[1-chloromethyl-4-fluoro-1,4-diazoniabicyclo-[2.2.2]octane bis(tetrafluoroborate), trademarked Selectfluor, is a convenient fluoride-atom source useful for the electrophilic fluorination of organic compounds. It is an air and moisture tolerant white solid, non-hygroscopic, soluble in polar solvents (water, nitromethane, DMF, acetonitrile). Since most electrophilic fluorinations were originally done using fluorine gas (a pain to handle), selectfluor provides a practical alternative, evidenced by its commercialization.[1]
The reagent can be cheaply purchased from a variety of chemical vendors. It is not worth synthesizing in-house.
Notes
- Selectfluor is not limited to fluorinations, as there are reports highlighting its ability to act as an oxidizing agent and partake in other types of reactions (Amination, hydrogen-atom transfer).[2]
- Selectfluor is industrially synthesized via a three-step procedure starting from DABCO. The base is methylated with DCM, followed by an anion exchange with NaBF4, and fluorination with F2.[3]
[1] a) Banks, R. E. (Air Products and Chemicals, Inc., USA), US 5086178, 1992, p. 9. b) Banks, R. E.; Besheesh, M. K.; Mohialdin-Khaffaf, S. N.; Sharif, I. J. Chem. Soc. Perkin Trans. 1996, 1, 2069.
[2] Aguilar Troyano, F. J.; Merkens, K.; Gomez-Suarez, A. Asian J. Org. Chem. 2020, 9, 992-1007.
[3] Nyffeler, P. T.; Gonzalez Duron, S.; Burkart, M. D.; Vincent, S. P.; Wong, C.-H. Selectfluor: Mechanistic Insight and Applications. Angew. Chem. Int. Ed. 2005, 44, 192-212.