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Revisiting empirical rules for the determination of the absolute configuration of cascarosides and other (ox‐)anthrones
Author(s) -
Demarque Daniel P.,
Pinho Danielle R.,
Lopes Norberto P.,
Merten Christian
Publication year - 2018
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.22803
Subject(s) - stereocenter , chemistry , absolute configuration , vibrational circular dichroism , circular dichroism , diastereomer , spectral line , molecule , stereospecificity , computational chemistry , stereochemistry , organic chemistry , quantum mechanics , physics , enantioselective synthesis , catalysis
The introduction of the C 10 ‐stereocenter of (ox‐)anthrones by plant organisms is not stereospecific. Consequently, often, both (10S)‐ and (10R)‐diastereomers can be found in the same plant. Motivated by the importance of a correct assignment of the configuration at C 10 , this study revisits the nuclear magnetic resonance and electronic circular dichroism‐based empirical rules for the determination of the absolute configuration by molecular dynamic simulations and electronic circular dichroism spectrum calculations. Furthermore, a vibrational circular dichroism spectroscopic characterization of these large and conformationally very flexible molecules reveals spectral signatures, which can be used to specifically distinguish the C 10 stereochemistry. A detailed analysis of the underlying vibrational modes suggests that the observed spectral pattern of the investigated cascarosides may be generally characteristic for the C 10 ‐stereocenter of (ox‐)anthrones and that they can be used for empirical spectra‐structure correlations.