title: Heliespirones B and C: two new plant heliespiranes with a novel spiro heterocyclic sesquiterpene skeleton.
abstract: From the medium, polar bioactive fractions of leaf aqueous extract of Helianthus annuus L., heliespirones B (2) and C (3) have been isolated. The structural elucidation was based on extensive spectral studies. A probable biogenesis of heliespirone skeleton is proposed and discussed. The structure of heliespirone B has been confirmed by X-ray diffraction analysis.
authors.affiliation: Grupo de Alelopatía, Departamento de Química Organica, Universidad de Cadiz, Facultad de Ciencias, C/República Saharaui s/n, 11510 Puerto Real, Cadiz, Spain.
authors.forename: Francisco A
authors.initials: FA
authors.lastname: Macías
authors.forename: José L G
authors.initials: JL
authors.lastname: Galindo
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Varela
authors.forename: Ascensión
authors.initials: A
authors.lastname: Torres
authors.forename: José M G
authors.initials: JM
authors.lastname: Molinillo
authors.forename: Frank R
authors.initials: FR
authors.lastname: Fronczek
mesh_terms: D016227:Benzoquinones / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006571:Heterocyclic Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010944:Plants / Q000737:chemistry*; D012717:Sesquiterpenes / Q000737:chemistry*
chemical_list: D016227:Benzoquinones; D006571:Heterocyclic Compounds; D012717:Sesquiterpenes; C520940:heliespirone B; C520941:heliespirone C