title: BI- and tricyclic diterpenoids from Halimium viscosum.
abstract: The study of the acid and neutral parts of the n-hexane extract of Halimium viscosum (S. João da Pesqueira, Portugal) has led to the isolation of various known diterpenoids with the ent-halimane skeleton. Five new compounds have now been isolated, one with the ent-halimane skeleton, and four with the valparane skeleton, two of them with the valparane skeleton degraded. The structures of these compounds, determined by spectroscopic methods using 2D experiments (1H-13C, HMQC and HMBC), were dimethyl 1(10)-halimen-15,18-dioate, dimethyl 3,19-dinor-15-valparen-2,4-dioate, methyl 16-nor-2,3-secovalpara-3,15-dioxo-2-oate, 1,3,5,1 5-valparatetraene and 3R-4alpha-methoxy-15-valparen-2-one.
authors.affiliation: Departmento de Química, Universidade da Beira Interior, Covilhã, Portugal.
authors.forename: J M
authors.initials: JM
authors.lastname: Rodilla
authors.forename: D I
authors.initials: DI
authors.lastname: De Mendonça
authors.forename: M I
authors.initials: MI
authors.lastname: Ismael
authors.forename: J A
authors.initials: JA
authors.lastname: Figueiredo
authors.forename: M L
authors.initials: ML
authors.lastname: Silva
authors.forename: E
authors.initials: E
authors.lastname: Lopes
mesh_terms: D030601:Cistaceae / Q000737:chemistry*; D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification*; D008401:Gas Chromatography-Mass Spectrometry; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010946:Plants, Medicinal / Q000737:chemistry*; D011174:Portugal; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D004224:Diterpenes