Acrylamide derivatives: A dynamic nuclear magnetic resonance study

Substituted acrylamides have found an extensive application in organic and medical chemistry; therefore, it is very important to get insight into their features such as electronic structure, spectral properties, and stereochemical transformations. A correct interpretation of the chemical behavior and biological activity of these heteroatomic systems is impossible without knowledge of the structure of stereodynamic forms and factors determining their relative stability. The structure and peculiarities of stereodynamic behavior of substituted acrylamides and their model compounds were studied by dynamic and multinuclear ¹ H, ¹³ C, and ¹⁵ N nuclear magnetic resonance (NMR) spectroscopy in CDCl₃ and DMSO-d₆ solution. It has been established that acrylamides in solution are realized as Z- and E-isomers, with the E-rotamer being somewhat predominant. The obtained experimental values of the free activation energy of rotamers vary within 15-17 kcal/mol, depending on the stereochemical structure of the molecule. ¹⁵ N NMR spectroscopy is the most reliable and fastest method for determining the structural and stereochemical features of nitrogen-containing compounds.