Regioselective Synthesis of Thiocyanate‐Containing Isoxazolines via FeIII/K2S2O8‐Mediated Radical Thiocyanation/Cyclization Cascade Reaction of β,γ‐Unsaturated Oximes

Ji, Fei; Fan, Yun; Yang, Run Ze; Yang, Yueyan; Yu, Dianwen; Wang, Minyu; Li, Zhiyu

doi:10.1002/ajoc.201700050

Cited by 18 publications

(8 citation statements)

References 53 publications

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“…On the basis of the control experimental results (Scheme ) and previous related literature,,,,, a plausible reaction mechanism is proposed for the formation of 2‐phenyl‐3‐thiocyanato‐2 H ‐indazole as depicted here in Scheme . Initially, ferric thiocyanate complex ( A ) is formed by ligand exchange (SCN − ) and it is oxidized to generate the SCN radical in presence of K 2 S 2 O 8 . Meanwhile, coordination of 2‐phenyl‐2 H‐ indazole with Fe (III) leads to formation of intermediate B .…”

Section: Figurementioning

confidence: 77%

Potassium Persulfate‐Mediated Thiocyanation of 2H‐Indazole under Iron‐Catalysis

Dey

Hajra

2018

Adv Synth Catal

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Potassium persulfate-mediated thiocyanation of 2H-indazoles has been developed using ammonium thiocyanate as thiocyanating agent under iron-catalysis at room temperature. 2-Aryl-3thiocyanato-2H-indazoles are synthesized in good yields with a broad substrates scope. This methodology is also applicable for the selenocyanation of 2H-indazoles. The mechanistic study suggests the reaction probably proceeds through a radical pathway.

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Section: Figurementioning

confidence: 77%

Potassium Persulfate‐Mediated Thiocyanation of 2H‐Indazole under Iron‐Catalysis

Dey

Hajra

2018

Adv Synth Catal

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“…Another example of the oxidative cyclization of oximes with the formation of an isoxazoline ring and C-S bond is the reaction of aromatic β,γ-unsaturated oximes 159 with the FeCl 3 / KSCN/K 2 S 2 O 8 system that affords thiocyanates 160 (Scheme 54) [143].…”

Section: Both Aliphatic (Example 118c) and Aromatic (Examplesmentioning

confidence: 99%

Oxime radicals: generation, properties and application in organic synthesis

Krylov¹,

Paveliev²,

Budnikov³

et al. 2020

Beilstein J. Org. Chem.

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N-Oxyl radicals (compounds with an N–O• fragment) represent one of the richest families of stable and persistent organic radicals with applications ranging from catalysis of selective oxidation processes and mechanistic studies to production of polymers, energy storage, magnetic materials design and spectroscopic studies of biological objects. Compared to other N-oxyl radicals, oxime radicals (or iminoxyl radicals) have been underestimated for a long time as useful intermediates for organic synthesis, despite the fact that their precursors, oximes, are extremely widespread and easily available organic compounds. Furthermore, oxime radicals are structurally exceptional. In these radicals, the N–O• fragment is connected to an organic moiety by a double bond, whereas all other classes of N-oxyl radicals contain an R2N–O• fragment with two single C–N bonds. Although oxime radicals have been known since 1964, their broad synthetic potential was not recognized until the last decade, when numerous selective reactions of oxidative cyclization, functionalization, and coupling mediated by iminoxyl radicals were discovered. This review is focused on the synthetic methods based on iminoxyl radicals developed in the last ten years and also contains some selected data on previous works regarding generation, structure, stability, and spectral properties of these N-oxyl radicals. The reactions of oxime radicals are classified into intermolecular (oxidation by oxime radicals, oxidative C–O coupling) and intramolecular. The majority of works are devoted to intramolecular reactions of oxime radicals. These reactions are classified into cyclizations involving C–H bond cleavage and cyclizations involving a double C=C bond cleavage.

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“…For a typical example, a specially designed β,γ-unsaturated oxime has been synthesized and employed as the starting material to efficiently synthesize isoxazolines and their derivatives. [4] In particular, the reported strategy enables the one-step construction of the isoxazoline skeleton and simultaneously incorporates functional groups into the products that are often adjacent to the isoxazoline heterocycle by difunctionalizing the carbon-carbon double bonds. To our knowledge, these functional groups, which act as nucleophiles for the cyclization of oximes, mainly include carbon, nitrogen, oxygen, and others and indicate the powerful ability of this cyclization strategy.…”

Section: Introductionmentioning

confidence: 99%

“…To our knowledge, these functional groups, which act as nucleophiles for the cyclization of oximes, mainly include carbon, nitrogen, oxygen, and others and indicate the powerful ability of this cyclization strategy. [4][5] Interestingly, Kang's group recently found that β,γ-unsaturated oximes could react with t-BuONO to afford isoxazolines with a nitrooxy substituent. [5] The author suggests that the presence of molecular oxygen acting as an oxidizing reagent is crucial for the metal-free nitrooxylation of β,γ-unsaturated oximes, which generates cyclization products in good yields at low temperature.…”

Section: Introductionmentioning

confidence: 99%

Iron‐Promoted Radical Cyclization of β, γ‐Unsaturated Oximes: Dual Role of Iron(III) Nitrate as a Promoter and Nitrooxy Source

Wang

et al. 2021

Asian J Org Chem

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A method for the radical cyclization of β,γunsaturated oximes to access the isoxazoline backbone has been developed, in which iron(III) nitrate plays a dual role as a promoter and a nitrooxy source. Iron-promoted cyclization is well tolerated with a series of aryl-and alkyl-substituted β,γ-unsaturated oximes, which readily affords the desired isoxazolines that can be easily transformed into useful compounds. Mechanistic experiments support that a radical pathway may be involved in the cyclization of β,γ-unsaturated oximes.

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Regioselective Synthesis of Thiocyanate‐Containing Isoxazolines via Fe^III/K₂S₂O₈‐Mediated Radical Thiocyanation/Cyclization Cascade Reaction of β,γ‐Unsaturated Oximes

Abstract: Scheme1.Strategy for the synthesis of thiocyanate-containing isoxazolines.[a] Dr.

Cited by 18 publications

References 53 publications

Potassium Persulfate‐Mediated Thiocyanation of 2H‐Indazole under Iron‐Catalysis

Potassium Persulfate‐Mediated Thiocyanation of 2H‐Indazole under Iron‐Catalysis

Oxime radicals: generation, properties and application in organic synthesis

Iron‐Promoted Radical Cyclization of β, γ‐Unsaturated Oximes: Dual Role of Iron(III) Nitrate as a Promoter and Nitrooxy Source

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