title: Absolute configuration of labdanes and ent-clerodanes from Chromolaena pulchella by vibrational circular dichroism.
abstract: The aerial parts of Chromolaena pulchella biosynthesize two groups of diterpenes belonging to opposite enantiomeric series, specifically, the furanoid ent-clerodanes (5R,8R,9S,10R)-(-)-hardwikiic acid (1), methyl (5R,8R,9S,10R)-(-)-hardwikiate (2), (5S,8R,9S,10R)-(-)-hautriwaic acid lactone (3), methyl (5R,8R,9S,10R)-(-)-nidoresedate (4) and methyl (8R,9R)-(-)-strictate (5), as well as the labdanes (5S,8R,9R,10S)-(+)-(13E)-labd-13-ene-8,15-diol (6) and (5S,8R,9R,10S)-(+)-isoabienol (7). The absolute configuration of the two groups of diterpenes was unambiguously assigned by comparison of the vibrational circular dichroism spectra of 3 for ent-clerodanes, and of 7 for labdanes with their theoretical spectra obtained by density functional theory calculations. The results support a biogenetic proposal to diterpenes found in the studied botanical species.
authors.affiliation: Área Académica de Química, Universidad Autónoma del Estado de Hidalgo, Km 4.5 Carretera Pachuca-Tulancingo, Mineral de la Reforma, Hidalgo 42184, Mexico.
authors.forename: Mario A
authors.initials: MA
authors.lastname: Gómez-Hurtado
authors.forename: J Martín
authors.initials: JM
authors.lastname: Torres-Valencia
authors.forename: Jesús
authors.initials: J
authors.lastname: Manríquez-Torres
authors.forename: Rosa E
authors.initials: RE
authors.lastname: del Río
authors.forename: Virginia
authors.initials: V
authors.lastname: Motilva
authors.forename: Sofía
authors.initials: S
authors.lastname: García-Mauriño
authors.forename: Javier
authors.initials: J
authors.lastname: Avila
authors.forename: Elena
authors.initials: E
authors.lastname: Talero
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Cerda-García-Rojas
authors.forename: Pedro
authors.initials: P
authors.lastname: Joseph-Nathan
mesh_terms: D036604:Chromolaena / Q000737:chemistry*; D002942:Circular Dichroism / Q000379:methods*; D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification*; D045785:Diterpenes, Clerodane / Q000737:chemistry* / Q000302:isolation & purification*; D008800:Mexico; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D004224:Diterpenes; D045785:Diterpenes, Clerodane