Fluorination of fluoro-cyclobutene with high-valency metal fluoride

Fluorinations of 1,4,4-trifluorocyclobutene and 3,3,4,4-tetrafluorocyclobutene using high-valency metal fluorides such as CoF₃, MnF₃, AgF₂, CeF₄ and KCoF₄, and elemental fluorine were examined. In these reactions with CoF₃ and MnF₃, vic-difluorination proceeded mainly. While, 1,4,4-trifluorocyclobutene yielded 3,3,4,4-tetrafluorocyclobutene, and 3,3,4,4-tetrafluorocyclobutene yielded 1,3,3,4,4-pentafluorocyclobutene mainly in the case of AgF₂. The further fluorinated products were increased under severer conditions. Also, the plausible reaction mechanism was suggested.