A Dual Cobalt and Photoredox Catalysis for Hydrohalogenation of Alkenes

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

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Photo‐ and Cobalt‐Catalyzed Synthesis of Heterocycles via Cycloisomerization of Unactivated Olefins

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

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

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

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Challenges and Future Perspectives in Photocatalysis: Conclusions from an Interdisciplinary Workshop

JACS Au, Journal Year: 2024, Volume and Issue: 4(8), P. 2746 - 2766

Published: Aug. 8, 2024

Photocatalysis is a versatile and rapidly developing field with applications spanning artificial photosynthesis, photo-biocatalysis, photoredox catalysis in solution or supramolecular structures, utilization of abundant metals organocatalysts, sustainable synthesis, plastic degradation. In this Perspective, we summarize conclusions from an interdisciplinary workshop young principal investigators held at the Lorentz Center Leiden March 2023. We explore how diverse fields within photocatalysis can benefit one another. delve into intricate interplay between these subdisciplines, by highlighting unique challenges opportunities presented each multidisciplinary approach drive innovation lead to solutions for future. Advanced collaboration knowledge exchange across domains further enhance potential photocatalysis. Artificial photosynthesis has become promising technology solar fuel generation, instance, via water splitting CO

Language: Английский

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

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

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Recent advances in C(sp³)–N bond formation via metallaphoto-redox catalysis

Chemical Communications, Journal Year: 2024, Volume and Issue: 60(50), P. 6340 - 6361

Published: Jan. 1, 2024

In this review, the state-of-the-art advances in radical-involved C(sp 3 )–N bond formation via metallaphotoredox catalysis have been highlighted, which are organized according to different catalytic modes, reaction types, and substrate classes.

Language: Английский

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Fe/Thiol Cooperative Hydrogen Atom Transfer Olefin Hydrogenation: Mechanistic Insights That Inform Enantioselective Catalysis

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(25), P. 17296 - 17310

Published: June 14, 2024

Asymmetric hydrogenation of activated olefins using transition metal catalysis is a powerful tool for the synthesis complex molecules, but traditional catalysts have difficulty with enantioselective reduction electron-neutral, electron-rich, and minimally functionalized olefins. Hydrogenation based on radical, metal-catalyzed hydrogen atom transfer (mHAT) mechanisms offers an outstanding opportunity to overcome these difficulties, enabling mild challenging selectivity that complementary hydrogenations H2. Further, mHAT presents asymmetric induction through cooperative (cHAT) chiral thiols. Here, we report insights from mechanistic study iron-catalyzed achiral cHAT reaction leverage deliver stereocontrol Kinetic analysis variation silane structure point hydride iron as likely rate-limiting step. The data indicate selectivity-determining step quenching alkyl radical by thiol, which becomes more potent H donor when coordinated iron(II). resulting iron(III)–thiolate in equilibrium other species, including FeII(acac)2, shown be predominant off-cycle species. enantiodetermining nature thiol trapping enables net commercially available glucose-derived catalyst up 80:20 enantiomeric ratio. To best our knowledge, this first demonstration via mHAT. These findings advance understanding act proof principle development reactions.

Language: Английский

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Magnesium/methanol-d1: a practical reductive deuteration system for the deuterium labeling of α,β-unsaturated esters, nitriles and amides

Organic & Biomolecular Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

The use of magnesium and methanol in the reduction various functional groups has been well established. In this study, we present a reductive deuteration system using Mg/CH

Language: Английский

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Hydride-Free Hydrogenation: Unraveling the Mechanism of Electrocatalytic Alkyne Semihydrogenation by Nickel–Bipyridine Complexes

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(31), P. 17103 - 17111

Published: July 25, 2023

Hydrogenation reactions of carbon-carbon unsaturated bonds are central in synthetic chemistry. Efficient catalysis these classically recourses to heterogeneous or homogeneous transition-metal species. Whether thermal electrochemical, C-C multiple bond catalytic hydrogenations commonly involve metal hydrides as key intermediates. Here, we report that the electrocatalytic alkyne semihydrogenation by molecular Ni bipyridine complexes proceeds without mediation a hydride intermediate. Through combined experimental and theoretical investigation, disclose mechanism primarily involves nickelacyclopropene resting state upon binding low-valent Ni(0) A following sequence protonation electron transfer steps

Language: Английский

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Manganese/Cobalt Bimetallic Relay Catalysis for Divergent Dehydrogenative Difluoroalkylation of Alkenes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(42)

Published: Aug. 29, 2023

The involvement of manganese radical for halogen atom transfer (XAT) reactions has been esteemed as one reliable method but encountered with limited catalytic models. In this paper, a novel bimetallic relay catalysis Mn2 (CO)10 and cobaloxime developed divergent dehydrogenative difluoroalkylation alkenes using commercially available difluoroalkyl bromides. A wide range structurally diverse terminal, cyclic internal well tetrasubstituted are found to be good coupling partners deliver difluoroalkylated allylic products difluoromethylated products, accompanied the production H2 by-product. This strategy features broad substrate scope, mild reaction conditions excellent functional group compatibility. Its success represents an important step-forward expedite construction rich library products.

Language: Английский

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