Efficient one-pot ring-opening/aldol reactions using (cyclopropyl)methylstannanes

(Cyclopropyl)methylstannanes, substituted with an electron-withdrawing group, have been found to be effective homoallylating reagents of aldehydes and ketones. The reaction proceeds by Lewis-acid catalyzed ring opening, followed by an aldol condensation of the resulting enolate, providing homoallylation products in excellent yields. The diastereoselectivity of the process was found to be highly dependent upon the temperature and the solvent, the reaction giving mainly anti adducts at −78 °C and syn compounds at 0 °C.