Silicon-assisted ring opening of cyclopropyl ketones with boron trifluoride-acetic acid complex.

Abstract

2-(Trimethylsilylmethyl) cyclopropyl ketones were smoothly cleaved with boron trifluorideacetic acid complex under mild reaction conditions with the assistance of the trimethylsilyl group to give γ, δ-enones in good yields. The major effect of the trimethylsilyl group in the ring opening of the cyclopropyl ketones was unambiguously confirmed in the dicyclopropyl ketone 15 : one of its two cyclopropyl rings, which has a trimethylsilylmethyl group, was selectively cleaved. Furthermore, the reaction was applied to the formal total synthesis of cis-jasmone.