Hydroamination of Triisopropylsilyl Acetylene Sulfur Pentafluoride – a Bench‐top Route to Pentafluorosulfanylated Enamines

Abstract

AbstractSynthetic access to a variety of aliphatic and vinylic pentafluorosulfanylated building blocks remains a major challenge in contemporary organofluorine chemistry hampering its 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 α‐SF5‐enamines under mild reaction conditions in good to excellent yields (up to 95 %). This reaction combines the protodesilylation of the commercially available precursor TASP with the in situ hydroamination of HC≡C−SF5. The on‐site use of highly toxic gases or corrosive reagents is avoided, making access to this motif applicable to a wide chemical audience. The excellent E‐diastereoselectivity of this two‐step cascade reaction is suggested to be the result of the convergence of the fast Z‐/E‐ isomerization of a vinyl anion as well as the isomerization of the iminium ion. The remarkable thermal stability of these SF5‐enamines encourages further studies of their synthetic utility.