Mechanochemical Fluorination of Naproxen and Its Salts with F–TEDA–BF4.

The mechanochemical fluorination of naproxen and its salts (Li, Na, and K) with 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor, F–TEDA–BF4) was studied. The reaction of naproxen with an excess of Selectfluor gives 2-(5,5-difluoro-6-oxo-5,6-dihydronaphthalen-2-yl)propionic acid in high yield. Small additives of Al2O3, SiO2, M2CO3 (M = Na, K, Rb, Cs), ionic liquids (ILs), crown ethers, and N-bases accelerate the reaction of naproxen with Selectfluor and increases the monofluorination/difluorination product ratio. [ABSTRACT FROM AUTHOR]