摘要
Addition of dihalocarbene with olefin is the most important method to prepare the derivatives of gem-dihalocyclopropanes. Up till now, the method reported by Makosza in 1969, which is α-elimination of haloform by strong base under phase transfer catalysis, is the most widely used one in the generation of dihalocarbenes. But it would cause the side reaction of groups in olefin molecules, which are sensitive to bases. Besides, haloform, 3—10 equivalents of olefin, is used to act as a solvent, so it is impossible to control the
