Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2487 - 2649

Опубликована: Ноя. 9, 2021

Redox processes are at the heart of synthetic methods that rely on either electrochemistry or photoredox catalysis, but how do and catalysis compare? Both approaches provide access to high energy intermediates (e.g., radicals) enable bond formations not constrained by rules ionic 2 electron (e) mechanisms. Instead, they 1e mechanisms capable bypassing electronic steric limitations protecting group requirements, thus enabling chemists disconnect molecules in new different ways. However, while providing similar intermediates, differ several physical chemistry principles. Understanding those differences can be key designing transformations forging disconnections. This review aims highlight these similarities between comparing their underlying principles describing impact electrochemical photochemical methods.

Язык: Английский

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Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2017 - 2291

Опубликована: Ноя. 23, 2021

We present here a review of the photochemical and electrochemical applications multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms which both an proton exchanged together, often concerted elementary step. As such, MS-PCET can function as non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from wide variety common functional groups. introduction practitioner’s guide reaction design, with emphasis on unique energetic selectivity features that characteristic this class. then chapters oxidative N–H, O–H, S–H, C–H homolysis methods, generation corresponding neutral species. Then, reductive PCET activations involving carbonyl, imine, other X═Y π-systems, heteroarenes, where ketyl, α-amino, heteroarene-derived radicals be generated. Finally, we asymmetric catalysis materials device applications. Within each chapter, subdivide by group undergoing homolysis, thereafter type transformation being promoted. Methods published prior end December 2020 presented.

Язык: Английский

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Recent advances in visible light-activated radical coupling reactions triggered by (i) ruthenium, (ii) iridium and (iii) organic photoredox agents

Chemical Society Reviews, Год журнала: 2021, Номер 50(17), С. 9540 - 9685

Опубликована: Янв. 1, 2021

Visible light-activated reactions continue to expand and diversify. The example shown here is a Birch reduction achieved by organophotoredox reagents.

Язык: Английский

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Enantioselective Photochemical Reactions Enabled by Triplet Energy Transfer

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 1626 - 1653

Опубликована: Июль 6, 2021

For molecules with a singlet ground state, the population of triplet states is mainly possible (a) by direct excitation and subsequent intersystem crossing or (b) energy transfer from an appropriate sensitizer. The latter scenario enables catalytic photochemical reaction in which sensitizer adopts role catalyst undergoing several cycles photon absorption to substrate. If product molecule triplet-sensitized process chiral, this can proceed enantioselectively upon judicious choice chiral An enantioselective also occur dual approach which, apart achiral sensitizer, second activates substrate toward sensitization. Although idea reactions via intermediates has been pursued for more than 50 years, notable selectivities exceeding 90% enantiomeric excess (ee) have only realized past decade. This review attempts provide comprehensive survey on various were rendered

Язык: Английский

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Photocatalytic Late-Stage C–H Functionalization

Chemical Reviews, Год журнала: 2023, Номер 123(8), С. 4237 - 4352

Опубликована: Янв. 24, 2023

The emergence of modern photocatalysis, characterized by mildness and selectivity, has significantly spurred innovative late-stage C–H functionalization approaches that make use low energy photons as a controllable source. Compared to traditional strategies, photocatalysis paves the way toward complementary and/or previously unattainable regio- chemoselectivities. Merging compelling benefits with workflow offers potentially unmatched arsenal tackle drug development campaigns beyond. This Review highlights photocatalytic strategies small-molecule drugs, agrochemicals, natural products, classified according targeted bond newly formed one. Emphasis is devoted identifying, describing, comparing main mechanistic scenarios. draws critical comparison between established ionic chemistry photocatalyzed radical-based manifolds. aims establish current state-of-the-art illustrate key unsolved challenges be addressed in future. authors aim introduce general readership functionalization, specialist practitioners evaluation methodologies, potential for improvement, future uncharted directions.

Язык: Английский

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Chiral Photocatalyst Structures in Asymmetric Photochemical Synthesis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 1654 - 1716

Опубликована: Окт. 4, 2021

Asymmetric catalysis is a major theme of research in contemporary synthetic organic chemistry. The discovery general strategies for highly enantioselective photochemical reactions, however, has been relatively recent development, and the variety photoreactions that can be conducted stereocontrolled manner consequently somewhat limited. photocatalysis complicated by short lifetimes high reactivities characteristic photogenerated reactive intermediates; design catalyst architectures provide effective enantiodifferentiating environments these intermediates while minimizing participation uncontrolled racemic background processes proven to key challenge progress this field. This review provides summary chiral structures have studied solution-phase asymmetric photochemistry, including sensitizers, inorganic chromophores, soluble macromolecules. While some photocatalysts are derived from privileged both ground-state transformations, others structural designs unique offer insight into logic required photocatalysis.

Язык: Английский

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Alkoxy Radicals See the Light: New Paradigms of Photochemical Synthesis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2429 - 2486

Опубликована: Окт. 6, 2021

Alkoxy radicals are highly reactive species that have long been recognized as versatile intermediates in organic synthesis. However, their development has impeded due to a lack of convenient methods for generation. Thanks advances photoredox catalysis, enabling facile access alkoxy from bench-stable precursors and free alcohols under mild conditions, research interest this field renewed. This review comprehensively summarizes the recent progress radical-mediated transformations visible light irradiation. Elementary steps radical generation either or central reaction development; thus, each section is categorized discussed accordingly. Throughout review, we focused on different mechanisms well impact synthetic utilizations. Notably, catalytic abundant still early stage, providing intriguing opportunities exploit diverse paradigms.

Язык: Английский

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Photoenzymatic enantioselective intermolecular radical hydroalkylation

Nature, Год журнала: 2020, Номер 584(7819), С. 69 - 74

Опубликована: Июнь 8, 2020

Язык: Английский

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Phosphorus-Based Catalysis

ACS Central Science, Год журнала: 2021, Номер 7(4), С. 536 - 558

Опубликована: Март 16, 2021

Phosphorus-based organocatalysis encompasses several subfields that have undergone rapid growth in recent years. This Outlook gives an overview of its various aspects. In particular, we highlight key advances three topics: nucleophilic phosphine catalysis, organophosphorus catalysis to bypass oxide waste, and compound-mediated single electron transfer processes. We briefly summarize five additional chiral phosphoric acid Lewis base iminophosphorane super phosphonium salt phase frustrated pair catalysis. Although it is not catalytic nature, also discuss novel discoveries are emerging phosphorus(V) ligand coupling. conclude with some ideas about the future

Язык: Английский

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Strain-Release [2π + 2σ] Cycloadditions for the Synthesis of Bicyclo[2.1.1]hexanes Initiated by Energy Transfer

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(18), С. 7988 - 7994

Опубликована: Апрель 27, 2022

Saturated bicycles are becoming ever more important in the design and development of new pharmaceuticals. Here a strategy for synthesis bicyclo[2.1.1]hexanes is described. These significant because they have defined exit vectors, yet many substitution patterns underexplored as building blocks. The process involves sensitization bicyclo[1.1.0]butane followed by cycloaddition with an alkene. scope mechanistic details method discussed.

Язык: Английский

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