(1R,3S,8R)-3,7,7,10-Tetramethyltricyclo[6.4.0.01,3]dodec-9-en-11-one

The absolute configuration of the title compound, C16H24O, has been deduced from the chemical pathway. The six-membered ring has a roughly half-chair conformation with the quaternary C atom as the flap. The seven-membered ring displays a chair conformation. In the crystal, there is a weak C—H⋯O hydrogen bond between the methylene group of the cyclopropane ring and the carbonyl group of a screw-axis-related molecule, which builds up a zigzag-like chain along the b-axis direction.

The absolute configuration of the title compound, C 16 H 24 O, has been deduced from the chemical pathway. The sixmembered ring has a roughly half-chair conformation with the quaternary C atom as the flap. The seven-membered ring displays a chair conformation. In the crystal, there is a weak C-HÁ Á ÁO hydrogen bond between the methylene group of the cyclopropane ring and the carbonyl group of a screw-axisrelated molecule, which builds up a zigzag-like chain along the b-axis direction.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FY2107).
A view of the molecule is represented in Fig. 1. As observed in related compounds (Gassman & Gorman, 1990;Lassaba et al., 1997;Benharref et al., 2012), each molecule is built up from two fused six-and seven-membered rings. The sixmembered ring has roughly half-chair conformation with the puckering parameters: Q = 0.4166 (11)  There is a weak C-H···O hydrogen bond, which builds up a zigzag-like chain developing along the b axis (Table 1, Fig. 2)
In the absence of significant anomalous scattering, the absolute configuration could not be reliably determined and any references to the Flack parameter were removed. The 0 0 1 reflection appears affected by the beam stop and it has been removed.

Figure 1
The asymmetric unit of (I) with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small spheres of arbitrary radii.