Anhydrous phosphazenium fluorides as sources for extremely reactive fluoride ions in solution.

Several peralkylated polyaminophosphazenium cations were evaluated for the generation of novel anhydrous F- salts. Two of them have been characterized by X-ray analysis and are particularly soluble, even in apolar aprotic solvents like benzene or THF, one of them even at -30 degrees C. Such solutions probably represent the most basic metal-free and stable media known to date. Comparison of these fluorides with known F- sources demonstrates that they are of unprecedented reactivity and selectivity in E2 elimination reactions.