Epoxidations with Oxone

To mimic the square-pyramidal coordination of iron bleomycin, a series of iron (Il)complexes with pyridine-containing macrocycles 4 was synthesized and used for the epoxidation of alkenes with H2O2 (Scheme 4) [35]. These macrocycles bear an aminopropyl pendant arm and in presence of poorly coordinating acids like triflic acid a reversible dissociation of the arm is possible and the catalytic active species is formed. These complexes perform well in alkene epoxidations (66-89% yield with 90-98% selectivity in 5 min at room temperature). Furthermore, recyclable terpyridines 5 lead to highly active Fe -complexes, which show good to excellent results (up to 96% yield) for the epoxidation with oxone at room temperature (Scheme 4) [36]. 

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

Denmark and Wu used 0-labeled ketone 81 in their studies of epoxidation of 1-phenylcyclohexene, yielding the conclusion that dioxiranes are the reactive oxidants in monophasic epoxidations with Oxone <1997JOC8964>. 

Scheme 23 (a) The Tp Cu-catalyzed styrene epoxidation with oxone. (b) The catalytic... 

Scheme 14 Epoxidation with oxone and a supported Cu catalyst...

The synthetic route of sulfite-linked cycloaliphatic epoxy resin is presented in Figure 8.13 [38]. The synthesis of intermediate is achieved via the nucleophilic substitution reaction of thionyl chloride with cyclohex-3-enyl-1-methanol. Subsequently, Epo-S is obtained by epoxidation with OXONE oxidant. Epo-S is liquid at room temperature which is favorable for the underfilling encapsulation for high-density electronic packaging technologies such as flip chip plastic ball grid array (FC-PBGA) and MCM. 

Oxone, K2C03 Shi s asymmetric epoxidation with ketone 1. 

Epoxidation of cyclooctene and other alkenes with Oxone (KHSO5) was promoted effectively in an aqueous micellar solution of an amphiphilic ketone (3.3).52 The amphiphilic ketone can be easily derived from hepta(ethylene glycol) monodecyl ether. 

Wang and Shi have published a detailed study of their fructose-based dioxirane epoxidation catalyst system with hydroxyalkene substrates. The ees obtained were highly pH dependent. The lower enantioselectivity obtained at low pH is attributed to the substantial contribution of direct epoxidation by Oxone. The results obtained with... 

Asymmetric epoxidation of olefins is an effective approach for the synthesis of enan-tiomerically enriched epoxides. A variety of efficient methods have been developed [1, 2], including Sharpless epoxidation of allylic alcohols [3, 4], metal-catalyzed epoxidation of unfunctionalized olefins [5-10], and nucleophilic epoxidation of electron-deficient olefins [11-14], Dioxiranes and oxazirdinium salts have been proven to be effective oxidation reagents [15-21], Chiral dioxiranes [22-28] and oxaziridinium salts [19] generated in situ with Oxone from ketones and iminium salts, respectively, have been extensively investigated in numerous laboratories and have been shown to be useful toward the asymmetric epoxidation of alkenes. In these epoxidation reactions, only a catalytic amount of ketone or iminium salt is required since they are regenerated upon epoxidation of alkenes (Scheme 1). 

In 2001, Yang and coworkers studied the use of in situ generated acyclic iminium salts as epoxidation catalysts [159]. Epoxidations of a number of aUcenes proceed with 20-50 mol% of amine 85 and aldehyde 86 with Oxone as the primary oxidant (Fig. 28.) Methylstilbene can be obtained in 100% conversion and 59% ee. 

Several efficient procedures for alkene epoxidation using Oxone were reported, such as Oxone/aqueous NaOH, Oxone/acetone, Oxone/water , Oxone/PTC/benzene/ aqueous buffer solution or Oxone/2-butanone system. Thus, sorbic acid can be regioselectively oxidized using Oxone/aqueous NaOH to 4,5-epoxy-2-hexenoic acid in 84% yield. Similarly, cyclooctene is oxidized to cyclooctene oxide in 81% yield, just by stirring it with Oxone in water . 1-Dodecene is epoxidized in good yield by Oxone/PTC in benzene aqueous buffer solution. It is otherwise difficult to epoxidize 1-dodecene by other oxidizing reagents. ... 

Recently, Crousse and coworkers reported that new fluoro ketones serve as efficient catalysts for the epoxidation reactions with Oxone in hexafluoropropan-2-ol (HFIP) (equation 46). ... 

Previously, some fluorocyclohexanones were used in a catalytic amount with Oxone for asymmetric epoxidation reaction, but they gave a poor ee . It was found later that chiral ketones derived from fructose work well as asymmetric epoxidation catalysts and show high enantioselectivity in reactions of /rani-disubstituted and trisubsti-tuted olefins ". Cis and terminal olefins show low ee under these reaction conditions. Interestingly, the catalytic efficiency was enhanced dramatically upon raising the pH. Another asymmetric epoxidation was also reported using Oxone with keto bile acids. ... 

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... 

Recently, oxaziridinium salts derived in situ from chiral iminium salts (1 and 2) and Oxone were found to catalyze epoxidation with moderate-to-good enantioselectivity (up to 73% ee) (Scheme 6B.4) [6], Although the substrates are limited to conjugated olefins, this reaction has an advantage in being catalytic with respect to chiral iminium salts. 

A series of dihydoisoquinolium salts (3) based on a dioxane-containing structure have been synthesized and used in the asymmetric epoxidation of alkenes with Oxone... 

Homologous biphenyl and binaphthyl tertiary azepines (4) and quaternary iminium salts, prepared from (+)-(5,5 )-L-acetonamine, behave as effective catalysts for the enantioselective epoxidation of unfunctionalized alkenes with Oxone (ee up to 83%).113... 

Another immobilized system was recently reported by Wei and Liu [64] using amphiphilic coblock polymers consistent of ethylene glycol and methyl acrylate monomers that had been functionalized with imidazole groups. In combination with oxone (KHS05) as the oxidant in an ethyl acetate/water mixture, this system yields the 1,2-diol product in 62% yield, which is probably formed by ring opening of the epoxide by the acidic oxone. 

A number of new oxaziridinium epoxidation reagents have been reported. A new axially chiral epoxidation catalyst 4 has been reported <070BC501>. These catalysts, as are others, are converted to an oxaziridinium with Oxone, which then epoxidizes the olefin. This study examined several chiral groups on the nitrogen as well as both atropisomers. The (S,F)-isomer 4 provided the (1R,2R) epoxide with moderate enantioselectivity and 82% conversion. The (.V,A/)-isomcr of 4 provided the (lS,2S)-epoxide in slightly lower enantiomeric excess (76%) and lower conversion as well. 

The heterocyclic hemi-aminal 44 was formed as a model for the synthesis of the marine alkaloids zoanthamine and zoanthenol and is derived from the cyclic imine formed by the reduction of an appropriated substituted azide <07H(72)213>. A pyrrolidine-fused azepine has been isolated from the venom of the ant Myrmicaria melanogaster and assigned as 45 based upon GC and FT-IR comparison with synthetic material <07JNP160>. The axially chiral doubly bridged biphenyl azepine 46 has been synthesised and used with oxone as an epoxidation catalyst in a biphasic system <070BC501>. 

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