Peroxy-derivatives

Pentafluorobenzaldehyde is analogously oxidized to hydroperoxy and peroxy derivatives with yields of 82 6 and 96%, respectively [69]... 

Thus, radicals are the most reactive and destructive of protein structure, followed by peroxy derivatives, singlet oxygen, and other oxygen compounds. The oxidative reactivity of some of these oxygen species is so high that just contact of the pure compound with paper or cotton fabrics can cause combustion (e.g., superoxide). 

Autoxidation of secondary acetonitriles under phase-transfer catalytic conditions [2] avoids the use of hazardous and/or expensive materials required for the classical conversion of the nitriles into ketones. In the course of C-alkylation of secondary acetonitriles (see Chapter 6), it had been noted that oxidative cleavage of the nitrile group frequently occurred (Scheme 10.7) [3]. In both cases, oxidation of the anionic intermediate presumably proceeds via the peroxy derivative with the extrusion of the cyanate ion [2], Advantage of the direct oxidation reaction has been made in the synthesis of aryl ketones [3], particularly of benzoylheteroarenes. The cyanomethylheteroarenes, obtained by a photochemically induced reaction of halo-heteroarenes with phenylacetonitrile, are oxidized by air under the basic conditions. Oxidative coupling of bromoacetonitriles under basic catalytic conditions has been also observed (see Chapter 6). 

Certain classes of organic compounds containing oxygen atoms, such as aldehydes and ethers, may react with oxygen to form peroxy derivatives ... 

Some unstable peroxy esters are also reported. The reaction of pentaphenylphosphine with tert-butylhydroperoxide or silicon and germanium hydroperoxides gave the corresponding peroxy derivatives 56, which cannot be isolated (equation 91). 

Peroxy derivatives of steroids have been isolated from both marine and terrestrial sources. They are most commonly 5a, 8a-endoperoxides with variations in the side-chains. The ergosterol peroxide 102 is the most ubiquitous endoperoxide-containing natural product and is isolated from a large number of sources. Ergosterol peroxide 102 was found to have antitumour activity against breast cancer and carcinosarcoma cell lines. A number of other steroidal endoperoxides have been reported which differ in the nature of the side-chain. Compound 103 was found to be an inhibitor of tumour promotion in mouse studies . 

Trialkyl derivatives of boron, and in fact many other molecules such as boroxines with carbon-boron bonds, react readily with oxygen. The initial products are peroxy derivatives with BOOR bonds, which tend to react further to form borate esters. The ease of the initial reaction is shown by the fact that reported examples of vinyl polymerization induced by trialkyl borons require oxygen and are actually radical processes induced by the boron oxygen reaction or intermediate peroxides (7). 

Despite the limited information about the coordination environment of the metal center, a mechanism for the a-keto acid-dependent enzymes has been proposed (Figure 27) [222] in which the a-keto acid binds to the iron center and primes it for 02 binding. Attack of the bound 02 on the coordinated a-keto acid at the C-2 position results in decarboxylation of the a-keto acid to give an Fe(II)-peroxy derivative that can react with substrate either directly or via a high-valent iron-oxo intermediate to give the oxygenated substrate, a carboxylic acid, and the starting Fe(II) enzyme. 

Thus, oxygen attack at the terminal 5,6-double bond position, followed by the formation of a peroxy epoxide and cleavage of the C-C and 0-0 bonds, resulted in 5,6-epoxy-B-ionone, while rearrangement of the 5,6-epoxy derivative, followed by reduction and oxidation, resulted in the formation of dihydroactinidiolide. Furthermore, a peroxy derivative was formed and cleaved to form 8-ionone, which then led to the formation of dihydroactinidiolide as a secondary oxidation product. 

Another silylated alkyne unexpectedly afforded an alkynyl peroxy derivative of o-iodosylbenzoic acid [8]. Generally, several cyclic and non-cyclic derivatives of the acid are known, some of which are shown below ... 

The exact nature of the tanning reaction is not known and a number of mechanisms have been proposed. It has been shown, however, that as the process progresses, the degree of unsaturation of the oil reduces, peroxy-derivatives are formed, hydroxyl functions appear and, more specifically, acrolein, CH2=CH CHO, is produced. It is thought that this and other aldehyde compounds are responsible for the chemical cross-linking and that coating the fibres with polymerised oils imparts the special physical characteristics to the leather. 

Reactions of Imidazoles. The action of sodamide on the chloro(ethynyl)-imidazole (413 R = Cl, = H) results in the formation of the isomer (413 R = H, R = Cl) similar transhalogenations have been observed for chloro(ethynyl)-pyrazoles and -1,2,4-triazoles. The imidazolium salt (414) undergoes base-induced ring-expansion to the pyrazine derivative (415). 2,4,5-Tribromo-l-methylimidazole reacts with xenon difluoride to give the imidazolidinetrione (416). Low-temperature H n.m.r. studies of the sensitized photo-oxygenation of imidazoles (417 R, R, R = H or Me) give direct evidence for the formation of unstable enr/o-peroxides (418) 2-methyl-4,5-diphenylimidazole yields the peroxy-derivative (419) in this reaction.Irradiation of the N-oxide (420) produces the diamine (422) by way of the oxaziridine (421)."" ... 

Recently some related peroxy derivatives have been obtained 344). 

The most widely used room-temperature curing agents of unsaturated polyesters are the peroxy derivatives of methyl ethyl ketone, that is, methyl ethyl ketone peroxide (MEK peroxide). These are generally available as 60 percent solutions containing 11 percent active oxygen. The major producers of ketone peroxides offer standard types, which differ in their reactivity. This provides the processor with the ability to select a curing agent for their particular requirements. 

The friction of the polymer surface induces not only changes in their superficial layer, but, as result of mechano-destruction, it is accompanied by the elimination of some low molecular weight compounds, such as monomers, peroxy derivatives, etc. The particularities of this process are mainly related to the polymer and environmental medium nature [982],... 

EPR spectra of purple enzyme solutions, formed by addition of saturating amounts of substrates or product to the enzyme, have indicated the existence of fatty acid alkyl and peroxy radicals that are bound to the enzyme and may be intermediates of the catalytic reaction [328]. Recently, the alkyl radical has been characterized as an allyl radical delocalyzed over C9 through Cll of linoleic acid, and the peroxyl radical as a 9-peroxy derivative of linoleic acid [329]. Based on these results, a mechanism involving both of ally radical and Fe -allylic hydroperoxide complex has been proposed as shown in Scheme 17. 

Lxitnjnculia Peroxy derivatives, terpenes, macrolactones, cyclic depsipeptides, heterocycles... 

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