Mechanisms of Photoredox Catalysis Featuring Nickel–Bipyridine Complexes

ACS Catalysis, Год журнала: 2024, Номер 14(11), С. 9055 - 9076

Опубликована: Май 29, 2024

Metallaphotoredox catalysis can unlock useful pathways for transforming organic reactants into desirable products, largely due to the conversion of photon energy chemical potential drive redox and bond transformation processes. Despite importance these processes cross-coupling reactions other transformations, their mechanistic details are only superficially understood. In this review, we have provided a detailed summary various photoredox mechanisms that been proposed date Ni-bipyridine (bpy) complexes, focusing separately on photosensitized direct excitation reaction By highlighting multiple key findings, depict how mechanisms, which ultimately define substrate scope, themselves defined by ground- excited-state geometric electronic structures Ni-based intermediates. We further identify knowledge gaps motivate future studies development synergistic research approaches spanning physical, organic, inorganic chemistry communities.

Язык: Английский

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Electrocatalytic Formal C(sp²)−H Alkylations via Nickel‐Catalyzed Cross‐Electrophile Coupling with Versatile Arylsulfonium Salts

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(29)

Опубликована: Май 2, 2024

Producing sp

Язык: Английский

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Alkyl Cyclopropyl Ketones in Catalytic Formal [3 + 2] Cycloadditions: The Role of SmI₂ Catalyst Stabilization

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(18), С. 12799 - 12807

Опубликована: Апрель 25, 2024

Alkyl cyclopropyl ketones are introduced as versatile substrates for catalytic formal [3 + 2] cycloadditions with alkenes and alkynes previously unexplored enyne partners, efficiently delivering complex, sp3-rich products. The key to effectively engaging this relatively unreactive new substrate class is the use of SmI2 a catalyst in combination substoichiometric amounts Sm0; latter likely acting prevent deactivation by returning SmIII cycle. In absence Sm0, background degradation can outrun product formation. For most recalcitrant alkyl ketones, catalysis "switched-on" using these robust conditions, otherwise unattainable products delivered. Combined experimental computational studies have been used identify probe reactivity trends among including more complex bicyclic which react quickly various partners give addition establishing burgeoning field catalysis, our study provides vital mechanistic insight robust, practical approaches nascent SmI2.

Язык: Английский

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Light Activation and Photophysics of a Structurally Constrained Nickel(II)–Bipyridine Aryl Halide Complex

Inorganic Chemistry, Год журнала: 2024, Номер 63(9), С. 4120 - 4131

Опубликована: Фев. 20, 2024

Transition-metal photoredox catalysis has transformed organic synthesis by harnessing light to construct complex molecules. Nickel(II)–bipyridine (bpy) aryl halide complexes are a significant class of cross-coupling catalysts that can be activated via direct excitation. This study investigates the effects molecular structure on photophysics these considering an underexplored, structurally constrained Ni(II)–bpy in which and bpy ligands covalently tethered alongside traditional unconstrained complexes. Intriguingly, is photochemically stable but features reversible Ni(II)–C(aryl) ⇄ [Ni(I)···C(aryl)•] equilibrium upon photoexcitation. When electrophile introduced during photoirradiation, we demonstrate preference for photodissociation over recombination, rendering parent Ni(II) source reactive Ni(I) intermediate. Here, characterize photochemical behavior kinetic analyses, quantum chemical calculations, ultrafast transient absorption spectroscopy. Comparison previously characterized indicates structural constraints considered here dramatically influence excited state relaxation pathway provide insight into characteristics excited-state Ni(II)–C bond homolysis radical reassociation dynamics. enriches understanding offers new possibilities designing customized photoactive precise synthesis.

Язык: Английский

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Dynamic stereomutation of vinylcyclopropanes with metalloradicals

Nature, Год журнала: 2024, Номер 631(8019), С. 80 - 86

Опубликована: Июнь 19, 2024

Abstract The ever increasing demands for greater sustainability and lower energy usage in chemical processes call fundamentally new approaches reactivity principles. In this context, the pronounced prevalence of odd-oxidation states less precious metals bears untapped potential distinct modes via metalloradical catalysis 1–3 . Contrary to well-established paradigm that organic free radicals, upon addition a vinylcyclopropane, lead rapid ring opening under strain release—a transformation serves widely as mechanistic probe (radical clock) 4 intermediacy radicals 5 —we herein show metal-based radical, is, Ni (I) metalloradical, triggers reversible cis / trans isomerization instead opening. proceeds chiral inversion and, depending on substitution pattern, occurs at room temperature than min, requiring solely non-precious catalyst. Our combined computational experimental studies support origin profound reactivity, rationalize observed stereoinversion reveal key features process, including its reversibility. These insights enabled iterative thermodynamic enrichment enantiopure mixtures towards single diastereomer through multiple rounds also extensions divinylcyclopropanes, which constitute strategic motifs natural product- total syntheses 6 While -isomer usually requires heating approximately 200 °C trigger thermal racemization -divinylcyclopropane, then undergoes facile Cope-type rearrangement, analogous contra-thermodynamic process is shown proceed mild conditions without any loss stereochemical integrity, enabling stereochemically pure access seven-membered rings, fused systems spirocycles.

Язык: Английский

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Late-Stage C(sp²)–C(sp³) Diversification via Nickel Oxidative Addition Complexes

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(31), С. 21264 - 21270

Опубликована: Июль 25, 2024

Herein, we describe nickel oxidative addition complexes (Ni-OACs) of drug-like molecules as a platform to rapidly generate lead candidates with enhanced C(sp3) fraction. The potential Ni-OACs access new chemical space has been assessed not only in C(sp2)–C(sp3) couplings but also additional bond formations without recourse specialized ligands and improved generality when compared Ni-catalyzed reactions. development an automated diversification process further illustrates the robustness Ni-OACs, thus offering gateway expedite design–make–test–analyze (DMTA) cycle drug discovery.

Язык: Английский

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Water and Air Stable Copper(I) Complexes of Tetracationic Catenane Ligands for Oxidative C−C Cross‐Coupling

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(28)

Опубликована: Апрель 25, 2024

Abstract Aqueous soluble and stable Cu(I) molecular catalysts featuring a catenane ligand composed of two dicationic, mutually repelling but mechanically interlocked macrocycles are reported. The interlocking not only fine‐tunes the coordination sphere kinetically stabilizes against air oxidation disproportionation, also buries hydrophobic portions ligands prevents their dissociation which necessary for good water solubility sustained activity. These complexes can catalyze oxidative C−C coupling indoles tetrahydroisoquinolines in water, using H 2 O as green oxidant with substrate scope. successful use exploiting aqueous catalysis thus highlights many unexplored potential mechanical bond design element exploring transition metal under challenging conditions.

Язык: Английский

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Insight into copper coordination in O2 reduction by water-soluble cytochrome c oxidase models

Dalton Transactions, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

Iron-copper complexes have been extensively studied in the search for efficient cytochrome c oxidase models. Whereas most dinuclear materials usually focus on fine-tuning coordination of heme-Fe, this work shows that copper models should be carefully taken into consideration. A β-cyclodextrin dimer was built around a bipyridine linker and combined with Fe-tetraphenylsulfonatoporphyrinate (FeTPPS) to generate self-assembled hydrosoluble model. Cyclic voltammetry rotating ring disk electrode experiments showed model tetrahedral copper(I) is reduction molecular oxygen an average 3.6 electrons indicating preference efficiency four-electron water.

Язык: Английский

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Copper-Catalyzed Annulation of α,β-Unsaturated Ketoximes with Dialkyl Acetylenedicarboxylates for the Synthesis of Highly Substituted Pyridines

Organic Letters, Год журнала: 2025, Номер unknown

Опубликована: Янв. 24, 2025

A copper-catalyzed [4 + 2] annulation protocol from readily available α,β-unsaturated ketoximes and dialkyl acetylenedicarboxylates has been achieved. The approach enables the expedient construction of a series structurally new highly substituted pyridines with good functional group tolerance.

Язык: Английский

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Electrochemical Nickel-Catalyzed C(sp²)-H Functionalization of Tropones with Aldehydes

ACS Catalysis, Год журнала: 2025, Номер unknown, С. 3184 - 3190

Опубликована: Фев. 6, 2025

A direct electroreductive functionalization of tropones employing aldehydes as alkylating agents is reported. This C(sp2)-H process leverages the mediation electroactive nickel complexes, enabling a wide range both native and substituted (44 examples) to be alkylated selectively at α-position in high yields (up 90%). Combined electrochemical, spectroelectrochemical, computational analyses disclosed whole mechanistic pathway revealed key role played by reduced Ni complexes activating tropone core toward condensation with aldehydes.

Язык: Английский

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