Enabling Cross-Coupling Reactivity of α-Pentafluorosulfanyl Compounds with a Thermally Stable Organozinc α-SF5 Reagent.

Herein, we report the first successful turnover of α-SF5 substrates in metal-catalyzed cross-coupling chemistry. Previously reported conditions suitable to couple CF3-derivatives under Negishi-type conditions lead to complete decomposition of the corresponding SF5 derivatives. We report the first thermally stable α-SF5 organometallic reagent, which allows for a set of catalytic key transformations, delivering the reaction products in good to excellent yields (up to 96%). This organozinc platform allows for extensive downstream functionalization by protonation, allylation and acylation reactions under copper catalysis, as well as palladium-catalyzed Negishi-type cross-coupling conditions. Connecting our experimental results to computational analysis shines first light on the parameters critical for successful turnover of α-SF5 substrates. We challenge our key hypothesis of the critical contribution of the M─C─S angle to reduce orbital overlap, promoting β-F elimination. While we found a significant contribution of a secondary S─M bond, the central component responsible for suppression of β-F elimination seems to be the steric bulk of the SF5 substituent itself. Additionally, the close proximity of the two potential energy surfaces is proposed to facilitate either reductive elimination, forming alkene π-complexes, or thermodynamically favored β-F elimination, highlighting the requirement for careful kinetic control of the reaction.