Photoredox Catalytic Hydropentafluorosulfanylation of Alkynes by Sulfur Hexafluoride

The interest in organic compounds bearing the pentafluorosulfanyl (SF$_5$) group has increased significantly. The photocatalytic utilization of the cheap and nontoxic sulfur hexafluoride (SF$_6$) as an SF$_5$-donating motif is an extremely valuable and still underdeveloped pathway in comparison to the well-established methodology employing the highly toxic SF$_5$Cl gas. However, due to the high stability and associated low redox potential of SF$_6$, paired with the ambiphilicity of the SF$_5$ radical, the development of catalytic systems to gain SF$_5$-bearing organic molecules from SF$_6$ is particularly challenging. We hereby present the first photocatalytic hydropentafluorosulfanylation of aryl acetylenes by SF$_6$ using Ir(ppy)$_3$ as a visible-light photoredox catalyst and Hantzsch ester as a sacrificial reductant as well as a hydrogen atom transfer (HAT) reagent. The method delivers the corresponding pentafluorosulfanylated alkenes in good to excellent yields.