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

Acta Cryst. (2012). E68, o526–o527 (http://doi.org/fx56d4)

The title compound was isolated during our investigation into the chemical composition and bioactive constituents of Centipeda cunninghamii (Asteraceae), an Australian Aboriginal traditional medicine. The ent-kaurane possesses a carbon skeleton composed of three six- and one five-membered rings in a chair, twist-boat, half-chair and envelope conformation, respectively. Previous studies have established a relationship between the solution and crystal conformation of this structure class. The absolute stereochemistry of the enantiopure diterpene was established from the optical rotation measurements and comparison to the closely related grandiflorenic acid.