Reducing the Lipophilicity of Perfluoroalkyl Groups by CF₂-F/CF₂-Me or CF₃/CH₃ Exchange

Fluorination is commonly employed to optimize bioactivity and pharmaco-kinetic properties of drug candidates. Aliphatic fluorination often reduces the lipophilicity (log P), but polyfluoroalkylation typically increases lipophilicity. Hence, identification of polyfluorinated motifs that nonetheless lead to similar or even reduced lipophilicities is of interest to expand the arsenal of medicinal chemistry tools in tackling properties such as compound metabolic stability or off-target selectivity. We show that changing a CF₃-group of a perfluoroalkyl chain to a methyl group leads to a drastic reduction in lipophilicity. We also show that changing a C-F bond of a trifluoromethyl group, including when incorporated as part of a perfluoroalkyl group, to a C-Me group, leads to a reduction in log P, despite the resulting chain elongation. The observed lipophilicity trends were identified in fluorinated alkanol models and reproduced when incorporated in analogues of a drug candidate, and the metabolic stability of these motifs was demonstrated.