Photoredox Catalytic Hydropentafluorosulfanylation of Alkynes by Sulfur Hexafluoride

The interest in organic compounds bearing the pentafluorosulfanyl (SF₅) group has increased significantly. The photocatalytic utilization of the cheap and nontoxic sulfur hexafluoride (SF₆) as an SF₅-donating motif is an extremely valuable and still underdeveloped pathway in comparison to the well-established methodology employing the highly toxic SF₅Cl gas. However, due to the high stability and associated low redox potential of SF₆, paired with the ambiphilicity of the SF₅ radical, the development of catalytic systems to gain SF₅-bearing organic molecules from SF₆ is particularly challenging. We hereby present the first photocatalytic hydropentafluorosulfanylation of aryl acetylenes by SF₆ 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.