Résumé: A stereoselective approach towards the synthesis of a (nor)nardosinane sesquiterpene scaffold is reported, going via a key dienic precursor. The synthetic route involved the introduction of four contiguous stereogenic centres onto the bicyclic backbone, and the diene intermediate was obtained in 14 % yield over seven steps from (S)-carvone.
Résumé: The title compound, C15H20O5, presents a bis-norsesquiterpene skeleton, with a trans-deca-line backbone constrained by the lactone bridge. The α-hy-droxy substituent and the methyl group belonging to the two deca-line rings are in axial positions, whereas the other methyl group and the acyl group occupy the sterically preferred equatorial positions. The mol-ecular structure is stabilized by an intra-molecular C-H⋯O hydrogen bond. In the crystal, mol-ecules are linked into chains along  by O-H⋯O hydrogen bonds.