title: Structural revision of stemoburkilline from an E-alkene to a Z-alkene.
abstract: Semisynthesis studies starting from (11Z)-1',2'-didehydrostemofoline (4) indicated that the known Stemona alkaloid stemoburkilline is the Z-isomer and not the E-isomer as initially reported. The semisynthesis involved conversion of (11Z)-1',2'-didehydrostemofoline (4) to 11(S),12(S)-dihydrostemofoline (3) followed by a stereoselective base-catalyzed ring-opening reaction to give (Z)-stemoburkilline (8). The same product was obtained using a similar synthetic protocol starting from isostemofoline (6) via a based-catalyzed ring-opening reaction of 11(S),12(R)-dihydrostemofoline (1). A re-examination of the crude root extracts of Stemona burkillii Prain and further NOE studies established stemoburkilline as the Z-isomer (8).
authors.affiliation: School of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia.
authors.forename: Kwankamol
authors.initials: K
authors.lastname: Sastraruji
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Pyne
authors.forename: Alison T
authors.initials: AT
authors.lastname: Ung
authors.forename: Pitchaya
authors.initials: P
authors.lastname: Mungkornasawakul
authors.forename: Wilford
authors.initials: W
authors.lastname: Lie
authors.forename: Araya
authors.initials: A
authors.lastname: Jatisatienr
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D000475:Alkenes / Q000737:chemistry*; D005663:Furans / Q000737:chemistry*; D006576:Heterocyclic Compounds, 4 or More Rings / Q000737:chemistry*; D015394:Molecular Structure; D041901:Stemonaceae / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: C493706:11(S),12(R)-dihydrostemofoline; D000470:Alkaloids; D000475:Alkenes; D005663:Furans; D006576:Heterocyclic Compounds, 4 or More Rings; C481859:didehydrostemofoline; C493707:stemoburkilline