Oxepanes from an unusual acetal cleavage of 6,8-dioxabicyclo[3.2.1]octanes

Article abstract of DOI:10.1016/0040-4039(95)02167-1

On treatment with BF₃ · OEt₂ and TMSCN, epoxy ketone 1 cyclized to the bicyclic acetal 2, which then cleaved to give primarily the oxepane 5 as a single stereoisomer. Reductive decyanation of 5 led to the oxepane 7, a structural unit present in the brevetoxin family of natural products. The scope and limitations of this reaction sequence were investigated.