- Generation of Iminoxyl Radicals by Photoredox Catalysis Enables Oxidant-Free Hydroxygenation of β,γ-Unsaturated Oximes
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A visible-light photocatalytic generation of iminoxyl radicals has been accomplished under oxidant-free conditions. This approach offers a mild, atom-economical, and redox-neutral synthesis of 5-methylisoxazolines through radical hydroxygenation of β,γ-unsaturated oximes in the absence of an additional hydrogen source.
- Chen, Huiming,Li, Zhenming,Qian, Lijie,Xu, Xiangsheng
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supporting information
p. 293 - 295
(2021/11/30)
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- Ni/Chiral Sodium Carboxylate Dual Catalyzed Asymmetric O-Propargylation
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A highly enantioselective O-propargylation catalyzed by combining a phosphine-nickel complex and an axially chiral sodium dicarboxylate has been developed. The transformation features mild reaction conditions, a broad substrate scope, and excellent functional group tolerance, offering an efficient approach to an array of enantioenriched O-propargyl hydroxylamines. Mechanistic studies support the presumed role of the chiral carboxylate as a counterion for nickel catalysis enabling the discovery of highly stereoselective transformations. The power of this reaction is illustrated by its application in the asymmetric total synthesis of potent firefly luciferase inhibitors and (S)-dihydroyashabushiketol.
- Chang, Xihao,Guo, Chang,Peng, Lingzi,Xu, Xianghong
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p. 21048 - 21055
(2021/12/14)
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- Study of the Features of the Reaction of Arylcyclopropanes with Nitrozonium Ethyl Sulfate or Nitrozonium Tetrafluoroborate
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Abstract: The reactions of diaryl-, aryl-, and alkyl–arylcyclopropanes with ethyl nitrite in the presence of sulfur trioxide and sulfur trioxide dioxane complex, as well as the reactions of 1-alkyl-2-arylcyclopropanes with NOBF4 were studied. It was found that the attack of the nitrosonium cation, accompanied by the formation of a benzyl carbocation, leads to the formation of isoxazolines. The introduction of bulky alkyl substituents into the cyclopropane ring changes the regioselectivity of nitrosation, favoring the attack of the electrophilic particle on the benzyl position and leading to the competitive formation of an alkyl carbocation. Depending on the structure of the alkyl substituent, both products of intramolecular heterocyclization accompanied by skeletal rearrangements and products formed with the participation of an external nucleophile are formed.
- Bondarenko, O. B.,Gavrilova, A. Yu.,Solodovnikova, T. A.,Tikhanushkina, V. N.,Zyk, N. V.
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p. 753 - 762
(2020/07/03)
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- Cobalt-catalyzed aerobic oxidative cyclization of β,γ- unsaturated oximes
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Cobalt complex Co(nmp)2 can efficiently catalyze the aerobic oxidative 5-exo cyclization of β,γ-unsaturated oximes to afford isoxazolines. The key cyclization step involves the generation of carbon-centred radicals. The products are largely dep
- Li, Weifei,Jia, Pingjing,Han, Bing,Li, Dianjun,Yu, Wei
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p. 3274 - 3280
(2013/04/24)
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- A tandem oximation-cyclization route to Δ2-isoxazolines
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3,5-Disubstituted Δ2-isoxazolines can be prepared from the corresponding β,γ-unsaturated ketones by treatment with hydroxylamine hydrochloride and sodium hydroxide. Evidence indicates that the mechanism of this reaction involves the formation o
- Norman, Amber L.,Shurrush, Khriesto A.,Calleroz, Amanda T.,Mosher, Michael D.
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p. 6849 - 6851
(2008/02/12)
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- Addition of allylindium bromide to nitrile oxides in aqueous media: Convenient synthesis of 5-methylisoxazolines
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5-Methylisoxazolines were obtained in good yields through a highly selective nucleophilic addition of allylindium reagent to benzonitrile oxides with concominant C-O heterocyclization. Copyright
- Sawant, Sanghapal D.,Singh, Parvinder P.,Qazi, Naveed A.,Kumar, H. M. Sampath
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p. 296 - 297
(2008/02/04)
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- The preparation of 2-isoxazolines from O-propargylic hydroxylamines via a tandem rearrangement-cyclisation reaction
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A method for the conversion of O-propargylic hydroxylamines into 2-isoxazolines in 60-84% yield is described. For 3-alkylpropargyl or 3-arylpropargyl hydroxylamines this was achieved by heating a methanolic solution of the hydrochloride salt in the presen
- Pennicott, Lewis,Lindell, Stephen
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p. 463 - 465
(2007/10/03)
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- SELECTIVE SYNTHESIS OF 3,5-DISUBSTITUTED ISOAZOLES FROM β-SUBSTITUTED ENONES AND HYDROXYLAMINE HYDROCHLORIDE IN THE PRESENCE OF VARIOUS BASES
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The synthesis of two isomeric isoxazoles could be selectively controlled in the reaction of β-substituted enones with 3 species of hydroxylamine; hydroxyammonium cation (1), free hydroxylamine (2) and aminoHydroxy anion (3).
- Kashima, Choji,Yoshiwara, Nobutoshi,Shirai, Shun-ichi,Omote, Yoshimori
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p. 1455 - 1458
(2007/10/02)
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- PHOTOCHEMISTRY OF 3-ARYL-2-ISOXAZOLINE
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3-Phenyl-2-isoxazoline (1) was irradiated to give 4-phenyl-2-oxazoline (3), β-aminoaldehyde (14) and benzonitrile from its ?-?* singlet excited state.Several related derivatives afforded similar photoproducts on irradiation.The quantum yields of the photoreactions were dependent on the magnitudes of the singlet energies of the 2-isoxazolines. p-Cyanophenyl-2-isoxaline (1c) formed a one-to-one photoadduct (22) with benzene.
- Kumagai, T.,Shimizu, K.,Kawamura, Y.,Mukai, T.
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p. 3365 - 3376
(2007/10/02)
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