ABSTRACT: The title compound {systematic name: (S)-1-[(2S,4aR,8aR)-2,4b,8,8-tetra-methyl-2,3,4,4a,4b,5,6,7,8,8a,9,10-dodeca-hydro-phenanthren-2-yl]ethane-1,2-diol}, C(20)H(34)O(2), is an ent-pimarane diterpenoid which was isolated from the stem bark of Ceriops tagal. In the asymmetric unit, there are two crystallographically independent mol-ecules, which are conformationally almost identical. In each mol-ecule, the two cyclo-hexane rings of the fused three-ring system adopt chair conformations, while the cyclo-hexene ring is in an envelope conformation, with the methylene C atom next to the side chain as the flap atom. In the crystal, mol-ecules are stacked in columns along the b axis through O-H⋯O hydrogen bonds.
