Alkanes dimethyldioxirane

In general, peroxomonosulfates have fewer uses in organic chemistry than peroxodisulfates. However, the triple salt is used for oxidizing ketones (qv) to dioxiranes (7) (71,72), which in turn are useful oxidants in organic chemistry. Acetone in water is oxidized by triple salt to dimethyldioxirane, which in turn oxidizes alkenes to epoxides, polycycHc aromatic hydrocarbons to oxides and diones, amines to nitro compounds, sulfides to sulfoxides, phosphines to phosphine oxides, and alkanes to alcohols or carbonyl compounds. 

Two new reactive, very powerful organic peroxides, dimethyldioxirane and methyl(trifluoromethyl)dioxirane (4), have been introduced.81-83 The latter is more reactive and can be used more conveniently.84 85 Acyclic alkanes give a mixture of isomeric ketones on oxidation with methyl(trifluoromethyl)dioxirane,84,85 while cyclohexanone is the sole product in the oxidation of cyclohexane (99% selectivity at 98% conversion).85 With the exception of norbomane, which undergoes oxidation at the secondary C-2 position, highly selective tertiary hydroxylations can be carried out with regioselectivities in the same order of magnitude as in oxidations by peracids.85-87 A similar mild and selective tertiary hydroxylation by perfluorodialkyloxaziridines was also reported.88 Oxidation with dioxiranes is highly stereoselective 85... 

The mechanism of oxidation of alkanes with dimethyldioxirane has been examined by measurement of the primary kinetic isotope effect for the oxidation of cyclohexane and methylcyclohexane in solution and in the gas phase. These experiments indicated that the major products (cyclohexanol and methylcyclohexanol) are probably formed via an electrophilic oxygen-insertion reaction while minor by-products may arise from radical reactions.90... 

Deoxygenation of pyridine A-oxides has been achieved using dimethyldioxiran <95CC1831> and palladium with sodium hypophosphite <95GCI(124)385>. Pyridine A-oxides, with ruthenium porphyrin catalysts, have been used as an oxidant of aromatic compounds <95JA(117)8879> or olefins, alcohols, sulfides and alkanes <95FI(40)867>. 

The general features of reactivity and selectivity of this novel oxidant are displayed in Table 3. It is significant that the fluoro derivative, i.e. methyl-(trifluormethyl)dioxirane [6], is at least 1000-fold more reactive than dimethyldioxirane. As a consequence, the fluorinated dioxirane oxidizes alkanes to the corresponding alcohols and/or ketones within minutes even at subambient temperatures [7]. 

A theoretical study on the oxidation of methane, propane and isobutane with dioxirane, dimethyldioxirane, difluorodioxirane and methyl(trifluoromethyl)di-oxirane has provided a rational for the formation of radical intermediales when dioxygen is rigorously excluded and supported the generally accepted, highly exothermic, concerted oxygen insertion mechanism for the oxidation under typical preparative conditions. The activation barriers for the oxidation of methane (44.2), propane (30.3) and isohutane (22.4 kcal mol" ) with dimethyldioxirane have been evaluated [48e]. Perfluorodialkyloxaziridines are also mild and selective reagents for the hydroxylation of alkanes [49] ... 

The oxidation of organic compounds by dioxiranes has attracted considerable interest in recent years. Bravo et al. have reported that the oxidation of a variety of organic compounds (alkanes, alcohols, ethers, aldehydes, and alkenes) by dimethyl-dioxirane may be explained via a radical mechanism. The proposed molecule-induced homolysis of dimethyldioxirane is supported by radical trapping with CBrCls or protonated quinolines. The presence of oxygen has also been shown to have a significant effect on these reactions and supports a radical mechanism. The... 

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