Stereoselective Synthesis of Cyclopropanes via Homoallylic Participation

Abstract

A facile method for synthesizing trans-disubstituted cyclopropanes is described. Upon conversion to the corresponding triflate, γ,γ-dimethyl homoallyl alcohols undergo smooth cyclization to give cyclopropanes in excellent trans selectivity and with an inversion of the hydroxyl center. Various functionalities could be introduced at the α-position of the newly formed cyclopropane ring. Alternatively, treatment of the intermediary triflate with triethylamine effects clean elimination of a triflic acid to give high yields of cyclopropanes with a 2-propenyl group, which are convertible to cyclopropyl methyl ketones by ozonolysis.