(1 R ,4 R ,6 S ,7 S )-5,5-Dichloro-1,4,8,8-tetramethyltricyclo[5.4.1 1,7 .0 4,6 ]dodecan-12-one

The title compound, C 16 H 24 Cl 2 O, was synthesized in three steps from β-himachalene (3,5,5,9-tetramethyl-2,4a,5,6,7,8-hexahydro-1 H -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.