Mechanism, hydroperoxides diols

Epoxidation and Dihydroxylation of Alkenes There are several ways to convert alkenes to diols. Some of these methods proceed by syn addition, but others lead to anti addition. An important example of syn addition is osmium tetroxide-catalyzed dihydroxylation. This reaction is best carried out using a catalytic amount of OSO4, under conditions where it is reoxidized by a stoichiometric oxidant. Currently, the most common oxidants are f-butyl hydroperoxide, potassium ferricyanide, or an amine oxide. The two oxygens are added from the same side of the double bond. The key step in the reaction mechanism is a [3 + 2] cycloaddition that ensures the syn addition. 

Jerneren F, Garscha U, Hoffmann I, Hamberg M, Oliw EH (2010) Reaction mechanism of 5,8-lino-leate diol synthase, lOR-dioxygenase, and 8,11-hydroperoxide isomerase of Aspergillus clavatus. Biochim Biophys Acta 1801 503-507... 

Homologous oxidation products of certain olefins have been isolated this evidence indicates that at least two routes of attack on the olefin molecule are possible. Bruyn (1954) isolated n-hexadecanediol-1,2 as a product of n-hexadecene-1 oxidation by the yeast Candida lipolytica. The primary attack in this case is at the double bond. Isotopic oxygen experiments with this system have not been reported. It may be surmized that the diol oxygen originates from O. The second route of olefin oxidation occurs on the terminal methyl carbon of the saturated end of the molecule, catalyzed by the ester bacterium of Stewart et al. (1960). Terminal hydroperoxide formation similar to that occurring during alkane oxidation undoubtedly occurs here since the double bond remains intact and appears in the alcohol moiety of the final ester product. It is too early to say if the above two mechanisms are characteristic of yeasts and bacteria, respectively. (See the Addendum.)... 

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