Conformational and Stereodynamic Behavior of Five- to Seven-Membered 1-Aryl-2-iminoazacycloalkanes.

The stereodynamic behavior of 1-arylpyrrolidin-2-imines, having a C-N stereogenic axis, has been studied by means of dynamic nuclear magnetic resonance and density functional theory calculations, evaluating the steric effect of -aryl substituents. The rotational barrier due to / isomerism about the -C=N-H bond was also determined. The dynamic stereochemistry of homologous six- and seven-membered iminoazacycloalkane rings and their oxo-analogues was also comparatively investigated, evidencing a ring size effect. It was found that the seven-membered heterocycle shows additional dynamic features because of ring inversion.