Syntheses of gem-dihalocyclopropanes and their use in organic synthesis

This review demonstrates that the syntheses of gem-dihalocyclopropane derivatives can be accomplished by several highly efficient procedures, among which the phase-transfer catalytic method is the method of choice. The general concept of PTC and its basic mechanistic features are discussed, along with its major benefits and advantages in the chemistry of dihalocarbenes and gem-dihalocyclopropanes. The main types of gem-dihalocyclopropane transformations that have been described in recent years are discussed. Some transformations of 1,1-dihalo-2-phenylcyclopropanes are shown to illustrate the importance of this type of reaction.