Fluorocyclization of norbornenecarboxylic acids with F-TEDA-BF4

The reactions of 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) with cis-5-norbornene-endo- 2,3-dicarboxylic acid, its monomethyl ester and 5-norbornene-endo-2-carboxylic acid in acetonitrile lead to the formation of corresponding fluorinated γ-lactones.