Spectroscopic Characterization of the Tertiary Amine, N-(5-Hydroxypentyl)-N-(3aminopropyl)dodecanamide (1)

We are presenting educational work that could be implemented in chemistry teaching labs on the process of pyramidal inversion, also known as nitrogen inversion. Compounds 1and 2, N-(5-Hydroxypentyl)-N-(3-aminopropyl)hexanamide, and N-(5-Hydroxypentyl)-N-(3-aminopropyl)dodecanamide respectively were prepared as two intermediates during the synthesis of the natural product Acarnidine 3, N-[5-(guanidinopentyl)-N-[3-[(3-methyl-1-oxo-2-butenyl)amino]propyldodecanamide and its analog 3a, N-[5-(guanidinopentyl)-N-[3-[(3-methyl-1-oxo-2-butenyl)amino]propylhexanamide. The starting materials 4, 5-aminopentanol, and 4a, acrylonitrile, were converted to 3 and 3a in six steps. Compounds 1 and 2, found as mixtures of rotamers (1a & 1b) and (2a & 2b) respectively, were produced from their precursors 5 and 6 respectively. The 1H-NMR spectra for compound 1, in DMSO-d6 at 20 and 75°C or in CDCl3, are presented here and analyzed. Here I am trying to present the basic phenomenon, sometimes overlooked by many researchers, which occurred to certain nitrogen-containing compounds known as pyramidal or nitrogen inversion.