Photoinduced Cobalt Catalysis for the Reductive Coupling of Pyridines and Dienes Enabled by Paired Single‐Electron Transfer** DOI Creative Commons

Jingyang Qin,

Manuel Barday,

Samikshan Jana

et al.

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(45)

Published: Sept. 7, 2023

Abstract Selective hydroarylation of dienes has potential to provide swift access useful building blocks. However, most existing methods rely on stabilised by an aromatic group and transmetallation or nucleophilic attack steps require electron‐rich aryl coupling partners. As such, there are few examples which tolerate wide‐spread heteroarenes such as pyridine. Whilst allylic C−H functionalisation could be considered alternative approach, the positional selectivity unsymmetrical substrates is hard control. Here, we report a general approach for selective hydropyridylation under mild conditions using metal catalysed hydrogen‐atom transfer. Photoinduced, reductive enable simultaneous formation cobalt‐hydride catalyst persistent radical easily‐synthesised pyridyl phosphonium salts. This facilitates in traceless manner at C4‐position wide‐range pyridine substrates. The mildness method underscored its functional‐group tolerance demonstrated applications late‐stage functionalisation. Based combination experimental computational studies, propose mechanistic pathway proceeds through non‐reversible transfer (HAT) from cobalt hydride species uniquely presence other olefins due much higher relative barrier associated with olefin HAT.

Language: Английский

Catalytic hydrogen atom transfer to alkenes: a roadmap for metal hydrides and radicals DOI Creative Commons
Sophia L. Shevick,

Conner V. Wilson,

Simona Kotesova

et al.

Chemical Science, Journal Year: 2020, Volume and Issue: 11(46), P. 12401 - 12422

Published: Jan. 1, 2020

Hydrogen atom transfer from metal hydrides to alkenes appears underlie widely used catalytic methods – the mechanistic implications are fascinating.

Language: Английский

Citations

261
Enantioselective Radical Reactions Using Chiral Catalysts DOI
Shovan Mondal, Frédéric Dumur, Didier Gigmès

et al.

Chemical Reviews, Journal Year: 2022, Volume and Issue: 122(6), P. 5842 - 5976

Published: Jan. 24, 2022

Benefiting from the impressive increase in fundamental knowledge, last 20 years have shown a continuous burst of new ideas and consequently plethora catalytic methods for enantioselective radical reactions. This review aims to provide complete survey progress achieved over this latter period. The first part focuses on use chiral organocatalysts, these include catalysts covalently linked substrate those that interact with by weaker interactions like hydrogen bonds. second is devoted transition-metal redox catalysis which organized according increasing atomic number first-row transition metals (Ti, Cr, Fe, Mn, Co, Ni, Cu). Bioinspired manganese- iron-mediated hydroxylations oxidations are also discussed. A specific section dedicated reactivity Ru, Rh, Ir complexes as Lewis acids special focus at metal. Absorption photons result different events such energy transfer, single-electron hydrogen-atom transfer facilitating formation radicals. Organocatalysis has been successfully combined photocatalysts, opened pathways enlarging precursors available. merger photocatalysis organo- or metalla-photocatalysis brought novelty allowed discovery large original transformations. enzyme-catalyzed reactions involving intermediates largely benefit visible-light irradiation included review. provides comprehensive inventory goal detailing reaction mechanisms involved transformations any nonspecialist could find their own creativity invent yet unknown applications.

Language: Английский

Citations

253
A Triple Photoredox/Cobalt/Brønsted Acid Catalysis Enabling Markovnikov Hydroalkoxylation of Unactivated Alkenes DOI

Masanari Nakagawa,

Yuki Matsuki,

Kazunori Nagao

et al.

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(18), P. 7953 - 7959

Published: April 27, 2022

We demonstrate Markovnikov hydroalkoxylation of unactivated alkenes using alcohols through a triple catalysis consisting photoredox, cobalt, and Brønsted acid catalysts under visible light irradiation. The realizes three key elementary steps in single catalytic cycle: (1) Co(III) hydride generation by photochemical reduction Co(II) followed protonation, (2) metal hydrogen atom transfer (MHAT) hydride, (3) oxidation the alkyl complex to Co(IV). precise control protons electrons allows elimination strong acids external reductants/oxidants that are required conventional methods.

Language: Английский

Citations

80
Photo‐ and Electrochemical Cobalt Catalysed Hydrogen Atom Transfer for the Hydrofunctionalisation of Alkenes DOI Creative Commons

Samikshan Jana,

Victor J. Mayerhofer,

Christopher J. Teskey

et al.

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(41)

Published: May 15, 2023

Catalytic hydrogen atom transfer from metal-hydrides to alkenes allows feedstock olefins be used as alkyl radical precursors. The chemoselectivity of this process makes it an attractive synthetic tool and such has been regularly in synthesis complex molecules. However, onwards reactivity is limited by compatibility with the conditions which form key metal-hydride species. Now, through merger photocatalysis or electrochemistry, milder methods are emerging can unlock entirely new offer perspectives on expanding these unprecedented directions. This review outlines most recent developments electro- photochemical cobalt catalysed offers suggestions future outlook.

Language: Английский

Citations

57
Electrocatalytic Access to Azetidines via Intramolecular Allylic Hydroamination: Scrutinizing Key Oxidation Steps through Electrochemical Kinetic Analysis DOI
Steve Park, Geunsu Bae,

Ahhyeon Choi

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(28), P. 15360 - 15369

Published: July 10, 2023

Azetidines are prominent structural scaffolds in bioactive molecules, medicinal chemistry, and ligand design for transition metals. However, state-of-the-art methods cannot be applied to intramolecular hydroamination of allylic amine derivatives despite their underlying potential as one the most prevalent synthetic precursors azetidines. Herein, we report an electrocatalytic method sulfonamides access azetidines first time. The merger cobalt catalysis electricity enables regioselective generation key carbocationic intermediates, which could directly undergo C-N bond formation. mechanistic investigations including electrochemical kinetic analysis suggest that either catalyst regeneration by nucleophilic cyclization or second oxidation intermediate is involved rate-determining step (RDS) our protocol highlight ability electrochemistry providing ideal means mediate oxidation.

Language: Английский

Citations

56
Co-Catalyzed Hydrofluorination of Alkenes: Photocatalytic Method Development and Electroanalytical Mechanistic Investigation DOI
Jinjian Liu, Jian Rong, Devin Wood

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(7), P. 4380 - 4392

Published: Feb. 1, 2024

The hydrofluorination of alkenes represents an attractive strategy for the synthesis aliphatic fluorides. This approach provides a direct means to form C(sp3)–F bonds selectively from readily available alkenes. Nonetheless, conducting using nucleophilic fluorine sources poses significant challenges due low acidity and high toxicity associated with HF poor nucleophilicity fluoride. In this study, we present new Co(salen)-catalyzed simple utilizing Et3N·3HF as sole source both hydrogen fluorine. process operates via photoredox-mediated polar-radical-polar crossover mechanism. We also demonstrated versatility method by effectively converting diverse array activated varying degrees substitution into hydrofluorinated products. Furthermore, successfully applied methodology 18F-hydrofluorination reactions, enabling introduction 18F potential radiopharmaceuticals. Our mechanistic investigations, conducted rotating disk electrode voltammetry DFT calculations, unveiled involvement carbocation CoIV–alkyl species viable intermediates during fluorination step, contribution each pathway depends on structure starting alkene.

Language: Английский

Citations

29
A Dual Cobalt and Photoredox Catalysis for Hydrohalogenation of Alkenes DOI

Shotaro Shibutani,

Kazunori Nagao, Hirohisa Ohmiya

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(7), P. 4375 - 4379

Published: Feb. 1, 2024

We demonstrate hydrohalogenation of aliphatic alkenes with collidine·HX salts through dual photoredox/cobalt catalysis. The catalysis enables conversion a proton and halide anion from salt to nucleophilic hydrogen radical equivalent an electrophilic halogen delivery them alkene moiety. This protocol allows for introduction fluorine, chlorine, bromine, or iodine atom alkene, producing highly functionalized alkyl halides.

Language: Английский

Citations

25
Photo‐ and Cobalt‐Catalyzed Synthesis of Heterocycles via Cycloisomerization of Unactivated Olefins DOI Creative Commons
Henry Lindner, Willi M. Amberg, Tristano C. Martini

et al.

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(19)

Published: Feb. 28, 2024

Abstract We report a general, intramolecular cycloisomerization of unactivated olefins with pendant nucleophiles. The reaction proceeds under mild conditions and tolerates ethers, esters, protected amines, acetals, pyrazoles, carbamates, arenes. It is amenable to N ‐, O as well C ‐nucleophiles, yielding number different heterocycles including, but not limited to, pyrrolidines, piperidines, oxazolidinones, lactones. Use both benzothiazinoquinoxaline organophotocatalyst Co‐salen catalyst obviates the need for stoichiometric oxidant or reductant. showcase utility protocol in late‐stage drug diversification synthesis several small natural products.

Language: Английский

Citations

19
Mechanism of Alkene Hydrofunctionalization by Oxidative Cobalt(salen) Catalyzed Hydrogen Atom Transfer DOI

Conner V. Wilson,

Patrick L. Holland

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(4), P. 2685 - 2700

Published: Jan. 16, 2024

Oxidative MHAT hydrofunctionalization of alkenes provides a mild cobalt-catalyzed route to forming C–N and C–O bonds. Here, we characterize relevant salen-supported cobalt complexes their reactions with alkenes, silanes, oxidant, solvent. These stoichiometric investigations are complemented by kinetic studies the catalytic reaction catalyst speciation. We describe solution characterization an elusive cobalt(III) fluoride complex, which surprisingly is not species that reacts silane under conditions; rather, aquo complex more active. Accordingly, addition water (0.15 M) speeds reaction, show enables product formation in 2 h at −50 °C acetone. Under these conditions, resting states can be observed UV–vis spectrophotometry, including cobalt(III)-alkyl complex. It comes from transient hydride formed turnover-limiting step cycle. This readily degrades but H2; it releases H+ through bimetallic pathway explains [Co]2 dependence off-cycle reaction. In contrast, rate follows power law kobs[Co]1[silane]1. Because different [Co] degradation lower loading improves yield reducing relative unproductive silane/oxidant consumption. illuminate mechanistic details oxidative lay groundwork for understanding other mediated alkyl complexes.

Language: Английский

Citations

18
Cobalt‐Catalyzed Radical Hydroamination of Alkenes with N‐Fluorobenzenesulfonimides DOI
Tao Qin, Guowei Lv, Qi Meng

et al.

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(49), P. 25949 - 25957

Published: Sept. 25, 2021

An efficient and general radical hydroamination of alkenes using Co(salen) as catalyst, N-fluorobenzenesulfonimide (NFSI) its analogues both nitrogen source oxidant was successfully disclosed. A variety alkenes, including aliphatic styrenes, α, β-unsaturated esters, amides, acids, well enones, were all compatible to provide desired amination products. Mechanistic experiments suggest that the reaction underwent a metal-hydride-mediated hydrogen atom transfer (HAT) with alkene, followed by pivotal catalyst controlled SN 2-like pathway between in situ generated organocobalt(IV) species nitrogen-based nucleophiles. Moreover, virtue modified chiral cobalt(II)-salen an unprecedented asymmetric version also achieved good excellent level enantiocontrol. This novel C-N bond construction opens new door for challenging hydrofunctionalization.

Language: Английский

Citations

103