SYNTHESIS, PROPERTIES, AND REACTIONS OF NEW PERFLUORINATED DIKETONES

(Trifluoromethyl)trimethylsilane reacts with diacyl fluorides F(O)C(CF2)nC(O)F (n = 2,3) in the presence of excess KF in benzonitrile to give the cyclic alkoxides CF3(F)C(CF2)nCO(CF3)O-K+. The alkoxides are formed by the formal nucleophilic substitution of CF3- on F(O)C- followed by a rapid cyclization of the diketone by fluoride ion to give the observed alkoxides. The free diketones CF3(O)C(CF2)nC(O)CF3 are isolated by a 1,4- loss of KF from the alkoxide by heating the latter under dynamic vacuum. The new diketones exhibit a high reactivity with many nucleophiles resulting in a facile intramolecular cyclization. With water the novel cyclic diols CF3(HO)C(CF2)nCO(OH)CF3 are formed in high yield. The structures of the cis- (n = 3) and trans- (n = 2) diols were obtained by single-crystal X-ray diffraction.