An elusive cross coupling of α-pentafluorosulfanylated S,S-ketene acetals

Herein, we report a first example of -SF5 cross-coupling reaction employing a previously developed -SF5 brominated S,S-ketene acetal derivative as a key starting material. Direct zinc insertion into the -SF5 C-Br bond proceeds smooths and leads to the formation of a thermally stable -SF5 organozinc reagent, which allows for extensive downstream functionalisation by protonation, allylation, and acylation reactions under the copper catalysis. Furthermore, palladium catalysed Negishi cross-coupling conditions could be successfully established, showing excellent tolerance to both electron-rich, -poor arenes and heterocycles. An initial ligand screening indicates a strong influence of the phosphine ligand on the coupling efficacy, resulting in an almost binary reaction outcome, which could not be correlated to purely steric nor electronic parameters. Only the use of highly bulky and electron donating P(t-Bu)3 delivers the reaction products in up to 93% yield. Preliminary results suggest the contribution of secondary ligand-metal interactions being responsible for this observation, but further investigations are needed to gain deeper understanding of the nature of these contributions.