Oxidative Fluorination of Heteroatoms Enabled by Trichloroisocyanuric Acid and Potassium Fluoride

In synthetic method development, the most rewarding path is seldom a straight line. While our initial entry into pentafluorosulfanyl (SF5) chemistry did not go according to plan (due to inaccessibility of reagents such as SF5Cl at the time), a "detour" led us to establish mild and inexpensive oxidative fluorination conditions that made aryl-SF5 compound synthesis more accessible. The method involved the use of potassium fluoride and trichloroisocyanuric acid (TCICA)-a common swimming pool disinfectant-as opposed to previously employed reagents such as F-2, XeF2, HF, and Cl-2. Thereafter, curiosity led us to explore applications of TCICA/KF as a more general approach to the synthesis of fluorinated Group 15, 16, and 17 heteroatoms in organic scaffolds; this, in turn, prompted SC-XRD, VT-NMR, computational, and physical organic studies. Ultimately, it was discovered that TCICA/KF can be used to synthesize SF5Cl, enabling SF5 chemistry in an unexpected way.