title: Cassane diterpenes from Caesalpinia platyloba.
abstract: The dichloromethane extract from the leaves of Caesalpinia platyloba provided cassane diterpenes whose structures were determined as (-)-(5S,6R,8S,9S,10R,14R)-6-acetoxyvouacapane (1), (-)-(5S,6R,8S,9S,10R,12Z,14R)-6-acetoxycassa-12,15-diene (3), and (-)-(5S,6R,8S,9S,10R,13E)-6-acetoxycassa-13,15-diene (4). Compound 1 was chemically correlated with (-)-(5S,6R,8S,9S,10R,14R)-6-hydroxyvouacapane (2), (+)-(5S,8S,9S,10R,14R)-6-oxovouacapane (5), and (+)-(5S,6S,8S,9S,10R,14R)-6-acetoxyvouacapane (6), the last one previously isolated from Dipteryx lacunifera. The absolute configurations of all six diterpenes 1-6 were established by comparison of DFT calculated vibrational circular dicroism spectra of 1, 2 and 5 with those obtained experimentally. In addition, several reported chemical shifts for 2 and 5 were reassigned based on two-dimensional NMR measurements.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B-1, Ciudad Universitaria, Morelia, Michoacán 58030, Mexico.
authors.forename: Mario A
authors.initials: MA
authors.lastname: Gómez-Hurtado
authors.forename: Fany E
authors.initials: FE
authors.lastname: Álvarez-Esquivel
authors.forename: Gabriela
authors.initials: G
authors.lastname: Rodríguez-García
authors.forename: Mauro M
authors.initials: MM
authors.lastname: Martínez-Pacheco
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Espinoza-Madrigal
authors.forename: Teresa
authors.initials: T
authors.lastname: Pamatz-Bolaños
authors.forename: José L
authors.initials: JL
authors.lastname: Salvador-Hernández
authors.forename: Hugo A
authors.initials: HA
authors.lastname: García-Gutiérrez
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Cerda-García-Rojas
authors.forename: Pedro
authors.initials: P
authors.lastname: Joseph-Nathan
authors.forename: Rosa E
authors.initials: RE
authors.lastname: del Río
mesh_terms: D029911:Caesalpinia / Q000737:chemistry*; D002942:Circular Dichroism; D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification*; D008800:Mexico; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D004224:Diterpenes
keywords: Absolute configuration; Caesalpinia platyloba; Cassane diterpenes; Density functional theory calculations; Fabaceae; Vibrational circular dichroism; Vouacapane derivatives