N-(2-Nitrophenyl)proline: an intramolecular hydrogen bond forming reagent for the determination of the absolute configuration of primary amines.

N-(2-Nitrophenyl)proline (2-NPP) amides of primary amines have a conformational preference for intramolecular hydrogen bonding. Because of the strong and selective anisotropic effects on the amine substituents, the absolute configuration of alpha-chiral primary amines can be assigned by comparing the 1H chemical shifts of diastereomeric 2-NPP amides.