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

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.