15α,20β-Dihydroxy-6β-methoxy-6,7-seco-6,20-epoxy-1,7-olide-ent-kaur-16-ene

Abstract

The title compound, C21H30O6, a natural ent-kaurane diterpenoid, was obtained from the medicinal plant Isodon serra. The five rings in the molecule exhibit the expected cis and trans junctions. The three six-membered rings adopt chair, twist-boat and boat conformations, while two five-membered rings adopt envelope conformations. There are two molecules in the asymmetric unit, related by a non-crystallographic twofold screw axis; the main difference is in the different degrees of distortion of ring B. In the crystal, the molecules are linked by intermolecular O—H...O hydrogen bonds, forming chains along the b axis.