Yannick Kraemer

We have developed a strain-release strategy for the pentafluorosulfanylation of aliphatic molecules. We envision that our methodology will allow for the synthesis of useful building blocks with applications in medicinal and agrochemistry.

Fluorinated functional groups are ubiquitous in medicinal chemistry, agrochemistry, and materials due to the unique properties fluorine atoms impart on their parent molecules. Methods to install fluorine on organic molecules have traditionally required hazardous reagents, creating a bottleneck to exploring applications of emerging fluorinated motifs, such as the pentafluorosulfanyl (SF 5 ) and related groups. Our research has taken advantage of the timely development of a user-friendly protocol to generate SF 5 Cl, an SF 5 transfer reagent. We merged the known radical reactivity of SF 5 Cl with strain- release functionalization to expand the repertoire of accessible C(sp 3 )–SF 5 compounds and to study structural features of novel fluorinated "hybrid isosteres." In one instance, upon addition of SF 5 Cl across [1.1.1]propellane, SC-XRD analysis revealed that the resultant SF 5 -BCP-Cl compound boasts one of the shortest non-bonding C•••C distances ever reported in the solid state. In a separate project, the same pentafluorosulfanylation logic was applied to [1.1.0]bicyclobutanes, another class of strain-release reagents, to synthesize a suite of achiral SF 5 -cyclobutanes. Over 60 new SF 5 -cyclobutanes were synthesized and characterized.