Diastereo- and Enantioselective Synthesis of Spirooxindoles with Contiguous Tetrasubstituted Stereocenters via Catalytic Coupling of Two Tertiary Radicals

Song, Zhiguang; Chen, Kun‐Quan; Chen, Xiangyu; Song, Ye

doi:10.1021/acs.joc.7b03161

Cited by 50 publications

(20 citation statements)

References 49 publications

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Section: Oxidative Nhc Catalysismentioning

confidence: 99%

“…The developed approach was distinguished as a highly diastereoselective and enantioselctive method. One year later, Ye et al reported a similar synthesis using β,β-disubstituted enals [71]. Less popular than the two-electron oxidation of the Breslow intermediate is oxidation via the SET process, in which instead of an acylazolium ion, a very reactive radical cation species is generated.…”

Section: Oxidative Nhc Catalysismentioning

confidence: 99%

“…The developed approach was distinguished as a highly diastereoselective and enantioselctive method. One year later, Ye et al reported a similar synthesis using β,β-disubstituted enals [71]. Sun and Ye developed the oxidative [3 + 2] annulation of dioxindoles and enals in 2017 [70].…”

Section: Oxidative Nhc Catalysismentioning

confidence: 99%

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N-Heterocyclic Carbene Catalysis under Oxidizing Conditions

Dzieszkowski

Rafiński

2018

Catalysts

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N-heterocyclic carbene organocatalysis under oxidizing conditions provides a vast range of various synthetic procedures via diverse mechanisms. The available catalysts, bases, oxidants, and oxidizing methods afford numerous opportunities for developing this branch of organocatalysis. Furthermore, implementation of tandem reactions and cooperative catalysis in the described methodology significantly expands the possibilities of modern organic chemistry. This approach allows the synthesis of different structurally complex and often enantiomerically enriched substances, which can be interesting in terms of biological activity and natural product synthesis. Many esters, amides, thioesters, lactams, lactones, and other cyclic compounds obtained in oxidative or oxygenative reactions promoted by N-heterocyclic carbenes can be interesting precursors in advanced organic synthesis. Sophistication and broad applicability prove that the described synthetic approaches are exceptionally worthy of further development.

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Section: Oxidative Nhc Catalysismentioning

confidence: 99%

Section: Oxidative Nhc Catalysismentioning

confidence: 99%

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N-Heterocyclic Carbene Catalysis under Oxidizing Conditions

Dzieszkowski

Rafiński

2018

Catalysts

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“…The subsequent cross‐coupling between the Breslow‐centered radical cation 34 and dioxindole radical 35 delivered the acyl azolium 36 , which can easily afford the lactone product 33 . Moreover, with this protocol, various β,β‐disubstituted enals were also successfully applied in the radical annulation, allowing the installation of two contiguous tetrasubstituted stereocenters on the spirooxindoles [20] …”

Section: Single‐electron Oxidation Processmentioning

confidence: 99%

Single‐Electron Transfer Reactions Enabled by N‐Heterocyclic Carbene Organocatalysis

Zeng

Han

et al. 2020

Chemistry A European J

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Over the past decades, N‐heterocyclic carbene (NHC) organocatalysis has undergone a flourish of development on the basis of closed‐shell reaction paths. By contrast, the emerging area of single‐electron transfer (SET) reactions enabled by NHC catalysis still remain underdeveloped, but offer plenty of opportunities to develop new catalytic modes and useful synthetic methods. A number of interesting transformations were triggered by the SET process from the electron‐rich Breslow intermediates to various single‐electron acceptors. In additions, recent studies revealed that the Breslow radical cations could also be generated by single‐electron reduction of the electron‐deficient acyl azolium intermediates. These discoveries open a new avenue for NHC organocatalysis to harness radical reactions. The present review will focus on the exciting advancements in the dynamic area of radical NHC organocatalysis.

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“…In contrast, catalytic formation and direct coupling of two radical intermediates to form ketones are much less studied. N-heterocyclic carbenes (NHCs) as organic catalysts [15][16][17][18][19][20][21] are proved effective in generating radical intermediates [22][23][24][25][26] for various reactions, as earlier disclosed by Scheidt, [27][28] Studer, [29][30] Rovis, [31][32] our laboratories, [33][34] Sun, 35 and Ye [36][37][38][39][40] . The NHC-derived radical intermediates are typically persistent radicals, and thus coupling with another transient radical become feasible.…”

Section: Introductionmentioning

confidence: 99%

Carbene and Photocatalyst-Catalyzed Decarboxylative Radical Coupling of Carboxylic Acids and Acyl Imidazoles to Form Ketones

Ren

Yang

Mondal

et al. 2021

Preprint

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The carbene and photocatalyst co-catalyzed radical coupling of acyl electrophile and a radical precursor is emerging as attractive method for ketone synthesis. However, previous reports mainly limited to prefunctionalized radical precursors and two-component coupling. Herein, an N-heterocyclic carbene and photocatalyst catalyzed decarboxylative radical coupling of carboxylic acids and acyl imidazoles is disclosed, in which the carboxylic acids were directly used as radical precursors. The acyl imidazoles could also be generated in situ by reaction of a carboxylic acid with CDI thus furnishing a formally decarboxylative coupling of two carboxylic acids. In addition, the reaction was successfully extended to three-component coupling by using alkene as a third coupling partner via a radical relay process. The mild conditions, operational simplicity, and use of carboxylic acids as the reacting partners make our method a powerful strategy for construction of complex ketones from readily available starting materials, and late-stage modification of natural products and medicines.

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Diastereo- and Enantioselective Synthesis of Spirooxindoles with Contiguous Tetrasubstituted Stereocenters via Catalytic Coupling of Two Tertiary Radicals

Cited by 50 publications

References 49 publications

N-Heterocyclic Carbene Catalysis under Oxidizing Conditions

N-Heterocyclic Carbene Catalysis under Oxidizing Conditions

Single‐Electron Transfer Reactions Enabled by N‐Heterocyclic Carbene Organocatalysis

Carbene and Photocatalyst-Catalyzed Decarboxylative Radical Coupling of Carboxylic Acids and Acyl Imidazoles to Form Ketones

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