NMR spectroscopic study of rotation around CC and CN bonds in diene δ-aminocarbonyl compounds

A relatively fast rotation around the α,β carbon–carbon double bond at the equilibrium of geometrical isomers and a comparatively slow rotation around the carbon-nitrogen single bond in compounds of the type (X1, X2 are electron-attracting substituents) were detected and investigated by the NMR technique. The relationships between the free energies of activation for these rotational processes and the character of the substituents, the number of double bonds, solvents and concentration were studied.