Chemistry of Benzocyclopropenes. 1H-and 13C-NMR. Spectra of 2, 5-dideuterio-1-fluorobenzocyclopropenium ion

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 (7a) .