Tracking SF I in the Iodopentafluorosulfanylation of Alkynes.

In the vibrant field of SF chemistry, SF X reagents (X=F, Cl, Br) are at the heart of current investigations in radical pentafluorosulfanylation reactions. SF I is the missing link whose existence has not been reported despite its potential as SF donor. This study reports the formal addition of the hitherto unknown SF I reagent to alkynes by means of a combination of SF Cl/KI/18-crown-6 ether. The exclusive regio- and stereoselective synthesis of unprecedented (E)-1-iodo-2-(pentafluoro-λ -sulfanyl) alkenes was achieved. A consensus was reached through computational and mechanistic studies for the realistic formation of SF anion but not SF I in solution and the rational involvement of SF and iodine radicals in the iodo pentafluorosulfanylation reaction.