Reactions involving fluoride ion. Part 21 [1]. Nucleophilic substitution reactions of perfluorocyclobutene oligomers

Reaction of perfluorocyclobutene oligomers, (1) - (4), with some simple nucleophiles gives products arising from S_N2′ displacement [N.B. this term is used here to describe the overall process of addition of a nucleophile to an alkene and elimination of an allylic fluorine and is not meant to imply that the reaction is concerted] or vinylic substitution of fluorine, or a mixture of both processes. The reactivity of the dimers, (1) and (2), is much greater than that of acyclic analogues and this can be attributed to the ring strain present in these compounds.