2,3,3,4,4,5,5-Heptafluoro-1-trifluoromethyl-1,2-epoxycyclopentane reacted with 2-isopropyl-acetophenone imine giving 2,3,3,4,4,5,5-heptafluoro-2-trifluoromethyl-1-(2'-isopropylimino-2'-phenylet hane) cyclopentan-1-ol, which in its turn underwent an intramolecular rearrangement yielding the linear 4,4,5,5,6,6,7,8,8,8-decafluoro-1-isopropylamino-oct-1-en-3-one, being characterized by X-ray structural analysis (triclinic, P-1, a=920.5(2), b=1027.9(3), c=1127.4(3)pm, α=110.99, β=105.68 o , γ=96.75 o ).