gem-Difluorocyclopropanes: An improved method for their preparation

Article abstract of DOI:10.1016/S0040-4020(01)87828-5

By treatment with dibromodifluoromethane and triphenylphosphine, four unfunctionalized olefins, four enethers and one bis-enether were converted to the gem-difluorocyclopropanes 1-9. The yields were considerably increased and isomerizations at the double bonds were avoided if the reactions were carried out in the presence of a macrocyclic polyether such as "18-crown-6" and if, in addition, the reagents were employed in moderate excess.