Application of phase-transfer catalysed systems2.3 (alkali metal hydroxide and a quaternary onium salt as a catalyst) for generation of dihalogenocarbenes from the corresponding haloforms in the presence of alkenes provides a simple and efficient preparation of gem-dihalogenocyclopropanes, with the exception of the gem-difluoro-derivatives.4 Starting from HCCIF2 and alkenes under the above conditions, the yields of ...
