Generation of Iminoxyl Radicals by Photoredox Catalysis Enables Oxidant-Free Hydroxygenation of β,γ-Unsaturated Oximes

Li, Zhenming; Qian, Lijie; Chen, Huiming; Xu, Xiangsheng

doi:10.1055/a-1684-0380

Cited by 3 publications

(1 citation statement)

References 17 publications

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“…Most existing methods for constructing dihydroisoxazoles involve intermolecular 1,3-dipolar cycloaddition reactions between nitrile oxides and unsaturated compounds, such as alkenes, enols, and alkynes . Recently, radical-mediated 5- exo -trig intramolecular cyclization of β,γ-unsaturated oximes have been reported to yield dihydroisoxazoles. − We have also reported a Mn(acac) 3 -catalyzed 5- exo -trig oxygenative cyclization of β,γ-unsaturated oximes employing very low catalyst loading (0.050–0.20 mol %) using O 2 in open flask conditions at room temperature (Figure a)…”

Section: Introductionmentioning

confidence: 99%

Manganese-Catalyzed 5-Endo-trig Oxygenative Cyclization of α,β-Unsaturated Oximes under Air and Ambient Conditions for the Synthesis of 4,5-Dihydroisoxazoles

Yamamoto,

Matsukawa,

Kikuchi

et al. 2024

J. Org. Chem.

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The stereoselective 5-endo-trig oxygenative cyclization of α,β-unsaturated oximes was achieved using molecular oxygen (O 2 ) and a manganese catalyst. Several 4-hydroxy-4,5dihydroisoxazoles were obtained in high yields by directly incorporating O 2 from the atmosphere (eliminating the necessity for a pure oxygen environment) and using an unprecedentedly low loading of Mn(acac) 3 (as little as 0.020 mol %) without additional additives. Because of its desirable features, such as operational simplicity, inexpensive catalyst, mild reaction conditions (open flask conditions at room temperature), and broad substrate compatibility, this novel reaction provides an attractive synthetic approach to producing 4-hydroxy-4,5-dihydroisoxazoles.

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Section: Introductionmentioning

confidence: 99%

Manganese-Catalyzed 5-Endo-trig Oxygenative Cyclization of α,β-Unsaturated Oximes under Air and Ambient Conditions for the Synthesis of 4,5-Dihydroisoxazoles

Yamamoto,

Matsukawa,

Kikuchi

et al. 2024

J. Org. Chem.

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Direct allylic acylation via cross-coupling involving cooperative N‑heterocyclic carbene, hydrogen atom transfer, and photoredox catalysis

et al. 2023

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Herein, we report a mild, operationally simple, multicatalytic method for the synthesis of β,γ-unsaturated ketones via allylic acylation of alkenes. Specifically, the method combines N‑heterocyclic carbene catalysis, hydrogen atom transfer catalysis, and photoredox catalysis for cross-coupling reactions between a wide range of feedstock carboxylic acids and readily available olefins to afford structurally diverse β,γ-unsaturated ketones without olefin transposition. The method could be used to install acyl groups on highly functionalized natural-product-derived compounds with no need for substrate pre-activation, and C–H functionalization proceed with excellent site selectivity. To demonstrate the potential applications of the method, we convert a representative coupling product into various useful olefin synthons.

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O–H bond activation of β,γ-unsaturated oximes via hydrogen atom transfer (HAT) and photoredox dual catalysis

Yi,

Zhu,

Chen

et al. 2023

Chem. Sci.

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Generation of Iminoxyl Radicals by Photoredox Catalysis Enables Oxidant-Free Hydroxygenation of β,γ-Unsaturated Oximes

Cited by 3 publications

References 17 publications

Manganese-Catalyzed 5-Endo-trig Oxygenative Cyclization of α,β-Unsaturated Oximes under Air and Ambient Conditions for the Synthesis of 4,5-Dihydroisoxazoles

Manganese-Catalyzed 5-Endo-trig Oxygenative Cyclization of α,β-Unsaturated Oximes under Air and Ambient Conditions for the Synthesis of 4,5-Dihydroisoxazoles

Direct allylic acylation via cross-coupling involving cooperative N‑heterocyclic carbene, hydrogen atom transfer, and photoredox catalysis

O–H bond activation of β,γ-unsaturated oximes via hydrogen atom transfer (HAT) and photoredox dual catalysis

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