Ni-Catalyzed Reductive Dicarbofunctionalization of Nonactivated Alkenes: Scope and Mechanistic Insights

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(35), P. 13812 - 13821

Published: Aug. 21, 2019

Olefins devoid of directing or activating groups have been dicarbofunctionalized here with two electrophilic carbon sources under reductive conditions. Simultaneous formation one C(sp3)–C(sp3) and C(sp3)–C(sp2) bond across a variety unbiased π-systems proceeds exquisite selectivity by the combination Ni catalyst TDAE as sacrificial reductant. Control experiments computational studies revealed feasibility radical-based mechanism involving, formally, interconnected Ni(I)/Ni(III) processes demonstrated different ability Ni(I) species (Ni(I)I vs PhNi(I)) to reduce C(sp3)–I bond. The role reductant was also investigated in depth, suggesting that one-electron reduction Ni(II) is thermodynamically favored. Further, preferential activation alkyl aryl halides ArNi(I) complexes well high affinity ArNi(II) for secondary over tertiary C-centered radicals explains lack undesired homo- direct coupling products (Ar–Ar, Ar–Alk) these transformations.

Language: Английский

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Activation of Dinitrogen by Polynuclear Metal Complexes

Chemical Reviews, Journal Year: 2020, Volume and Issue: 120(12), P. 5517 - 5581

Published: May 4, 2020

Activation of dinitrogen plays an important role in daily anthropogenic life, and the processes by which this fixation occurs have been a longstanding significant research focus within community. One major fields activation is use multimetallic compounds to reduce and/or activate N2 into more useful nitrogen-atom source, such as ammonia. Here we report comprehensive review multimetallic-dinitrogen complexes their utility toward activation, beginning with d-block metals from Group 4 11, then extending 13 (which exclusively populated B complexes), finally rare-earth actinide species. The considers all polynuclear metal aggregates containing two or centers coordinated activated (i.e., partial complete cleavage triple bond observed product). Our survey includes mononuclear are used building blocks generate homo- heteromultimetallic species, allow one evaluate potential heterometallic species for activation. We highlight some common trends throughout periodic table, differences between coordination modes it relates functionalization effect polarizing bridging ligand employing different ions differing Lewis acidities. By providing treatment Review aims outline past provide future directions continued area.

Language: Английский

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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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Controlling Ni redox states by dynamic ligand exchange for electroreductive Csp3–Csp2 coupling

Science, Journal Year: 2022, Volume and Issue: 376(6591), P. 410 - 416

Published: April 21, 2022

Cross-electrophile coupling (XEC) reactions of aryl and alkyl electrophiles are appealing but limited to specific substrate classes. Here, we report electroreductive XEC previously incompatible including tertiary bromides, chlorides, aryl/vinyl triflates. Reactions rely on the merger an electrochemically active complex that selectively reacts with bromides through 1e

Language: Английский

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

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(12), P. 5575 - 5582

Published: March 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.

Language: Английский

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Oxidative addition of an alkyl halide to form a stable Cu(III) product

Science, Journal Year: 2023, Volume and Issue: 381(6662), P. 1072 - 1079

Published: Sept. 7, 2023

The step that cleaves the carbon-halogen bond in copper-catalyzed cross-coupling reactions remains ill defined because of multiple redox manifolds available to copper and instability high-valent product formed. We report oxidative addition α-haloacetonitrile ionic neutral copper(I) complexes form previously elusive but here fully characterized copper(III) complexes. stability these stems from strong Cu−CF 3 high barrier for C( CF )−C( CH 2 CN ) bond-forming reductive elimination. mechanistic studies we performed suggest proceeds by means two different pathways: an S N 2-type substitution complex a halogen-atom transfer complex. observed pronounced ligand acceleration addition, which correlates with couplings azoles, amines, or alkynes alkyl electrophiles.

Language: Английский

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Mechanistic Investigation of Ni-Catalyzed Reductive Cross-Coupling of Alkenyl and Benzyl Electrophiles

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(27), P. 14705 - 14715

Published: June 26, 2023

Mechanistic investigations of the Ni-catalyzed asymmetric reductive alkenylation

Language: Английский

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General C(sp²)–C(sp³) Cross-Electrophile Coupling Reactions Enabled by Overcharge Protection of Homogeneous Electrocatalysts

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(12), P. 5884 - 5893

Published: Feb. 29, 2020

Cross-electrophile coupling (XEC) of alkyl and aryl halides promoted by electrochemistry represents an attractive alternative to conventional methods that require stoichiometric quantities high-energy reductants. Most importantly, electroreduction can readily exceed the reducing potentials chemical reductants activate catalysts with improved reactivities selectivities over systems. This work details mechanistically-driven development electrochemical methodology for XEC utilizes redox-active shuttles developed energy-storage community protect reactive from overreduction. The resulting electrocatalytic system is practical, scalable, broadly applicable reductive a wide range aryl, heteroaryl, or vinyl bromides primary secondary bromides. impact overcharge protection as strategy electrosynthetic methodologies underscored dramatic differences in yields reactions added redox (generally >80%) those without <20%). In addition excellent substrates, protected overreduction be performed at high currents on multigram scales.

Language: Английский

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Reaction scope and mechanistic insights of nickel-catalyzed migratory Suzuki–Miyaura cross-coupling

Nature Communications, Journal Year: 2020, Volume and Issue: 11(1)

Published: Jan. 21, 2020

Abstract Cross-coupling reactions have developed into powerful approaches for carbon–carbon bond formation. In this work, a Ni-catalyzed migratory Suzuki–Miyaura cross-coupling featuring high benzylic or allylic selectivity has been developed. With method, unactivated alkyl electrophiles and aryl vinyl boronic acids can be efficiently transferred to diarylalkane allylbenzene derivatives under mild conditions. Importantly, chlorides also successfully used as the coupling partners. To demonstrate applicability of we showcase that strategy serve platform synthesis terminal, partially deuterium-labeled molecules from readily accessible starting materials. Experimental studies suggest products are generated Ni(0/II) catalytic cycle. Theoretical calculations indicate chain-walking occurs at neutral nickel complex rather than cationic one. addition, original-site obtained by alternating ligand, wherein formation rationalized radical chain process.

Language: Английский

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Synthesis of gem-Difluoroalkenes by Merging Ni-Catalyzed C–F and C–C Bond Activation in Cross-Electrophile Coupling

Organic Letters, Journal Year: 2019, Volume and Issue: 21(8), P. 2723 - 2730

Published: March 29, 2019

By merging C–F and C–C bond activation in the cross-electrophile coupling, we developed an efficient cyanide-free synthesis of diverse functional-group-rich cyano-substituted gem-difluoroalkenes using cyclobutanone oxime esters trifluoromethyl alkenes as precursors. Notably, this Ni-catalyzed reaction is bestowed with broad substrate scope, low catalyst loading, complete regioselectivities, high tolerance a wide range sensitive functional groups. Preliminary mechanistic studies indicate that iminyl radical-initiated cleavage involved pathway.

Language: Английский

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