applications of 1-(trifluoromethyl)cyclopent-3-ene-1-carboxylic acid and itsesters, promising new trifluoromethylated cyclicbuildingblocks. Initially prepared starting from a pentafluorodithiopropanoic ester, a more convenient and effective approach has been developed starting from commercially available trifluoropropanoic acid or its methyl ester. The interest in these buildingblocks is exemplified