Sensitized dissociation of peroxides and peresters in the presence of thiopyrylium salts

Morlet‐Savary, Fabrice; Wieder, Fernand; Fouassier, Jean Pierre

doi:10.1039/a704951j

Cited by 19 publications

(10 citation statements)

References 10 publications

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“…The low rate of peroxide decomposition in the absence of substrate further corroborates an electron‐transfer mechanism making an energy‐transfer sensitization mechanism for peroxide decomposition unlikely as the major pathway 13c…”

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confidence: 77%

“…We reasoned that decomposition of t BPA might be initiated through a single electron‐transfer event from the excited‐state metal species Ir III * to the low‐lying π* orbital of the carbonyl, a pathway not accessible to other peroxides. The direct reduction of t BPA ( t BPB, E °=−1.95 V vs SCE)13c by Ir III * ( E °=−0.89 V vs SCE) is thermodynamically challenging, however, proton‐coupled electron transfer (PCET) under acidic conditions significantly lowers the barrier to reduction and may be kinetically feasible 18. The unstable α‐peroxy radical generated could decompose to acetic acid and tert ‐butoxy radical by homolytic cleavage of the weak OO bond.…”

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confidence: 99%

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Late‐Stage Functionalization of Biologically Active Heterocycles Through Photoredox Catalysis

et al. 2014

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The direct CH functionalization of heterocycles has become an increasingly valuable tool in modern drug discovery. However, the introduction of small alkyl groups, such as methyl, by this method has not been realized in the context of complex molecule synthesis since existing methods rely on the use of strong oxidants and elevated temperatures to generate the requisite radical species. Herein, we report the use of stable organic peroxides activated by visible-light photoredox catalysis to achieve the direct methyl-, ethyl-, and cyclopropylation of a variety of biologically active heterocycles. The simple protocol, mild reaction conditions, and unique tolerability of this method make it an important tool for drug discovery.

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confidence: 77%

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confidence: 99%

Late‐Stage Functionalization of Biologically Active Heterocycles Through Photoredox Catalysis

et al. 2014

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“…The direct single-electron reduction of peresters is thermodynamically challenging (e.g., for tert -butyl perbenzoate (TBPB), E 1/2 red = −1.95 V vs SCE in MeCN) 960 and is inaccessible to the Ir(III) photooxidants employed here (for [ Ir-3 ]PF 6 , E 1/2 Ir(IV)/*Ir(III)= −0.96 V vs SCE in MeCN; for [ Ir-6 ]PF 6 , E 1/2 Ir(IV)/*Ir(III)= −1.21 V vs SCE in MeCN). 68 However, a PCET mechanism was invoked to rationalize the observed reactivity.…”

Section: Reductive Transformations Of Carbonyls Imines and Other X=y Functional Groups Through Photochemical And Electrochemical Pcet Promentioning

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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“…Thiopyrilium salts (TP) have been used to achieve visible light‐sensitized decomposition of diacyl peroxides and peresters. The process has been described as an electron‐transfer from the excited state of the TP to the ground state peroxide …”

Section: Modes Of Reactivitymentioning

confidence: 99%

The Chemistry of Peresters

Locklear

Dussault

2020

Eur J Org Chem

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Sensitized dissociation of peroxides and peresters in the presence of thiopyrylium salts

Cited by 19 publications

References 10 publications

Late‐Stage Functionalization of Biologically Active Heterocycles Through Photoredox Catalysis

Late‐Stage Functionalization of Biologically Active Heterocycles Through Photoredox Catalysis

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

The Chemistry of Peresters

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