Potassium peroxymonosulfate, dioxirane

Potassium ozonide, 735 Potassium permanganate chemiluminescence, 643 hydrogen peroxide titration, 627 ozonide redox titration, 736 Potassium peroxymonosulfate, dioxirane preparation, 26, 1020-30, 1130 Potassium superoxide, commercial availability, 620... 

Several other oxidizing agents can be made from hydrogen peroxide and thus be derived indirectly from oxygen. These include sodium perborate, sodium percarbonate, urea peroxide, peracids, potassium peroxymonosulfate, amine oxides, dioxiranes, and iodosobenzene (4.24). 

Dioxiranes are good selective oxidants. Some /3-diketones have been oxidized to alcohols (4.56) in 95% or higher yield.269 The dioxiranes are made and used in solution. The nickel catalyst speeds up reaction 4.56. Hydrocarbons can be functionalized (4.57) in up to 92% yield in this way.270 A dioxirane phase-transfer catalyst, produced in situ with potassium peroxymonosulfate, has been used epoxidize an olefin to an epoxide (4.58) in up to 92% yield.271... 

Dioxiranes for alkene epoxidation may be prepared in situ from a catalytic amount of a ketone and Oxone (potassium peroxymonosulfate triple salt). )V,)V-Dimethyl-and A, A -dibenzylalloxans (20a) and (20b) (Figure 3) have been prepared and used as novel dioxirane catalysts for the epoxidation of a range of di- and tri-substituted alkenes in good to excellent yield. H2O2 (rather than the usual Oxone) has been successfully used as primary oxidant in asymmetric epoxidations with Shi s fructose-derived ketone (21) in acetonitrile. The ketone is converted into the dioxirane, which is responsible for epoxidation and the active oxidant responsible for dioxirane formation is proposed to be peroxyimidic acid formed by combination of H2O2 with acetonitrile. ... 

Epoxides are very versatile intermediates, and asymmetric epoxidation of olefins is an effective approach to the synthesis of enantiomericaUy enriched epoxides [1-3]. Great success has been achieved for the epoxidation of allyhc alcohols [1], the metal-catalyzed epoxidation of unfunctionalized olefins (particularly conjugated cis- and tri-substituted) [2], and the nucleophilic epoxidation of electron-deficient olefins [3]. In recent years, chiral dioxiranes have been shown to be powerful agents for asymmetric epoxidation of olefins. Dioxiranes can be isolated or generated in situ from Oxone (potassium peroxymonosulfate) and ketones (Scheme 3.1) [4,5]. When the di-oxirane is used in situ, the corresponding ketone is regenerated upon epoxidation. Therefore, in principle, a catalytic amount of ketone can be used. When a chiral ketone is used, asymmetric epoxidation should also be possible [6]. Extensive studies have been carried out in this area since the first chiral ketone was reported by Curd in 1984 [7]. This chapter describes some of the recent progress in this area. 

As close analogues of potassium peroxymonosulfate, arenesulfonic peracids generated from (arenesulfonyl)imida-zole-H202-NaOH have also been shown to react with acetone and trifluoroace-tone to generate dioxiranes as illustrated by 0-labeling experiments see ... 

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