Oxidative and Redox‐Neutral Approaches to Symmetrical Diamines and Diols by Single Electron Transfer/Hydrogen Atom Transfer Synergistic Catalysis

Fujita, Masashi; Kobayashi, Fumihisa; Ide, Takafumi; Egami, Hiromichi; Hamashima, Yoshitaka

doi:10.1002/ejoc.202001329

Cited by 8 publications

(3 citation statements)

References 76 publications

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“…Hamashima and co-workers in 2020 described a method for the homo-coupling of benzylic amines and alcohols under visible-light irradiation to form vicinal diamines and diols ( Scheme 277 ). 721 Through blue-light irradiation of a DMA solution of benzylic alcohol or amine substrate, thiobenzoic acid HAT co-catalyst ( 277.A ), pivaladehyde, and MgSO 4 as desiccant with [Ir(ppy) 2 (dtbbpy)]PF 6 ([ Ir-3 ]PF 6 ) as photocatalyst, the authors disclosed 12 examples of amine and alcohol homo-coupling with 23–80% yields ( 277.1 – 277.4 ). The scope included a small number of tertiary benzylic amines as well as primary and secondary benzylic alcohols differentiated primarily by arene substitution.…”

Section: S -Centered Radical Generation From S–h Bonds Through Photochemical and Electrochemical Pcet Processesmentioning

confidence: 99%

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

et al. 2021

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We present here a review of the photochemical and electrochemical applications of multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms in which both an electron and a proton are exchanged together, often in a concerted elementary step. As such, MS-PCET can function as a non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from a wide variety of common organic functional groups. We present an introduction to MS-PCET and a practitioner’s guide to reaction design, with an emphasis on the unique energetic and selectivity features that are characteristic of this reaction class. We then present chapters on oxidative N–H, O–H, S–H, and C–H bond homolysis methods, for the generation of the corresponding neutral radical species. Then, chapters for reductive PCET activations involving carbonyl, imine, other X=Y π-systems, and heteroarenes, where neutral ketyl, α-amino, and heteroarene-derived radicals can be generated. Finally, we present chapters on the applications of MS-PCET in asymmetric catalysis and in materials and device applications. Within each chapter, we subdivide by the functional group undergoing homolysis, and thereafter by the type of transformation being promoted. Methods published prior to the end of December 2020 are presented.

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Section: S -Centered Radical Generation From S–h Bonds Through Photochemical and Electrochemical Pcet Processesmentioning

confidence: 99%

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

et al. 2021

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“…More recently, visible light-mediated pinacol coupling reactions have been disclosed by several groups [15][16][17][18]. In addition to the reductive coupling of carbonyl compounds, oxidative homocoupling reactions of benzyl alcohols under transition metal-or semiconductor-based photoredox catalysis have been demonstrated as attractive approaches to access vic-1,2-diols [19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical formal homocoupling of sec-alcohols

Yamamoto¹,

Arita²,

Shiota³

et al. 2022

Beilstein J. Org. Chem.

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Electrochemical pinacol coupling of carbonyl compounds in an undivided cell with a sacrificial anode would be a promising approach toward synthetically valuable vic-1,2-diol scaffolds without using low-valent metal reductants. However, sacrificial anodes produce an equimolar amount of metal waste, which may be a major issue in terms of sustainable chemistry. Herein, we report a sacrificial anode-free electrochemical protocol for the synthesis of pinacol-type vic-1,2-diols from sec-alcohols, namely benzyl alcohol derivatives and ethyl lactate. The corresponding vic-1,2-diols are obtained in moderate to good yields, and good to high levels of stereoselectivity are observed for sec-benzyl alcohol derivatives. The present transformations smoothly proceed in a simple undivided cell under constant current conditions without the use of external chemical oxidants/reductants, and transition-metal catalysts.

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“…As part of our research program on C–H functionalization, we recently reported regioselective and chemoselective Cα–H arylation of benzylamines with a synergistic catalyst system consisting of Ir(ppy) 3 and thiobenzoic acid (TBA, 1 ) (Scheme B) . In this reaction, Ir(ppy) 3 serves as a SET catalyst and TBA works as a hydrogen atom abstractor.…”

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confidence: 99%

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

et al. 2020

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Thiobenzoic acid (TBA) can serve as a single-electron reducing agent under photoirradiation from a blue light-emitting diode, in the presence of appropriate electron acceptors, and the resulting sulfur-centered radical species undergoes hydrogen atom abstraction. This dual-role catalysis by TBA enables regioselectivie Cα−H arylation of benzylamines, benzyl alcohols, and ethers, as well as dihydroimidazoles, with cyano(hetero)arenes in good yield, without the need for a transition-metal photocatalyst and/or synthetically elaborated organic dyes.

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Oxidative and Redox‐Neutral Approaches to Symmetrical Diamines and Diols by Single Electron Transfer/Hydrogen Atom Transfer Synergistic Catalysis

Cited by 8 publications

References 76 publications

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Electrochemical formal homocoupling of sec-alcohols

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

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