Identification of Aminopyrimidine Regioisomers via Line Broadening Effects in 1H and 13C NMR Spectroscopy

Substituted mono- and diamino-pyrimidines were synthesized as part of our medicinal chemistry programmes. Primary amines substituted at the 4-position exhibited room-temperature line broadening effects in both 1H and 13C NMR spectroscopy due to the presence of rotamers, but these effects were not observed for substituents in the 2-position. This provided a simple diagnostic tool for the identification of regioisomers, a determination which would otherwise have required two-dimensional experiments.