Iridium‐Catalyzed Propenylation Reactions for the Synthesis of 4‐Pyridone Derivatives

Bai, Xue-Dan; Wang, Jie; He, Ying

doi:10.1002/adsc.201801177

Cited by 13 publications

(5 citation statements)

References 68 publications

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“…We also wished to explore the synthetic utility of the synthesized compounds 9 by oxidizing them into 4-pyridones, which are another class of useful intermediates in organic synthesis 35 and important subunits in biologically active compounds. 36 Methods for their synthesis include reactions of pyrons with primary amines, 37 self-condensation of N-aryl acetoamides, 38 NIS-promoted cyclizations of diynones, 39 cyclizations of 1,5-bis(dimethylamino)penta-1,4-dien-3-ones with amines, 40 [4 + 2] cycloaddition of 3-aminocyclobutenones with electron-deficient alkynes, 41 iridium-catalyzed alkenylation of 4-hydroxypyridones, 42 and oxidation of dihydropyridone with iodine. 16d We first explored the often used 2,3-dichloro-5,6-dicyano-pbenzoquinone (DDQ) as the oxidizing agent, but it did not provide the desired product from compound 9a.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Synthesis of 2,3-Dihydro-4-pyridones and 4-Pyridones by the Cyclization Reaction of Ester-Tethered Enaminones

2020

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2,3-Dihydro-4-pyridone skeleton is an important building block in organic synthesis because it features several reaction sites with nucleophilic or electrophilic properties. Herein, we disclose a method for its formation by intramolecular cyclization of ester-tethered enaminones, which can easily be synthesized from readily available materials, such as amines, activated alkynes, and activated alkenes. 2,3-Dihydro-4-pyridones have been isolated in 41−90% yields. We also demonstrate the transformation of these heterocycles into another important class of compounds, 4-pyridones, by utilizing 2,3,5,6-tetrachloro-pbenzoquinone (chloranil) as an oxidizing agent. The latter products were isolated in 65−94% yields.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Synthesis of 2,3-Dihydro-4-pyridones and 4-Pyridones by the Cyclization Reaction of Ester-Tethered Enaminones

2020

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“…He and co-workers had previously described an iridium-catalyzed propenylation reaction of 4-hydroxypyridines with allylic carbonates ( Scheme 160 ). 229 The iridium catalyst was generated in situ from complex [Ir(cod)Cl] 2 and Feringa’s phosphoramidite II with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). 4-Hydroxypyridines 1 reacted with allylic carbonates 346 in the presence of the iridium catalyst and DBU as a base to give N -alkenyl pyridones 347 in good yields by means of a tandem allylic substitution/isomerization sequence.…”

Section: Addition Of Other Nucleophilesmentioning

confidence: 99%

Recent Strategies in the Nucleophilic Dearomatization of Pyridines, Quinolines, and Isoquinolines

Escolano,

Gaviña,

Alzuet-Piña

et al. 2024

Chem. Rev.

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Dearomatization reactions have become fundamental chemical transformations in organic synthesis since they allow for the generation of three-dimensional complexity from two-dimensional precursors, bridging arene feedstocks with alicyclic structures. When those processes are applied to pyridines, quinolines, and isoquinolines, partially or fully saturated nitrogen heterocycles are formed, which are among the most significant structural components of pharmaceuticals and natural products. The inherent challenge of those transformations lies in the low reactivity of heteroaromatic substrates, which makes the dearomatization process thermodynamically unfavorable. Usually, connecting the dearomatization event to the irreversible formation of a strong C−C, C− H, or C−heteroatom bond compensates the energy required to disrupt the aromaticity. This aromaticity breakup normally results in a 1,2-or 1,4-functionalization of the heterocycle. Moreover, the combination of these dearomatization processes with subsequent transformations in tandem or stepwise protocols allows for multiple heterocycle functionalizations, giving access to complex molecular skeletons. The aim of this review, which covers the period from 2016 to 2022, is to update the state of the art of nucleophilic dearomatizations of pyridines, quinolines, and isoquinolines, showing the extraordinary ability of the dearomative methodology in organic synthesis and indicating their limitations and future trends.

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“…However, there are spaces remained for the improvement of branch/linear selectivity (<10:1 in half of the cases) [8a] . On the other hand, the desired allylic amination products from 4‐pyridones are prone to isomerize to the corresponding internal alkenes under basic conditions, which diminished the enantioselectivity [8b] . Indeed, a catalytic system allowing alkylation of 4‐pyridones with high chemo‐, regio‐ and enantioselectivities remains underexplored [8a,9] .…”

Section: Figurementioning

confidence: 99%

Iridium‐Catalyzed Intermolecular Asymmetric Allylic Amination with Pyridones

Nie

Zheng

et al. 2022

Adv Synth Catal

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We report herein a catalytic synthetic method for enantioenriched N‐substituted pyridones. By employing chiral iridium catalyst generated from the Carreira [P/olefin] ligand, intermolecular asymmetric allylic amination of allyl alcohols with pyridones proceeded smoothly with excellent chemo‐, regio‐ and enantioselectivities (>19:1 N/O, >19:1 b/l and ≥89% ee). The reaction was a kinetic resolution process under mild conditions and displayed a broad substrate scope for both pyridones and allylic alcohols. The potential of this method was demonstrated by a gram‐scale reaction with only 0.6 mol% catalyst loading and diverse transformations of the amination products to useful skeletons.

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Iridium‐Catalyzed Propenylation Reactions for the Synthesis of 4‐Pyridone Derivatives

Cited by 13 publications

References 68 publications

Synthesis of 2,3-Dihydro-4-pyridones and 4-Pyridones by the Cyclization Reaction of Ester-Tethered Enaminones

Synthesis of 2,3-Dihydro-4-pyridones and 4-Pyridones by the Cyclization Reaction of Ester-Tethered Enaminones

Recent Strategies in the Nucleophilic Dearomatization of Pyridines, Quinolines, and Isoquinolines

Iridium‐Catalyzed Intermolecular Asymmetric Allylic Amination with Pyridones

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