The title compound, C(21)H(32)O(3), results from modifications of the A and D rings of the aromatase substrate androstenedione. Ring A adopts a conformation between 10β-sofa and 1α,10β half-chair. Rings B and C are in slightly flattened chair conformations. Ring D approaches a 13β-envelope conformation, probably due to the acet-oxy substituent, and shows a very short Csp(3)-Csp(3) bond next to ...

In the title compound, C(21)H(30)N(2)O, there are five fused rings. The A and C rings adopt chair conformations, ring B adopts an 8β,9α-half-chair conformation and ring D adopts a 14α-envelope conformation. The pyrazole ring is planar. Inter-molecular O-H⋯N hydrogen bonds [H⋯N = 1.88 (5) Å] help to stabilize the crystal structure. The absolute structure was deduced from those of the starting ma...

The title compound, C27H34O2, was hemisynthesized through direct benzoyl-ation of the naturally occurring meroterpene totarol. The central fused six-membered ring has a half-chair conformation, whereas the terminal six-membered ring displays a chair conformation. The dihedral angle between the fused benzene ring and the benzoyl benzene ring is 73.05 (14)°. The S,S chirality of the mol-ecule is ...

In the title mol-ecule, C(28)H(44)O, two six-membered rings have regular chair conformations, while the six-membered ring containing the C=C double bond exhibits a distorted chair conformation. The five-membered ring adopts an envelope conformation. In the crystal, weak inter-molecular C-H⋯O inter-actions link mol-ecules into chains along the b axis. The absolute configuration was assigned to c...

In the title compound, C(12)H(22)O(2), the 4-methyl-tetra-hydro-pyran-4-ol ring adopts a conformation close to that of a chair and with the two O atoms syn; the cyclo-hexyl group occupies an equatorial position and adopts a chair conformation. In the crystal packing, supra-molecular chains along the b axis are sustained by O-H⋯O hydrogen bonds. These are connected into undulating layers in the ...

In the chromenothia-zole ring system of the title mol-ecule, C(20)H(25)N(3)O(2)S, the pyran ring is in a half-chair conformation. The dihedral angle between the thia-zole and benzene rings is 14.78 (6)°. The cyclo-hexane ring is in a chair conformation. The crystal structure is stabilized by weak inter-molecular C-H⋯N and C-H⋯O hydrogen bonds.

The title compound, C(17)H(22)O(6), was semi-synthesized from 9-hy-droxy-arthenolide, which was isolated from the chloro-form extract of the aerial parts of Anvillea radiata. The mol-ecule contains fused five- and ten-membered rings: the five-membered lactone ring has a twisted conformation, whereas the ten-membered ring displays an approximate chair-chair conformation. The dihedral angle betwe...

In the title compound, C(28)H(38)N(2)O(3), the central ring of the acridinedione system adopts a boat conformation, while one of the outer rings adopts a half-chair conformation and the conformation of the other outer ring is between a sofa and a half-chair. The acridinedione system is buckled, with an angle of 22.01 (3)°. The crystal packing comprises layers of mol-ecules laid parallel to the ...

In the title compound, C19H19ClO4, the di-hydro-pyran ring and the cyclo-hexane ring adopt a half-chair conformation and a chair conformation, respectively. The cyclo-hexene ring has an envelope conformation with the central CH2 C atom as the flap. This atom is disordered over two positions [site-occupancy ratio = 0.744 (12):0.256 (12)] above and below the mean plane formed by the other five at...

The title compound, C13H17NO3, adopts a conformation in which the aromatic ring and the mean plane of the piperidine ring are almost perpendicular to each other [dihedral angle = 79.25 (6)°]. The presence of the carbonyl group alters the conformation of the piperidine ring from a chair to a twisted half-chair conformation. In the crystal, pairs of strong O-H⋯O hydrogen bonds link the mol-ecules...