Electrophilic 1,2-Addition of Oxoammonium Salts to Olefins

Takata, Toshikazu; Tsujino, Yasunori; Nakanishi, Saburo; Nakamura, Kazuaki; Yoshida, Eri; Endō, Takeshi

doi:10.1246/cl.1999.937

Cited by 40 publications

(25 citation statements)

References 13 publications

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“…In particular, such secondary reactions may potentially generate the same diamagnetic addition products as the direct reaction of the nitroxide radical with a protein radical, which would lead to incorrect assignments of the protein-based radicals. That oxoammonium species can indeed generate stable addition products has been shown for electron-rich olefin systems such as vinyl ethers and enamines where an adduct was detected by mass spectrometry (11). …”

Section: Introductionmentioning

confidence: 87%

Spin Scavenging Analysis of Myoglobin Protein-Centered Radicals Using Stable Nitroxide Radicals: Characterization of Oxoammonium Cation-Induced Modifications

Lardinois

Maltby

Medzihradszky

et al. 2009

Chem. Res. Toxicol.

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Spin scavenging combined with chromatographic and mass spectrometric procedures can, in principle, be employed to detect and identify protein-based radicals within complex biological matrices. This approach is based on the well-known ability of stable synthetic nitroxide radicals to scavenge carbon-centered radicals, forming stable diamagnetic addition products. Hence, characterization of these addition products would allow for the identification of specific free radicals. In the present work, we have explored the use of the stable nitroxide radical 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL) in scavenging protein-based radicals generated in a horse heart metmyoglobin/hydrogen peroxide (metMb/H2O2) system. Inclusion of a substoichiometric amount of TEMPOL in the metMb/H2O2 system resulted in a complete loss of peroxyl and tyrosyl radical signals and effectively inhibited the formation of oxidatively-damaged heme species, as monitored by electron paramagnetic resonance and reverse-phase liquid chromatography. Scavenging of globin radicals by TEMPOL did not lead to the formation of stable diamagnetic addition adducts; in fact, reverse-phase liquid chromatographic studies and oxygen electrode measurements indicated that TEMPOL acts as a catalyst and is recycled in this system. The oxoammonium cation generated in the course of this reaction initiated secondary reactions resulting in the formation of a free carbonyl on the N-terminal Gly-residue of the protein. This oxidative deamination was confirmed through the combined use of reverse-phase liquid chromatographic purification, tandem MS experiments and chemical analysis (e.g. by use of 2,4-dinitrophenyl hydrazine). The results reveal the pitfalls inherent in using stable nitroxide radicals such as TEMPOL to identify sites of radical formation on hemoproteins.

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Section: Introductionmentioning

confidence: 87%

Spin Scavenging Analysis of Myoglobin Protein-Centered Radicals Using Stable Nitroxide Radicals: Characterization of Oxoammonium Cation-Induced Modifications

Lardinois

Maltby

Medzihradszky

et al. 2009

Chem. Res. Toxicol.

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“…[123b] Electron-rich enol ethers and enamides were also reported to undergo oxidative coupling with TEMPO-derived oxoammonium salts. [124] It is even possible to convert trisubstituted olefins into alkoxyamines by using oxoammonium salts. [125] Reactions occurred at room temperature and an ene-type mechanism was suggested for these transformations.…”

Section: Oxidation Of Enolates and Of Electron-rich Olefins Withmentioning

confidence: 99%

Nitroxides: Applications in Synthesis and in Polymer Chemistry

2011

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This Review describes the application of nitroxides to synthesis and polymer chemistry. The synthesis and physical properties of nitroxides are discussed first. The largest section focuses on their application as stoichiometric and catalytic oxidants in organic synthesis. The oxidation of alcohols and carbanions, as well as oxidative C-C bond-forming reactions are presented along with other typical oxidative transformations. A section is also dedicated to the extensive use of nitroxides as trapping reagents for C-centered radicals in radical chemistry. Alkoxyamines derived from nitroxides are shown to be highly useful precursors of C-centered radicals in synthesis and also in polymer chemistry. The last section discusses the basics of nitroxide-mediated radical polymerization (NMP) and also highlights new developments in the synthesis of complex polymer architectures.

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“…108. 51 When a nucleophile such as chloride is present, the reaction is a simple double bond addition. The chloride intermediate must be converted into the acetal before isolation.…”

Section: Rearrangement and Oxidation Of Tertiary Allylic Alcoholsmentioning

confidence: 99%

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

2009

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The discovery in 1959 of stable nitroxide‐based free radicals such as the prototypical 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) led to their use as electron spin resonance (ESR) spin labels in chemistry, biomedicine, and materials science. These nitroxides are prepared by the oxidation of secondary amines that contain no hydrogen atoms on the alpha‐carbons. The unique redox properties of nitroxides enable their use as oxidants in organic synthesis. The varied preparation and uses of oxoammonium salts as stoichiometric oxidants for alcohols are one subject of this review. Oxoammonium ions as oxidants for alcohols have a number of advantages, for example, the method is heavy‐metal free and some of the reactions can be performed in water or aqueous mixtures. A few side reactions are associated with these oxidations. The most serious is the fast reaction of the oxoammonium ion with free amines The several ways these oxidation reactions can be carried out are discussed in detail. They are: Oxidations using stoichimetric quantities of preformed oxoammonium salts carried out in either acidic, neutral, or basic conditions; reactions in which stoichiometric quantities of oxoammonium salts are generated in situ by disproportionation of a nitroxide in the presence of a strong acid; nitroxide‐catalyzed oxidations using a secondary oxidant; efficient nitroxide‐catalyzed oxidations of primary alcohols to carboxylic acids; and oxidations of primary alcohols or hemiacetals that can lead to lactones.

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Electrophilic 1,2-Addition of Oxoammonium Salts to Olefins

Cited by 40 publications

References 13 publications

Spin Scavenging Analysis of Myoglobin Protein-Centered Radicals Using Stable Nitroxide Radicals: Characterization of Oxoammonium Cation-Induced Modifications

Spin Scavenging Analysis of Myoglobin Protein-Centered Radicals Using Stable Nitroxide Radicals: Characterization of Oxoammonium Cation-Induced Modifications

Nitroxides: Applications in Synthesis and in Polymer Chemistry

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

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