Selective transformation reaction of 6,8-dioxabicyclo[3.2.1]octane structure to sigma,epsilon-enone and application to the synthesis of Douglas-fir tussock moth pheromone

摘要

Lewis acid induced C-O bond cleavage of a bicyclic ketal compound using AcCl-Nal produced a mixture of sigma,epsilon-enone,allylic acetate and diacetate derivatives via a common 5-membered acetoxonium intermediate.A selective method to the synthesis of sigma,epsilon-enone in high yield was introduced and applied to the synthesis of Douglas-fir tussock moth pheromone.The selective C-O bond cleavage of the 6,8-dioxabicy-clo[3.2.1]octane(1)system using many Lewis acids has been known.The preferable interaction of the O6 toward most Lewis acids followed by the C5-O6 bond cleavage was favored.The lanthanide-induced shift studies and the anomeric effects of the O8 oxygen may help understanding of this preference.