Dual-Role Catalysis by Thiobenzoic Acid in Cα–H Arylation under Photoirradiation

Kobayashi, Fumihisa; Fujita, Masashi; Ide, Takafumi; Ito, Yuta; Yamashita, Kenji; Egami, Hiromichi; Hamashima, Yoshitaka

doi:10.1021/acscatal.0c04722

Cited by 48 publications

(41 citation statements)

References 70 publications

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“…have shown that the excited state of a thiobenzoate anion could be engaged in the catalytic single-electron reduction of cyanoarenes (Scheme ). By leveraging the dual role of the thiobenzoate anion catalyst, namely a one-electron reducing catalyst and as HAT catalyst, this method allowed the direct benzylic Csp 3 –H arylation with cyanoarenes in the presence of a catalytic amount (20 mol %) of thiobenzoic acid under blue-light irradiation. The proposed mechanism of this transformation starts with deprotonation of XXI by base to produce thiobenzoate XXII , which could be excited by visible light.…”

Section: Light-induced Thiolate Catalysis Enabled By the Excited Stat...mentioning

confidence: 99%

“…Recently, Hamashima et al have shown that the excited state of a thiobenzoate anion could be engaged in the catalytic single-electron reduction of cyanoarenes (Scheme 12). 48 By leveraging the dual role of the thiobenzoate anion catalyst, namely a one-electron reducing catalyst and as HAT catalyst, this method allowed the direct benzylic Csp hydrogen atom from the substrate to give a carbon radical XXV, simultaneously regenerating the catalyst XXI. Further radical−radical coupling between XXIII and XXV affords the target product after releasing the cyanide anion.…”

Section: Light-induced Thiolate Catalysis Enabledmentioning

confidence: 99%

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Light-Induced Single-Electron Transfer Processes involving Sulfur Anions as Catalysts

Wang

König

2021

J. Am. Chem. Soc.

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Photoredox catalysis has evolved as an attractive approach to enable a wide variety of chemical reactions with high selectivity under mild conditions. The development of novel photocatalytic systems is key to obtaining new reactivity and improving their catalytic performances. In this context, cost-effective organic anion-based photocatalysts have recently attracted increasing interest. In particular, sulfur-based anionic catalysts are of interest due to their unique redox properties. This Perspective highlights and discusses recent advances in light-induced single-electron-transfer processes directly involving sulfur anions as catalysts. The content of this Perspective is organized along the different photoinduced electron-transfer pathways between catalysts and substrates.

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Section: Light-induced Thiolate Catalysis Enabled By the Excited Stat...mentioning

confidence: 99%

Section: Light-induced Thiolate Catalysis Enabledmentioning

confidence: 99%

Light-Induced Single-Electron Transfer Processes involving Sulfur Anions as Catalysts

Wang

König

2021

J. Am. Chem. Soc.

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“…For example, Hamashima recently reported photoinduced C–H arylation of benzyl amine 72 with 1,4-dicyanobenzene 73 in the presence of commercially available thiobenzoic acid ( 74 ) as a catalyst to produce diarylmethylamine 75 ( Scheme 10 ). 38 In this process, the photoexcited benzothioate ion 76* undergoes SET reduction of 1,4-dicyanobenzene 73 ( E red = –1.64 V vs SCE) 39 to generate a persistent anion radical of 1,4-dicyanobenzene 77 . The simultaneously formed thiyl radical 78 induces HAT from benzyl amine 72 to form the transient benzylic radical 79 , which could be coupled with the anion radical 77 to liberate the C–H arylated product 75 .…”

Section: Sulfur Anions As Photoredox and Hydrogen Atom Transfer Catalystsmentioning

confidence: 99%

Leveraging of Sulfur Anions in Photoinduced Molecular Transformations

Liu

Chiba

2021

JACS Au

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This perspective describes recent advances in the use of sulfur anions to promote molecular transformations under irradiation with visible light. The topics are classified by the following reaction modes performed by the key sulfur anions: (1) C–S coupling via electron donor–acceptor (EDA) interactions, (2) photoinduced molecular transformation via sulfur anion EDA catalysis, (3) sulfur anions as photoredox and hydrogen atom transfer (HAT) catalysts, and 4) dithiocarbamate and xanthate as nucleophilic catalysts for photoinduced radical cascade reactions.

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“…Template for SYNLETT Thieme Hamashima and co-workers later on discovered that the same -amino C(sp 3 )−H arylation of benzylamines can be achieved without any exogenous photocatalyst by realising the photocatalytic activity of thiobenzoic acid (TBA) (Figure 5). 23 Photoexcitation of the conjugate base 5a of TBA leads to SET with the electron-deficient arene partner to give radical anion 5e and sulfur centered radical 5b. Species 5b then engages in regioselective HAT with a benzylic -amino C(sp 3 )−H bond and the mechanism otherwise follows that in Template for SYNLETT Thieme steric hindrance and follows a Curtin-Hammett principle (Figure 6).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Site-Selective C(sp3)–H Functionalizations Mediated by Hydrogen Atom Transfer Reactions via α-Amino/α-Amido Radicals

Kaur¹,

Barham²

2021

Synthesis

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Amines and amides, as N-containing compounds, are ubiquitous in pharmaceutically active scaffolds, natural products, agrochemicals and peptides. Amides in nature bear key responsibility for three-dimensional structure, such as in proteins. Structural modifications to amines and amides, especially at their positions α- to N, bring about profound changes in biological activity oftentimes leading to more desirable pharmacological profiles of small molecule drugs. A number of recent developments in synthetic methodology for the functionalizations of amines and amides omit the need of directing groups or pre-functionalizations, achieving direct activation of the otherwise benign C(sp3)-H bond. Among these, hydrogen atom transfer (HAT) has proven a very powerful platform for the selective activation of amines and amides to their α-amino and α-amido radicals, which can then be employed to furnish C-C and C-X (X=heteroatom) bonds. The ability to both form these radicals and control their reactivity in a site-selective manner is of utmost importance for such chemistries to witness applications in late-stage functionalization. Therefore, this review captures contemporary HAT strategies to realize chemo- and regioselective amine and amide α-C(sp3)-H functionalization, based on bond strength, bond polarity, reversible HAT equilibria, traceless electrostatic directing auxiliaries and steric effects of in situ-generated HAT agents.

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Dual-Role Catalysis by Thiobenzoic Acid in Cα–H Arylation under Photoirradiation

Cited by 48 publications

References 70 publications

Light-Induced Single-Electron Transfer Processes involving Sulfur Anions as Catalysts

Light-Induced Single-Electron Transfer Processes involving Sulfur Anions as Catalysts

Leveraging of Sulfur Anions in Photoinduced Molecular Transformations

Site-Selective C(sp3)–H Functionalizations Mediated by Hydrogen Atom Transfer Reactions via α-Amino/α-Amido Radicals

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