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A method was developed for the synthesis of selectively labeled [15N]indole, allowing to obtain the target product with high chemical and isotopic purity. One-dimensional and two-dimensional 1H, 13C, and 15N NMR spectra were examined. The chemical shifts of 1H, 13C, and 15N nuclei were determined, as well as the spin-spin coupling constants of 15N nucleus and the isotopic chemical shifts of 13C nuclei for [15N]indole in CD3CN solution, caused by the replacement of 14N nucleus with a 15N nucleus. It was demonstrated that isotopic shifts of this type can provide important structural information. The NMR data set obtained in the current work can serve as an important reference point for establishing the structures of new aromatic heterocycles. [ABSTRACT FROM AUTHOR]

The fine multiplet structure of the 1H NMR spectrum and the proton-coupled 15N NMR spectrum of indole was solved. A complete set of 1H–1H and 1H–15N coupling constants for [15N]indole in CD3CN solution was acquired with high accuracy. Ab initio quantum-chemical calculations of coupling constants with the DFT/B3LYP method showed a high level of agreement between the calculated and experimental values. The obtained data could serve as a reliable starting point for establishing the structure of new nitrogen-containing aromatic heterocycles. [ABSTRACT FROM AUTHOR]