(1S,3R,8R,9R,10S)-2,2-Dibromo-3,7,7,10-tetra­methyl-9β,10β-ep­oxy-3,7,7,10-tetra­methyl­tricyclo­[6.4.0.01,3]dodeca­ne

The title compound, C16H24Br2O, was synthesized from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzocyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus atlantica). The mol-ecule contains fused six- and seven-membered rings, each linked to a three-membered ring. The six-membered ring has a half-chair conformation, while the seven-membered ring displays a chair conformation. The dihedral angle between the mean planes through the six- and seven-membered rings is 39.55 (12)°. The two three-membered rings, linked to the six- and seven-membered rings, are nearly perpendicular to the six-membered ring, making dihedral angles of 78.6 (2) and 80.5 (2)°, respectively. The absolute structure was established unambiguously from anomalous dispersion effects. In the crystal, each mol-ecule is linked to its symmetry-equivalent partner by C-H⋯O hydrogen bonds, forming zigzag chains parallel to [100].