(1S,3R,8R)-2,2-Dibromo-3,7,7,10-tetra-methyl-tricyclo-[6.4.0.0(1,3)]dodec-9-ene.

The title compound, C(16)H(24)Br(2), was synthesized from ß-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzocyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The mol-ecule is built up from two fused six- and seven-membered rings and an additional three-membered ring from the reaction of ß-himachalene with dibromo-carbene. The six-membered ring shows a screw-boat conformation, whereas the seven-membered ring displays a boat conformation; the dihedral angle between the mean planes through the rings is 57.9 (4)°. The absolute structure was established unambiguously from anomalous dispersion effects.

(1S,3R,8R,11S)-2,2-Dichloro-3,7,7,10-tetra-methyl-tricyclo-[6.4.0.0]dodec-9-en-11-ol.

The title compound, C(16)H(24)Cl(2)O, was synthesized from ß-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzocyclo-heptene), which was isolated from essential oil of the Atlas cedar (Cedrus atlantica). The two fused rings exhibit different conformations: the six-membered ring has a screw-boat conformation, while the seven-membered ring displays a boat conformation. The dihedral angle between the two rings is 56.56 (18)°. In the crystal, mol-ecules aggregate into supra-molecular chains along the c axis mediated by O-H⋯O hydrogen bonds.

(1S,3R,8R)-9-(1-Amino-ethyl-idene)-2,2-dichloro-3,7,7-trimethyl-tricyclo-[6.4.0.0]undecan-10-one.

The title compound, C(16)H(23)Cl(2)NO, was synthesised from ß-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzocyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The mol-ecule contains a seven membered ring, which is fused to a five- and a three-membered ring. The five-membered ring has a twisted conformation, whereas the seven-membered ring displays a chair conformation. The dihedral angle between the five- and seven-membered rings is 45.26 (9)°. The absolute structure was established unambiguously from anomalous dispersion effects. In the crystal, mol-ecules are linked into chains propagating along the b axis by inter-molecular N-H⋯O hydrogen bonds; an intramolecular N-H⋯O link also occurs.

7-Hy-droxy-8-isopropyl-1,1,4a-trimethyl-4a,9,10,10a-tetra-hydro-phenanthren-2(1H)-one.

The title compound, C(20)H(26)O(2), was isolated from a chloro-form extract of Tetra-clinis articulata wood. The mol-ecule contains three fused rings which exhibit different conformations. The non-aromatic oxo-substituted ring has a screw-boat conformation, while the central ring has a half-chair conformation. In the crystal, mol-ecules are linked to each other by inter-molecular O-H⋯O hydrogen bonds involving the carbonyl and hy-droxy groups.

2-Acetyl-3,5,5,9-tetra-methyl-6,7,8,9-tetra-hydro-5H-benzocyclo-hepten-7-one.

The title compound, C(17)H(22)O(2), was semi-synthesized from a mixture of α-atlantone (Z) and α-atlantone (E), which were isolated from the essential oil of the Atlas cedar (cedrus atlantica). The mol-ecule consists of fused six- and seven-membered rings. The seven-membered ring is in a screw-boat conformation.