Visible-light induced dearomatization reactions

Chemical Society Reviews, Journal Year: 2022, Volume and Issue: 51(6), P. 2145 - 2170

Published: Jan. 1, 2022

This review provides an overview of visible-light induced dearomatization reactions classified based on the manner in which aromaticity is disrupted.

Language: Английский

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Visible-light photocatalytic di- and hydro-carboxylation of unactivated alkenes with CO2

Nature Catalysis, Journal Year: 2022, Volume and Issue: 5(9), P. 832 - 838

Published: Sept. 15, 2022

Language: Английский

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The advent and development of organophotoredox catalysis

Chemical Communications, Journal Year: 2021, Volume and Issue: 58(9), P. 1263 - 1283

Published: Dec. 10, 2021

We herein discuss how and when organic photocatalysts can efficiently replace or outperform their metal counterparts.

Language: Английский

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CdS Quantum Dots as Potent Photoreductants for Organic Chemistry Enabled by Auger Processes

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(27), P. 12229 - 12246

Published: June 30, 2022

Strong reducing agents (<−2.0 V vs saturated calomel electrode (SCE)) enable a wide array of useful organic chemistry, but suffer from variety limitations. Stoichiometric metallic reductants such as alkali metals and SmI2 are commonly employed for these reactions; however, considerations including expense, ease use, safety, waste generation limit the practicality methods. Recent approaches utilizing energy multiple photons or electron-primed photoredox catalysis have accessed reduction potentials equivalent to Li0 shown how this enables selective transformations aryl chlorides via radicals. However, in some cases, low stability catalytic intermediates can turnover numbers. Herein, we report ability CdS nanocrystal quantum dots (QDs) function strong photoreductants present evidence that highly electron is generated two consecutive photoexcitations QDs with intermediate reductive quenching. Mechanistic experiments suggest Auger recombination, photophysical phenomenon known occur photoexcited anionic QDs, generates transient thermally excited electrons observed reductions. Using blue light-emitting diodes (LEDs) sacrificial amine reductants, phosphate esters up −3.4 SCE photoreductively cleaved afford hydrodefunctionalized functionalized products. In contrast small-molecule catalysts, stable under conditions numbers 47 500 been achieved. These also effect other challenging reductions, tosylate protecting group removal amines, debenzylation benzyl-protected alcohols, ring opening cyclopropane carboxylic acid derivatives.

Language: Английский

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Red Light-Based Dual Photoredox Strategy Resembling the Z-Scheme of Natural Photosynthesis

JACS Au, Journal Year: 2022, Volume and Issue: 2(6), P. 1488 - 1503

Published: June 10, 2022

Photoredox catalysis typically relies on the use of single chromophores, whereas strategies, in which two different light absorbers are combined, rare. In photosystems I and II green plants, separate chromophores P680 P700 both absorb independently one another, then their excitation energy is combined so-called Z-scheme, to drive an overall reaction that thermodynamically very demanding. Here, we adapt this concept perform photoredox reactions organic substrates with input red photons instead blue or UV light. Specifically, a CuI bis(α-diimine) complex combination situ formed 9,10-dicyanoanthracenyl radical anion presence excess diisopropylethylamine catalyzes ca. 50 dehalogenation detosylation reactions. This dual approach seems useful because less damaging has greater penetration depth than radiation. UV-vis transient absorption spectroscopy reveals subtle change solvent from acetonitrile acetone induces changeover mechanism, involving either dominant photoinduced electron transfer triplet-triplet pathway. Our study illustrates mechanistic complexity systems operating under multiphotonic conditions, it provides insights into how competition between desirable unwanted steps can become more controllable.

Language: Английский

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Formation and degradation of strongly reducing cyanoarene-based radical anions towards efficient radical anion-mediated photoredox catalysis

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Jan. 6, 2023

Cyanoarene-based photocatalysts (PCs) have attracted significant interest owing to their superior catalytic performance for radical anion mediated photoredox catalysis. However, the factors affecting formation and degradation of cyanoarene-based PC (PC•‒) are still insufficiently understood. Herein, we therefore investigate PC•‒ under widely-used photoredox-mediated reaction conditions. By screening various PCs, elucidate strategies efficiently generate with adequate excited-state reduction potentials (Ered*) via supra-efficient generation long-lived triplet excited states (T1). To thoroughly behavior in actual reactions, a reductive dehalogenation is carried out as model identified dominant photodegradation pathways PC•‒. Dehalogenation coexistent depending on rate electron transfer (ET) substrate strongly depends electronic steric properties PCs. Based understanding both PC•‒, demonstrate that efficient highly reducing allows catalyzed aryl/alkyl halides at loading low 0.001 mol% high oxygen tolerance. The present work provides new insights into reactions reactions.

Language: Английский

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Dicarboxylation of Alkenes with CO₂ and Formate via Photoredox Catalysis

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(3), P. 2149 - 2155

Published: Jan. 25, 2023

Herein, a photocatalytic strategy for the synthesis of succinic acids by alkene dicarboxylation with carbon dioxide (CO2) and formate salt as synergistic sources is described. The acts both C1 source reductant in reaction catalytic amount 1,4-diazabicyclo[2.2.2]octane (DABCO) hydrogen atom transfer reagent. Various mono-, di-, trisubstituted alkenes, acrylate, acrylamide, indole derivatives could be converted to corresponding diacids, which provided potential useful applications medicinal chemistry polymer industry.

Language: Английский

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Radical Hydrocarboxylation of Unactivated Alkenes via Photocatalytic Formate Activation

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(20), P. 10991 - 10997

Published: May 15, 2023

Herein we disclose a strategy to promote the hydrocarboxylation of unactivated alkenes using photochemical activation formate salts. We illustrate that an alternative initiation mechanism circumvents limitations prior approaches and enables this challenging substrate class. Specifically, found accessing requisite thiyl radical initiator without exogenous chromophore eliminates major byproducts have plagued attempts exploit similar reactivity for alkene substrates. This redox-neutral method is technically simple execute effective across broad range Feedstock alkenes, such as ethylene, are hydrocarboxylated at ambient temperature pressure. A series cyclization experiments indicate how described in report can be diverted by more complex processes.

Language: Английский

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Synthesis of 1-(Halo)alkyl-3-heteroaryl Bicyclo[1.1.1]pentanes Enabled by a Photocatalytic Minisci-type Multicomponent Reaction

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(8), P. 6247 - 6258

Published: April 10, 2024

Aryl-substituted bicyclo[1.1.1]pentane (BCP-aryl) derivatives represent the most important bioisosteres of biaryl scaffolds and widely exist in numerous complex pharmaceutical molecules. The current synthetic method limitations using only tertiary radical precursors, prefunctionalized heteroarenes, toxic transition metals, expensive photocatalysts make it urgent to develop a more simple practical protocol. To confront enrich Minisci-type chemistry, herein, we disclose photocatalytic multicomponent reaction for synthesis various (halo)alkyl BCP-aryls [1.1.1]propellane, alkyl halides, unfunctionalized heteroarenes as starting materials. Diverse kinds radicals (primary, secondary, carbons) derived from chlorides, bromides, fluoroalkyl iodides are very compatible this transformation. practicability is additionally boosted by product derivatizations late-stage functionalization pharmaceutically relevant mechanistic studies demonstrate that relay mechanism initiated consecutive photoinduced electron transfer (ConPET) process operation. We anticipate methodology would act useful tool biaryl-type drug derivatives, ultimately resulting great utility discovery program.

Language: Английский

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Electrophotocatalytic hydrogenation of imines and reductive functionalization of aryl halides

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: Jan. 22, 2024

Abstract The open-shell catalytically active species, like radical cations or anions, generated by one-electron transfer of precatalysts are widely used in energy-consuming redox reactions, but their excited-state lifetimes usually short. Here, a closed-shell thioxanthone-hydrogen anion species ( 3 ), which can be photochemically converted to potent and long-lived reductant, is under electrochemical conditions, enabling the electrophotocatalytic hydrogenation. Notably, TfOH regulate potential this system. In presence TfOH, precatalyst 1 ) reduction occur at low potential, so that competitive H 2 evolution inhibited, thus effectively promoting hydrogenation imines. absence reducing ability system reach potency even comparable Na 0 Li , thereby allowing hydrogenation, borylation, stannylation (hetero)arylation aryl halides construct C−H, C−B, C−Sn, C−C bonds.

Language: Английский

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