title: 8β-Eth-oxy-eremophil-3,7(11)-diene-8α,12;6α,15-diolide.
abstract: The title compound, C17H20O5, an eremophilane sesquiternoid, was isolated from the roots of Ligularia lapathifolia. The mol-ecule contains four fused rings of which the six-membered ring A adopts a half-chair conformation, the six-membered ring B adopts a chair conformation, the five-membered ring C is almost planar (r.m.s. deviation = 0.015 Å) and the five-membered ring D adopts an envelope conformation with the quaternary C atom as the flap. The methyl and the eth-oxy groups adopt a syn conformation and the A/B ring junction is cis-fused. No directional inter-molecular inter-actions could be identified in the crystal.
authors.affiliation: School of Pharmacy, Lanzhou University, Lanzhou 730000, People's Republic of China.
authors.forename: Dong-Qing
authors.initials: DQ
authors.lastname: Fei
authors.forename: Le-Le
authors.initials: LL
authors.lastname: Dong
authors.forename: Hui-Hong
authors.initials: HH
authors.lastname: Li
authors.forename: Zhan-Xin
authors.initials: ZX
authors.lastname: Zhang
references.citation: J Nat Prod. 2007 Feb;70(2):241-5
references.pmid: 17284071
references.citation: Acta Crystallogr A. 2008 Jan;64(Pt 1):112-22
references.pmid: 18156677