Stereoselectivity in the Fe(II)/Cu(II)-mediated Homolytic Decomposition of the cis- and trans-Isomers of Pinane Hydroperoxide

The outcome of the FeSO4/CuSO4-mediated homolytic decomposition of 2,6,6-trimethylbicyclo[3.1.1]heptane-2-hydroperoxide (pinane hydroperoxide, PHP) was found to be markedly dependent on its stereochemical configuration. The cis-isomer gave exclusively 1-(2,2-dimethyl-3-vinylcyclobut-1-yl)ethanone via beta-scission of the intermediate alkoxy radical followed by oxidation of the ensuing alkyl radical by CuSO4. In contrast, trans-PHP afforded the tricyclic ether 1,4-dimethyl-3-oxatricyclo[5.2.0.0 4,9]nonane, via intramolecular hydrogen abstraction and CuSO4 oxidation of the resulting alkyl radical, as the major product.