title: Hyperolactone C: determination of its absolute configuration by comparison of experimental and calculated CD spectra.
abstract: A detailed conformational analysis of hyperolactone C diastereomers and enantiomers ((5R,9R),(5S,9S) and (5S,9R),(5R,9S)) was done with molecular mechanics and density functional theory methods. Time-dependent density functional theory (B3PW91/TZVP) was used to calculate electronic transition energies (UV/vis spectra) and rotational strengths of the respective conformations. The effect of solvation (acetonitrile solution) on excitation energies and electronic circular dichroism was approximated by the polarizable continuum model. By comparison of the simulated CD spectrum with that measured for hyperolactone C isolated from Hypericum lloydii, its absolute configuration can be assigned as (5S,9S).
authors.affiliation: Institut für Pharmazeutische Wissenschaften--Pharmakognosie, Karl-Franzens Universität Graz, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schühly
authors.forename: Sara L
authors.initials: SL
authors.lastname: Crockett
authors.forename: Walter M F
authors.initials: WM
authors.lastname: Fabian
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D002942:Circular Dichroism; D004583:Electrons; D005663:Furans / Q000494:pharmacology*; D008956:Models, Chemical; D008958:Models, Molecular; D008962:Models, Theoretical; D008968:Molecular Conformation; D011487:Protein Conformation; D012997:Solvents / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D000097:Acetonitriles; D005663:Furans; D012997:Solvents; C488315:hyperolactone C; C032159:acetonitrile