19F NMR spectroscopy as a tool to detect rotations in fluorine substituted phenyl compounds

Atropisomerism becomes a popular structural feature in modern drug discovery. Using N-phenyl γ-lactam and phenyl-pyrazolone scaffolds, we showed that distinct 19F NMR peaks were present in atropisomers and dual signals emerged for covalently identical fluorine nuclei in hindered rotamers. Factors affecting 19F NMR chemical shifts in these molecules were discussed. We demonstrated that 19F NMR spectroscopy can be used to differentiate and detect atropisomers and rotamers in conformationally restricted molecules.