title: Observation of diastereotopic signals in (15) N NMR spectroscopy.
abstract: The first example in the literature of a compound showing anisochronous (15) N atoms resulting from diastereotopicity is described. Racemic 1,3-dimethyl-2-phenyloctahydro-1H-benzimidazole was prepared and studied by (1) H, (13) C and (15) N NMR spectroscopy. If convenient conditions were used (monitored by theoretical calculations of (2) JN-H spin-spin coupling constants), two (15) N NMR signals were observed and corresponded to the diastereotopic atoms. GIAO/density-functional calculations of chemical shifts were not only in good agreement with the experimental values but also served as prediction tools. This study suggests that (15) N NMR spectroscopy could be used to probe chirality.
authors: Instituto de Química Médica, IQM-CSIC, Consejo Superior de Investigaciones Científicas, Juan de la Cierva, 3, 28006 Madrid (Spain).
authors: Ibon
authors: I
authors: Alkorta
authors: Christophe
authors: C
authors: Dardonville
authors: José
authors: J
authors: Elguero
keywords: NMR spectroscopy; analytical methods; chirality; density functional calculations; nitrogen heterocycles