Polyfluorobicyclo[2,2,1]heptanes. Part V. Syntheses using bridgehead carbanions generated by removal of bridgehead hydrogen with aqueous bases

Strong amide–halothane hydrogen-bonding observed by nuclear magnetic resonance

“…Nevertheless, the electrostatic properties it represents may be reflected in the acidity of that C-H bond provided that the carbanion is charge-localized and of similar geometry to the hydrocarbon. It is particularly interesting that the pKa7s of 1, 3, and chloroform in cyclohexylamine (14) are 24.0, 24.4, and 24.4, respectively, that pentafluorobenzene, which has significant anaesthetic properties (15), has a pKa of 24.2, and that 4 and 5 are extremely powerful anaesthetics (16), and have pK,' s of 20.5 and 22.3. Less acidic fluorocarbons (CF,H, pK,, 30.5; CF,CF,H, pK, 28.2) are much less potent anaesthetics than 1 (1).…”

“…The polyfluorinated bicyclic con~pounds 4 and 5 are both highly acidic (14) and potent anaesthetics (16) and it was of interest to determine their C-H donor properties. Unlike 1 the chemical shift of the C-H in 4 is strongly temperature dependent, implying considerable selfassociation.…”

Functional group transformation of perfluoroadamantane derivatives

“…Their pH values were measured as 20.5 and 18.3, respectively [34]. It was reported that the hydrogen of 1H-perfluorobicyclo[2,2,1]heptane was subtracted by potassium hydroxide in aqueous polar solvent, and the formed carboanion behaved as nucleophile [33]. Thus, we applied the reaction condition to the reaction of 4 with formalin, and successfully obtained 5.…”

“…They also prepared 1-iodoperfluoroadamantane from 4. Further, Stephens, Tatlow et al prepared 1H-perfluorobicyclo[2,2,1]heptane and 1H-perfluorobicyclo[2,2,2]octane, and transformed them into several derivatives [25,[30][31][32][33]. Their pH values were measured as 20.5 and 18.3, respectively [34].…”