Formylation of Fluoroalkyl Imines through Visible-Light-Enabled H-Atom Transfer Catalysis: Access to Fluorinated α-Amino Aldehydes

Yang, Sen; Zhu, Shuangyu; Lu, Dengfu; Gong, Yuefa

doi:10.1021/acs.orglett.9b00128

Cited by 42 publications

(41 citation statements)

References 70 publications

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“…In 2019, Lu, Gong, and co-workers reported a photocatalytic, redox-neutral net formylation reaction of fluoroalkyl imines, with 1,3-dioxolane serving as a formyl equivalent ( Scheme 326 ). 894 The optimal reaction conditions require the use of 2,3-butanedione and N -hydroxysuccinimide (NHS), which were found to be the most efficient organic photocatalyst and HAT reagent for this transformation, respectively. In total, 29 examples were reported, affording various α-amino 1,3-dioxolanes in yields of 51–96%.…”

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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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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“…Su et al reported dioxolanylation-triggered cascade cyclizations, in which α,α-disubstituted acrylamides were employed to generate indoline products (Scheme c) . Gong and Lu reported the radical-chain formylation of imines; HAT initially occurred via O-centered radical derived from N -hydroxysuccinimide and 2,3-butadione (Scheme d). , …”

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confidence: 62%

Acetal Addition to Electron-Deficient Alkenes with Hydrogen Atom Transfer as a Radical Chain Propagation Step

2021

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We describe a visible-light-promoted addition of a hydrogen atom and an acetal carbon toward various electrondeficient alkenes. 1,3-Dioxolane is converted to its radical species in the presence of persulfate and an iridium catalyst upon visible light irradiation, which then reacts with electron-deficient alkenes. The reaction operates via a radical chain mechanism, a less commonly observed pathway for this class of transformation. Hydrogen atom transfer from 1,3-dioxolane to α-malonyl radicals is corroborated by experimental and density functional theory studies.

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“…Lastly, hydrogen atom transfer (HAT) has also been used in order to perform the C-H activation of different alkyl radical precursors and perform the desired alkylation reaction with activated imines (Scheme 7). Lu and Gong reported the α-oxyalkyl radical addition of 1,3-dioxolane to fluoroalkyl imines (Scheme 7, top) [19,20], while Dilman managed to install different alkyl and acyl radicals into N-sulfonyl imines (Scheme 7, bottom) [21][22][23]. Scheme 6.…”

Section: O Ho O [Glycosyl Carboxylic Acids] [Activation With Tcnhpi]mentioning

confidence: 99%

α-Functionalization of Imines via Visible Light Photoredox Catalysis

2020

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The innate electrophilicity of imine building blocks has been exploited in organic synthetic chemistry for decades. Inspired by the resurgence in photocatalysis, imine reactivity has now been redesigned through the generation of unconventional and versatile radical intermediates under mild reaction conditions. While novel photocatalytic approaches have broadened the range and applicability of conventional radical additions to imine acceptors, the possibility to use these imines as latent nucleophiles via single-electron reduction has also been uncovered. Thus, multiple research programs have converged on this issue, delivering creative and practical strategies to achieve racemic and asymmetric α-functionalizations of imines under visible light photoredox catalysis.

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Formylation of Fluoroalkyl Imines through Visible-Light-Enabled H-Atom Transfer Catalysis: Access to Fluorinated α-Amino Aldehydes

Cited by 42 publications

References 70 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

Acetal Addition to Electron-Deficient Alkenes with Hydrogen Atom Transfer as a Radical Chain Propagation Step

α-Functionalization of Imines via Visible Light Photoredox Catalysis

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