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A NMR investigation of proline and its derivatives. II—Conformational implications of the 1 H NMR spectrum of L‐proline at different pH
Author(s) -
Pogliani L.,
Ellenberger M.,
Valat J.
Publication year - 1975
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270070202
Subject(s) - geminal , chemistry , intramolecular force , vicinal , chemical shift , coupling constant , nmr spectra database , proline , carbon 13 nmr satellite , spectral line , stereochemistry , computational chemistry , crystallography , nuclear magnetic resonance spectroscopy , fluorine 19 nmr , organic chemistry , amino acid , physics , biochemistry , particle physics , astronomy
The 250 MHz 1 H NMR spectrum of L ‐proline is comprehensively analysed by computer simulation for different pH values. A fast endo – exo interconversion has already been proposed from chemical shift and coupling constant data. A critical comparison of the vicinal coupling constants leads to the conclusion that in basic solution the equilibrium is shifted towards a more endo conformation. The position of the carboxylic plane in the ring space is given by the relative intramolecular chemical shift of the geminal protons and by the typical patterns of the H α multiplet. These results are applied to the analysis of the spectra of ProNH 2 and AcProNH 2 .