Research into the oxidation of abietic acid–derived enone with atmospheric oxygen

This work presents results of methyl 7‐oxoabiet‐13(14)‐en‐18‐oate ( 3 ) self‐oxidation with air‐oxygen in the presence of various bases such as triethylamine or sodium t ‐butoxide. While under aerobic conditions, the use of sodium t ‐butoxide as a base results in the formation of four isomeric alcohols, an addition of triethylamine into reaction medium directs the enone 3 oxidation to hydroperoxides. To clarify this base dependence and to obtain more in‐depth information about this reaction additional studies with cyclohexenone as a reference enone have been undertaken. Their results demonstrated the predisposition of abietane hydroperoxides to oxidize α,β‐unsaturated ketones to epoxides in the presence of t ‐butoxide while reducing the hydroperoxide group to hydroxyl. This ability of hydroperoxides to epoxidize conjugated double bonds and confirmed by the present study intermolecular course allowed proposing a plausible mechanism for this reaction.