Synthesis of cycloocta-3,5-dien-1-ol and cycloocta-3,5-dien-1-one: SeO₂/O₂ oxidation of dienes

A useful synthesis of cycloocta-3,5-dien-1-ol was developed starting from cycloocta-1,3-diene. Oxidation of the diene with selenium oxide in refluxing acetic anhydride affords the homoallylic and allylic acetates in a 19:1 ratio and a 36% overall yield when O₂ is bubbled through the reaction mixture. Subsequent reduction with LAH affords the homoallylic alcohol (95%), which can be readily oxidized via TPAP/N-MMO (73%) to the corresponding non-conjugated dienone. This route represents the most efficient method for the preparation of cycloocta-3,5-dien-1-ol and cycloocta-3,5-dien-1-one reported to date, and may provide a general approach to the synthesis of homoallylic alcohols and non-conjugated enones.