• 1H, 13C, 15N, NMR;
  • conformation;
  • oxaziridines;
  • oxiranes;
  • spirocyclic

A structural and conformational analysis of 1-oxaspiro[2.5]octane and 1-oxa-2-azaspiro[2.5]octane derivatives was performed using 1H, 13 C, and 15 N NMR spectroscopy. The relative configuration and preferred conformations were determined by analyzing the homonuclear coupling constants and chemical shifts of the protons and carbon atoms in the aliphatic rings. These parameters directly reflected the steric and electronic effects of the substituent bonded to the aliphatic six-membered ring or to C3 or N2. The parameters also were sensitive to the anisotropic positions of these atoms in the three-atom ring. The preferred orientation of the exocyclic substituents directed the oxidative attack. Copyright © 2012 John Wiley & Sons, Ltd.