Synthesis of Benzofuran Derivatives through Cascade Radical Cyclization/Intermolecular Coupling of 2‐Azaallyls

Deng, Guogang; Li, Minyan; Yu, Kaili; Liu, Chunxiang; Liu, Zhengfen; Duan, Shengzu; Chen, Wen; Yang, Xiaodong; Zhang, Hongbin; Walsh, Patrick J.

doi:10.1002/ange.201812369

Cited by 13 publications

(2 citation statements)

References 29 publications

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“…They are synthetically useful for the synthesis of benzofurylethylamines (Fig. 3b ) and their isochromene analogs 55 , 56 . In the presence of bulky aryl iodides, where the coupling in Fig.…”

Section: Resultsmentioning

confidence: 99%

SET activation of nitroarenes by 2-azaallyl anions as a straightforward access to 2,5-dihydro-1,2,4-oxadiazoles

et al. 2021

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The use of nitroarenes as amino sources in synthesis is challenging. Herein is reported an unusual, straightforward, and transition metal-free method for the net [3 + 2]-cycloaddition reaction of 2-azaallyl anions with nitroarenes. The products of this reaction are diverse 2,5-dihydro-1,2,4-oxadiazoles (>40 examples, up to 95% yield). This method does not require an external reductant to reduce nitroarenes, nor does it employ nitrosoarenes, which are often used in N–O cycloadditions. Instead, it is proposed that the 2-azaallyl anions, which behave as super electron donors (SEDs), deliver an electron to the nitroarene to generate a nitroarene radical anion. A downstream 2-azaallyl radical coupling with a newly formed nitrosoarene is followed by ring closure to afford the observed products. This proposed reaction pathway is supported by computational studies and experimental evidence. Overall, this method uses readily available materials, is green, and exhibits a broad scope.

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Section: Resultsmentioning

confidence: 99%

SET activation of nitroarenes by 2-azaallyl anions as a straightforward access to 2,5-dihydro-1,2,4-oxadiazoles

et al. 2021

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“…4). 20 Notably, the 2-azaallynyl anion generated from the deprotonation of the ketimine substrate behaved as a super electron donor (SED) to initiate the radical process in this transformation.…”

Section: Introductionmentioning

confidence: 99%

Facile Access to Benzofuran Derivatives through Radical Reactions with Heteroatom-centered Super-electron-donors

Robin

Jiang

Wang

et al. 2023

Preprint

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Heteroatom anions are applied as super-electron-donors (SEDs) to initiate radical reactions for facile synthesis of 3-substituted benzofurans. Phosphines, thiols and anilines bearing different substitution patterns work well in this inter-molecular radical coupling reaction and the 3-functionalized benzofuran products bearing heteroatomic functionalities are given in moderate to excellent yields. The reaction mechanism is elucidated via control experiments and computational methods. The afforded products showed promising applications in both organic synthesis and pesticide development.

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Synthesis of Benzofurans from Sulfur Ylides and ortho‐Hydroxy‐Functionalized Alkynes

Tung

2022

Adv Synth Catal

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The synthesis of benzofurans from readily accessible sulfur ylides and ortho‐hydroxy aryl alkynes is reported. The transformation proceeds through an isomerization/nucleophilic addition/cyclization/aromatization cascade. The substrate scope is very general with respect to both reactants and the products are afforded in 43–94% yield under conditions which are catalyst‐free and additive‐free.

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Synthesis of Benzofuran Derivatives through Cascade Radical Cyclization/Intermolecular Coupling of 2‐Azaallyls

Cited by 13 publications

References 29 publications

SET activation of nitroarenes by 2-azaallyl anions as a straightforward access to 2,5-dihydro-1,2,4-oxadiazoles

SET activation of nitroarenes by 2-azaallyl anions as a straightforward access to 2,5-dihydro-1,2,4-oxadiazoles

Facile Access to Benzofuran Derivatives through Radical Reactions with Heteroatom-centered Super-electron-donors

Synthesis of Benzofurans from Sulfur Ylides and ortho‐Hydroxy‐Functionalized Alkynes

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