the trifluorovinyl group onto zinc chlorides for application in palladium-catalysed Negishi cross-coupling reactions. To the best of our knowledge there are no examples of reactions of HFC-134a which involve solely sp C-F bond activation. In this communication, we show that reaction of HFC-134a with a main group reagent containing a Mg-Mg bond leads to exclusive formation of 1,1difluoroethene due to the formal 1,2-elimination of two F atoms from the substrate. This is a rare example of selective sp C-F bond activation of this industrially important HFC. HFC-134a (1 bar, 25 °C, approx. 7 equiv.) was added to a degassed C6D6 solution of 1 and 4dimethylaminopyridine (DMAP, 2 equiv.). The reaction mixture was agitated and left to proceed for 16 h at 25 °C, during which time the dark red solution turned yellow. H and F NMR spectroscopy of the resultant reaction mixture reveal the formation of 2 (86 % yield) and 1,1-difluoroethene (Scheme 1). 2 has been previously reported and characterised by our group, and shows a diagnostic resonance at δ = -183.9 ppm in the 19 F NMR spectrum. 1,1-Difluoroethene has a resonance at δ = -81.8 ppm, in accordance with data in the literature. Due to its volatility and partitioning between solution and reaction headspace, the amount of 1,1-difluoroethene was not quantified, subsequent onwards reactions however, support generation in reasonable yields (vide infra). Jones and co-workers have shown that this magnesium nucleophile used in this reaction, 1, displays enhanced reactivity on the addition of a Lewis base, while we have recently demonstrated its use in the defluorination of PTFE. Defluorination of HFC-134a with 1 can also occur in the absence of DMAP, but requires heating to 80 °C, and results in 30 % yield of an analogue of 2 which does not have DMAP coordinated.