Acetone-Oxone system

The acetone-oxone system of Curci can be used for epoxidation of a,p-unsat-urated acids if NaHC03 is present as a buffer to prevent Baeyer-Villiger oxidation of acetone yields are in the range 60-92% (4 examples).2... 

Epoxidation. Oxone decomposes in the presence of a ketone (such as acetone) to form a species, possibly a dioxirane (a), which can epoxidize alkenes in high yield in reactions generally conducted in CH2C12-H20 with a phase-transfer catalyst. An added ketone is not necessary for efficient epoxidation of an unsaturated ketone. The method is particularly useful for preparation of epoxides that are unstable to heat or acids and bases.3 The acetone-Oxone system is comparable to m-chloroperbenzoic acid in the stereoselectivity of epoxidation of allylic alcohols. It is also similar to the peracid in preferential attack of the double bond in geraniol (dienol) that is further removed from the hydroxyl group.4... 

Arene oxides. The acetone-oxone system (11, 442) converts several polycyelic aromatic hydrocarbons into the K-region oxide, often in synthetically useful yield. Thus the 9,10-oxide of phenanthrene is formed with this system in 60% yield. 

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. ... 

Dioxirane chemistry is well documented . Extensive kinetic, stereochemical and 0-labeling data suggested that dimethyldioxirane is the oxygen-atom transfer reagent in the Oxone-acetone system . Murray and Jeyaraman have shown that dialkyl dioxiranes can be isolated by low-temperature distillation from the reaction mixture of oxone and ketone . 

There are other oxidants reported. The combination of m-CPBA and N-me thy I-morpholine-N-oxide is an effective anhydrous oxidant system for enantioselective oxidation with Mn(salen) compounds [224,225]. Dimethyldioxirane is prepared by the reaction of Oxone (potassium monoperoxysulfate) with acetone [317] and is a member of the smallest cyclic peroxide system. It is an active oxidant for a variety of olefins [318,319]. 

The epoxidation of conjugated double bonds also proceeds smoothly with the Oxone-acetone system, as illustrated by eq 9. The conversion of water-insoluble enones can be accomplished with this method using CH2CI2 as a cosolvent and a quaternary ammonium salt as a phase-transfer catalyst. However, a more convenient procedure utilizes 2-butanone both as a dioxirane precursor and as an immiscible cosolvent (eq 10). No phase-transfer agent is required in this case. 

The Oxone-acetone system has also been employed for the synthesis of simple oxaziridines fromiV-aLkylaldimines (eq 19). Interestingly, the A-phenyl analogs produce the isomeric nitrones rather than the oxaziridines (eq 20). It is noteworthy that MeCN can replace acetone as the solvent in this procedure. 

The Oxone/acetone system is also very effective for the formation of nitroxides from secondary amines without a-hydrogens (eq... 

Nitrogen Compounds. Previous methods for oxidizing anilines to nitro compounds with Oxone/acetone were ineffective with carboxylic acid and alcohol-containing systems. A new method using Oxone and acetone under totally aqueous conditions allows oxidation of carboxylic and alcoholic anilines as well (eq 51). In this case the reaction occurred in the absence of acetone but yields were significantly lower. The combination of Oxone and ozone has been used to oxidize amino sugars to nitro sugars as well (eq 52). ... 

Acylhydrazides are oxidized to iV,V -diacylhydrazines in high yields with aqueous Oxone (eq 66), although only aromatic hydrazides were effective. The oxidation of alkylcyano-hydrazines to azo-bis nitriles can be carried out with an Oxone/ JCBr system (eq 67). Nitriles can also be hydrolyzed to amides in moderate to good yields with Oxone/acetone (eq 68). ... 

A convenient alternative is to use the aqueous oxone-acetone system, buffering the reaction with NaHCOa [32]. Excellent yields of a,p-epoxyacids are obtained at 24-27°C in 2-3 h. By using oxone in water only at neutral pH, fumaric acid is epoxidized quantitatively but requires a long reaction time [15]. 

High conversion of double bmids in a 1,4-cts-PBD has been achieved using several transition metal catalysts (Ti, V, Cd, Ni, Zn, Mn, and Cu metals imi) and with Oxone/acetone as oxygen source [153]. A full conversion was obtained in the case of CUSO4 or Cu-DABTZ (2,2 -diamino-4,4 -bithiazole) [154]. Methyltrioxor-henium (MTO) was found to be an efficient catalyst in a biphasic system with hydrogen peroxide. Because all of the peroxide adds to double bonds of PBD, the epoxide content can be COTtrolled by the quantity of hydrogen peroxide added [155]. 

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