Optical activity of lactones and lactams—IV : Chiroptical properties of 4-imidazolidinones

The chiroptical properties of 4-imidazolidinones are reviewed. Several optically active compounds were obtained from amides and N-methylamides of corresponding N-acylamino acids. The origin of the two lowest energy electronic transitions is considered. The equilibrium between the two envelope conformations of heterocyclic ring was observed by means of NMR and CD spectra. The spectra of the compounds with non-protected amino group are affected by n → σ^* transition involving nitrogen lone pair.