1-[(1S,6R,7S,9R)-8,8-Di-bromo-5,5,9-tri-methyl-tri-cyclo-[4.4.0.1(7,9)]decan-1-yl]ethanone

The title compound, C16H24Br2O, was synthesized by three steps from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from essential oil of the Atlas cedar cedrus atlantica. The asymmetric unit contains two independent mol-ecules with almost identical conformations. Each mol-ecule is built up from two fused six-membered rings, one having a chair conformation and the other a boat conformation, and an additional three-membered ring arising from the reaction of himachalene with di-bromo-carbene. In the crystal, there are no significant intermolecular interactions present. The absolute structure of the title compound was confirmed by resonance scattering.