Oxidation of nitroxyl radicals by xenon difluoride

Golubev, Valery A; Solodova, V. V.; Aleinikov, N. N.; Корсунский, Б. Л.; Rozantsev, É. G.; Dubovitskii, F. I.

doi:10.1007/bf00923923

Cited by 3 publications

(4 citation statements)

References 3 publications

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“…m-ClCgH4C03-628 c2h3oh ^(CH3)2S(0)=NC6H4N02-, (522) 0-5 -c C. Nonbonding Control of Oxygenation Singlet oxygen reacted with the tetraene 629 and with the diene 630 by a highly selective syn attack to give a peroxide endo to the heterocyclic ring (eq 523,524). For comparison, singlet oxygen gave an anti peroxide when it reacted with the 633 c6h5c=s --c6h5cn + so ( N=0 S + S02)…”

Section: B Sulfiliminesmentioning

confidence: 99%

Increasing the index of covalent oxygen bonding at nitrogen attached to carbon

Boyer¹

1980

Chem. Rev.

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Section: B Sulfiliminesmentioning

confidence: 99%

Increasing the index of covalent oxygen bonding at nitrogen attached to carbon

Boyer¹

1980

Chem. Rev.

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“…As shown previously [23], nitroso compound XI is unstable, and it was not isolated as individual substance. The corresponding dimer was detected by HLPC as an impurity in diazene N,N′-dioxide IV (see Experimental).…”

Section: Methodsmentioning

confidence: 75%

“…For example, N-oxide VIII is likely to be formed via reaction of nitroso compound X with radical II according to Scheme 6. Addition of radical II to X gives radical XXI which was obtained previously by oxidation of II with xenon difluoride [23]. Cation Ia reversibly oxidizes radical XXI to cation XXII, and addition of hydroxide ion to the latter gives N-oxide XXIII.…”

Section: Methodsmentioning

confidence: 98%

Mechanism of autoreduction of 2,2,6,6-tetramethyl-1,4-dioxopiperidinium cation in alkaline medium

Golubev

Sen

2011

Russ J Org Chem

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Autoreduction of 2,2,6,6-tetramethyl-1,4-dioxopiperidinium ion to nitroxyl radical in alkaline medium involves a number of parallel and consecutive reactions. The primary products of the reaction of 2,2,6,6-tetramethyl-1,4-dioxopiperidinium with hydroxide ion are three nitroso compounds and N-hydroxy-2,2,6,6-tetramethylpiperidine N-oxide. Isomerization of the nitroso compounds and elimination of acetone from the N-oxide give cyclic hydroxylamines which reduce the initial cation to nitroxyl radical, being oxidized to nitrones.Stable nitroxyl radicals give rise to redox triad consisting of oxoammonium cation R 2 N + =O, nitroxyl radical R 2 N-O · , and hydroxylamine R 2 N-OH (Scheme 1), which possesses a unique set of parameters. Properties of two-electron redox couple R 2 N + =O/R 2 N-OH and one-electron redox couples R 2 N + =O/R 2 N-O · and R 2 N-O · /R 2 N-OH were utilized in such processes as selective oxidation of alcohols [1][2][3][4][5], design of chemical current sources with improved parameters [6,7], suppression of oxidative stress in living organisms [8], and even DNA-mediated signaling by base excision repair enzymes [9]. Oxoammonium derivatives of nitroso ureas were found to exhibit a strong antitumor activity [10,11]. nium salts are the corresponding nitroxyl radicals, it was presumed [12] that hydroxide ion acts as reducing agent in this reaction. Nevertheless, the equilibrium constant calculated from the reduction potentials of 2,2,6,6-tetramethyl-1-oxopiperidinium ion (0.75 V [14]) and hydroxyl radical OH · (1.89 V [15]) is very small, K 1 = k 1 /k -1 ≈ 5 × 10 -20 (Scheme 2).

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“…Nitroxides 24 , Scheme , can be oxidized chemically with various oxidants such as Cl 2 , Br 2 , − Ag 2 O, SbCl 5 − SnX 4 , NO 2 , m CPBA, XeF 2 , HBF 4 /NaOCl, tris(pentafluorophenyl)borane (BCF), , or the triphenylcarbenium salt , to the corresponding oxoammonium salts 25 . The reduction of oxoammonium salts 25 to nitroxides 24 can be achieved with tetrathiafulvalene in almost quantitative yields at room temperature within 1 min, but also the iodide anion can be used for this transformation .…”

Section: Physical Properties and Reactivitymentioning

confidence: 99%

Organic Synthesis Using Nitroxides

Leifert

Studer

2023

Chem. Rev.

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Nitroxides, also known as nitroxyl radicals, are long-lived or stable radicals with the general structure R 1 R 2 N−O • . The spin distribution over the nitroxide N and O atoms contributes to the thermodynamic stability of these radicals. The presence of bulky N-substituents R 1 and R 2 prevents nitroxide radical dimerization, ensuring their kinetic stability. Despite their reactivity toward various transient C radicals, some nitroxides can be easily stored under air at room temperature. Furthermore, nitroxides can be oxidized to oxoammonium salts (R 1 R 2 N�O + ) or reduced to anions (R 1 R 2 N−O − ), enabling them to act as valuable oxidants or reductants depending on their oxidation state. Therefore, they exhibit interesting reactivity across all three oxidation states. Due to these fascinating properties, nitroxides find extensive applications in diverse fields such as biochemistry, medicinal chemistry, materials science, and organic synthesis. This review focuses on the versatile applications of nitroxides in organic synthesis. For their use in other important fields, we will refer to several review articles. The introductory part provides a brief overview of the history of nitroxide chemistry. Subsequently, the key methods for preparing nitroxides are discussed, followed by an examination of their structural diversity and physical properties. The main portion of this review is dedicated to oxidation reactions, wherein parent nitroxides or their corresponding oxoammonium salts serve as active species. It will be demonstrated that various functional groups (such as alcohols, amines, enolates, and alkanes among others) can be efficiently oxidized. These oxidations can be carried out using nitroxides as catalysts in combination with various stoichiometric terminal oxidants. By reducing nitroxides to their corresponding anions, they become effective reducing reagents with intriguing applications in organic synthesis. Nitroxides possess the ability to selectively react with transient radicals, making them useful for terminating radical cascade reactions by forming alkoxyamines. Depending on their structure, alkoxyamines exhibit weak C−O bonds, allowing for the thermal generation of C radicals through reversible C−O bond cleavage. Such thermally generated C radicals can participate in various radical transformations, as discussed toward the end of this review. Furthermore, the application of this strategy in natural product synthesis will be presented.

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Oxidation of nitroxyl radicals by xenon difluoride

Cited by 3 publications

References 3 publications

Increasing the index of covalent oxygen bonding at nitrogen attached to carbon

Increasing the index of covalent oxygen bonding at nitrogen attached to carbon

Mechanism of autoreduction of 2,2,6,6-tetramethyl-1,4-dioxopiperidinium cation in alkaline medium

Organic Synthesis Using Nitroxides

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