Physicochemical and Biological Evaluation of gem-Difluorinated Saturated Oxygen Heterocycles as Bioisosteres for Drug Discovery

A comprehensive study on the physicochemical properties of gem-fluorinated O-heterocyclic substituents is reported. Systematic additive effects of introducing O- and gem-CF₂ group introduction on acidic properties (pK_a) of the corresponding carboxylic acids/protonated primary amines were demonstrated. The impact of the O/CF₂ moieties on lipophilicity (LogP) was found to be complex; significant mutual influence of the corresponding polar moieties governed the compound's overall properties in this case. Biological evaluation of MAPK kinase inhibitors incorporating the title substituents demonstrated their utility as promising fragments for bioisosteric replacements in drug discovery campaigns.