The Nuclear Magnetic Resonance Spectra of 2-Formylaminopyridine and 2-Formylamino-γ-picoline

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Abstract
The NMR spectra of 2-formylaminopyridine and 2-formylamino-γ-picoline have been recorded under various conditions. At low temperatures, these compounds were found to exist in two forms. In these two forms, the chemical shifts of the ring proton-3 differ much from each other because of the difference in the orientation of the formylamino group, which has a large magnetic anisotropy. The difference in the chemical shifts of the formyl protons in the two forms are too large to be explained by the anisotropic shielding effect of the pyridine-ring currents. At higher temperatures, the signal coalescence of these protons in two forms have been observed. The molecular structures of these compounds have been concluded to be planar.