Energy transfer photocatalysis: exciting modes of reactivity

Chemical Society Reviews, Год журнала: 2024, Номер 53(3), С. 1068 - 1089

Опубликована: Янв. 1, 2024

Leveraging light energy to expose the ‘dark’ reactive states describes whole essence of triplet–triplet transfer. This offers an impressive opportunity conduct a multitude diverse reactions and access sought-after molecular motifs.

Язык: Английский

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Energy-Transfer-Enabled Dearomative Cycloaddition Reactions of Indoles/Pyrroles via Excited-State Aromatics

Accounts of Chemical Research, Год журнала: 2022, Номер 55(17), С. 2510 - 2525

Опубликована: Авг. 9, 2022

Exploring the enormous chemical space through an expedient building-up of molecular diversity is important goal organic chemistry. The development synthetic methods toward molecules with unprecedented structural motifs lays foundation for wide applications ranging from pharmaceutical chemistry to materials science. In this regard, dearomatization arenes has been recognized as a unique strategy since it provides novel retrosynthetic disconnections various spiro or fused polycyclic increased saturation and stereoisomerism. However, inherent thermodynamic challenges are associated processes. disruption aromaticity arene substrates usually requires large energy inputs, which makes harsh conditions necessary many ground-state reactions. Therefore, further expansion scope reactions remains major problem not fully solved in chemistry.The past decade witnessed tremendous progress on photocatalytic under visible light. Particularly, via transfer mechanism have unlocked new opportunities Mediated by appropriately chosen photosensitizers, aromatic can be excited. This kind precise input might make feasible some that otherwise unfavorable thermal because significant increases substrates. Nevertheless, lifetimes key intermediates energy-transfer-enabled reactions, such excited-state aromatics downstream biradical species, quite short. How regulate reactivities these transient achieve exclusive selectivity certain reaction pathway among possibilities crucial issue addressed.Since 2019, our group reported series visible-light-induced dearomative cycloaddition indole pyrrole derivatives. It was found units excited irradiation light presence suitable photosensitizer. These readily undergo [m + n] tethered unsaturated functionalities including alkenes, alkynes, N-alkoxy oximes, (hetero)arenes, vinylcyclopropanes. yield indolines pyrrolines highly strained small- and/or medium-sized rings embedded, possess bridge- cagelike topologies. Systematic mechanistic studies confirmed involvement process. Density functional theory (DFT) calculations revealed correlation between substrate structure excitation efficiency, accelerated optimization parameters. Meanwhile, DFT demonstrated competition kinetically thermodynamically controlled pathways open-shell singlet intermediates, allowed complete switches [2 2] 1,5-hydrogen atom oximes [4 naphthalene. Furthermore, ab initio dynamics (AIMD) simulations uncovered post-spin crossing dynamic effects, determine regioselectivity recombination step pyrrole-derived vinylcyclopropanes.An increasing number scientists joined research contributed more elegant examples area. mechanism, although still its infancy, exhibited great potential synthesis hardly accessed other methods. We believe future will push boundary find related disciplines.

Язык: Английский

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Strain-Release Photocatalysis

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(38), С. 20716 - 20732

Опубликована: Сен. 15, 2023

The concept of strain in organic compounds is as old modern chemistry and was initially introduced to justify the synthetic setbacks along synthesis small ring systems (pars construens strain). In last decades, chemists have developed an arsenal strain-release reactions destruens strain) which can generate─with significant driving force─rigid aliphatic that act three-dimensional alternatives (hetero)arenes. Photocatalysis added additional dimension processes by leveraging energy photons create chemical complexity under mild conditions. This perspective presents latest advancements photocatalysis─with emphases on mechanisms, catalytic cycles, current limitations─the unique architectures be produced, possible future directions.

Язык: Английский

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Synthesis of Polysubstituted 2-Oxabicyclo[2.1.1]hexanes via Visible-Light-Induced Energy Transfer

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(44), С. 20207 - 20213

Опубликована: Окт. 27, 2022

Synthesis of bicyclic scaffolds has attracted growing interest because they are high importance in modern pharmaceutical development. Here we report a strategy to access polysubstituted 2-oxabicyclo[2.1.1]hexanes single operation from readily accessible benzoylformate esters and bicyclo[1.1.0]butanes via visible-light-induced triplet energy transfer catalysis. The process is proposed involve formal [2π + 2σ] photocycloaddition/backbone C-H abstraction/aryl group migration sequence. A diverse range (hetero)aryl groups successfully underwent the backbone (C2) position provide previously inaccessible molecules, ester product can serve as handle for downstream manipulation, thus offering opportunities rapidly build up molecular complexity new sp3-rich chemical space.

Язык: Английский

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ortho-Selective Dearomative [2π + 2σ] Photocycloadditions of Bicyclic Aza-Arenes

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(22), С. 12324 - 12332

Опубликована: Май 26, 2023

Dearomative photocycloadditions are valuable chemical transformations, serving as an efficient platform to create three-dimensional molecular complexity. However, the photolability of original addition product especially within context ortho cycloadditions often causes undesired consecutive rearrangements, rendering these cycloadducts elusive. Herein, we report ortho-selective intermolecular photocycloaddition bicyclic aza-arenes including (iso)quinolines, quinazolines, and quinoxalines by utilizing a strain-release approach. With bicyclo[1.1.0]butanes coupling partners, this dearomative [2π + 2σ] cycloaddition enables straightforward construction C(sp3)-rich bicyclo[2.1.1]hexanes directly connected N-heteroarenes. Photophysical experiments DFT calculations revealed origin selectivity indicate that, in originally proposed energy transfer or direct excitation pathways, chain reaction mechanism is operative depending on conditions.

Язык: Английский

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Photoredox-Enabled Dearomative [2π + 2σ] Cycloaddition of Phenols

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(4), С. 2789 - 2797

Опубликована: Янв. 18, 2024

Dearomative photocycloaddition of monocyclic arenes is an appealing strategy for comprehending the concept "escape from flatland". This brings replacement readily available planar aromatic hydrocarbon units with a 3D fused bicyclic core sp3-enriched carbon units. Herein, we outline intermolecular approach dearomative phenols. In order to circumvent ground-state aromaticity and construct conformationally restrained building blocks, bicyclo[1.1.0]butanes were chosen as coupling partners. renders straightforward access bicyclo[2.1.1]hexane unit cyclic enone moiety, which further contributed synthetic linchpin postmodifications. Mechanistic experiment advocates plausible onset both reactants, depending on redox potential.

Язык: Английский

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Recent Strategies in the Nucleophilic Dearomatization of Pyridines, Quinolines, and Isoquinolines

Chemical Reviews, Год журнала: 2024, Номер 124(3), С. 1122 - 1246

Опубликована: Янв. 2, 2024

Dearomatization reactions have become fundamental chemical transformations in organic synthesis since they allow for the generation of three-dimensional complexity from two-dimensional precursors, bridging arene feedstocks with alicyclic structures. When those processes are applied to pyridines, quinolines, and isoquinolines, partially or fully saturated nitrogen heterocycles formed, which among most significant structural components pharmaceuticals natural products. The inherent challenge lies low reactivity heteroaromatic substrates, makes dearomatization process thermodynamically unfavorable. Usually, connecting event irreversible formation a strong C–C, C–H, C–heteroatom bond compensates energy required disrupt aromaticity. This aromaticity breakup normally results 1,2- 1,4-functionalization heterocycle. Moreover, combination these subsequent tandem stepwise protocols allows multiple heterocycle functionalizations, giving access complex molecular skeletons. aim this review, covers period 2016 2022, is update state art nucleophilic dearomatizations showing extraordinary ability dearomative methodology indicating their limitations future trends.

Язык: Английский

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Energy-transfer-induced [3+2] cycloadditions of N–N pyridinium ylides

Nature Chemistry, Год журнала: 2023, Номер 15(8), С. 1091 - 1099

Опубликована: Июнь 26, 2023

Язык: Английский

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Photochemical Dearomative Cycloadditions of Quinolines and Alkenes: Scope and Mechanism Studies

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(38), С. 17680 - 17691

Опубликована: Сен. 15, 2022

Photochemical dearomative cycloaddition has emerged as a useful strategy to rapidly generate molecular complexity. Within this context, stereo- and regiocontrolled intermolecular para-cycloadditions are rare. Herein, method achieve photochemical of quinolines alkenes is shown. Emphasis placed on generating sterically congested products reaction highly substituted allenes. In addition, the mechanistic details process studied, which revealed reversible radical addition selectivity-determining recombination. The regio- stereochemical outcome also rationalized.

Язык: Английский

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Visible Light‐Mediated Cyclopropanation: Recent Progress

European Journal of Organic Chemistry, Год журнала: 2022, Номер 2022(44)

Опубликована: Окт. 21, 2022

Abstract Cyclopropanes are one of the most important strained rings existing in various pharmaceutical products and secondary metabolites. They also widely used total synthesis natural products, medicinal chemistry, materials science. In past years, photochemical cyclopropanation has been gradually developed as a robust attractive synthetic method to prepare diverse cyclopropane backbones. this review, we summarize recent advances visible light‐mediated synthesis, especially using carbene transfer strategy photocatalytic radical reactions.

Язык: Английский

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