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.
The pentafluorosulfanyl group is suggested to be a promising candidate adding to the toolbox of emerging fluorinated motifs. While the synthesis of non-aromatic SF5 bulding blocks generally requires on-site fluorination or pentafluorosulfanylation steps employing toxic and/or gaseous reagents, downstream processing of commercially available prefunctionalized molecules is proposed as an alternative strategy to allow access to this motif by less specialized laboratories. Herein, we report a benign bench-top protocol for the synthesis of Z-configured beta-pentafluorosulfanylated vinyl sulfides in good to excellent yields with excellent Z-diasteroselectivity and broad functional group tolerance. This general method exploits an in-situ protodesilylation-hydrothiolation sequence of commercially available liquid and high-boiling TIPS-CΞC-SF5 (TASP). This so far uncharted class of compounds was analyzed by means of NMR-spectroscopy as well as SC-XRD. Furthermore, we suggest the reaction to proceed via a kinetically controlled closed-shell reaction pathway corroborated by in-silico experiments.
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