Catalytic Synthesis of 1<i>H</i>-2-Benzoxocins: Cobalt(III)-Carbene Radical Approach to 8-Membered Heterocyclic Enol Ethers

Zhou, Minghui; Wolzak, Lukas A.; Li, Zirui; Zwart, Felix J. de; Mathew, Simon; Bruin, Bas de

doi:10.1021/jacs.1c10927

Cited by 20 publications

(10 citation statements)

References 87 publications

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“…Cobalt(II) complexes of porphyrins are unique potent metalloradical catalysts that are found to be useful for a wide variety of cyclization and insertion reactions . The research groups of Zhang, de Bruin, and Chattopadhyay have significantly contributed to Co II metalloradical chemistry for the synthesis of a myriad of carbo- and heterocycles. − The metalloradical catalysis is a promising approach, which has attractive features over traditional Fischer-type carbene chemistry; however, certain aspects of metalloradical catalysis have seldom been explored and need more attention such as (1) the rate of carbene radical generation between two distinct carbene precursors and (2) the reactivity of the carbene radicals in multicomponent reactions.…”

Section: Resultsmentioning

confidence: 99%

Stereoselective gem-Difunctionalization of Diazo Compounds with Vinyl Sulfoxonium Ylides and Thiols via Metalloradical Catalysis

Bhardwaj,

Gopalakrishnan,

Deshwal

et al. 2024

ACS Catal.

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Multicomponent reactions that involve carbenes with nucleophiles and electrophiles have demonstrated broad applications in synthetic chemistry. However, because of the high reactivity of transient carbenes, reactions involving two carbene precursors with the nucleophile in the presence of a metal catalyst remain unexplored. Herein, a three-component stereoselective gem-difunctionalization of diazo compounds with thiols and vinyl sulfoxonium ylide is disclosed via Co(II)-based metalloradical catalysis. The key aspect of the present strategy is to exploit the intrinsic difference in the reactivity of vinyl sulfoxonium ylides and diazo compounds with thiol and metal catalysts. The present Doyle−Kirmse rearrangement of a sulfonium ylide involves a convergent assembly of two in situ-generated intermediates, such as allyl sulfide and αmetalloalkyl radical complex, to provide expeditious access to tertiary sulfide scaffolds. Combined experimental and quantum chemical calculations unveil the intricate mechanism of this three-component reaction. Furthermore, theoretical studies on noncovalent interactions of selectivity-determining transition states explain the origin of the experimentally obtained diastereoselectivity.

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Section: Resultsmentioning

confidence: 99%

Stereoselective gem-Difunctionalization of Diazo Compounds with Vinyl Sulfoxonium Ylides and Thiols via Metalloradical Catalysis

Bhardwaj,

Gopalakrishnan,

Deshwal

et al. 2024

ACS Catal.

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“…Furthermore, Co(II)‐based metalloradical system for radical cascade cyclization has been demonstrated as a powerful approach to the efficient synthesis of multifunctionalized eight‐membered ring structures. Examples include dibenzocyclooctenes ( 78 ), [90] monobenzocyclooctadienes ( 79 ), [91] and 1 H ‐benzo[c]oxocines ( 80 ), [92] all of which have been synthesized in good to excellent yields. These structures result from intramolecular cyclization reactions of α‐aryldiazomethane derivatives generated in situ.…”

Section: Mrc By Cobalt Complexes Of Porphyrinsmentioning

confidence: 99%

Metalloradical Catalysis: General Approach for Controlling Reactivity and Selectivity of Homolytic Radical Reactions

Lee,

Zhang

2024

Angewandte Chemie

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Since Friedrich Wohler’s groundbreaking synthesis of urea in 1828, organic synthesis over the past two centuries has predominantly relied on the exploration and utilization of chemical reactions rooted in two‐electron heterolytic ionic chemistry. While one‐electron homolytic radical chemistry is both rich in fundamental reactivities and attractive with practical advantages, the synthetic application of radical reactions has been long hampered by the formidable challenges associated with the control over reactivity and selectivity of high‐energy radical intermediates. To fully harness the untapped potential of radical chemistry for organic synthesis, there is a pressing need to formulate radically different concepts and broadly applicable strategies to address these outstanding issues. In pursuit of this objective, researchers have been actively developing metalloradical catalysis (MRC) as a comprehensive framework to guide the design of general approaches for controlling over reactivity and stereoselectivity of homolytic radical reactions. Essentially, MRC exploits the metal‐centered radicals present in open‐shell metal complexes as on‐electron catalysts for homolytic activation of substrates to generate metal‐entangled organic radicals as the key intermediates to govern the reaction pathway and stereochemical course of subsequent catalytic radical processes. Different from the conventional two‐electron catalysis by transition metal complexes, MRC operates through one‐electron chemistry utilizing stepwise radical mechanisms.

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“…The authors have cited additional references within the supporting information. [74][75][76][77][78][79]…”

Section: Supporting Informationmentioning

confidence: 99%

Creating Conjugated C−C Bonds between Commercial Carbon Electrode and Molecular Catalyst for Oxygen Reduction to Hydrogen Peroxide

et al. 2023

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Immobilizing molecular catalysts on electrodes is vital for electrochemical applications. However, creating robust electrode‐catalyst interactions while maintaining good catalytic performance and rapid electron transfer is challenging. Here, without introducing any foreign elements, we show a bottom‐up synthetic approach of constructing the conjugated C−C bond between the commercial Vulcan carbon electrode and an organometallic catalyst. Characterization results from FTIR, XPS, aberration‐corrected TEM and EPR confirmed the successful and uniform heterogenization of the complex. The synthesized Vulcan‐LN4−Co catalyst is highly active and selective in the oxygen reduction reaction in neutral media, showing an 80 % hydrogen peroxide selectivity and a 0.72 V (vs. RHE) onset potential which significantly outperformed the homogenous counterpart. Based on single‐crystal XRD and NMR data, we built a model for density functional theory calculations which showed a nearly optimal binding energy for the *OOH intermediate. Our results show that the direct conjugated C−C bonding is an effective approach for heterogenizing molecular catalysts on carbon, opening new opportunities for employing molecular catalysts in electrochemical applications.

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Catalytic Synthesis of 1H-2-Benzoxocins: Cobalt(III)-Carbene Radical Approach to 8-Membered Heterocyclic Enol Ethers

Cited by 20 publications

References 87 publications

Stereoselective gem-Difunctionalization of Diazo Compounds with Vinyl Sulfoxonium Ylides and Thiols via Metalloradical Catalysis

Stereoselective gem-Difunctionalization of Diazo Compounds with Vinyl Sulfoxonium Ylides and Thiols via Metalloradical Catalysis

Metalloradical Catalysis: General Approach for Controlling Reactivity and Selectivity of Homolytic Radical Reactions

Creating Conjugated C−C Bonds between Commercial Carbon Electrode and Molecular Catalyst for Oxygen Reduction to Hydrogen Peroxide

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