Trapping of Transient Zwitterionic Intermediates by <i>N</i>-Acylpyridinium Salts: A Palladium-Catalyzed Diastereoselective Three-Component Reaction

Zhang, Dan; Kang, Zhenghui

doi:10.1021/acs.joc.7b00560

Cited by 14 publications

(4 citation statements)

References 40 publications

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“…Recently, the combination of transition metal‐catalyzed formal C−H functionalization of diazo compounds with other chemistry has led to versatile novel synthetic methods [3e,,n–q] . In 2012, Hu and co‐workers reported a Rh(II) and chiral phosphoric acid synergistically catalyzed cascade C−H functionalization/asymmetric imine addition process, furnishing chiral oxindole and indole derivatives [3e] .…”

Section: Methodsmentioning

confidence: 99%

Palladium‐Catalyzed Cascade C−H Functionalization/Asymmetric Allylation Reaction of Aryl α‐Diazoamides and Allenes: Lewis Acid Makes a Difference

Ruan

Han

et al. 2022

Chemistry A European J

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A Pd‐catalyzed cascade C−H functionalization/asymmetric allylation reaction with aryl α‐diazoamides and allenes has been developed. The reaction provides an efficient approach to construct chiral 3,3‐disubstituted oxindole derivatives in high levels of yield and enantioselectivity (up to 93 % ee). Notably, the chromium complex works as Lewis acid to facilitate the formation of palladium carbene and to enhance acidity of carboxylic acid, allowing for higher stereochemical control and efficiency.

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Section: Methodsmentioning

confidence: 99%

Palladium‐Catalyzed Cascade C−H Functionalization/Asymmetric Allylation Reaction of Aryl α‐Diazoamides and Allenes: Lewis Acid Makes a Difference

Ruan

Han

et al. 2022

Chemistry A European J

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“…The same authors also reported a palladium-catalyzed three-component reaction of pyridine derivatives 1 , chloroformates 364 , and N -aryl diazoamides 365 ( Scheme 171 ). 244 The reaction proceeded through trapping of transient zwitterionic intermediates ( B – C ) by in situ formed N -acylpyridinium salts in a regioselective 1,4-addition fashion, giving access to biologically relevant 4-(2-oxoindolin-3-yl)-1,4-dihydropyridine derivatives 366 in high yields with moderate to very good diastereoselectivities. Different chloroformates efficiently gave the corresponding products.…”

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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“…In the same year, the same group developed a palladiumcatalyzed dearomative reaction of pyridines in the presence of chloroformate using N-aryl diazoamides as the source of nucleophiles, providing poly-substituted 1,4-dihydropyridine derivatives 83 that contain an oxindole moiety (Scheme 22a). 48 In the postulated mechanism, the palladium catalyst decomposes N-aryl diazoamide 82 to give palladium carbene intermediate 84 in the first step. Then, the zwitterionic intermediate 85 or its enol form 86 is generated from palladium carbene intermediate 84 via intramolecular cyclization.…”

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confidence: 99%

Transition-Metal-Catalyzed Nucleophilic Dearomatization of Electron-Deficient Heteroarenes

Jia

Xia

2021

Synthesis

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Transition-metal-catalyzed nucleophilic dearomatization of electron-deficient heteroarenes, such as pyridines, quinolines, isoquinolines and nitroindoles, has become a powerful method for the access of unsaturated heterocycles in recent decades. This short review summarizes nucleophilic dearomatization of electron-deficient heteroarenes with carbon- and heteroatom-based nucleophiles via transition-metal catalysis. A great number of functionalized heterocycles were obtained in this transformation. Importantly, many of these reactions were carried out in an enantioselective manner by means of asymmetric catalysis, providing a unique method for the construction of enantioenriched heterocycles. 1 Introduction 2 Transition-metal-catalyzed nucleophilic dearomatization of heteroarenes via alkynylation 3 Transition-metal-catalyzed nucleophilic dearomatization of heteroarenes via arylation 4 Transition-metal-catalyzed nucleophilic dearomatization of heteroarenes with other nucleophiles 5 Transition-metal-catalyzed nucleophilic dearomatization with nucleophiles formed in situ 6 Conclusion and outlook

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Trapping of Transient Zwitterionic Intermediates by N-Acylpyridinium Salts: A Palladium-Catalyzed Diastereoselective Three-Component Reaction

Cited by 14 publications

References 40 publications

Palladium‐Catalyzed Cascade C−H Functionalization/Asymmetric Allylation Reaction of Aryl α‐Diazoamides and Allenes: Lewis Acid Makes a Difference

Palladium‐Catalyzed Cascade C−H Functionalization/Asymmetric Allylation Reaction of Aryl α‐Diazoamides and Allenes: Lewis Acid Makes a Difference

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

Transition-Metal-Catalyzed Nucleophilic Dearomatization of Electron-Deficient Heteroarenes

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