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 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 center dot center dot center dot 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.

Automated summary

By leveraging the accessibility of SF5Cl and Ar-SF4Cl compounds, we combined the chemistry of SF5 and SF4Ar groups with strain-release functionalization to synthesize structurally unique bicyclopentanes bearing distinct bioisosterism elements. These previously unknown structures not only expand the options for highly desired three-dimensional fluorinated building blocks but also provide insights into a more general effect observed in bicyclopentanes.