~1H NMR spectroscopy and conformational analysis of N-benzylimidazolidines

摘要

~1H NMR spectra of a series of 1-benzyl- and 1,3-dibenzylimidazolidines are analyzed and correlated with their conformational features. The spectra are assigned on the basis of chemical shifts and proton coupling constant values, and confirmed by NOESY spectra. C_2-Unsubstituted imidazolidines (1,9) show a fast inversion of the nitrogen atoms. By contrast, 1,2,3-trisubstituted imidazolidines display a preferential conformation with a transoid orientation of the N_1, N_3, and C_2 substituents.