title: Verticillane derivatives from Bursera suntui and Bursera kerberi.
abstract: The stems of Bursera suntui afforded two new verticillane derivatives, (1S,3Z,7E,11S,12S)-(+)-verticilla-3,7-dien-12,20-diol (1) and (1S,3Z,7E,11S,12S)-(+)-verticilla-3,7-dien-12,20-diol 20-acetate (2), together with (1S,3E,7E,11R)-(+)-verticilla-3,7,12(18)-triene (3), (1R,3E,7E,11R,12Z)-(+)-verticilla-3,7,12-triene (4), (1R,7E,11Z)-(-)-verticilla-4(20),7,11-triene (5), and (1S,3E,7E,11S,12S)-(+)-verticilla-3,7-dien-12-ol (6). Compounds 3 and 4 are new enantiomerically pure natural products whose racemic mixtures, derived from synthetic approaches toward the taxane skeleton, were obtained previously. The stems of Bursera kerberi afforded the new (1S,3E,7E,11S,12R)-(+)-verticilla-3,7-dien-12-ol (7) together with 3-5. This is the first time that verticillane derivatives have been isolated from the genus Bursera. Their structures and stereochemistry were elucidated by 1D and 2D NMR data, including COSY, NOESY, HSQC, and HMBC experiments, while the absolute configuration was determined by comparison of the optical rotatory dispersion data with that of recently revised (1S,3E,7E,11S,12S)-(+)-verticilla-3,7-dien-12-ol (6), obtained from Sciadopitys verticillata, and those of (1R,3E,7E,11R,12R)-(-)-verticilla-3,7-dien-12-ol (8) and (1R,3E,7E,11R,12S)-(-)-verticilla-3,7-dien-12-ol (9), isolated from the liverwort Jackiella javanica. The conformational preferences of 1-7 were studied by molecular mechanics modeling employing the Monte Carlo protocol.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Apartado 137, Morelia, Michoacán, 58000 Mexico. jdiego@zeus.umich.mx
authors.forename: Juan D
authors.initials: JD
authors.lastname: Hernández-Hernández
authors.forename: Luisa U
authors.initials: LU
authors.lastname: Román-Marín
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Cerda-García-Rojas
authors.forename: Pedro
authors.initials: P
authors.lastname: Joseph-Nathan
mesh_terms: D031233:Bursera / Q000737:chemistry*; D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification*; D008800:Mexico; D008968:Molecular Conformation; D015394:Molecular Structure; D018547:Plant Stems / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C506376:(1S,3Z,7E,11S,12S)-(+)-verticilla-3,7-dien-12,20-diol; D004224:Diterpenes