The hydroamination of TIPS-C≡C-SF5 – A bench-top route to pentafluorosulfanylated enamines

Synthetic access to a variety of aliphatic and vinylic pentafluorosulfanylated building blocks remains a major challenge in contemporary organofluorine chemistry hampering its broad investigation in the context of medicinal chemistry, agrochemistry and functional materials. Herein, we report a bench-top protocol to access the virtually unknown class of a-SF5-enamines under rather benign reaction conditions. This reaction combines the in-situ protodesilylation of the commercially available precursor TASP with the unprecedented hydroamination of HC≡C-SF5. The on-site use of highly toxic gases is completely avoided, granting access to a-SF5-enamines to conventional labs. Furthermore, employing a combined experimental and computational approach, we revealed a two-step cascade reaction. The excellent E-diastereoselectivity of the reaction is suggested to be the result of the convergence of the fast Z-/E- isomerization of a vinyl anion as well as isomerization of the iminium ion in the equilibrium. The remarkably thermal stability of these SF5-enamines encourages further studies of its synthetic utility.