Prins cyclization of 1,3-dioxinone: synthesis of 11-epi-badkhysin

Abstract

The asymmetric synthesis of highly functional 11-epi-badkhysin has been accomplished using a structure-unit based approach. Key reactions of the synthesis are a ketone-participated Prins cyclization of 1,3-dioxinone to install the decahydro-4,8-epoxyazulene scaffold, a BBr₃-promoted homoallylenol formation to prepare the common intermediate for sesquiterpenoids, and an alkylation/reduction/lactonization sequence to construct the core 5-7-5 tricyclic ring system bearing the cis-annulated γ-butyrolactone moiety.