In the title compound, C(37)H(34)N(2)O(2), the pyridinone ring adopts a half-chair conformation. In the octa-hydro-indolizine fused-ring system, the piperidine ring is in a chair conformation and the pyrrole ring is twisted about the N-C(piperidine) bond. The mol-ecular structure features a weak intra-molecular C-H⋯O inter-action.

The mol-ecule of title compound, C(39)H(56)O(5), contains five fused six-membered rings, four of which (rings A, B, D and E) adopt a chair conformation, while the other (ring C) has a half chair conformation. The acet-oxy and carb-oxy-benzyl groups occupy equatorial positions.

In the title compound, C(21)H(30)O(3), the five-membered ring adopts an envelope conformation, the cyclo-hexene ring displays a half-chair conformation and the two cyclo-hexane rings have normal chair conformations. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonding links the mol-ecules into supra-molecular chains running along [100].

In the title compound, C16H22N2O, the azepan-2-one ring adopts a chair conformation, while the 1,2,3,4-tetra-hydro-pyridine ring adopts a half-chair conformation. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, forming supra-molecular chains propagated along [10-1], with weak C-H⋯O inter-actions occurring between the chains.

The title compound, C(21)H(26)O, was semisynthesized from isocostic acid, isolated from the aerial part of Inula Viscosa- (L) Aiton [or Dittrichia Viscosa- (L) Greuter]. The cyclo-hexene ring has a half-chair conformation, whereas the cyclo-hexane ring displays a chair conformation.

The title mol-ecule, C(16)H(24)O(8)S, is a dihydro-agrofuran derivative and has a heteropolycyclic structure. One cyclohexane ring exhibits a chair conformation and the other a non-chair conformation. In the crystal structure there is an inter-molecular C-H⋯O hydrogen-bonding inter-action to stabilize the packing.

The title compound, C(23)H(35)BrO(3), synthesized by esterification and bromination of isosteviol, comprises a fused four-ring system. Two of the six-membered rings adopt a regular chair conformation, whereas the remaining six-membered ring is an unsymmetrical distorted chair. The stereochemistry at the two six-membered ring junctions is trans, while the five-membered ring adopts an envelope co...

The title compound, C(23)H(31)NO, was semisynthesized from isocostic acid, isolated from the aerial part of Inula Viscosa- (L) Aiton [or Dittrichia Viscosa- (L) Greuter]. The cyclo-hexene ring has a half-chair conformation, whereas the cyclo-hexane ring displays a chair conformation. The dihedral angle between the latter ring and its substituent is 83.6 (7)°.

In the title compound, C(20)H(20)N(2), the quinoxaline ring adopts a very distorted half-chair conformation [N=C-C=N = 22.7 (2)° for the nominally coplanar atoms] and the cyclo-hexane ring adopts a chair conformation. The quinoxaline and cyclo-hexane rings are cis-fused. The two phenyl rings form a dihedral angle of 63.88 (7)°.

In the chiral title compound, C(18)H(28)O(3), the two six-membered rings of the perhydronaphthalenone adopt a rigid chair-chair conformation and the five-membered dioxolanyl ring adopts an envelope conformation. The crystal structure is stabilized only by weak inter-actions.