Shining Fresh Light on Complex Photoredox Mechanisms through Isolation of Intermediate Radical Anions

ACS Catalysis, Год журнала: 2023, Номер 13(14), С. 9392 - 9403

Опубликована: Июнь 30, 2023

Photoredox catalysis (PRC) has gained enormous and wide-ranging interest in recent years but also been subject to significant mechanistic uncertainty, even controversy. To provide a method by which the missing understanding can begin be filled in, we demonstrate herein that it is possible isolate as authentic materials one-electron reduction products of representative PRC catalysts (PCs). Specifically, KC8 both 9,10-dicyanoanthracene naphthalene monoamide derivative presence cryptand provides convenient access corresponding [K(crypt)+][PC·-] salts clean fully characterized techniques including EPR XRD. Because PC·- states are key intermediates reactions, such isolation allows for highly controlled study these anions' specific reactivity hence their roles. As demonstration this principle, show used conveniently interrogate mechanisms recent, high-profile "conPET" "e-PRC" currently acute Using very simple experiments, able striking insights into reactions' underlying observe surprising levels hidden complexity would otherwise have challenging identify emphasize care control needed when interrogating interpreting mechanisms. These studies foundation far broader range questions around conPET, e-PRC, other reaction future, using same strategy isolation.

Язык: Английский

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The mechanism of visible light-induced C–C cross-coupling by C_sp³–H bond activation

Chemical Society Reviews, Год журнала: 2023, Номер 52(16), С. 5373 - 5387

Опубликована: Янв. 1, 2023

The chemistry and the reaction mechanisms behind four catalytic protocols currently available for visible light-induced C–C cross-coupling by activation of C sp 3 –H bonds are described.

Язык: Английский

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Electron‐Poor Acridones and Acridiniums as Super Photooxidants in Molecular Photoelectrochemistry by Unusual Mechanisms

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(44)

Опубликована: Авг. 16, 2023

Abstract Electron‐deficient acridones and in situ generated acridinium salts are reported as potent, closed‐shell photooxidants that undergo surprising mechanisms. When bridging acyclic triarylamine catalysts with a carbonyl group (acridones), this completely diverts their behavior away from open‐shell, radical cationic, ‘beyond diffusion’ photocatalysis to closed‐shell, neutral, diffusion‐controlled photocatalysis. Brønsted acid activation of dramatically increases excited state oxidation power (by +0.8 V). Upon reduction protonated acridones, they transform electron‐deficient even more potent (* E 1/2 =+2.56–3.05 V vs SCE). These oxidize arenes where conventional salt have thusfar been limited electron‐rich arenes. Surprisingly, upon photoexcitation these appear two electron reductive quenching form acridinide anions, spectroscopically‐detected forms. This new behaviour is partly enabled by catalyst preassembly the arene, contrasts SET salts. Critically, study illustrates how redox active chromophoric molecules initially considered photocatalysts can during reaction catalytically species different spectroscopic properties.

Язык: Английский

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Mechanophotocatalysis: A Generalizable Approach to Solvent‐minimized Photocatalytic Reactions for Organic Synthesis

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(13)

Опубликована: Янв. 24, 2024

This proof-of-concept study cements the viability and generality of mechanophotocatalysis, merging mechanochemistry photocatalysis to enable solvent-minimized photocatalytic reactions. We demonstrate transmutation four archetypal solution-state reactions a environment driven by combined actions milling, light, photocatalysts. The chlorosulfonylation alkenes pinacol coupling aldehydes ketones were conducted under solvent-free conditions with competitive or superior efficiencies their analogues. Furthermore, decarboxylative alkylations are shown function efficiently conditions, while photoinduced energy transfer promoted [2+2] cycloaddition chalcone experiences significant initial rate enhancement over its variant. work serves as platform for future discoveries in an underexplored field: validating that is not only generalizable photocatalysis, but can also offer valuable advantages.

Язык: Английский

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Photochemistry in Pharmaceutical Development: A Survey of Strategies and Approaches to Industry-wide Implementation

Organic Process Research & Development, Год журнала: 2024, Номер 28(4), С. 831 - 846

Опубликована: Март 8, 2024

We present and analyze the results of a pharmaceutical industry-wide survey strategies approaches that companies have for implementing photochemical reactions in discovery chemistry, process development, commercial manufacturing. The questions encompass types pursue why, reactors (batch flow) used, how they are characterized photochemistry, scale-up reactions, prioritize resources developing among other topics. focuses on many these topics from perspectives chemists scientists to highlight similarities differences between their specific transformations materials construction used reactors. clearly demonstrate photochemistry is viable synthetic strategy producing active ingredients (APIs), all way commercialization. While more prevalent early stage indicate leveraging successful scale-ups later stages often using flow significant knowledge resulting experiences. Nevertheless, there still gaps adopting across development very limited experience discussing with regulatory agencies. Overall, offers considerable benefits synthesizing APIs API processes, such as greenness sustainability, shortening routes, potential improved product quality.

Язык: Английский

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Basic Concepts and Activation Modes in Visible-Light-Photocatalyzed Organic Synthesis

Synthesis, Год журнала: 2022, Номер 55(02), С. 164 - 192

Опубликована: Авг. 29, 2022

Abstract Visible light photocatalysis has established itself as a promising sustainable and powerful strategy to access reactive intermediates, i.e. radicals radical ions, under mild reaction conditions using visible irradiation. This field enables the development of formerly challenging or even previously inaccessible organic transformations. In this tutorial review, an overview essential concepts techniques visible-light-mediated chemical processes most common types photochemical activation molecules, photoredox catalysis photosensitization, are discussed. Selected photocatalytic alkene functionalization reactions included examples illustrate basic with particular attention given understanding their mechanisms. 1 Introduction 2 Photocatalysts 3 Photophysical Electrochemical Properties 3.1 Excited-State Energy 3.2 Ground-State Redox Potentials 3.3 3.4 Local Absorbance Maximum for Lowest Absorption 3.5 Lifetime 3.6 [Ru(bpy)3]2+ Case Study 3.7 Basic Laws Equations Photochemistry Photocatalysis 3.8 Common Terminology in 4 Activation Modes 4.1 Photoinduced Electron Transfer 4.2 5 Conclusions Outlook

Язык: Английский

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Photocatalyst‐ and Transition‐Metal‐Free Light‐Induced Formation of Carbon‐Chalcogen Bonds

Advanced Synthesis & Catalysis, Год журнала: 2023, Номер 366(2), С. 168 - 182

Опубликована: Дек. 16, 2023

Abstract Photoinduced chemical transformations have become a promising aspect of organic synthesis. This review focuses on the recent advancements in harnessing photoinduced processes for formation carbon‐chalcogen (C−O, C−S, C−Se, and C−Te) bonds under catalyst‐free conditions. These pathways typically involve either radical mechanism or creation electron‐donor‐acceptor (EDA) complexes. The explores intricacies underlying mechanisms, discusses limitations, evaluates applicability various methodologies this field. Notably, photocatalyst transition metal‐free photochemical reactions offer effective alternatives to enhance sustainability research area.

Язык: Английский

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Sustainable Synthesis through Catalyst‐Free Photoinduced Cascaded Bond Formation

Chemistry - An Asian Journal, Год журнала: 2024, Номер 19(14)

Опубликована: Май 8, 2024

The beginning of photochemical reactions revolutionized synthetic chemistry through sustainable practices. This review explores cutting-edge developments in leveraging light-induced processes for generating cascaded C-C and C-hetero bonds without catalysts. Significantly, catalyst-free photoinduced methodologies have garnered considerable attention, especially the creation varied heterocyclic frameworks drug design synthesis natural products. article delves into underlying mechanisms, addresses limitations, evaluates various methodologies, emphasizing potential photocatalyst transition metal-free to enhance sustainability. Divided two sections, it covers recent strides C-heteroatom multiple bond formation reactions.

Язык: Английский

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Hydrosulfonylation of Unactivated Alkenes Involving Sulfonyl Radical Generation via Photocatalytic Activation of Symmetrical Disulfones by an Energy Transfer Mimicry

ACS Catalysis, Год журнала: 2024, Номер 14(16), С. 12282 - 12296

Опубликована: Авг. 2, 2024

A visible-light-photocatalyzed hydrosulfonylation of unactivated alkenes with symmetrical disulfones using 2,4,6-triisopropylthiophenol as a hydrogen atom donor (H-D) has been developed. Generation two sulfonyl radicals from via activation visible light photocatalysis is involved. Mechanistic studies rule out that are generated disulfone an energy transfer mechanism previously found for lower oxidation state sulfur–sulfur-based reactants (i.e., thiosulfonates and disulfides). Instead, mimic process occurs. This involves photoinduced electron (PET) oxidative quenching the excited photocatalyst (*PC) disulfone, which generates radical sulfinate byproduct, followed by reduction oxidized (PC•+) this byproduct (SET) generating second (PC). The reaction can be performed in dimethyl carbonate at room temperature, features broad functional group compatibility, allows easy recycling disulfide provided 2,4,6-trisubstituted thiophenol used H-D. compared state-of-the-art green metrics.

Язык: Английский

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Photocatalyst‐ and Transition Metal‐Free Light‐Induced Borylation Reactions

Chemistry - An Asian Journal, Год журнала: 2023, Номер 18(21)

Опубликована: Сен. 25, 2023

The increasing global warming concerns have propelled a surge in the demand for sustainable energy sources within domain of synthetic organic chemistry. A particularly prominent area research has been development mild strategies generating heterocyclic compounds. Heterocyclic compounds containing boron notably risen to prominence as pivotal reagents myriad transformations, showcasing their wide-ranging applicability. This comprehensive review is aimed at collecting literature pertaining borylation reactions induced by light, specifically focusing on photocatalyst-free and transition metal-free methodologies. central emphasis delving into selective mechanistic investigations. amalgamation analysis these insights elucidate substantial potential inherent eco-friendly approaches synthesizing compounds, thus propelling landscape

Язык: Английский

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