(3R,4S,5S,8S,10R,13R)-3-Hydroxykaura-9(11),16-dien-18-oic acid

Abstract

The title compound, C20H28O3, was isolated during our investigation into the chemical composition and pharmacological activity of Centipeda cunninghamii (DC.) A. Braun & Asch. (Asteraceae). The enantiopure compound, a diterpene with a carbon skeleton, is composed of three six- and one five-membered rings in chair, twist-boat, half-chair and envelope conformations, respectively. Each molecule makes one intra- and one intermolecular O—H...O hydrogen bond in the crystal lattice, forming hydrogen-bonded chains along [010]. The absolute configuration of the compound was assigned on the basis of optical rotation measurements.