Nitro compounds by oxidation

SYNTHESIS OF NITRO COMPOUNDS BY OXIDATION 2.2.1 Oxidation of Amines... 

In a typical reaction, w-butylamine (0.052 g, 0.7 mmol) in 5 ml of acetone is treated with 95 ml of dimethyldioxirane in acetone solution (0.05 M). The solution is kept at room temperature for 30 min with the exclusion of light (Eq. 2.53). Aromatic amines are converted into nitro compounds by oxidation using OXONE itself.113... 

The reaction of alkenes with dinitrogen tetroxide, following a radical mechanism, generally affords mixtures of 1,2-dinitro compounds, /(-nitro nitrites and jS-nitroso nitro compounds. By oxidation of /(-nitro nitrites with dinitrogen tetroxide itself or oxygen, /(-nitro nitrates are produced11 111. 

Nitrosyl chloride, being a powerful oxidant, affords chloro-nitro-compounds by oxidation at the initial chloro-nitroso stage. frons-Addition of nitrosyl chloride seems to be usual, but an exceptional ds-addition occurred with methyl 3a,7a-diacetoxy-5)3-chol-ll-enoate, giving the lla-chloro-12a-nitro-compound. The rate of reaction was increased in the presence of nitrogen dioxide a free-radical mechanism is thought likely. ... 

Nitro compounds are oxidized at carbon bonded to nitro group 2-nuoronitro compounds and silyl mtronates are converted to 2-fluorocarbonyl compounds by ceric ammonium salt [7l (equation 73)... 

Nitroso compounds are oxidized to nitro compounds by hydrogen peroxide and dinitragen tetroxide [S2] (equation 74)... 

Aiiphadc md aromadc primary amines are rapidly md efficiently oxidized to nitro compounds by dimethyldioxirime. Dimethyldioxirime is prepared by teacdon of OXONE (Du-... 

Dimethyl dioxirane in wet acetone oxidizes isocyanates to nitro compounds (RNCO —> RN02). Oximes can be oxidized to nitro compounds with peroxytri-fluoroacetic acid, or Oxone ," sodiumperborate," among other ways. " Primary and secondary alkyl azides have been converted to nitro compounds by treatment with PhjP followed by ozone. Aromatic nitroso compounds are easily oxidized to nitro compounds by many oxidizing agents. ... 

Aliphatic and aromatic primary amines are rapidly and efficiently oxidized to nitro compounds by dimethyldioxirane.111 Dimethyldioxirane is prepared by reaction of OXONE (DuPont trademark)-2KHS05-KHS04-K2S04 with buffered aqueous acetone.112... 

W. P., Katsuki, S., Kimura, H., Guanylate cyclase activation by azide, nitro compounds, nitric oxide, and hydroxyl radical and inhibition by... 

Nef reaction.4 Nitro compounds, primary or secondary, are converted to tri-alkylsilyl nitronates in greater than 90% yield by reaction with a trialkylsilyl chloride and DBU in CH2C12. The silyl nitronates derived from secondary nitro compounds are oxidized by C1QH4C03H at 25° to ketones in high yield. This sequence is not useful for conversion of primary nitro compounds to aldehydes. 

Secondary nitro compounds are oxidized to the corresponding ketones in moderate yields by a catalytic amount of tetra-n-propylammonium perruthenate in the presence of N-methyImorpholine-A-oxide and a silver salt [46]. Oxidation with a stoichiometric amount of the ammonium perruthenate has also been reported [47]. 

The structure of aristolochic acid II (2) was determined by Pailer and Schlep-pnik in the same way as aristolochic acid I. Decarboxylation of aristolochic acid II gave a nitro compound (62). Oxidation of 62 and cleavage with HCl formed... 

TABLE 13. Base catalyzed oxidation of nitro compounds by BTSP... 

Krohn and coworkers reported that aliphatic and aromatic primary amines are oxidized to the corresponding nitro compounds by reaction with a combination of Zr(OBu-t)4 and The oxidation of a variety of aliphatic primary amines with different... 

These mixtures found no practical application since picric acid gradually reacts with salts to form picrates with the evolution of free acid. The picrates so formed are highly sensitive to friction and impact, and the free acid acts corrosively. Mixtures with chlorates showed a particular sensitiveness to friction and impact, hence doubt was expressed as to their practical value. Nevertheless, the idea of completing the defective oxygen balance in aromatic nitro compounds by the addition of such oxidizing agents as nitrates was carried out in such a way as to produce mixtures useful for various practical purposes. 

Arylhydroxy la mines, whether derived from nitro compounds by reduction or amines by N-hydroxylation, have been shown to be involved in the toxicity of a number of compounds. The possibility of reduction followed by oxidation in a cyclical fashion with the continual production of toxic metabolites has important toxicological implications. 

The present method is the result of a study by Cason, Harman, Goodwin, and Allen.6 7 The sequence of electrolytic reduction followed by oxidation has been used for the preparation of 5-bromotoluquinone,8 5-chlorotoluquinone,9 and 3-chlorotolu-quinone.10 The preparation of an intermediate />-aminophenol from the corresponding aromatic nitro compound by electrolytic reduction is a useful general method.11-18 Chloro-/>-quinone has been prepared by acid dichromate oxidation of chlorohydro-quinone 19-22 or 2-chloro-4-aminophenol.23 24 It has been shown that pure chloro-/>-quinone is obtained only with some difficulty when chlorohydroquinone is used.7... 

Nitrile oxides are often generated by the dehydration of nitro compounds by reagents such as phenyl isocyanate. Azomethine ylides can be generated by the pyrolysis of aziridines or by the prototopic isomerization of imines upon heating. 

Most of the processes relate to the reduction of organic compounds, particularly the reduction of nitro-compounds, but oxidation methods have been utilised successfully, and in many cases substitution products and dye-stuffs have been prepared by electrolytic means. 

Introducing a nitro group by oxidation of a primary amino group. The method of oxidizing a primary amino group to a nitro group is sometimes used commercially. A nitroso compound is an intermediate product of the reaction and it can generally be isolated ... 

The oxidation of nitrobenzene to o- nitrophenol (with traces of the p- isomer) when mixed with dry sodium hydroxide, and slightly heated, may be another example of the oxidation of nitro compounds by nucleophilic substitution (Wohl [46]) ... 

Secondary amines can be oxidized at the N-H bond to hydroxylamines and nitroxides, and via nitrones via C-N oxidation. Nitrones are valuable intermediates in the production of isoxazolines. Initial C-N oxidation of secondary amines gives imines which can react further to oxaziridines. The latter can be converted to nitrones, and both to amides. Primary amines are oxidized at the N-H bond to mono-substituted hydroxylamines, which are readily converted further to nitroso and nitro compounds by the more activated peroxygen... 

Oxidation. The salt effects rapid cleavage of glycols in high yield. It can be used also for the oxidation of secondary nitro compounds to ketones (Nef reaction).- An excess of the guanidine base is used to form the nitronatc, which is then oxidized to the ketone by the salt. Yields are —80-95%, and are higher than those obtained with iodosylbenzene, C HjIO. Oxidation of primary nitro compounds by his method gives only low to moderate yields of aldehydes. 

Aromatic and aliphatic primary amines can be oxidized to the corresponding nitro compounds by peroxy acids and by a number of other reagents. The peroxy acid oxidations probably go by way of intermediate hydroxylamines and nitroso compounds (Scheme 2). Various side reactions can therefore take place, the nature of which depends upon the structure of the starting amine and the reaction conditions. For example, aromatic amines can give azoxy compounds by reaction of nitroso compounds with hy-droxylamine intermediates aliphatic amines can give nitroso dimers or oximes formed by acid-catalyz rearrangement of the intermediate nitrosoalkanes (Scheme 3). 

Nitroso compounds are readily oxidized to the corresponding nitro compounds by peroxides, peroxy acids, oxygen, ozone and dinitrogen tetroxide. ... 

Reactions which formally involve the oxidation of azides have been reviewed by Boyer. Other oxidations with useful synthetic applications include two which start from nitrogen ylides. Sulfimides (50) derived from electron-deficient aromatic and heterocyclic amines are oxidized to the corresponding nitroso compounds by MCPBA. - This is a very useful method of preparation of some otherwise inaccessible nitroso compounds such as 2-nitrosopyridine and 1-nitrosoisoquinoline. They can be further oxidized, for example by ozone, to the nitro compounds. Phosphimides (51) are oxidized directly by ozone to the nitro compounds, although the nitroso compounds are intermediates. Isocyanates can also be oxidized to the corresponding nitro compounds, by dimediyldioxiraiK (1). ... 

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