Reaction of 1, 1-dichloro-2, 5-diphenylbenzocyclopropene (10a) with 1 equiv. of silver fluoride yields 1-chloro-1-fluoro-2, 5-diphenylbenzocyclopropene (10c). Both 10a and 10c react with excess silver fluoride to give the difluoro compound 10b. Both 10b and 10c are also prepared via cyclo-additions of 1, 2-dichloro-3, 3-difluorocyclopropene (14) or 1, 2, 3-flurocyclopropene (13) with diphenylbutadiene
and faceselectivities of the cycloaddition of 1,2,3-trichloro-3-fluorocyclopropene (1a) with acyclic dienes and furans has been re-investigated by X-ray determination and correlation of 19F-NMR data. The isolated adducts of dienes exclusively have exo-configuration, and exo-Configuration predominates with furans. The Cl substituents of the resulting cyclopropane ring are cis-oriented. The face selectivity