title: Three new guaianolides from Siyekucai (Ixeris chinenseis).
abstract: Three new guaianolides, 10alpha-hydroxy-3-oxoguaia-4(15),11(13)-dieno-12,6alpha-lactone (1), 10alpha-hydroxy-3-oxo-4betaH-guaia-11(13)-eno-12,6alpha-lactone (2), and 10alpha-hydroxy-3-oxoguaia-4,11(13)-dieno-12,6alpha-lactone (3), named chinensiolides A, B, and C were isolated from the whole plant of Siyekucai (Ixeris chinensis). The structures were determined by HREIMS, UV, IR, and one- and two-dimensional NMR techniques ((1)H and (13)C NMR, COSY, HMQC, HMBC, and NOE difference and NOESY experiments). Compounds 1 and 2 were indicated to be a mixture of flexible conformers by analyses of their 1D NOE and NOESY spectra as well as the temperature dependence of their (1)H and (13)C NMR spectra. Chinensiolide B (2) was transformed to chinensiolide C (3) in a three-step conversion.
authors.affiliation: Graduate School of Science and Technology and Department of Chemistry and Chemical Engineering, Niigata University, Ikarashi, 2-8050, Niigata 950-2181, Japan.
authors.forename: Shujun
authors.initials: S
authors.lastname: Zhang
authors.forename: Jinlan
authors.initials: J
authors.lastname: Wang
authors.forename: Hongyan
authors.initials: H
authors.lastname: Xue
authors.forename: Qigang
authors.initials: Q
authors.lastname: Deng
authors.forename: Fenglan
authors.initials: F
authors.lastname: Xing
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Ando
mesh_terms: D019659:Asteraceae / Q000737:chemistry*; D002384:Catalysis; D002681:China; D007783:Lactones / Q000737:chemistry* / Q000302:isolation & purification*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D012717:Sesquiterpenes / Q000737:chemistry* / Q000302:isolation & purification*; D013696:Temperature
chemical_list: D007783:Lactones; D012717:Sesquiterpenes; C473438:chinensiolide A; C473439:chinensiolide C