Reactions involving fluoride ion. Part 17. Oligomers of perfluorocyclobutene

Reaction of perfuorocyclobutene (1) with fluoride ion gives mainly a trimer (6) together with dimers (3) and (4) and a tetramer (7). The tetramer (7) is also obtained directly from the dimers (3) and (4). Reaction of (1) with pyridine provides a useful route to dimers (3) and (4) and a different trimer (10). The structures of these oligomers have been established and mechanisms for their formation are presented.