N-(2-Nitrophenyl)proline (2-NPP) can be used in a wide range of solvents as an effective chiral auxiliary for the absolute configuration assignment of alpha-chiral primary amines. Even in competitive hydrogen-bonding solvents, 2-NPP amides of primary amines retain the conformation preference for intramolecular hydrogen bonding and produce significant anisotropic effects on the amine substituents. As a result, the absolute configuration can be assigned by comparing the H-1 NMR spectra of diastereomeric 2-NPP amides recorded in polar NMR solvents.