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
Preparation of 1, 1-difluorobenzocyclopropene (4) and of its 2, 5- and 3, 4-dideuterio derivatives 4a and 4b is reported. Upon ionization in cold fluorosulfonic acid, 4 affords 1-fluorobenzocyclopropenium ion (6). 1H- and 13C-NMR. spectra of 4 and 6 are assigned on the basis of the data for the specifically deuteriumlabelled compounds 4a and 6a. Hydrolysis of 6a leads to 2, 5-dideuteriobenzoic acid