The Stereochemistry of Autoxidation of 2-Bromo-1-methylcyclohexane

Autoxidation of cis-2-bromo-1-methylcyclohexane and subsequent reduction of the resulting hydroperoxide with lithium aluminium hydride gave only t-2-bromo-1-methyl-r-1-cyclohexanol to the exclusion of the c-2-bromoisomer. The reactivity ratio of the C–1 hydrogen in cis-2-bromo-1-methylcyclohexane to that in 1, c-3, c-5-trimethylcyclohexane towards abstraction was estimated to be about 4 by competitive oxidation experiments. An explanation for the acceleration of hydrogen abstraction and the stereospecific oxygen attack on the intermediate radical is given in terms of a bromine bridged radical. Autoxidation of a sample of 2-bromo-1-methylcyclohexane, containing about 90% of the trans isomer, took place very slowly as compared with the cis isomer.