Selenium Dioxide Oxidation of Endocyclic Olefins. Evidence for a Dissociation-Recombination Pathway

Article abstract of DOI:10.1021/jo00136a017

The selenium-catalyzed oxidation of some simple alicyclic olefins with tert-butyl hydroperoxide produced, in addition to the expected allylic alcohols, allylic tert-butyl peroxides and allylic tert-butyl ethers.Unlike the peroxides, the ether products were not inhibited by hydroquinone, and their relative amounts increased with decreasing ring size.Analogous products were detected in minor amounts in the selenium dioxide-tert-butyl hydroperoxide oxidation of β-pinene, with isomer distribution suggestive of a symmetrical intermediate.It is proposed that the etherproducts arise via a dissociation-recombination pathway competitive with the <2,3> sigmatropic shift leading to the alcohol.Examination of the literature suggests that such a pathway may also be significant in selenium dioxide oxidations of small ring compounds in which ring oxidation occurs and may lead to unexpected products in which the double bond has moved from its original position.