Nickel and Palladium Catalysis: Stronger Demand than Ever

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(2), P. 1180 - 1200

Published: Jan. 5, 2022

Key similarities and differences of Pd Ni in catalytic systems are discussed. Overall, catalyze a vast number similar C–C C–heteroatom bond-forming reactions. However, the smaller atomic radius lower electronegativity Ni, as well more negative redox potentials low-valent species, often provide higher reactivity oxidative addition or insertion reactions persistence alkyl-Ni intermediates against β-hydrogen elimination, thus enabling activation reluctant electrophiles, including alkyl electrophiles. Another key point relates to stability open-shell electronic configurations Ni(I) Ni(III) compared with Pd(I) Pd(III). Nickel very involve interconvertible Ni(n+) active species variable oxidation states (Ni(0), Ni(I), Ni(II), Ni(III)). In contrast, involving Pd(III) still relatively less developed may require facilitation by special ligands merging photo- electrocatalysis. high Pd(n+) ensure their facile reduction Pd(0) under assistance numerous reagents solvents, providing concentrations molecular Pd1(0) complexes that can reversibly aggregate into Pdn clusters nanoparticles form cocktail Pdn(0) various nuclearities (i.e., values "n"). Ni(0) strong reductants; they sensitive deactivation air other oxidizers and, consequence, operate at catalyst loadings than palladium same The ease robustness versatility for catalysis, whereas variety enables diverse uncommon reactivity, albeit requiring efforts stabilization nickel systems. As discussion, we note easily "cocktail particles" different but (Pd1, Pdn, NPs), behave species" is stable nuclearities. Undoubtedly, there stronger demand ever not only develop improved efficient catalysts also understand mechanisms

Language: Английский

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Photoinduced Copper-Catalyzed Asymmetric C–O Cross-Coupling

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(33), P. 13382 - 13392

Published: Aug. 10, 2021

The construction of carbon–heteroatom bonds is one the most active areas research in organic chemistry because function molecules often derived from presence heteroatoms. Although considerable advances have recently been achieved radical-involved catalytic asymmetric C–N bond formation, there has little progress corresponding C–O bond-forming processes. Here, we describe a photoinduced copper-catalyzed cross-coupling readily available oxime esters and 1,3-dienes to generate diversely substituted allylic with high regio- enantioselectivity (>75 examples; up 95% ee). reaction proceeds at room temperature under excitation by purple light-emitting diodes (LEDs) features use single, earth-abundant copper-based chiral catalyst as both photoredox for radical generation source induction coupling. Combined experimental density functional theory (DFT) computational studies suggest formation π-allylcopper complexes redox-active bifunctional reagents through radical–polar crossover process.

Language: Английский

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Schiff base metal complexes as a versatile catalyst: A review

Journal of Organometallic Chemistry, Journal Year: 2023, Volume and Issue: 999, P. 122825 - 122825

Published: July 23, 2023

Language: Английский

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Stereodivergent Synthesis of Allenes with α,β‐Adjacent Central Chiralities Empowered by Synergistic Pd/Cu Catalysis

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(9)

Published: Jan. 3, 2023

The stereodivergent synthesis of allene compounds bearing α,β-adjacent central chiralities has been realized via the Pd/Cu-catalyzed dynamic kinetic asymmetric alkylation racemic allenylic esters. matched reactivity bimetallic catalytic system enables challenging reaction aryl-substituted acetates with sterically crowded aldimine esters smoothly under mild conditions. Various chiral non-natural amino acids a terminal allenyl group are easily synthesized in high yields and excellent diastereo- enantioselectivities (up to >20 : 1 dr, >99 % ee). Importantly, all four stereoisomers product can be readily accessed by switching configurations two metal catalysts. Furthermore, easy interconversion between uncommon η3 -butadienyl palladium intermediate featuring weak C=C/Pd coordination bond stable Csp2 -Pd is beneficial for transformation process (DyKAT).

Language: Английский

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Facile Access to Quaternary Carbon Centers via Ni-Catalyzed Arylation of Alkenes with Organoborons

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 16, 2025

Quaternary carbon centers are widespread structural motifs, thus representing extensive interest in organic synthesis. We describe here an efficient nickel-catalyzed intermolecular, Markovnikov-selective arylation of minimally functionalized alkenes with stable organoborons, affording a broad range cyclic or acyclic quaternary under mild conditions. The utilization the diimine ligand is critical for high reactivity and chemoselectivity. Furthermore, using bulky chiral as Ni catalyst, stereocenters can be readily prepared levels enantiocontrol. Mechanism studies suggest that, before protonation, rare nickel shift from alkyl to aryl might occur.

Language: Английский

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Cobalt-Catalyzed Diastereo- and Enantioselective Reductive Allyl Additions to Aldehydes with Allylic Alcohol Derivatives via Allyl Radical Intermediates

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(32), P. 12755 - 12765

Published: Aug. 5, 2021

Catalytic generation of ambiphilic π-allyl–metal complexes and their utility in enantioselective transformations constitutes a powerful approach for introduction allyl groups to molecule. Herein an unprecedented cobalt-catalyzed highly site-, diastereo-, protocol stereoselective formation nucleophilic allyl–Co(II) followed by addition aldehydes is presented. The reaction features diastereo- enantioconvergent conversion easily accessible allylic alcohol derivatives diversified enantioenriched homoallylic alcohols with remarkably broad scope that can be introduced. Mechanistic studies indicated radical intermediates were involved this process. These new discoveries establish strategy development through capture radicals chiral Co complexes, pushing forward the frontier catalysis.

Language: Английский

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Photoinduced Copper-Catalyzed Asymmetric Acylation of Allylic Phosphates with Acylsilanes

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(5), P. 2218 - 2224

Published: Jan. 6, 2022

We report a visible-light-induced copper-catalyzed highly enantioselective umpolung allylic acylation reaction with acylsilanes as acyl anion equivalents. Triplet-quenching experiments and DFT calculations supported our design, which is based on copper-to-acyl metal-to-ligand charge transfer (MLCT) photoexcitation that generates charge-separated triplet state reactive intermediate. According to the calculations, phosphate substrate in excited undergoes novel molecular activation into an radical weakly bound copper complex. The allyl fragment copper-mediated regio- stereocontrolled coupling group under influence of chiral N-heterocyclic carbene ligand.

Language: Английский

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Rh-Catalyzed Regio- and Enantioselective Allylic Phosphinylation

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(7), P. 2893 - 2898

Published: Feb. 14, 2022

Transition-metal-catalyzed branched and enantioselective allylic substitution of monosubstituted precursors with carbon, nitrogen, oxygen, sulfur, fluoride nucleophiles has been well-established. However, such a selective carbon–phosphorus bond formation not realized probably due to the catalyst deactivation by strong coordinating nature phosphinylating reagents. Herein, we report Rh-catalyzed highly regio- synthesis phosphine oxides in presence chiral bisoxazoline-phosphine ligand. The application α-hydroxylalkylphosphine keep low concentration secondary is essential for high yields. addition diphenyl phosphoric acid was found only activate alcohols but also accelerate formation.

Language: Английский

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Asymmetric Redox Allylic Alkylation to Access 3,3′‐Disubstituted Oxindoles Enabled by Ni/NHC Cooperative Catalysis

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(22)

Published: March 3, 2022

The feasibility of cooperative catalysis between chiral N-heterocyclic carbenes and nickel in asymmetric reactions has been demonstrated convincingly. high efficiency this catalytic system enables the allylic alkylation isatin-derived enals with carbonates [3+3] annulation racemic vinyl epoxides to provide straightforward access highly enantioenriched 3,3'-disubstituted oxindoles. great practicality method organic synthesis showcased by facile product modification enantioselective key building block (-)-debromoflustramine B.

Language: Английский

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Copper-Catalyzed Three-Component Photo-ATRA-Type Reaction for Asymmetric Intermolecular C–O Coupling

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(17), P. 10925 - 10937

Published: Aug. 22, 2022

Atom transfer radical addition (ATRA) reaction of alkenes has had a significant impact on the field difunctionalization alkenes. Particularly, in three-component photo-ATRA-type processes, rich chemical space and structural diversity could be achieved by smart combination redox-active precursors third coupling components (e.g., halides, C-, N-, O-nucleophiles) under mild conditions. However, inherent complicated mechanisms involving chain or outer-sphere SET incipient intermediates have led to dearth general catalytic methods for highly enantioselective variants, especially those regarding asymmetric intermolecular C–O bond formation. Here, we report visible-light-induced copper-catalyzed with oxime esters carboxylic acids. In this process, cross-coupling between sp3-hybridized carbon radicals acids was enabled formation an aryl π-bond-engaged [σ + π]-copper complex. This working hypothesis renders naphthyl extended conjugation suitable substrates allows good stereocontrol. exhibits broad substrate scope high functional group tolerance respect each component, giving desired products generally yields enantioselectivity (>70 examples; up 97% ee). Preliminary experimental computational studies are also performed gain insight into mechanism stereoregulatory elements. finding provides promising platform development other benzylic-type radical-based reactions.

Language: Английский

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