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The Prediction of the Absolute Stereochemistry of Primary and Secondary 1,2‐Diols by 1 H NMR Spectroscopy: Principles and Applications
Author(s) -
Freire Félix,
Seco José M.,
Quiñoá Emilio,
Riguera Ricardo
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500181
Subject(s) - absolute configuration , chemistry , diol , spectroscopy , asymmetric carbon , circular dichroism , coupling constant , nmr spectra database , nuclear magnetic resonance spectroscopy , spectral line , deuterium , chemical shift , stereochemistry , crystallography , organic chemistry , optically active , atomic physics , physics , particle physics , quantum mechanics , astronomy
The absolute configuration of 1,2‐diols formed by a primary and a secondary (chiral) hydroxyl group can be deduced by comparison of the 1 H NMR spectra of the corresponding ( R )‐ and bis‐( S )‐MPA esters (MPA=methoxyphenylacetic acid). This method involves the use of the chemical shifts of substituents L 1 /L 2 attached to the secondary (chiral) carbon, and of the hydrogen atom linked to the chiral center (CαH) as diagnostic signals. Theoretical (AM1, HF, and B3 LYP calculations) and experimental data (dynamic and low‐temperature NMR spectroscopy, studies on deuterated derivatives, constant coupling analysis, circular dichroism (CD) spectra, and NMR studies with a number of diols of known absolute configuration) prove that the signs of the Δ δ RS obtained for those signals correlate with the absolute configuration of the diol. A graphical model for the reliable assignment of the absolute configuration of a 1,2‐diol by comparison of the NMR spectra of its bis‐( R )‐ and bis‐( S )‐MPA esters is presented.