Biomimetic Syntheses of Analogs of Hongoquercin A and B by Late-Stage Derivatization

Mies, Thomas; White, Andrew J. P.; Parsons, Philip J.; Barrett, Anthony G. M.

doi:10.1021/acs.joc.0c02638

“…An alternative second pathway involves the 1,5‐H abstraction of photoexcited carbonyls due to the above mentioned highly electrophilic nature of the oxygen‐radical. It is known from previous studies that the carbonyls of dioxinone protected resorcylates are in close proximity to the benzylic methyl group through H‐bonding, which significantly affects the acidity of the benzylic protons [48,49] . Thus, ISC of S 1 to T 1 p and H‐transfer would give a 1,4‐biradical intermediate T 1 b [39,40,42,43] .…”

Section: Resultsmentioning

confidence: 99%

“…It is known from previous studies that the carbonyls of dioxinone protected resorcylates are in close proximity to the benzylic methyl group through H-bonding, which significantly affects the acidity of the benzylic protons. [48,49] Thus, ISC of S 1 to T 1 p and H-transfer would give a 1,4-biradical intermediate T 1 b. [39,40,42,43] A tautomeric structure of this would be the 1,2-biradical T 1 b2.…”

Section: Photophysical Considerationsmentioning

confidence: 99%

Photolytic Studies on the Generation and Trapping of 6‐Oxomethylidenecyclohexa‐2,4‐diene‐1‐one Derivatives with Various Nucleophiles

Mies

¹

,

White

²

,

Parsons

³

et al. 2021

Helvetica Chimica Acta

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Dedicated to Prof. Ernst Peter Kündig on the occasion of his 75th birthday α-Oxoketenes and cyclohexadiene α-oxoketenes are reactive intermediates, particularly the latter due to their high re-aromatization potential. In this communication, we report photolytic studies on the generation of such species from 4-OMe and 4-OMOM protected resorcylate dioxinones and their trapping to give resorcylate esters and amides as well as the formation of adducts with enol-ethers as trapping reagents.

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“…Full experimental details, including general procedures, optimization tables, compound characterization, unproductive attempts, computational details, and additional reaction pathways can be found in the supporting information [49–89] …”

Section: Supporting Informationmentioning

confidence: 99%

Electrochemically Driven Nickel‐Catalyzed Halogenation of Unsaturated Halide and Triflate Derivatives

Chen,

Charvet,

Payard

et al. 2023

Angew Chem Int Ed

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A robust electrochemically driven nickel‐catalyzed halogen exchange of unsaturated halides and triflates (Br to Cl, I to Cl, I to Br, and OTf to Cl) is reported. A combination of NiCl2 ⋅ glyme as the precatalyst, 2,2′‐bipyridine as a ligand, NMP as the solvent, and electrochemistry allowed the generation of a nickel species that promotes reductive elimination of the desired product. This paired electrochemical halogenation is compatible with a range of unsaturated halides and triflates, including heterocycles, dihaloarenes, and alkenes with good functional‐group tolerance. Joint experimental and theoretical mechanistic investigations highlighted three catalytic events: i) oxidative addition of the aryl halide to a Ni(0) species to deliver a Ni(II) intermediate; ii) halide metathesis at Ni(II); iii) electrochemical oxidation of Ni(II) to Ni(III) to enable the formation of the desired aryl halide upon reductive elimination. This methodology allows the replacement of heavy halogens (I or Br) or polar atoms (O) with the corresponding lighter and more lipophilic Cl group to block undesired reactivity or modify the properties of drug and agrochemical candidates.

show abstract

“…Full experimental details, including general procedures, optimization tables, compound characterization, unproductive attempts, computational details, and additional reaction pathways can be found in the supporting information [49–89] …”

Section: Supporting Informationmentioning

confidence: 99%

Electrochemically Driven Nickel‐Catalyzed Halogenation of Unsaturated Halide and Triflate Derivatives

Chen,

Charvet,

Payard

et al. 2023

Angewandte Chemie

0

View full text Add to dashboard Cite

A robust electrochemically driven nickel‐catalyzed halogen exchange of unsaturated halides and triflates (Br to Cl, I to Cl, I to Br, and OTf to Cl) is reported. A combination of NiCl2 ⋅ glyme as the precatalyst, 2,2′‐bipyridine as a ligand, NMP as the solvent, and electrochemistry allowed the generation of a nickel species that promotes reductive elimination of the desired product. This paired electrochemical halogenation is compatible with a range of unsaturated halides and triflates, including heterocycles, dihaloarenes, and alkenes with good functional‐group tolerance. Joint experimental and theoretical mechanistic investigations highlighted three catalytic events: i) oxidative addition of the aryl halide to a Ni(0) species to deliver a Ni(II) intermediate; ii) halide metathesis at Ni(II); iii) electrochemical oxidation of Ni(II) to Ni(III) to enable the formation of the desired aryl halide upon reductive elimination. This methodology allows the replacement of heavy halogens (I or Br) or polar atoms (O) with the corresponding lighter and more lipophilic Cl group to block undesired reactivity or modify the properties of drug and agrochemical candidates.

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Biomimetic Syntheses of Analogs of Hongoquercin A and B by Late-Stage Derivatization

Cited by 6 publications

References 67 publications

Photolytic Studies on the Generation and Trapping of 6‐Oxomethylidenecyclohexa‐2,4‐diene‐1‐one Derivatives with Various Nucleophiles

Photolytic Studies on the Generation and Trapping of 6‐Oxomethylidenecyclohexa‐2,4‐diene‐1‐one Derivatives with Various Nucleophiles

Electrochemically Driven Nickel‐Catalyzed Halogenation of Unsaturated Halide and Triflate Derivatives

Electrochemically Driven Nickel‐Catalyzed Halogenation of Unsaturated Halide and Triflate Derivatives

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