(1S,3R,8R,11S)-11-Bromo-10-bromo-methyl-2,2-di-chloro-3,7,7-tri-methyl-tricyclo-[6.4.0.0(1,3)]dodec-9-ene.

The title compound, C16H22Br2Cl2, was synthesized from β-him-achalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The mol-ecule is built up from fused six- and seven-membered rings and an appended three-membered ring. The six-membered ring has a half-chair conformation, whereas the seven-membered ring displays a chair conformation. The dihedral angle between the two best plane through each ring is 59.5 (2)°. No specific inter-molecular inter-actions were discerned in the crystal packing.