title: Amoenolide A and related acetylated labdane diterpenes from Amphiachyris amoena.
abstract: Four new labdane diterpenes, amoenolide A [1] and its 19-acetate [2], 6-acetate [3], and 6,19-diacetate [4], were isolated from the above-ground parts of Amphiachyris amoena and their structures established by spectral and chemical methods. High-field 1H- and 13C-nmr assignments were made for each compound using 1D and 2D nmr techniques including 1H single-frequency spin-coupling and nOe difference experiments, one-bond and long-range carbon-hydrogen correlations, and the INADEQUATE carbon-carbon connectivity experiment. The absolute stereochemistry was established by the Horeau partial-resolution chemical method with amoenolide A and racemic 2-phenylbutyric anhydride, and by the cd exciton splitting physical method on the synthetic amoenolide A 2-acetate 6,19-dibenzoate [9].
authors.affiliation: Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, Ohio State University, Columbus 43210-1291.
authors.forename: D P
authors.initials: DP
authors.lastname: O'Mathúna
authors.forename: R W
authors.initials: RW
authors.lastname: Doskotch
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification; D000107:Acetylation; D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009284:Naphthols / Q000737:chemistry* / Q000302:isolation & purification; D010946:Plants, Medicinal / Q000737:chemistry*
chemical_list: D004224:Diterpenes; D009284:Naphthols; C089561:amoenolide A; D015107:4-Butyrolactone