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Oxone® potassium alkenes

Dioxiranes are extremely useful reagents for the epoxidation of alkenes under neutral conditions. Since the oxygen atom transfer to the alkene regenerates the initial ketone, this epoxidation is catalytic. Dioxiranes are easily generated by the action of an oxone (potassium persulfate) on a ketone (usually acetone) either in a biphasic mixture or in a homogeneous aqueous organic solution. [Pg.295]

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. ... [Pg.228]

The epoxidation of nonfunctionalized alkenes may also be effected by chiral dioxiranes. These species, formed in situ using the appropriate ketone and potassium caroate (Oxone), can be formed from C-2 symmetric chiral ketones (29)[93], functionalized carbohydrates (30)[94] or alkaloid derivatives (31)[95]. One example from the laboratories of Shi and co-workers is given in Scheme 19. [Pg.24]

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). [Pg.94]

Potassium 1-alkenyltrifluoroborates permitted alkene epoxidation with oxone or m-CPBA with excellent conversions without cleavage of the G-B bond (Equation (77)).448... [Pg.182]

Amide 266 was also used for the synthesis of 5 (Scheme 37),109 employing syn-epoxidation to afford 284 in 96% yield. Alternatively, alkaline hydrolysis of 266 furnished 281, which could be trichloroacetylated to afford alkene 282. Treatment of 282 with potassium peroxymonosulfate ( oxone ) formed the corresponding syn-epoxide 283 in 60% yield. Epoxide 284 proved resistant to acid but did undergo slow hydrolysis upon using 2 1 H20-TFA to afford in 1 1.6 ratio the desired product 285 (32%) and its isomer 286 (52%), which for further characterization were transformed into the corresponding peracetates 289 (93%) and 290 (90%). Under similar conditions,... [Pg.79]

Dimethyldioxirane (DMDO) is a mild reagent for epoxidation under neutral conditions of electron-rich as well as of electron-deficient alkenes.Moreover, dimethyldioxirane is often the oxidant of choice for the preparation of labile epoxides. The reagent is prepared by oxidation of acetone with potassium caroate KHSO5 (Oxone) and is stable in acetone solution at —20 °C for several days. ... [Pg.164]

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]. [Pg.958]

Oxone (a mixture of potassium sulfate, potassium hydrogensulfate and potassium hydrogen persulfate) is a commercially available oxidant which is generally used in aqueous ethanol. Oxone is highly chemoselective and will cleanly oxidise sulfides containing other functional groups for example, keto, hydroxy and alkenic double bonds are not attacked by this reagent. [Pg.197]

A variety of alkenes undergo azidoiodination with sodium azide, potassium iodide, and Oxone on wet alumina to give azido-iodo compounds regioselectively in high yield (eq 79). These compounds are useful precursors to vinyl azides, amines, and aziridines and are typically synthesized with more expensive and exotic reagents. Similar methods have been used in the iodolac-tonization and iodoetherification of unsaturated carboxylic acids and alcohols to make five- and six-membered lactones, tetrahy-drofurans, and tetrahydropyrans (eq 80). ... [Pg.343]

The most general reagents for conversion of simple alkenes to epoxides are peroxycarboxylic acids. w-Chloroperoxybenzoic acid (MCPBA) is a particularly convenient reagent, but it is not commercially available at the present time. The magnesium salt of monoperoxyphthalic acid has been recommended as a replacement. Potassium hydrogen peroxysulfate, which is sold commercially as oxone, is a convenient reagent for epoxidations that can be done in aqueous methanol. Peroxyacetic acid, peroxybenzoic acid, and peroxytrifluoroacetic acid have also been used frequently for epoxidation. All of the peroxycarboxylic acids are potentially hazardous materials and require appropriate precautions. [Pg.767]


See other pages where Oxone® potassium alkenes is mentioned: [Pg.95]    [Pg.410]    [Pg.245]    [Pg.22]    [Pg.104]    [Pg.1091]    [Pg.767]    [Pg.657]    [Pg.1172]    [Pg.364]    [Pg.292]    [Pg.131]    [Pg.454]    [Pg.824]   
See also in sourсe #XX -- [ Pg.1743 ]




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