7-Ethenyl-1-[(Z)-hydroxymethylidene]-4b,7,10a-trimethylperhydrophenanthren-2-one

Abstract

The title compound, C20H30O2, also known as tagalsin F, is a diterpenoid which was isolated from Ceriops tagal (Perr.). One of the three fused cyclo­hexane rings adopts a half-chair conformation and the other two cyclo­hexane rings are in standard chair conformations. The hydroxy­methyl­idene substituent is attached to the half-chair cyclo­hexane. The mol­ecular structure is stabilized by intra­molecular O—H⋯O hydrogen bonds and weak inter­molecular C—H⋯O inter­actions. In the crystal structure, mol­ecules are arranged alternately in a head-to-tail and tail-to-head fashion along the b axis.