Acyl nitroxides

Perkins, M. J.

doi:10.1007/bf03155650

Cited by 10 publications

(4 citation statements)

References 17 publications

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“…Such radicals in other studies were produced by different methods and/or from different substrates than those reported here (for reviews see Aurich. 1982;Forrester et al, 1968;Keana, 1984;Perkins, 1982Perkins, , 1986. In our study they were either present in ambient light or generated with UV irradiation.…”

Section: Discussionmentioning

confidence: 53%

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Electron Spin Resonance Study of the Relationship of Uv Irradiation to Nitroxide Radical Formation in Desferrioxamine (Desferal) and Related Hydroxamate and Hydroxylamine Derivatives

Hinojosa

Jacks

Calamari

et al. 1989

Photochem & Photobiology

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UV irradiation of desferoxamine (Desferal) produced a well resolved electron spin resonance spectrum that we attributed to a nitroxide radical on the basis of the g value and hyperfine splitting constants. Of related hydroxylamines, only N, N‐dialkyl or N‐isopropyl and larger branched N‐alkyl derivatives formed nitroxides and UV was not needed; smaller N‐alkyl and N, N‐dicarbonyl derivatives were inert to UV. Of related acetohydroxamates, the N‐methyl and N‐ethyl derivatives required UV irradiation for radical formation; the other, larger branched N‐alkyl derivatives readily formed free radicals without UV. Nitroxides from hydroxamates, as represented by UV‐irradiated desferoxamine, were predominant at acidic pH values; those from hydroxylamines, as represented by N, N‐dimethyl hydroxylamine, were so at alkaline values. The results were related to the electron donating and withdrawing properties of the N‐substituting groups and the derealization of the unpaired electron.

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Section: Discussionmentioning

confidence: 53%

“…However, with N-carbonyl-N-alkyl derivatives such as the N-alkyl acetohydroxamates ( Table 3 ) . which contain electron-donating alkyl groups, the nitroxide radical was stabilized by nitrogen lonepair delocalization towards the carbonyl moiety, resulting in spin localization on the nitroxide oxygen (Perkins, 1986), as shown in Fig. 5.…”

Section: Discussionmentioning

confidence: 99%

Electron Spin Resonance Study of the Relationship of Uv Irradiation to Nitroxide Radical Formation in Desferrioxamine (Desferal) and Related Hydroxamate and Hydroxylamine Derivatives

Hinojosa

Jacks

Calamari

et al. 1989

Photochem & Photobiology

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“…We conclude that the systems explored here are inappropriate ones with which to develop the analysis of equithermal reactions discussed in ref. 12.…”

Section: Discussionmentioning

confidence: 99%

Enantioselectivity in a free-radical oxidation: measurement of small enantiomeric excesses

Brooks¹,

Perkins²,

Smith³

et al. 1992

J. Chem. Soc., Perkin Trans. 2

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Partial conversion of 2-methyl-1 -phenylpropan-1 -01 into isobutyrophenone by the acyl aminoxyl radicals formed on oxidation of enantiomerically pure N-fenchelylbenzohydroxamic acid or its paranitro derivative occurs with small but measurable enantioselectivity. This has been demonstrated using H PLC with diode-laser-based polarimetric detection to examine unchanged alcohol in the reaction mixtures.Enantioselectivity in intermolecular hydrogen-atom transfer has been demonstrated by allowing incomplete reaction of a dissymmetric radical with a racemic substrate. lP3 Recovered substrate from such a reaction has been found to be optically active, showing that selective removal of one enantiomer has taken place. Examples include the reaction of dissymmetric alkoxyl radicals with 2-phenylbutane,' and oxidation of racemic benzoin by the pinanecarbonyl aminoxyl 1. ' We have

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“…Later, however, it was shown that desferrioxamine B acts as a chain-breaking radical scavenger by donating an electron or hydrogen atom from the hydroxamate center (11). This capacity could be attributed to the hydroxamate centers that produce a resonance-stabilized center following the donation of a hydrogen atom (12).…”

mentioning

confidence: 99%

Antioxidant properties of desferrioxamine E, a new hydroxamate antioxidant

Shimoni

Ampel

Zähner

et al. 1998

J Americ Oil Chem Soc

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Antioxidant properties of desferrioxamine E, a cyclic trihydroxamate produced by microorganisms, were tested and compared to those of desferrioxamine B and butylated hydroxyanisole (BHA). Desferrioxamine E exhibited significant antioxidant effects in linoleic acid emulsions as well as in emulsions of linoleic acid and β-carotene. In concentrations of 100 ppm, the effect of both desferrioxamines in linoleic acid emulsion was equal to that of BHA. The antioxidant activity of the desferrioxamines in emulsions of β-carotene and linoleic acid was significantly higher than that of BHA. In addition, the initial rate of β-carotene destruction was significantly lower when desferrioxamines were added to the emulsion. FIG. 1. Structure of desferrioxamine E (A) and B (B).

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Acyl nitroxides

Cited by 10 publications

References 17 publications

Electron Spin Resonance Study of the Relationship of Uv Irradiation to Nitroxide Radical Formation in Desferrioxamine (Desferal) and Related Hydroxamate and Hydroxylamine Derivatives

Electron Spin Resonance Study of the Relationship of Uv Irradiation to Nitroxide Radical Formation in Desferrioxamine (Desferal) and Related Hydroxamate and Hydroxylamine Derivatives

Enantioselectivity in a free-radical oxidation: measurement of small enantiomeric excesses

Antioxidant properties of desferrioxamine E, a new hydroxamate antioxidant

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