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Unambiguous assignment of the 13 C NMR spectra of methylindoles
Author(s) -
MoralesRíos M. S.,
Del Río R. E.,
JosephNathan P.
Publication year - 1988
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260260705
Subject(s) - chemistry , homonuclear molecule , heteronuclear molecule , hydrogen bond , carbon 13 nmr , spectral line , nmr spectra database , pyrrole , carbon 13 nmr satellite , proton nmr , ring (chemistry) , solvent , chemical shift , crystallography , computational chemistry , stereochemistry , nuclear magnetic resonance spectroscopy , molecule , fluorine 19 nmr , organic chemistry , physics , astronomy
Abstract The 13 C NMR spectra of all possible indoles substituted with one, two or three methyl groups on the pyrrole ring were assigned from heteronuclear two‐dimensional 13 C/ 1 H contour plots and homonuclear hydrogen‐hydrogen decoupling experiments at a specific concentration of 0.83 M in CDCl 3 and in DMSO‐ d 6 . The results confirm controversial assignments for some compounds, and provide the assignments for those compounds not previously studied by this technique. In addition, d euterium/ h ydrogen NMR i sotope e ffect on 13 C c hemical s hifts (DHIECS) for indoles, wherein the labile NH was partially exchanged to ND, are reported. In this way DHIECS values over two, three, four and five bonds were measured. The results in each solvent are discussed in terms of the number of bonds between the exchanged hydrogen and the observed carbon, and also according to their geometric dependence. This provides some evidence of the vibrational origin of the DHIECS.