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Abstract

We leveraged the recent increase in synthetic accessibility of SF₅Cl and Ar−SF₄Cl compounds to combine chemistry of the SF₅ and SF₄Ar groups with strain-release functionalization. By effectively adding SF₅ and SF₄Ar 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.