Simple synthesis of?-silyloxyacylcyclopropanes and the homoallyl rearrangement of cyclopropylcarbinols by the action of trimethylsilyl halides in the presence of zinc halides

Abstract

The ZnCl2 catalyzed condensation of 1-trimethylsilyloxyvinylcyclopropane with aldehydes and ketones gave β-silyloxyacylcyclopropanes, which were converted by the action of TsOH in boiling benzene into 1-cyclopropyl-2E-alken-1-ones. Reduction of the latter gave saturated and allyl cyclopropylcarbinols, which by means of Me3SiX and catalytic amounts of ZnX2 (X=Cl, Br) were highly selectively converted into the corresponding linear mono- and dienic E-homoallyl halides. The sequence of reactions that was worked out provided an effective synthesis of 3E-dodecenyl acetate, a sex pheromone of the sugar beet moth.