Strain‐Release Pentafluorosulfanylation and Tetrafluoro(aryl)sulfanylation of [1.1.1]Propellane: Reactivity and Structural Insight**

Abstract

Abstract We leveraged the recent increase in synthetic accessibility of SF 5 Cl and Ar−SF 4 Cl compounds to combine chemistry of the SF 5 and SF 4 Ar groups with strain‐release functionalization. By effectively adding SF 5 and SF 4 Ar radicals across [1.1.1]propellane, we accessed structurally unique bicyclopentanes, bearing two distinct elements of bioisosterism. Upon evaluating these “hybrid isostere” motifs in the solid state, we measured exceptionally short transannular distances; in one case, the distance rivals the shortest nonbonding C ⋅⋅⋅ C contact reported to date . This prompted SC‐XRD and DFT analyses that support the notion that a donor‐acceptor interaction involving the “wing” C−C bonds is playing an important role in stabilization. Thus, these heretofore unknown structures expand the palette for highly coveted three‐dimensional fluorinated building blocks and provide insight to a more general effect observed in bicyclopentanes.