Fluoroalkyl-Containing 1,2-Disubstituted Cyclobutanes: Advanced Building Blocks for Medicinal Chemistry

Synthesis of previously unavailable 1,2-disubstituted cyclobutane building blocks bearing mono-, di- and trifluoromethyl groups are disclosed. The key steps included deoxofluorination or TMAF-mediated nucleophilic substitution in the appropriate bifunctional cyclobutanes; for the CF₃-substituted derivatives, alternative methods based on cyano- or azidotrifluoromethylation of cyclobutene using the Togni reagent II were also proposed. All methods provided trans diastereomers of the target primary amines and carboxylic acids (6 representatives) and were suitable for their multigram preparation. Furthermore, dissociation constants (pK_a) and lipophilicity (logP) values were measured to evaluate the effect of the fluoroalkyl substituents on acidity/basicity and lipophilicity of the building blocks obtained.