Cassane diterpenes from Caesalpinia platyloba

• Published in: Phytochemistry (Oxford) 2013-12, Vol.96, p.397-403
• Main Authors: Gómez-Hurtado, Mario A., Álvarez-Esquivel, Fany E., Rodríguez-García, Gabriela, Martínez-Pacheco, Mauro M., Espinoza-Madrigal, Rosa M., Pamatz-Bolaños, Teresa, Salvador-Hernández, José L., García-Gutiérrez, Hugo A., Cerda-García-Rojas, Carlos M., Joseph-Nathan, Pedro, del Río, Rosa E.
• Format: Article
• Language: English
• Subjects: Absolute configuration; Caesalpinia; Caesalpinia - chemistry; Caesalpinia platyloba; Cassane diterpenes; Circular Dichroism; Density functional theory calculations; Dipteryx; Diterpenes - chemistry; Diterpenes - isolation & purification; diterpenoids; Fabaceae; leaves; methylene chloride; Mexico; Molecular Structure; nuclear magnetic resonance spectroscopy; Plant Leaves - chemistry; Stereoisomerism; Vibrational circular dichroism; Vouacapane derivatives
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2013.09.028

Leaves of Caesalpinia platyloba afforded three cassane diterpenes whose absolute configuration was ascertained by vibrational circular dichroism. Compound 1 was also chemically correlated with diterpenes from Dipteryx lacunifera. •Leaves of Caesalpinia platyloba provided cassane diterpenes.•Vibrational circular dichroism assigned their absolute configurations.•A chemical correlation with a vouacapane from Dipteryx lacunifera was carried out. 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.