F₅S–CC–CF₃ can be easily prepared in high yields in two steps from 3,3,3-trifluoropropyne. It is a powerful, versatile dienophile in Diels–Alder reactions. Reactions at room temperature provide the corresponding products in up to quantitative yields allowing the introduction of the pentafluorosulfanyl group and trifluoromethyl group at the 1,2 position.