Cyclic voltammetry and chronoamperometry: mechanistic tools for organic electrosynthesis

Chemical Society Reviews, Journal Year: 2023, Volume and Issue: 53(2), P. 566 - 585

Published: Dec. 5, 2023

This tutorial review explains the use of cyclic voltammetry and chronoamperometry to interrogate reaction mechanisms, optimize electrochemical reactions, or design new reactions.

Language: Английский

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Ni-Electrocatalytic Enantioselective Doubly Decarboxylative C(sp³)–C(sp³) Cross Coupling

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(21), P. 11518 - 11523

Published: May 16, 2023

The first examples of enantioselective doubly decarboxylative cross coupling are disclosed. Malonate half amides smoothly coupled to a variety primary carboxylic acids after formation the corresponding redox-active esters under Ni-electrocatalytic conditions using new chiral ligand based on PyBox, resulting in with α-alkylated stereocenters. scope reaction is broad, tolerating numerous functional groups, and uniformly proceeds high ee. Finally, potential utility this radical–radical reductive simplify synthesis demonstrated case studies.

Language: Английский

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Enantioselective C(sp²)–C(sp³) Bond Construction by Ni Catalysis

Accounts of Chemical Research, Journal Year: 2024, Volume and Issue: 57(5), P. 751 - 762

Published: Feb. 12, 2024

ConspectusAfter decades of palladium dominating the realm transition-metal-catalyzed cross-coupling, recent years have witnessed exciting advances in development new nickel-catalyzed cross-coupling reactions to form C(sp3) centers. Nickel possesses distinct properties compared with palladium, such as facile single-electron transfer electrophiles and rapid C–C reductive elimination from NiIII. These properties, among others, make nickel particularly well-suited for (RCC) which two are coupled an exogenous reductant is used turn over metal catalyst. Ni-catalyzed RCCs use readily available stable starting materials exhibit good functional group tolerance, makes them appealing applications synthesis complex molecules. Building upon foundational work by groups Kumada, Durandetti, Weix, well advancements enantioselective redox-neutral cross-couplings led Fu co-workers, we initiated a program explore feasibility developing highly RCCs. Our research has also been driven keen interest unraveling factors contributing enantioinduction electrophile activation seek avenues advancing our understanding further these reactions.In first part this Account, organize reported methods on basis identity electrophiles, including benzylic chlorides, N-hydroxyphthalimide (NHP) esters, α-chloro esters nitriles. We highlight how selection specific chiral ligands plays pivotal role achieving high cross-selectivity enantioselectivity. In addition, show that reduction can be accomplished not only heterogeneous reductants, Mn0, but soluble organic tetrakis(dimethylamino)ethylene (TDAE), electrochemically. The homogeneous TDAE, suited studying mechanism transformation. Although Account primarily focuses RCCs, using trifluoroborate (BF3K) salts radical precursors dual-Ni/photoredox systems.At end summarize relevant mechanistic studies closely related asymmetric alkenylation developed laboratory provide context between others. discuss ligand influence rates mechanisms mode generation optimize yield RCC. endeavors offer insights intricate at play goal rate improve substrate scope anticipate share guidance field.

Language: Английский

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Mechanisms of Photoredox Catalysis Featuring Nickel–Bipyridine Complexes

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(11), P. 9055 - 9076

Published: May 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.

Language: Английский

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C–heteroatom coupling with electron-rich aryls enabled by nickel catalysis and light

Nature Catalysis, Journal Year: 2024, Volume and Issue: 7(6), P. 733 - 741

Published: May 7, 2024

Abstract Nickel photoredox catalysis has resulted in a rich development of transition-metal-catalysed transformations for carbon–heteroatom bond formation. By harnessing light energy, the transition metal can attain oxidation states that are difficult to achieve through thermal chemistry catalytic manifold. For example, nickel reactions have been reported both synthesis anilines and aryl ethers from aryl(pseudo)halides. However, oxidative addition simple systems is often sluggish absence special, electron-rich ligands, leading catalyst decomposition. Electron-rich electrophiles therefore currently fall outside scope many field. Here we provide conceptual solution this problem demonstrate nickel-catalysed C–heteroatom bond-forming arylthianthrenium salts, including amination, oxygenation, sulfuration halogenation. Because redox properties salts primarily dictated by thianthrenium, highly donors be unlocked using NiCl 2 under irradiation form desired C‒heteroatom bonds.

Language: Английский

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Computational Methods Enable the Prediction of Improved Catalysts for Nickel-Catalyzed Cross-Electrophile Coupling

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(5), P. 3043 - 3051

Published: Jan. 26, 2024

Cross-electrophile coupling has emerged as an attractive and efficient method for the synthesis of C(sp2)–C(sp3) bonds. These reactions are most often catalyzed by nickel complexes nitrogenous ligands, especially 2,2′-bipyridines. Precise prediction, selection, design optimal ligands remains challenging, despite significant increases in reaction scope mechanistic understanding. Molecular parameterization statistical modeling provide a path to development improved bipyridine that will enhance selectivity existing broaden electrophiles can be coupled. Herein, we describe generation computational ligand library, correlation observed outcomes with features silico Ni-catalyzed cross-electrophile coupling. The new nitrogen-substituted display 5-fold increase product formation versus homodimerization when compared current state art. This yield was general several couplings, including challenging aryl chloride N-alkylpyridinium salt.

Language: Английский

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Ni-Catalyzed Enantioselective Desymmetrization: Development of Divergent Acyl and Decarbonylative Cross-Coupling Reactions

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

Published: Jan. 14, 2025

Ni-catalyzed asymmetric reductive cross-coupling reactions provide rapid and modular access to enantioenriched building blocks from simple electrophile precursors. Reductive coupling that can diverge through a common organometallic intermediate two distinct families of products are particularly versatile but underdeveloped. Here, we describe the development bis(oxazoline) ligand enables desymmetrization meso-anhydrides. When secondary benzylic electrophiles employed, doubly stereoselective acyl proceeds give ketone with catalyst control over three newly formed stereogenic centers. Alternatively, use primary alkyl halides in presence an additional halogen atom transfer results decarbonylative alkylation β-alkyl acids. Analysis reaction rates for range both catalysts substrates supports notion tuning different activation steps is required enhanced performance. These studies illustrate how design Ni-acyl either or highlight dual systems be used engage unactivated coupling.

Language: Английский

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Red-Light-Active N,C,N-Pincer Bismuthinidene: Excited State Dynamics and Mechanism of Oxidative Addition into Aryl Iodides

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

Published: Feb. 10, 2025

Despite the progress made in field of synthetic organic photocatalysis over past decade, use higher wavelengths, especially those deep-red portion electromagnetic spectrum, remains comparatively rare. We have previously disclosed that a well-defined N,C,N-pincer bismuthinidene (1a) can undergo formal oxidative addition into wide range aryl electrophiles upon absorption low-energy red light. In this study, we map out photophysical dynamics 1a and glean insights nature excited state responsible for activation electrophiles. Transient emission techniques reveal that, irradiation with light, complex undergoes direct S0 → S1 metal-to-ligand charge transfer (MLCT) transition, followed by rapid intersystem crossing (ISC) to highly reducing emissive triplet (−2.61 V vs Fc+/0 MeCN). The low dissipative losses incurred during ISC (∼6% incident light energy) help rationalize ability convert useful chemical energy. Spectroelectrochemical computational data support charge-separated excited-state structure radical-anion character on ligand radical-cation bismuth. Kinetic studies competition experiments afford mechanism iodides; concerted inner-sphere processes from are ruled out, strongly supporting pathway proceeds via outer-sphere dissociative electron transfer.

Language: Английский

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Enantioselective Reductive Cross-Couplings of Olefins by Merging Electrochemistry with Nickel Catalysis

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(44), P. 23910 - 23917

Published: Oct. 26, 2023

The merger of electrochemistry and transition metal catalysis has emerged as a powerful tool to join two electrophiles in an enantioselective manner. However, the development electroreductive cross-couplings olefins remains challenge. Inspired by advantages synergistic use with nickel catalysis, we present here Ni-catalyzed cross-coupling acrylates aryl halides alkyl bromides, which affords chiral α-aryl carbonyls good excellent enantioselectivity. Additionally, this catalytic reaction can be applied (hetero)aryl chlorides, is difficult achieve other methods. combination cyclic voltammetry analysis electrode potential studies suggests that NiI species activates oxidative addition bromides single-electron transfer.

Language: Английский

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A Paradigm Shift in Catalysis: Electro- and Photomediated Nickel-Catalyzed Cross-Coupling Reactions

Accounts of Chemical Research, Journal Year: 2023, Volume and Issue: 56(20), P. 2851 - 2865

Published: Sept. 29, 2023

ConspectusTransition-metal catalyzed cross-coupling reactions are fundamental in organic chemistry, facilitating strategic bond formations for accessing natural products, materials, agrochemicals, and pharmaceuticals. Redox chemistry enables access to elusive mechanisms through single-electron processes as an alternative classical two-electron strategies predominated by palladium catalysis. The seminal reports of Baran, MacMillan, Doyle, Molander, Weix, Lin, Fu, Reisman, others merging redox perturbation (photochemical, electrochemical, purely chemical) with catalysis pivotal the current resurgence mechanistic understanding first-row transition metal-based hallmark this platform is systematic modulation transition-metal oxidation states a photoredox catalyst or at heterogeneous electrode surface. Electrocatalysis photocatalysis enhance metal catalysis' capacity formation electron- energy-transfer that promote otherwise challenging elementary steps mechanisms. Cross-coupling conditions promoted electrocatalysis mild, proceeds exceptionally high chemoselectivity wide functional group tolerance. interfacing abundant has brought about paradigm shift technology practitioners quickly applying these tools synthesizing fine chemicals pharmaceutically relevant motifs. In particular, merger Ni electro- photochemistry ushered new era carbon-carbon carbon-heteroatom cross-couplings expanded generality compared their thermally driven counterparts. Over past decade, we have developed enabling photo- electrochemical methods throughout our combined research experience industry (BMS, AstraZeneca) academia (Professor Scripps Research) cross-disciplinary collaborative environments. Account, will outline recent progress from present laboratories electrochemically mediated Ni-catalyzed cross-couplings. By highlighting methodologies, also compare features both photochemical forging C(sp2)-C(sp3), C(sp3)-C(sp3), C-O, C-N, C-S bonds. Through side-by-side comparisons, hope demystify subtle differences between two complementary enact control over Finally, building off collective ourselves rest community, propose tactical user guide aid practitioner rapidly such synthetic designs.

Language: Английский

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