We have developed an efficient diastereoselective synthetic route towards a nardosinane sesquiterpene scaffold. The strategy used a key bicyclic diene intermediate 11a, and allowed access to valuable polyoxygenated sesquiterpenes 21 and 22, which may be regarded as analogues of the natural sesquiterpenes laevinol B and fulvol acetate, respectively.

The title compound, C15H20O5, presents a bis­norsesquiterpene skeleton, with a trans-deca­line backbone constrained by the lactone bridge. The α-hy­droxy substituent and the methyl group belonging to the two deca­line rings are in axial positions, whereas the other methyl group and the acyl group occupy the sterically preferred equatorial positions. The mol­ecular structure is stabilized by an intra­molecular C—H⋯O hydrogen bond. In the crystal, mol­ecules are linked into chains along [010] by O—H⋯O hydrogen bonds