Transformation of carboxylic acid esters into 2-substituted allyl halides through tertiary cyclopropyl sulfonates.: Application in the synthesis of (±)-ipsenol and (±)-ipsdienol, components of Ips typographus spark beetle pheromone

Cyclopropanation of the ester group in ethyl 3-chloropropanoate and subsequent cleavage of the three-membered carbocycle in intermediate 1-(2-chloroethyl)cyclopropyl methanesulfonate gave 2-bromomethyl-4-chlorobut-1-ene, and the latter was used as key intermediate in the synthesis of racemic ipsenol and ipsdienol which are components of Ips typographus L. European spruce spark beetle pheromone.