Ketones, unsaturated with peroxy acids

In contrast to the stereospecific epoxidation of acyclic alkenes with peroxy acids, oxidation of acyclic a,(3-unsaturated ketones with alkaline hydrogen peroxide is stereoselective in that only one stereoisomer is formed from cis- and trans-enones ... 

Reaction of <%,/ -unsaturated ketones with peroxy acids does not usually lead to peroxides instead, rearrangements follow attack of the peroxy acid on the carbon group.41,42... 

The diminished rr electron density m the double bond makes a p unsaturated aide hydes and ketones less reactive than alkenes toward electrophilic addition Electrophilic reagents—bromine and peroxy acids for example—react more slowly with the carbon-carbon double bond of a p unsaturated carbonyl compounds than with simple alkenes... 

Selenoxides are useful intermediates in the preparation of a,3-unsat-urated carbonyl compounds and esters. The treatment of aldehydes, ketones, or esters with benzeneselenyl chloride, C6H5SeCl, followed by the oxidation of the selenides to selenoxides by hydrogen peroxide, peroxy acids, or sodium periodate, gives a,3-unsaturated aldehydes, ketones, or esters. Thus, dehydrogenation with the formation of a carbon-carbon double bond is accomplished under very mild conditions [167, 169] (equation 593). 

Peroxy adds may epoxidize unsaturated ketones [299, 332], but a concomitant Baeyer-Villiger reaction is possible [254] (equations 389 and 391). Other ways of forming epoxy ketones are reactions with salts of hypochloric acid [691, 704] and with V-bromosuccinimide [746]. Mesityl oxide is converted into its epoxide, as shown in equation 437 [142, 220, 254, 746]. 

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