Mechanisms of Nickel-Catalyzed Cross-Coupling Reactions

Trends in Chemistry, Год журнала: 2019, Номер 1(9), С. 830 - 844

Опубликована: Сен. 13, 2019

Язык: Английский

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Cross-Coupling and Related Reactions: Connecting Past Success to the Development of New Reactions for the Future

Organometallics, Год журнала: 2018, Номер 38(1), С. 3 - 35

Опубликована: Ноя. 27, 2018

Cross-coupling reactions, which were discovered almost 50 years ago, are widely used in both industry and academia. Even though cross-coupling reactions now represent mature technology, there is still a significant amount of research this area that aims to improve the scope these develop more efficient catalysts, make practical. In tutorial, brief background provided, then major advances over last 20 described. These include development improved ligands precatalysts for extension much wider range electrophiles. For example, common with sp3-hybridized electrophiles as well ester, amide, ether, aziridine substrates. many modern substrates, traditional palladium-based catalysts less than systems based on first-row transition metals such nickel. Conventional have also inspired related cross-electrophile decarboxylative couplings metallaphotoredox chemistry. The new probably at same stage 30 tutorial highlights how strategies may be applicable making

Язык: Английский

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N-Heterocyclic Carbene Complexes of Copper, Nickel, and Cobalt

Chemical Reviews, Год журнала: 2019, Номер 119(6), С. 3730 - 3961

Опубликована: Март 7, 2019

The emergence of N-heterocyclic carbenes as ligands across the Periodic Table had an impact on various aspects coordination, organometallic, and catalytic chemistry 3d metals, including Cu, Ni, Co, both from fundamental viewpoint but also in applications, catalysis, photophysics, bioorganometallic chemistry, materials, etc. In this review, emergence, development, state art these three areas are described detail.

Язык: Английский

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Computational Approach to Molecular Catalysis by 3d Transition Metals: Challenges and Opportunities

Chemical Reviews, Год журнала: 2018, Номер 119(4), С. 2453 - 2523

Опубликована: Окт. 30, 2018

Computational chemistry provides a versatile toolbox for studying mechanistic details of catalytic reactions and holds promise to deliver practical strategies enable the rational in silico catalyst design. The reactivity nontrivial electronic structure effects, common systems based on 3d transition metals, introduce additional complexity that may represent particular challenge standard computational strategies. In this review, we discuss challenges capabilities modern methods reaction mechanisms promoted by metal molecular catalysts. Particular focus will be placed ways addressing multiconfigurational problem calculations role expert bias utilization available methods. development density functionals designed address metals is also discussed. Special emphasis account solvation effects multicomponent nature systems. This followed an overview recent studies processes catalysts metals. Cases involve noninnocent ligands, systems, metal-ligand metal-metal cooperativity, as well modeling complex such metal-organic frameworks are presented. Conventionally, heavily dependent chemical intuition input researcher. Recent developments advanced automated path analysis hold eliminating human-bias from catalysis studies. A brief these approaches presented final section review. paper closed with general concluding remarks.

Язык: Английский

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Mechanisms of Nickel-Catalyzed Coupling Reactions and Applications in Alkene Functionalization

Accounts of Chemical Research, Год журнала: 2020, Номер 53(4), С. 906 - 919

Опубликована: Апрель 2, 2020

ConspectusNickel complexes exhibit distinct properties from other group 10 metals, including a small nuclear radius, high paring energy, low electronegativity, and redox potentials. These enable Ni catalysts to accommodate stabilize paramagnetic intermediates, access radical pathways, undergo slow β-H elimination. Our research program investigates how each of these fundamental attributes impact the catalytic Ni, in particular context alkene functionalization.Alkenes are versatile functional groups, but stereoselective carbofunctionalization reactions alkenes have been underdeveloped. This challenge may derive difficulty controlling selectivity via traditional two-electron migratory insertion pathways. could lead different stereodetermining steps mechanisms, allowing molecular scaffolds that otherwise difficult prepare. For example, an asymmetric diarylation reaction developed by our relies upon Ni(III) intermediates control enantioselectivity give library chiral α,α,β-triarylethane molecules with biological activity.Mechanistic studies on two-component reductive 1,2-difunctionalization shed light origin cross-electrophile selectivity, as C sp2 sp3 electrophiles independently activated at Ni(I) respectively. Catalyst reduction has identified be turnover-limiting step this system. A closer investigation formation using (Xantphos)Ni(I)Ar model complex reveals initiates concerted halogen-abstraction pathway.The potentials allowed us develop reductive, trans-selective diene cyclization, wherein classic mechanism operates Ni(I)/Ni(III) platform, accounting for chemo- stereoselectivity. found applications efficient synthesis pharmaceutically relevant molecules, such 3,4-dimethylgababutin.The tendency one-electron processes prompted explore dinuclear Ni-mediated bond formations. provide insight into Ni–Ni bonding two metal centers react cooperatively promote C–C, C–X, N–N forming elimination.Finally, isolation β-agostic Pd X-ray neutron diffraction characterization highly reactive molecules. The parameters serve unambiguous evidence interactions help rationalize slower elimination relative Pd. Overall, elucidated several contexts. Greater mechanistic understanding facilitates catalyst design helps reactivity Ni-catalyzed functionalization reactions.

Язык: Английский

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Metal Drugs and the Anticancer Immune Response

Chemical Reviews, Год журнала: 2018, Номер 119(2), С. 1519 - 1624

Опубликована: Ноя. 29, 2018

The immune system deploys a multitude of innate and adaptive mechanisms not only to ward off pathogens but also prevent malignant transformation ("immune surveillance"). Hence, clinically apparent tumor already reflects selection for those cell clones capable evading recognition evasion"). Metal drugs, besides their well-investigated cytotoxic anticancer effects, massively interact with the cancer-immune interface can reverse important aspects evasion. This topic has recently gained intense attention based on combination approaches immunotherapy (e.g., checkpoint inhibitors), strategy delivering first exciting results in clinical settings. review summarizes promising still extremely fragmentary knowledge interplay metal drugs fidelity responses role adverse effects. It highlights that, at least some cases, induce long-lasting responses. Important steps this process comprise altered visibility susceptibility cancer cells toward immunity, as well direct impacts populations microenvironment. On basis gathered information, we suggest initiating joint multidisciplinary programs implement comprehensive analyses into strategies develop novel smart compounds.

Язык: Английский

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Mechanistic Interrogation of Co/Ni-Dual Catalyzed Hydroarylation

Journal of the American Chemical Society, Год журнала: 2018, Номер 140(38), С. 12056 - 12068

Опубликована: Авг. 28, 2018

Cobalt/nickel-dual catalyzed hydroarylation of terminal olefins with iodoarenes builds complexity from readily available starting materials, a high preference for the Markovnikov (branched) product. Here, we advance mechanistic model this reaction through use progress kinetic analysis (RPKA), radical clock experiments, and stoichiometric studies. Through exclusion competing hypotheses, conclude that proceeds an unprecedented alkylcobalt to nickel direct transmetalation. Demonstration catalytic alkene prefunctionalization, via spectroscopic observation organocobalt species, distinguishes Csp2–Csp3 cross-coupling method conventional transmetalation process, which employs organometallic nucleophile, bimetallic oxidative addition organohalide across nickel, described by scission subsequent alkyl capture at second center. A refined understanding leads optimized procedure excludes exogenous oxidant, demonstrating is net redox neutral. Catalytic prefunctionalization cobalt engagement cycles provides new platform merge these two rich areas chemistry in preparatively useful ways.

Язык: Английский

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Mechanistic Characterization of (Xantphos)Ni(I)-Mediated Alkyl Bromide Activation: Oxidative Addition, Electron Transfer, or Halogen-Atom Abstraction

Journal of the American Chemical Society, Год журнала: 2019, Номер 141(4), С. 1788 - 1796

Опубликована: Янв. 6, 2019

Ni(I)-mediated single-electron oxidative activation of alkyl halides has been extensively proposed as a key step in Ni-catalyzed cross-coupling reactions to generate radical intermediates. There are four mechanisms through which this could take place: addition, outer-sphere electron transfer, inner-sphere and concerted halogen-atom abstraction. Despite considerable computational studies, there is no experimental study evaluate all pathways for formation. Herein, we report the isolation series (Xantphos)Ni(I)–Ar complexes that selectively activate over aryl eject radicals form Ni(II) complexes. This observation allows application kinetic studies on steric, electronic, solvent effects, combination with DFT calculations, systematically assess possible pathways. Our data reveal (Xantphos)Ni(I)-mediated halide proceeds via abstraction mechanism. result corroborates previous (terpy)Ni(I)- (py)Ni(I)-mediated formation, contrasts transfer pathway observed (PPh3)4Ni(0)-mediated activation. model system provides insight into overall mechanism offers basis differentiating electrophiles cross-electrophile coupling reactions.

Язык: Английский

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E -Olefins through intramolecular radical relocation

Science, Год журнала: 2019, Номер 363(6425), С. 391 - 396

Опубликована: Янв. 25, 2019

Olefin shuffle for just a nickel Controlling the geometry of carbon-carbon double bonds is central component chemical manufacturing. One useful trick to shift hydrogen atoms around interconvert C=C isomers selectively. However, this approach typically requires precious metals. Kapat et al. now report that more-abundant can catalyze rapid conversion terminal olefins into internal with high selectivity trans geometry. The odd-electron complex relies on radical mechanism shuttle carbon from saturated adjacent bond. Science , issue p. 391

Язык: Английский

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Oxidative Addition of Aryl Halides to a Ni(I)-Bipyridine Complex

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(12), С. 5575 - 5582

Опубликована: Март 17, 2022

The oxidative addition of aryl halides to bipyridine- or phenanthroline-ligated nickel(I) is a commonly proposed step in nickel catalysis. However, there scarcity complexes this type that both are well-defined and undergo with halides, hampering organometallic studies process. We report the synthesis Ni(I) complex, [(CO2Etbpy)NiICl]4 (1). Its solution-phase speciation characterized by significant population monomer redox equilibrium can be perturbed π-acceptors σ-donors. 1 reacts readily bromides, mechanistic consistent pathway proceeding through an initial → Ni(III) form species. Such process was demonstrated stoichiometrically for first time, affording structurally complex.

Язык: Английский

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