Synthesis and conformational properties of 2,6-bis-anilino-3-nitropyridines

The synthesis of 2,6-bis-anilino-3-nitropyridines that are alkylated or acylated at the anilino nitrogen atoms is described. These derivatives show characteristic differences in the ¹H-NMR spectra compared with the unsubstituted parent compound. These differences are used to determine structure–conformation relationships of this type of compounds. The conclusions drawn from the ¹H-NMR spectra in this respect are supported by X-ray crystallographic data and by ¹H-NMR data of conformationally restricted analogues. Preliminary investigations indicate that these relationships can in principle be extended to other diarylamines.