Epoxidation Potassium peroxomonosulfate

Among many other methods for epoxidation of disubstituted E-alkenes, chiral dioxiranes generated in situ from potassium peroxomonosulfate and chiral ketones have appeared to be one of the most efficient. Recently, Wang et /. 2J reported a highly enantioselective epoxidation for disubstituted E-alkenes and trisubstituted alkenes using a d- or L-fructose derived ketone as catalyst and oxone as oxidant (Figure 6.3). 

Chiral ketone-catalyzed asymmetric epoxidation has received intensive interest since the first reported by Curci et al. in 1984. The reaction is performed with oxone (potassium peroxomonosulfate) as the primary oxidant which generates the chiral dioxirane catalytic species in situ, which in turn, transfers the oxygen... 

Epoxides (see also a,(3-Epoxy alcohols, etc., Glycidic acids, esters, nitriles) From alkenes by epoxidation Dimethyldioxirane, 120 Fluorine-Acetonitrile, 135 Potassium peroxomonosulfate, 259 From carbonyl compounds Alumina, 14... 

EPOXIDATION Bromomethyllithium. Chloro-methyllithium. Hydro] en peroxide-So-dium tungstate. Peroxytrichloroacetimidic acid. Potassium o-nitrpbenzeneperoxysul-fonate. Potassium perOxomonosulfate. Potassium superoxide. 

Potassium peroxomonosulfate (Oxone ) is also an effective oxidizing agent for the epoxidation of various alkenes in the presence of Mn porphyrin and a PT catalyst [79]. The biphasic epoxidation of various olefins is readily catalyzed by Co and Ni" phthalocyanines with NaClO as the oxygen donor and Bu4N" Br" as the PT agent [80]. The PTC oxidation of alkenes with NaClO is also catalyzed by square-planar Ni complexes [81-83]. 

Curd, R., Fiorentino, M., Serio, M. R. Asymmetric epoxidation of unfunctionalized alkenes by dioxirane intermediates generated from potassium peroxomonosulfate and chiral ketones. J. Chem. Soc., Chem. Common. 1984,155-156. 

Shi and co-workers <97JOC2328, 97JA11224> have optimized their chiral dioxirane protocol for the asymmetric epoxidation of non-functionalized rra/i.v-olefins (e.g., 44), such that the chiral ketone 42 can be used in catalytic quantities with potassium peroxomonosulfate (Oxone) as the stoichiometric oxidant. The key to preserving the lifetime of the chiral auxiliary is pH control during the reaction the optimum range was found to be 10.5 or above, which is conveniently maintained with potassium carbonate. 

An epoxidizing agent that has found widespread use is dimethyl dioxirane (DMDO). The reagent is generated from acetone and Oxone , a source of potassium peroxomonosulfate (KHSO5) (5.50). Epoxidation with DMDO occurs under mild, neutral conditions, without any nucleophilic component, which is ideal for preparing sensitive epoxides. For example, the enol ether 41 was epoxidized selectively using DMDO (5.51). ... 

The methodology described above allows the asymmetric epoxidation of allylic alcohols or cis-substituted conjugated alkenes and the resolution of terminal epoxides. The asymmetric synthesis of trans-di- and trisubstituted epoxides can be achieved with the dioxirane formed from the fructose-derived ketone 64, developed by Shi and co-workers. The oxidizing agent potassium peroxomonosulfate... 

Lie Ken lie, M.S.F., and M.K. Pasha, Epoxidation Reactions of Unsaturated Fatty Esters with Potassium Peroxomonosulfate, Lipids 33 633-637 (1998). 

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