A multinuclear magnetic resonance study of protonation in imidazo[1,2‐a]pyrazine

Abstract 1H and 13C NMR spectra are reported and assigned for imidazo[1,2‐a] pyrazine and for N‐1‐methyl‐ and N‐7‐methyl‐imidazo[1,2‐a] pyrazinium iodides. The effect of protonation on the chemical shifts of the parent molecule is demonstrated, and through the use of 13C and 15N NMR spectra the site of protonation is deduced to be at N‐1, in contrast to 2‐aryl substituted compounds synthesised as potential cardiotonic agents where protonation occurs at N‐7.