(1R,4R,6S,7S)-5,5-Di­chloro-1,4,8,8-tetra­methyl­tri­cyclo­[5.4.1^1,7.0^4,6]dodecan-12-one

The title compound, C₁₆H₂₄Cl₂O, was synthesized in three steps from β-himachalene (3,5,5,9-tetra­methyl-2,4a,5,6,7,8-hexa­hydro-1H-benzo­cyclo­heptene), which was isolated from essential oil of the Atlas cedar (cedrus atlantica). The asymmetric unit contains two independent mol­ecules with similar conformations. Each mol­ecule is built up from two fused seven-membered rings and an additional three-membered ring arising from the reaction of himachalene with di­chloro­carbene. The dihedral angles between the mean planes of the two seven-membered rings are 75.03 (9) and 75.02 (9)° in the two independent mol­ecules.