Catalytic Asymmetric Intermolecular [3 + 2] Photocycloaddition of Cyclopropylamines with Electron-Deficient Olefins

Dai, Yating; Huang, Hong Hai; Liang, Shuangshuang; Yin, Yanli; Ban, Xu; Zhao, Xiaowei

doi:10.1021/acs.orglett.3c01585

Cited by 7 publications

(7 citation statements)

References 39 publications

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“…The reaction demonstrated good enantioselectivity with up to 93% ee and high yields, reaching up to 97% yield. This was accomplished through a tandem radical conjugate addition and enantioselective protonation process using various hydrocarbons and silanes (40) reacting with different α-branched 2-vinylazaarenes (39). The reaction employed TBADT (PC-6) as a photocatalyst and (S)-SPINOL-based CPA-12 or -13 as a hydrogen bonding catalyst, enabling the desired outcomes.…”

Section: Cpa Joint Tbadt Photocatalystmentioning

confidence: 99%

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Asymmetric Catalytic Synthesis by Synergistic Chiral Phosphoric Acid Photoredox Catalyzed Reactions

Liu

Cao

2023

Adv Synth Catal

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Chiral phosphoric acid (CPA) has been established as a cornerstone in chemical synthesis reactions for over five decades, owing to its distinctive molecular structure and remarkable catalytic effect. However, in recent years, a revolutionary approach to asymmetric synthesis has emerged, utilizing photocatalytic excitation of molecules to generate free radicals, effectively surpassing the limitations of classical organic synthesis methodologies.A prominent and significant area of research has been dedicated to the investigation of chiral phosphoric acid synergistic photocatalysis for enantioselective chemical synthesis. This unique catalytic system encompasses a bifunctional hydrogen‐bonding catalyst, enabling simultaneous interactions between radical intermediates and substrates. The review paper focuses on the application and progress of this catalytic system in asymmetric synthesis throughout the past decade.

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Section: Cpa Joint Tbadt Photocatalystmentioning

confidence: 99%

“…They further studied the application of this reaction and successfully reduced the ketone of product A to spiro-1,3-amino B. (Scheme 32) [40]…”

Section: The Enantioselective Synthesis Using Cpa and Dpzmentioning

confidence: 99%

Asymmetric Catalytic Synthesis by Synergistic Chiral Phosphoric Acid Photoredox Catalyzed Reactions

Liu

Cao

2023

Adv Synth Catal

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“…Very recently, the same group demonstrated dual photoredox-chiral phosphoric acid catalyzed enantioselective intermolecular [3 + 2] cycloaddition of N-aryl cyclopropylamines with electron deficient alkenes. [32] Series of alkenes undergo cycloaddition under dual catalytic system comprising DPZ as photocatalyst and SPINOL derived CPAs as chiral hydrogen bonding catalyst to afford the range of substituted cyclopentylamines in high yields (up to 92 %), enatio-(up to 96 % ee) and diastereoselectivity (up to > 20 : 1 dr). Among the electron deficient alkenes, α-aryl acrylates have been extensively employed in this reaction (Scheme 23).…”

Section: Photochemical Transformation Through Dual Photoredox-chiral ...mentioning

confidence: 99%

Synergistic Dual Photoredox and Chiral Hydrogen Bonding Catalysis: Recent Advances

Selvakumar

2023

Asian J Org Chem

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In the last two decades, chiral hydrogen bonding catalysis has been enormously utilized to trigger several valuable synthetic transformations. Similarly, modern day radical chemistry has witnessed the potency of visible light photoredox catalysis to generate radicals via single electron transfer pathway. Recently, their cooperative effect has proved to be a key strategy to access many elegant transformations that are only feasible under the synergistic action of these two catalytic systems. This dual catalytic system demonstrates high efficiency for introducing molecular complexity in an enantioselective fashion. In this mini review, we have compiled the most recent development of this dual catalytic system that surfaced in the last three years with particular attention paid to the mechanistic details and its substrate scope. We hope that this mini review will provide readers with a brief overview of the advancement and application of photoredox catalysts and chiral hydrogen bond donors for synergistic dual catalytic reactions.

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“…This methodology exemplified a single-atom extrusion under mild conditions, which rapidly afforded novel vectors for additional bond formations and biological interactions. Specifically for derivatives of piperidine, the third most frequently encountered ring system in small-molecule FDA-approved drugs as of 2020, the ring contraction yielded derivatized aminocyclopentanes that themselves are valuable biorelevant targets. ,, …”

Section: Introductionmentioning

confidence: 99%

Mechanistic Investigation, Wavelength-Dependent Reactivity, and Expanded Reactivity of N–Aryl Azacycle Photomediated Ring Contractions

Kim,

Schwarz,

Jurczyk

et al. 2024

J. Am. Chem. Soc.

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Under mild blue-light irradiation, α-acylated saturated heterocycles undergo a photomediated one-atom ring contraction that extrudes a heteroatom from the cyclic core. However, for nitrogenous heterocycles, this powerful skeletal edit has been limited to substrates bearing electron-withdrawing substituents on nitrogen. Moreover, the mechanism and wavelength-dependent efficiency of this transformation have remained unclear. In this work, we increased the electron richness of nitrogen in saturated azacycles to improve light absorption and strengthen critical intramolecular hydrogen bonding while enabling the direct installation of the photoreactive handle. As a result, a broadly expanded substrate scope, including underexplored electron-rich substrates and previously unsuccessful heterocycles, has now been achieved. The significantly improved yields and diastereoselectivities have facilitated reaction rate, kinetic isotope effect (KIE), and quenching studies, in addition to the determination of quantum yields. Guided by these studies, we propose a revised ET/PT mechanism for the ring contraction, which is additionally corroborated by computational characterization of the lowest-energy excited states of α-acylated substrates through time-dependent DFT. The efficiency of the ring contraction at wavelengths longer than those strongly absorbed by the substrates was investigated through wavelength-dependent rate measurements, which revealed a red shift of the photochemical action plot relative to substrate absorbance. The elucidated mechanistic and photophysical details effectively rationalize empirical observations, including additive effects, that were previously poorly understood. Our findings not only demonstrate enhanced synthetic utility of the photomediated ring contraction and shed light on mechanistic details but may also offer valuable guidance for understanding wavelength-dependent reactivity for related photochemical systems.

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Catalytic Asymmetric Intermolecular [3 + 2] Photocycloaddition of Cyclopropylamines with Electron-Deficient Olefins

Cited by 7 publications

References 39 publications

Asymmetric Catalytic Synthesis by Synergistic Chiral Phosphoric Acid Photoredox Catalyzed Reactions

Asymmetric Catalytic Synthesis by Synergistic Chiral Phosphoric Acid Photoredox Catalyzed Reactions

Synergistic Dual Photoredox and Chiral Hydrogen Bonding Catalysis: Recent Advances

Mechanistic Investigation, Wavelength-Dependent Reactivity, and Expanded Reactivity of N–Aryl Azacycle Photomediated Ring Contractions

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