Stereochemistry of iminoxy radicals

Alberti, Angelo; Barbaro, Gaetano; Battaglia, Arturo; Guerra, Maurizio; Bernardi, Fernando; Dondoni, Alessandro; Pedulli, Gian Franco

doi:10.1021/jo00317a018

Cited by 33 publications

(11 citation statements)

References 4 publications

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“…It is known that the angular structure is characteristic for the CNO fragment of oxime radicals, and in the case of different substituents at the carbon atom, two isomers (E and Z) exist. The isomerization of oxime radicals proceeds much easier than for the corresponding oximes; the observation of individual isomers is generally possible only at low temperatures [68,69] (about 190 K). According to quantum chemical calculations, the oxime radicals have an increased C=N-O angle and a shortened N-O bond compared to the corresponding oximes ( Figure 3) [44,52,70].…”

Section: Methodsmentioning

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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Section: Methodsmentioning

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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“…1 H NMR (CDCl 3 ) δ 8.13 (1 H, m), 7.68 (1 H, s), 7.26 (3 H, s), 3.87 (3 H, s), 3.77 (3 H, s). MS (EI) m/z (relative intensity) 189 (M ϩ , 70%), 158 (100), 148 (5), 130 (18), 115 (2), 103 (7). This material (2.6 g, 13.8 mmol) was dissolved in a solution of potassium hydroxide (1 M, 100 cm 3 ) in acetonitrile (100 cm 3 ) and the solution heated under reflux for 1.5 h. The solution was cooled and acidified with 1 M HCl and the resulting white precipitate collected and washed with water, to give 1-methylindole-3-carboxylic acid (2.4 g, 100%), mp 202-203 ЊC.…”

Section: -Methylindole-3-carboxamidementioning

confidence: 99%

Iminoxyl radicals and stable products from the one-electron oxidation of 1-methylindole-3-carbaldehyde oximes

Everett

Naylor

Stratford

et al. 2001

J. Chem. Soc., Perkin Trans. 2

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“…The importance of including correlation is shown by the results with the UHF/6-31G(d) method, which gives a CNO bond angle of only 125°, close to calculated values in the literature based on the INDO method. 16 We used the MP2/6-31(G) method to calculate the Scheme 2 energy profiles as illustrated in Figure 4. The energy profiles are for the extension of the CNO angle where all other parameters were optimized at each point.…”

Section: Spectral Datamentioning

confidence: 99%