Zur konformativen Anordnung dipolarer Substituenten in 5-Stellung von 1,3-Dioxanen

Summary The conformation of a series of 5-nitro-1,3-dioxanes, 1,3-dioxane-5-hydroxylamines and the corresponding nitrones, obtained from the latter, has been studied by NMR spectroscopy. In the case of the nitrones, a preferred conformation of the -N(O)CHR³ substituent to the C⁵, N single bond was found, and it was concluded therefrom on the identical conformational behaviour of the nitro analogoues. A structurally similar spiro compound confirms the suggestions given. In the case of the spiro compound, the intramolecular N-inversion process could be studied by dynamic NMR spectroscopy; the free energy of activation is given.