Diels–Alder reactions of polyfluorocyclohexa-1,3-dienes. Part IV. Addition of alkynes to 1H,2H-hexafluorocyclohexa-1,3-diene

Abstract

1H,2H-Hexafluorocyclohexa-1,3-diene (1) dimerizes slowly at room temperature; with perfluorobut-2-yne and 3,3,3-trifluoropropyne at 200° the diene (1) gives 2,3-bis(trifluoromethyl)-1,6,7,7,8,8-hexafluorobicyclo[2,2,2]-octa-2,5-diene (5) and 2-trifluoromethyl-4,5,7,7,8,8-hexafluorobicyclo[2,2,2]octa-2,5-diene (4) respectively, together with dimer. Pyrolysis of (4) gives 3,4-difluorobenzotrifluoride which was also prepared from 3-amino-4-fluorobenzotrifluoride by way of pyrolysis of the diazonium tetrafluoroborate.