Alkenes, hydroxylation

Alkene hydroxylation does not involve a carbocation intermediate but instead occurs through an intermediate cyclic osmate, which is thought to be formed in a single step by addition of OsO to the alkene. This cyclic osmate is then cleaved in a second, separate step using aqueous sodium bisulfite, NaHSOa-... 

Diols are oxidatively cleaved by reaction with periodic acid (HIO4) to yield carbonyl compounds, a reaction similar to the KMnO cleavage of aJkenes just discussed. The sequence of (1) alkene hydroxylation with OsO< j followed by (2) diol cleavage with HIO4 is often an excellent alternative to direct alkene cleavage with ozone or potassium permanganate. 

Oxidation of Alkenes Hydroxylation and Cleavage 252 Biological Alkene Addition Reactions 255... 

B.6.2.2 Alkenes Hydroxyl and nitrate radicals as well as ozone can react with alkenes. Although hydrogen abstraction is possible with the two radicals, addition to the double bond is the preferred reaction ... 

Two kinds of systems based on Fe(III) or Mn(III) porphyrins are available now for the oxidation of hydrocarbons. The first ones involve such a metalloporphyrin catalyst and an oxygen atom donor like PhIO, H2O2 or O2 and a reducing agent 2-10 They reproduce quite well the reactions catalyzed by cytochrome P450-dependent monooxygenases and involve a high-valent metal-oxo active species which is able to epoxidize alkenes, hydroxylate alkanes and aromatic compounds and perform N- or S- oxidations. 

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