title: Grindelane diterpenoids from Stevia subpubescens.
abstract: Four new 9R,13R-epoxylabdane diterpenes (1-4) and a known clerodane derivative, 3,4beta-epoxy-5beta,10beta-cis-17alpha, 20alpha-clerod-13(14)-en-15,16-olide, were isolated from the leaves of Stevia subpubescens. The structures, which correspond to the grindelane class of diterpenoids, were elucidated by NMR data, chemical correlation, and single-crystal X-ray diffraction analysis of monoacetate 5. The absolute configuration of 1-4 is based on the optical activity of ketone 3 as compared with data of closely related substances.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Apartado 137, Morelia, Michoacán, 58000 México.
authors.forename: L U
authors.initials: LU
authors.lastname: Román
authors.forename: J I
authors.initials: JI
authors.lastname: Cambrón
authors.forename: R E
authors.initials: RE
authors.lastname: del Río
authors.forename: J D
authors.initials: JD
authors.lastname: Hernández
authors.forename: C M
authors.initials: CM
authors.lastname: Cerda-García-Rojas
authors.forename: P
authors.initials: P
authors.lastname: Joseph-Nathan
mesh_terms: D000107:Acetylation; D019659:Asteraceae / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004224:Diterpenes / Q000737:chemistry*; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D013055:Spectrophotometry, Infrared
chemical_list: D004224:Diterpenes; D010936:Plant Extracts