Advancements in organocatalysis for radical-mediated asymmetric synthesis: A recent perspective

Yang, Fuxing; Huang, Tao; Lin, Yu-Mei; Gong, Lei

doi:10.1016/j.checat.2023.100812

“…However, they still suffer from low catalytic efficiency and limited substrates. , On the other hand, for chiral catalysis, more and more new strategies are being developed to realize challenging reactions by utilizing the synergy between different types of catalysts and the coupling of various excitation effects. Thereinto, photodriven chiral catalysis is one of the cleanest and most efficient ways to produce chiral compounds, which has recently gained much attention. − Two kinds of strategies are mainly adopted in photodriven chiral catalysis: dual catalyst system − and single catalyst system (bifunctional organic photocatalyst as a representative). − The former requires a chiral catalyst to provide a chiral environment as well as additional photocatalysts to trigger the process of photoredox or energy transfer. The bifunctional organic photocatalyst is a combination of organic photocatalyst moieties, which can be activated by light with chiral catalysts responsible for enantioselective induction. , For example, Bach first reported the highly enantioselective photochemical reaction where a chiral hydrogen-bonding-based thioxanthone was used as a bifunctional visible-light photosensitizer to promote an intramolecular asymmetric [2 + 2] cycloaddition .…”

Section: Introductionmentioning

confidence: 99%

Enantioselective and Band-Gap Modulation in Photocatalysis of Metal-Free Chiral Carbon Dots

Zhang,

Du

et al. 2024

ACS Appl. Mater. Interfaces

1

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Photodriven chiral catalysis is the combination of photocatalysis and chiral catalysis and is considered one of the cleanest and most efficient methods for the synthesis of chiral compounds or drugs. Furthermore, due to the potential metal contamination associated with most metal-based catalysts, metal-free chiral photocatalysts are ideal candidates. In this work, we demonstrate that metal-free chiral carbon dots (CDs) exhibit size-dependent enantioselective photocatalytic activity. Using serine as the raw material, chiral CDs with well-defined structures and average sizes of 2.22, 3.01, 3.70, 4.77, and 7.21 nm were synthesized using the electrochemical method. These chiral CDs possess size-dependent band gaps and exhibit photoresponsive enantioselective catalytic activity toward the oxidation of dihydroxyphenylalanine (DOPA). Under light-assisted conditions, chiral CDs (L72, 500 μg/mL) exhibit high selectivity (selectivity factor: 2.07) and maintain a certain level of catalytic activity (1.34 μM/min) even at a low temperature of 5 °C. The high catalytic activity of the chiral CDs arises from their photoelectrons reducing O2 to generate O2 –, as the active oxygen species for DOPA oxidation. The high enantioselectivity of the chiral CDs is attributed to their differential adsorption capabilities toward DOPA enantiomers. This study provides a new approach for designing metal-free chiral photocatalysts with high enantioselectivity.

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Modular Assembly of Acridines by Integrating Photo‐Excitation of o‐Alkyl Nitroarenes with Copper‐Promoted Cascade Annulation

Huang,

Jiang,

Yuan

et al. 2024

Angewandte Chemie

0

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Acridine frameworks stand as pivotal architectural elements in pharmaceuticals and photocatalytic applications, owing to their chemical adaptability, biological activity, and unique excited‐state dynamics. Conventional synthetic routes often entail specialized starting materials, anaerobic or moisture‐free conditions, and elaborate multi‐stage manipulations for incorporating diverse functionalities. Herein, we present a convergent approach integrating photo‐excitation of readily available ortho‐alkyl nitroarenes with copper‐promoted cascade annulation. This innovative system enables an aerobic, one‐pot reaction of o‐alkyl nitroarenes with arylboronic acids, thereby streamlining the modular construction of a wide array of acridine dervatives with various functional groups. This encompasses symmetrical, unsymmetrical and polysubstituted varieties, some of which are otherwise exceptionally difficult to synthesize. Furthermore, it significantly improves the production of structurally varied acridinium salts, featuring enhanced photophysical properties, high excited state potentials (E*red = 2.08−3.15 V), and exhibiting superior performance in intricate photoredox transformations.

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Modular Assembly of Acridines by Integrating Photo‐Excitation of o‐Alkyl Nitroarenes with Copper‐Promoted Cascade Annulation

Huang,

Jiang,

Yuan

et al. 2024

Angew Chem Int Ed

0

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Acridine frameworks stand as pivotal architectural elements in pharmaceuticals and photocatalytic applications, owing to their chemical adaptability, biological activity, and unique excited‐state dynamics. Conventional synthetic routes often entail specialized starting materials, anaerobic or moisture‐free conditions, and elaborate multi‐stage manipulations for incorporating diverse functionalities. Herein, we present a convergent approach integrating photo‐excitation of readily available ortho‐alkyl nitroarenes with copper‐promoted cascade annulation. This innovative system enables an aerobic, one‐pot reaction of o‐alkyl nitroarenes with arylboronic acids, thereby streamlining the modular construction of a wide array of acridine dervatives with various functional groups. This encompasses symmetrical, unsymmetrical and polysubstituted varieties, some of which are otherwise exceptionally difficult to synthesize. Furthermore, it significantly improves the production of structurally varied acridinium salts, featuring enhanced photophysical properties, high excited state potentials (E*red = 2.08−3.15 V), and exhibiting superior performance in intricate photoredox transformations.

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Advancements in organocatalysis for radical-mediated asymmetric synthesis: A recent perspective

Cited by 4 publications

References 136 publications

Enantioselective and Band-Gap Modulation in Photocatalysis of Metal-Free Chiral Carbon Dots

Enantioselective and Band-Gap Modulation in Photocatalysis of Metal-Free Chiral Carbon Dots

Modular Assembly of Acridines by Integrating Photo‐Excitation of o‐Alkyl Nitroarenes with Copper‐Promoted Cascade Annulation

Modular Assembly of Acridines by Integrating Photo‐Excitation of o‐Alkyl Nitroarenes with Copper‐Promoted Cascade Annulation

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