title: Biscembranoids formed from an α,β-unsaturated γ-lactone ring as a dienophile: structure revision and establishment of their absolute configurations using theoretical calculations of electronic circular dichroism spectra.
abstract: Four new biscembranoids, bislatumlides C-F (1-4), were isolated from the Hainan soft coral Sarcophyton latum . Their structures were elucidated by detailed analysis of spectroscopic data and by comparison with reported data of related derivatives, leading to the structure revision of co-occurring bislatumlides A (5) and B (6) at the C-21 configuration. The absolute configurations of bislatumlides C and E (1 and 3) were determined by TDDFT calculations of their solution ECD spectra, allowing the configurational assignment of the related bislatumlides D and F (2 and 4) and A and B (5 and 6) as well. Bislatumlides A-F (1-6) represent the only biscembranoids formed by the undescribed coupling pattern of Diels-Alder cycloaddition between the Δ(1(2)) double bond involving an α,β-unsaturated γ-lactone ring as a dienophile group and a trisubstituted conjugated Δ(21(34))/Δ(35(36))-butadiene moiety. An endo-cycloaddition gave 1, 2, 5, and 6, whereas an exo-cycloaddition produced 3 and 4. This is the first report of exo-addition dicembranoids from marine sources and from nature. Bislatumlides C and E (1, 3) could be used as ECD reference compounds in the determination of absolute configuration for related derivatives.
authors: State Key Laboratory of Drug Research, Institute of Materia Medica, Chinese Academy of Sciences, Zu Chong Zi Rd. 555, Zhangjiang Hi-Tech Park, Shanghai 201203, P. R. China.
authors: Rui
authors: R
authors: Jia
authors: Tibor
authors: T
authors: Kurtán
authors: Attila
authors: A
authors: Mándi
authors: Xiao-Hong
authors: XH
authors: Yan
authors: Wen
authors: W
authors: Zhang
authors: Yue-Wei
authors: YW
authors: Guo
mesh_terms: D000818:Animals; D037421:Anthozoa; D002942:Circular Dichroism; D004224:Diterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D004583:Electrons; D007783:Lactones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011789:Quantum Theory
chemical_list: D004224:Diterpenes; D007783:Lactones; C544693:cembra-2,7,11-triene-4,6-diol