Titanium-mediated diastereoselective formation of (E)-2-alkyl-1-ethenylcyclopropanols from β-haloesters

The titanium(IV)-mediated cyclopropanation of ethyl β-chloropropionate by Grignard reagents and in situ tosylation, followed by base-induced dehydrochlorination provided diastereoselectivity pure (E)-2-alkyl-1-ethenyl-1-(tosyloxy)cyclopropanes, suitable precursors of 1,1-ethyleneallylmetal species of significant synthetic potential.