Specific features were elucidated for the intramolecular cyclization of 2-trifluoromethyl-4-pentenoic acids (Ia)-(Ic) under acid catalysis and upon bromination and epoxidation of the double bond. Feasibility was demonstrated for the lactonization of acids (Ia)-(Ic) upon the trifluoroacetoxylation of the double bond and some properties of the butanolide products were studied.