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

Abstract

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.