title: cis,cis-Germacranolides and melampolides from Mikania thapsoides.
abstract: The aerial parts of Mikania thapsoides afforded six new cis,cis-germacranolide-type sesquiterpene lactones (1-6), of which three (1-3) have an unusual 3,4-epoxy function, and also afforded two new melampolides (7 and 8). All compounds have a trans C-8 lactone ring closure. Their structures were elucidated using 1D and 2D NMR measurements, and the absolute configuration of 1 was determined using the Mosher ester method.
authors.affiliation: Instituto de Química Orgánica, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 491, S M de Tucumán, 4000, Argentina.
authors.forename: César A N
authors.initials: CA
authors.lastname: Catalán
authors.forename: María
authors.initials: M
authors.lastname: Del R  Cuenca
authors.forename: Luis R
authors.initials: LR
authors.lastname: Hernández
authors.forename: Pedro
authors.initials: P
authors.lastname: Joseph-Nathan
mesh_terms: D001118:Argentina; D003500:Cyclization; D007783:Lactones / Q000737:chemistry* / Q000302:isolation & purification*; D035742:Mikania / Q000737:chemistry*; D008968:Molecular Conformation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010946:Plants, Medicinal / Q000737:chemistry*; D045788:Sesquiterpenes, Germacrane / Q000737:chemistry* / Q000302:isolation & purification*; D013237:Stereoisomerism
chemical_list: D007783:Lactones; D045788:Sesquiterpenes, Germacrane