains elusive. In this study, we report synthesis investigation complexes, which exclusively undergo a Cu-C homolysis pathway to generate radicals CuII species. Kinetic studies suggest bond dissociation energy 28.6 kcal/mol CuIII-C bonds. Moreover, four-coordinate could be converted solvated alkyl-CuIII-(CF3)2, undergoes highly efficient C-CF3 bond-forming reductive elimination even at low temperatures (-4 °C). These results provide strong support recombination with form species, elusive step that Cu-catalyzed mechanisms. Furthermore, our work demonstrated significantly influenced by subtle changes coordination environment. Lastly, reactive neutral alkyl-CuIII-(CF3)2 species (or weakly bound solvent molecules) suggests they might true intermediates many trifluoromethylation reactions.

Язык: Английский

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Mechanistic Investigations of Cobalt-Catalyzed, Aminoquinoline-Directed C(sp²)–H Bond Functionalization

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Янв. 10, 2025

Monoanionic, bidentate-auxiliary-directed, cobalt-catalyzed C–H bond functionalization has become a very useful tool in organic synthesis. A comprehensive investigation into isolated organometallic intermediates and their reactivity within the catalytic cycle is lacking. We report here mechanistic studies of cobalt-catalyzed, aminoquinoline-directed C(sp2)–H functionalization. number Co(III) have been structurally characterized, including, for first time aminoquinoline system, complexes arising from migratory insertion cobalt–carbon bonds. The stoichiometric reactions cobalt(III) aryls with alkenes, alkynes, carbon monoxide, cyclic secondary amines, benzamides explored. oxidation state cobalt product-forming step depends on nature coupling component. Specifically, annulation alkynes carbonylation CO likely proceed via Co(I)/Co(III) cycle. Carbon–hydrogen alkenes as well benzamide homocoupling, (formally) Co(IV) species involve oxidatively induced reductive elimination.

Язык: Английский

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Speciation and Reactivity of Mono- and Binuclear Ni Intermediates in Aminoquinoline-Directed C–H Arylation and Benzylation

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(26), С. 18128 - 18135

Опубликована: Июнь 20, 2024

This paper describes detailed organometallic studies of the aminoquinoline-directed Ni-catalyzed C-H functionalization 2,3,4,5-tetrafluoro-

Язык: Английский

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An open-shell Ir(II)/Ir(IV) redox couple outperforms an Ir(I)/Ir(III) pair in olefin isomerization

Nature Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Янв. 20, 2025

Язык: Английский

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Insights into the mechanism of 3d transition-metal-catalyzed directed C(sp³)–H bond functionalization reactions

Chemical Society Reviews, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

This review provides an overview of the research advaces in Ni-, Cu-, Fe- and Co-catalyzed directed C(sp 3 )–H bond functionalization reactions; including design principles, mechanistic discussions, along with potential applications limitations.

Язык: Английский

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Exploration of Organometallic Cobalt Intermediates in an Aminoquinoline-Directed Dehydrogenative Dimerization Reaction

Organometallics, Год журнала: 2024, Номер unknown

Опубликована: Сен. 16, 2024

Язык: Английский

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Overcoming Copper Reduction Limitation in Asymmetric Substitution: Aryl-Radical-Enabled Enantioconvergent Cyanation of Alkyl Iodides

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(46), С. 31982 - 31991

Опубликована: Ноя. 6, 2024

Cu-catalyzed enantioconvergent cross-coupling of alkyl halides has emerged as a powerful strategy for synthesizing enantioenriched molecules. However, this approach is intrinsically limited by the weak reducing power copper(I) species, which restricts scope compatible nucleophiles and necessitates extensive ligand optimization or use complex chiral scaffolds. To overcome these challenges, we introduce an aryl-radical-enabled that decouples halide activation step from Cu center. We demonstrate merging iodine abstraction with asymmetric radical functionalization enables conversion racemic α-iodoamides to nitrile products good yield enantioselectivity. The rational design ligands identified new class carboxamide-containing BOX ligands. Mechanistic studies support pathway unique hydrogen-bonding ability in newly designed This substitution reaction potential significantly expand reactions.

Язык: Английский

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C–N Bond Formation at Discrete Cu^III–Aryl Complexes

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(49), С. 26810 - 26816

Опубликована: Дек. 5, 2023

Copper(III) aryl species are widely proposed as intermediates in Cu-catalyzed C–C and C-heteroatom bond formation reactions. Despite their wide utility, mechanistic aspects of at CuIII centers well factors that lead to byproducts, e.g., Ar–H, Ar–Ar, remain elusive due the rarity discrete CuIII–Ar complexes. Herein, we report synthesis reactivity a series CuII complexes closely mimic C–N coupling Copper(II) [TBA][LCuII–ArR] were synthesized via treatment with range donors, such ZnAr2R, TMS–ArR, ArR–Bpin. Oxidation produces formal copper(III) LCuIII–ArR. Treatment neutral nitrogen nucleophiles product up 64% yield, along commonly observed Ar–H Ar–Ar. Hammett analysis performed various N-nucleophiles shows ρ value −1.66, consistent electrophilic character We propose mechanisms for common side reactions Ar–Ar Ar–H.

Язык: Английский

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