Fluorination of 6 to form -fluoroamine, 7, using MF catalysed by boranes was explored as a test reaction to determine if there is any correlation between borane fluoride affinity and phase transfer / nucleophilic fluorination reactivity (Table ). Attempts to perform fluorination of 6 with KF (with 1 / BEt3 as catalysts) led to no fluorination in CHCl3, thus all further fluorination studies were performed using CsF. With both BEt3 and ArBPin based boranes haloalkane solvents gave better outcomes than other solvents, e.g. MeCN, thus only results in DCM or chloroform are discussed. Note a control reaction in the absence of borane led to no fluorination with CsF under these conditions. From this study phase transfer fluorination of 6 using CsF was effective with both 10 mol% BEt3 and 1. This demonstrates that borane phase transfer catalysts can be used to access important fluorinated molecules. As expected the identity of the borane is all important, with weaker Lewis acids e.g. PhBPin, and stronger Lewis acids (e.g. BPh3) both giving poorer outcomes. The former is consistent with a minimum fluoride affinity being required to form the Cs[fluoroborate] salt, while the latter indicates that if the fluoride affinity is too high then this disfavours transfer of fluoride from boron in the fluoroborate to the electrophile (fluoroborate formation is observed with higher FIA boranes). However, there are additional factors beyond fluoride affinity controlling fluorination using boranes, as 3 was a relatively poor catalyst despite having an identical calculated fluoride affinity to 1.