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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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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Diboron(4)‐Catalyzed Remote [3+2] Cycloaddition of Cyclopropanes via Dearomative/Rearomative Radical Transmission through Pyridine

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(52)

Опубликована: Ноя. 8, 2022

Abstract Ring structures such as pyridine, cyclopentane or their combinations are important motifs in bioactive molecules. In contrast to previous cycloaddition reactions that necessitated a directly bonded initiating functional group, this work demonstrated novel through‐(hetero)arene radical transmission concept for selective activation of remote bond. An efficient, metal‐free and atom‐economical [3+2] between 4‐pyridinyl cyclopropanes alkenes alkynes has been developed modular synthesis pyridine‐substituted cyclopentanes, cyclopentenes bicyclo[2.1.1]hexanes difficult access using known methods. This complexity‐building reaction was catalyzed by very simple inexpensive diboron(4) compound took place via dearomative/rearomative processes. The substrate scope broad more than 100 new compounds were prepared generally high yields. Mechanistic experiments density function theory (DFT) investigation supported relay catalytic cycle involving alkylidene dihydropyridine intermediates boronyl transfer.

Язык: Английский

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Photochemical Formal (4 + 2)-Cycloaddition of Imine-Substituted Bicyclo[1.1.1]pentanes and Alkenes

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(50), С. 21223 - 21228

Опубликована: Дек. 13, 2021

Amines containing bridged bicyclic carbon skeletons are desirable building blocks for medicinal chemistry. Herein, we report the conversion of bicyclo[1.1.1]pentan-1-amines to a wide range polysubstituted bicyclo[3.1.1]heptan-1-amines through photochemical, formal (4 + 2)-cycloaddition an intermediate imine diradical. To our knowledge, this is first reported method convert bicyclo[1.1.1]pentane skeleton bicyclo[3.1.1]heptane skeleton. Hydrolysis products gives complex, sp3-rich primary amine blocks.

Язык: Английский

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Asymmetric Photocatalysis Enabled by Chiral Organocatalysts

ChemCatChem, Год журнала: 2021, Номер 14(1)

Опубликована: Окт. 21, 2021

Abstract Visible‐light photocatalysis has advanced as a versatile tool in organic synthesis. However, attaining precise stereocontrol photocatalytic reactions been longstanding challenge due to undesired photochemical background and the involvement of highly reactive radicals or radical ion intermediates generated under conditions. To address this problem expand synthetic utility reactions, number innovative strategies, including mono‐ dual‐catalytic approaches, have recently emerged. Of these, exploiting chiral organocatalysis, such enamine catalysis, iminium‐ion Brønsted acid/base N ‐heterocyclic carbene induce chirality transfer widely explored. This Review aims provide current, comprehensive overview asymmetric enabled by organocatalysts published through June 2021. The substrate scope, advantages, limitations, proposed reaction mechanisms each are discussed. review should serve reference for development visible‐light‐induced promote improvement chemical reactivity stereoselectivity these reactions.

Язык: Английский

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Formal Cycloadditions Driven by the Homolytic Opening of Strained, Saturated Ring Systems

Angewandte Chemie International Edition, Год журнала: 2022, Номер 62(4)

Опубликована: Окт. 14, 2022

Abstract The field of strain‐driven, radical formal cycloadditions is experiencing a surge in activity motivated by renaissance free chemistry and growing demand for sp 3 ‐rich ring systems. former has been driven large part the rise photoredox catalysis, latter adoption “Escape from Flatland” concept medicinal chemistry. In years since these broader trends emerged, dozens cycloadditions, including catalytic, asymmetric variants, have developed that operate via mechanisms. While cyclopropanes studied most extensively, variety strained systems are amenable to design analogous reactions. Many processes generate lucrative, functionally decorated difficult access other means. Herein, we summarize recent efforts this area analyze state field.

Язык: Английский

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Ion-pair reorganization regulates reactivity in photoredox catalysts

Nature Chemistry, Год журнала: 2022, Номер 14(7), С. 746 - 753

Опубликована: Апрель 14, 2022

Язык: Английский

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Asymmetric [3 + 2] Photocycloaddition of β-Keto Esters and Vinyl Azides by Dual Photoredox/Nickel Catalysis

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(22), С. 12233 - 12243

Опубликована: Май 24, 2023

Photocatalytic [3 + 2] cycloadditions and control of stereochemistry have remained a substantial challenge, particularly in the context heterocycle synthesis; sporadic successful examples involved enantioselective photocycloaddition between redox-active direct group-containing cyclopropanes alkenes for creation cyclopentanes. Herein, we report cooperative catalytic system comprising chiral nickel Lewis acid catalyst an organic photocatalyst fueled by visible-light irradiation that allows hitherto elusive asymmetric β-keto esters with vinyl azides under redox-neutral conditions. This protocol enables highly construction polycyclic densely substituted 3,4-dihydro-2H-pyrrole heterocycles featuring two contiguous tetrasubstituted carbon stereocenters, including useful N,O-ketal motif is not easily accessible other methods. Mechanistic studies revealed overall reactivity relies on seamless integration dual roles catalysts formation substrate/Ni complex, assisting both photoredox event radical addition.

Язык: Английский

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Stereoselective Photoredox Catalyzed (3+3) Dipolar Cycloaddition of Nitrone with Aryl Cyclopropane

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

Опубликована: Сен. 13, 2023

Abstract By resorting to the principle of remote activation, we herein demonstrate first photoredox catalyzed (3+3) dipolar cycloaddition nitrones with aryl cyclopropanes. Key fidelity reaction resides in a facile manner substrate activation by single‐electron transfer (SET) oxidation catalysis, and takes place through stepwise cascade encompassing three‐electron‐type nucleophilic substitution triggered cyclopropane ring‐opening diastereoselective 6‐endo‐ trig radical cyclization manifold. The proceeds under mild conditions excellent regio‐ stereoselectivity, nicely complementing well‐developed Lewis acid donor‐acceptor Other merits protocol include wide scope cyclopropanes diversified patterns good functional‐group compatibility. A mechanism involving an cation promoted mode was also proposed supported mechanistic experiments.

Язык: Английский

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Recent Advances in Nonprecious Metal Catalysis

Organic Process Research & Development, Год журнала: 2023, Номер 27(3), С. 423 - 447

Опубликована: Фев. 17, 2023

Nonprecious-metal-catalyzed alternatives to powerful precious metal transformations are of increasing interest in academia and the pharmaceutical industry due lower cost, better sustainability, toxicity. With continual growth broad field nonprecious catalysis (NPMC), we have chosen highlight selected articles published from March June 2022 which intended examples NPMC that feel may be especially relevant development. We aim inspire academic industrial innovation through discussion herein.

Язык: Английский

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