Acyl derivatives of cyclic secondary amines. Part 2. Dynamic 1H and 13C nuclear magnetic resonance studies on bis- and tris-amides: equilibria of syn-anti interconversion

Abstract

Variable-temperature ¹H and ¹³C n.m.r. spectra are reported for 1,3-diacylimidazolidines, 1,3-diacylhexahydropyrimidines, and 1,3,5-triacylhexahydro-sym-triazines. Peaks for the individual conformers found at low temperature were assigned by using model compounds, from relative intensities, and by internal consistencies. Conformer populations are deduced and compared with those calculated assuming energy differences arise only from dipole-dipole interactions and good agreement is noted.