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Absolute Configuration of Oplopanone Derivatives From Serphidium stenocephalum : ECD Spectra of Acyclic Ketones With Front‐Octant Contributions
Author(s) -
Shafiq Nusrat,
Saleem Muhammad,
Riaz Naheed,
Tousif Muhammad Imran,
Jabbar Abdul,
Tareen Rasool Bakhsh,
Pescitelli Gennaro
Publication year - 2014
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.22263
Subject(s) - octant (instrument) , chemistry , time dependent density functional theory , absolute configuration , chirality (physics) , ketone , spectral line , vibrational circular dichroism , stereochemistry , density functional theory , circular dichroism , computational chemistry , organic chemistry , quantum mechanics , optics , physics , nambu–jona lasinio model , chiral symmetry breaking , quark
The electronic circular dichroism (ECD) spectra of two sesquiterpenoids ( 1 and 2 ) related to oplopanone, obtained from a methanolic extract of the plant Serphidium stenocephalum ( Artemisia stenocephala ), were measured and reproduced by means of time‐dependent density functional theory (TDDFT) calculations, establishing their absolute configuration. The application of ketone octant rule for carbonyl n‐π* ECD band to compounds 1 and 2 , which include an acyclic carbonyl group, was critically assessed. The peculiar oplopanone skeleton makes a straightforward application of the octant rule impossible, because of the uncertainty related to the shape of the so‐called third nodal surface separating front and back octants. The various group contributions to the carbonyl n‐π* ECD band were estimated with TDDFT calculations on selected molecular models obtained by consecutive dissections from 1 . Chirality 26:39–43, 2013. © 2013 Wiley Periodicals, Inc.