Catalytic hydrogen atom transfer to alkenes: a roadmap for metal hydrides and radicals

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

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Enantioselective Radical Reactions Using Chiral Catalysts

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

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Hydroamination, Aminoboration, and Carboamination with Electrophilic Amination Reagents: Umpolung-Enabled Regio- and Stereoselective Synthesis of N-Containing Molecules from Alkenes and Alkynes

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(2), P. 648 - 661

Published: Jan. 6, 2022

Nitrogen (N) is ubiquitously found in bioactive molecules, pharmaceutical agents, and organic functional materials. Accordingly, development of new C–N bond-forming catalysis has been one the long-standing research subjects synthetic chemistry. In this Perspective, recent advances highly selective amination reactions with electrophilic reagents are described: by taking advantage concept nitrogen umpolung, otherwise challenging aminofunctionalizations, such as hydroamination, aminoboration, carboamination, readily available feedstock-like alkenes alkynes possible, giving densely functionalized complex often chiral alkylamines high selectivity. The scope, limitations, reaction mechanism briefly summarized.

Language: Английский

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

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

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Photo‐ and Electrochemical Cobalt Catalysed Hydrogen Atom Transfer for the Hydrofunctionalisation of Alkenes

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

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Iron and cobalt catalysis: new perspectives in synthetic radical chemistry

Chemical Society Reviews, Journal Year: 2020, Volume and Issue: 49(23), P. 8501 - 8542

Published: Jan. 1, 2020

Iron and cobalt complexes are at the origin of high valuable synthetic pathways involving radical intemediates.

Language: Английский

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Visible-Light-Enabled Ortho-Selective Aminopyridylation of Alkenes with N-Aminopyridinium Ylides

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(28), P. 12420 - 12429

Published: July 2, 2020

By utilizing an underexplored reactivity mode of N-aminopyridinium ylides, we developed the visible-light-induced ortho-selective aminopyridylation alkenes via radical-mediated 1,3-dipolar cycloaddition. The photocatalyzed single-electron oxidation ylides generates corresponding radical cations that enable previously inaccessible 1,3-cycloaddition with a broader range alkene substrates. resulting cycloaddition adducts rapidly undergo subsequent homolytic cleavage N-N bond, conferring substantial thermodynamic driving force to yield various β-aminoethylpyridines. Remarkably, amino and pyridyl groups can be installed into both activated unactivated modular control ortho-selectivity 1,2-syn-diastereoselectivity under metal-free mild conditions. Combined experimental computational studies are conducted clarify detailed reaction mechanism origins site selectivity diastereoselectivity.

Language: Английский

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Catalyst- and Silane-Controlled Enantioselective Hydrofunctionalization of Alkenes by Cobalt-Catalyzed Hydrogen Atom Transfer and Radical-Polar Crossover

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(31), P. 13481 - 13490

Published: July 10, 2020

The catalytic enantioselective synthesis of tetrahydrofurans, which are found in the structures many biologically active natural products, via a transition-metal-catalyzed hydrogen atom transfer (TM-HAT) and radical-polar crossover (RPC) mechanism is described herein. Hydroalkoxylation nonconjugated alkenes proceeded efficiently with excellent enantioselectivity (up to 94% ee) using suitable chiral cobalt catalyst, N-fluoro-2,4,6-collidinium tetrafluoroborate, diethylsilane. Surprisingly, absolute configuration product was highly dependent on steric hindrance silane. Slow addition silane, dioxygen effect solvent, thermal dependence, DFT calculation results supported unprecedented scenario two competing selective mechanisms. For less-hindered diethylsilane, high concentration diffused carbon-centered radicals invoked diastereoenrichment an alkylcobalt(III) intermediate by radical chain reaction, eventually determined product. On other hand, more hindered silane resulted less opportunity for instead facilitating kinetic resolution during late-stage nucleophilic displacement alkylcobalt(IV) intermediate.

Language: Английский

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Cobalt‐Catalyzed Radical Hydroamination of Alkenes with N‐Fluorobenzenesulfonimides

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

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NiH-Catalyzed Proximal-Selective Hydroamination of Unactivated Alkenes

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(48), P. 20470 - 20480

Published: Nov. 18, 2020

Reported herein is a modular, NiH-catalyzed system capable of proximal-selective hydroamination unactivated alkenes with diverse amine sources. The key to the successful implementation this approach promotion NiH insertion into even highly substituted olefins via coordination bidentate directing group nickel complex. A wide range primary and secondary amines can be installed in both internal terminal excellent regiocontrol under optimized reaction conditions. This protocol flexible general for preparation variety valuable β- γ-amino acid building blocks that would otherwise difficult synthesize. utility transformation was further demonstrated by site-selective late-stage modification complex medicinally relevant molecules. Combined experimental computational studies illuminate detailed mechanism.

Language: Английский

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