ent-(15S)-Pimar-8(14)-ene-15,16-diol.

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.

Dammarane triterpenes from the hypocotyls and fruits of Ceriops tagal.

Three new dammarane triterpenes, cereotagaloperoxide, cereotagalol A, and cereotagalol B, together with four known dammarane triterpenes, an oleanane triterpene, and 13 known lupane triterpenes were isolated from the hypocotyls and fruits of Ceriops tagal. The structures of 1-3 were characterized on the basis of their spectroscopic data.