title: Gymnothelignans A-O: conformation and absolute configuration analyses of lignans bearing tetrahydrofuran from Gymnotheca chinensis.
abstract: Fifteen new lignans, gymnothelignans A-O (1-15), bearing tetrahydrofuran with variable conformations belonging to three potentially related skeletons were isolated from  Gymnotheca chinensis  Decne. The structures were elucidated by means of detailed spectroscopic analysis. Absolute configurations were assigned using X-ray single-crystal diffraction and chemical transformations. Moreover, by the homology, compounds 1-11 and eupomatilones were confirmed to have uniform R-configuration at C-5. However, a synthesized congener has long been mistaken as 5-epimer of eupomatilone-6. This work provides guidance for the absolute configuration establishment of the subeupomatilone family with trans-H-4-H-5 configuration.
authors.affiliation: Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China.
authors.forename: Dahai
authors.initials: D
authors.lastname: He
authors.forename: Lisheng
authors.initials: L
authors.lastname: Ding
authors.forename: Hongxi
authors.initials: H
authors.lastname: Xu
authors.forename: Xinxiang
authors.initials: X
authors.lastname: Lei
authors.forename: Hongping
authors.initials: H
authors.lastname: Xiao
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry*; D001688:Biological Products / Q000032:analysis* / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005663:Furans / Q000737:chemistry*; D017705:Lignans / Q000032:analysis* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D001572:Benzofurans; D001688:Biological Products; D005663:Furans; D017705:Lignans; C485126:eupomatilone-6; C018674:tetrahydrofuran