The title compound, C24H34O5, a fungal-transformed metabolite of the injectable contraceptive medroxyprogesterone acetate, consists of four fused rings (A, B, C and D; steroid labelling). Ring A exists in a half-chair conformation while trans-fused rings B and C adopt chair conformations. The five-membered ring D adopts an envelope conformation with the C atom bound to the methyl group at the flap. In the crystal, adjacent molecules are linked by O—H⋯O and C—H⋯O hydrogen bonds, forming infinite chains along the a axis.
In the title compound, C37H32N2O3, an intramolecular O—H⋯N hydrogen bond generates a five-membered ring, producing an S(5) motif. The piperidone ring adopts a half-chair conformation. The two fused pyrrolidine rings have similar envelope conformations. The interplanar angles between the benzene rings A/B and C/D are 75.68 (7) and 30.22 (6)°, respectively. In the crystal structure, adjacent molecules are interconnected into chains propagating along the  direction via intermolecular C—H⋯O hydrogen bonds. Further stabilization is provided by weak C—H⋯π interactions.
In the title compound, C20H22O5, an S(6) ring motif is formed by an intramolecular C—H⋯O hydrogen bond, which contributes to the stabilization of the molecule. In the xanthene system, the cyclohexane ring adopts a chair conformation, the cyclohexene ring adopts a half-boat conformation and the tetrahydropyran ring adopts a half-chair conformation. The mean plane of the four essentially planar atoms of the tetrahydropyran ring [r.m.s deviation = 0.092 (1) Å] forms a dihedral angle of 64.13 (6)° with the mean plane of the methoxyphenyl group. In the crystal, intermolecular O—H⋯O and weak C—H⋯O hydrogen bonds link molecules into chains along the a axis, which are further stabilized by C—H⋯π interactions.
The title compound, C21H28O, was isolated from the cytotoxic lipid extract of the Fidjian soft coral Nephthea sp. The steroid showed inhibitory activity to human colon adenocarcinoma SW480 cells (IC50 = 2.5 µg ml−1). The molecular structure indicates that the A ring is almost planar (r.m.s. deviation = 0.032 Å), the B and C rings adopt chair conformations and the five-membered D ring is a half-chair. The B/C and C/D ring junctions are trans-fused.
In the indane ring system of the title molecule, C13H12O4, the hydroxy-bearing C atom is 0.134 (1) Å out of the plane of the remaining essentially planar atoms (r.m.s. deviation = 0.010 Å). In the crystal, molecules are linked into chains along the b axis by intermolecular O—H⋯O hydrogen bonds. Additional stabilization is provided by weak intermolecular C—H⋯O hydrogen bonds.
The title compound, Artonol B, C24H20O7, isolated from the stem bark of Artocarpus kemando, consists of four six-membered rings and one five-membered ring. The tricyclic xanthone ring system is almost planar [maximum deviation 0.115 (5) Å], whereas the pyranoid ring is in a distorted boat conformation·The furan ring is almost coplanar with the fused aromatic ring, making a dihedral angle of 3.76 (9)°. The phenol ring serves as a intramolecular hydrogen-bond donor to the adjacent carbonyl group and also acts as an intermolecular hydrogen-bond acceptor for the methyl groups of adjacent molecules, forming a three-dimensional network in the crystal.
In the title compound, C35H28N2O3, an intramolecular O—H⋯N hydrogen bonds generates a five-membered ring, producing an S(5) ring motif. The piperidone ring adopts a half-chair conformation and the two pyrrolidine rings adopt an envelope conformation. The dihedral angles formed between adjacent benzene rings are 74.39 (5) and 37.70 (6)°. In the crystal crystal, intermolecular C—H⋯O hydrogen bonds link molecules into dimers, which are further interconnected into two-dimensional networks parallel to the ac plane by intermolecular C—H⋯O hydrogen bonds. The crystal structure is consolidated by weak C—H⋯π interactions.
In the title compound (kokosanolide B), C30H48O3, the hexahydro- and octahydronaphthalen-2-one ring systems are connected through an ethylene fragment, with a C—CH2—CH2—C torsion angle of 176.2 (2)°. The cyclohexene ring adopts a half-chair conformation, while the other six-membered rings adopt distorted chair conformations. In the crystal, adjacent molecules are linked into a zigzag chain along the b axis by O—H⋯O hydrogen bonds involving the hydroxy and carbonyl groups.
In the title compound, C33H30N2O3, the pyrrolidine ring adopts an envelope conformation in which the H atom attached the an ortho-C atom deviates from the plane, whereas the cyclohexanone ring in the tetrahydronaphthalene fused-ring system adopts a sofa conformation. The oxindoline ring system is almost perpendicular with respect to the mean plane of the pyrrolidine ring, with a dihedral angle of 89.0 (1)°. Five intramolecular C—H⋯O close contacts are observed. In the crystal, molecules associate via O—H⋯O hydrogen bonds, forming R
2(14) dimers. In addition, there are weak C—H⋯π interactions.
In the title hydrate, C12H13NO4·H2O, the piperidine ring that is fused to the benzene ring is in a sofa conformation with the chiral C atom lying 0.4084 (18) Å out of the plane of the nine fused-ring atoms. In the crystal, O—H⋯O and N—H⋯O hydrogen bonds link the organic molecules and water molecules into chains running along the b-axis direction. The chains are further connected into layers parallel to the bc plane by π–π interactions between inversion-related benzene rings [centroid–centroid distance = 3.8846 (9) Å].
The title eremophilenolide, C15H22O3, is a natural compound isolated from Senecio laetus Edgew. The two cis-fused six-membered rings have chair confomations and the five-membered ring has a planar envelope conformation [maximum deviation = 0.010 (1) Å]. The β-hydroxy group participates in intermolecular O—H⋯O hydrogen bonding, forming molecular chains along the a axis.
In the title compound, C19H19ClO4, the central fused ring and the attached cyclohexene ring adopt envelope conformations, while the cyclohexane ring adopts a chair conformation. The crystal packing is stabilized by O—H⋯O hydrogen bonds, which link the molecules into a chain along the b axis. Weak C—H⋯O bonds also occur.
The title compound, C21H23NO3, is a phenylimine derivative of the well known anthelmintic agent α-santonin. The trans-fused cyclohexane and γ-lactone rings of the α-santonin ring system adopt chair and envelope conformations, respectively, whereas the hexadiene ring is approximately planar [maximum deviation = 0.029 (4) Å] and forms a dihedral angle of 62.30 (11)° with the benzene ring. An intramolecular O—H⋯N hydrogen bond is observed.
The title compound, C21H30O, was isolated from the soft coral Sinularia sp. The molecule contains four alicyclic rings, all trans-fused, among which three six-membered rings are in different distorted chair conformations while a five-membered ring assumes an envelope form.
In the title compound, C30H26N2O3, the two pyrrolidine rings adopt twisted and envelope conformations, whereas the cyclopentane ring adopts an envelope conformation. The least-squares planes through the pyrrolidine rings form a dihedral angle of 41.72 (10)°. The molecular structure is stabilized by an intramolecular O—H⋯N hydrogen bond, which generates an S(5) ring motif. Centrosymmetrically related molecules are linked via two pairs of intermolecular C—H⋯O interactions, forming R
2(16) ring motifs. In the crystal packing, the molecules are linked into two-dimensional networks parallel to the ab plane via C—H⋯O interactions.
In the title compound, C20H22O5, the tetrahydropyran, cyclohexene and cyclohexane rings of the xanthene ring system adopt half-chair, half-boat and chair conformations, respectively. The mean plane of the four roughly planar atoms of the tetrahydropyran ring (r.m.s. deviation = 0.111 Å) forms a dihedral angle of 82.91 (4)° with the methoxybenzene group. In the crystal, molecules are linked via O—H⋯O and C—H⋯O hydrogen bonds into sheets lying parallel to the ac plane. The crystal is further consolidated by weak C—H⋯π interactions.
In the title compound, C19H20O5, the pyran ring is in an envelope conformation, whereas the benzene and dihydropyran ring system is planar with an r.m.s. deviation of 0.0190 (1) Å. The hydroxy group is coplanar with the attached benzene ring [r.m.s. deviation = 0.0106 (1) Å]. An intramolecular O—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, molecules are linked into chains along the b axis by weak C—H⋯O interactions. These chains are stacked along the a axis. C—H⋯π and weak π–π interactions [centroid–centroid distance = 3.7698 (7) Å] are also observed.
The dihydropyridine ring in the title compound, C25H31NO4, adopts an envelope conformation with the methine C atom representing the flap. The cyclohexenone rings also adopt envelope conformations with the C atoms bearing the methyl C atoms representing the flaps. The phenolic hydroxy group forms an intramolecular hydrogen bond to one of the two keto O atoms. The hydroxy group of the N-bonded alkyl chain forms an intermolecular hydrogen bond to the other keto O atom of an adjacent molecule. The latter hydrogen bond leads to the formation of a helical chain running along the b axis.
In the title compound, C38H32N2O2, the pyrrolidine ring adopts an envelope conformation, whereas the cyclohexanone ring in the tetrahydronaphthalene fused-ring system adopts a half-chair conformation. The benzyl ring is oriented at an angle of 67.1 (1)° with respect to the naphthyl ring system. Four intramolecular C—H⋯O close contacts and C—H⋯π interaction are observed. In the crystal, molecules associate via C—H⋯O hydrogen bonds, forming a C(12) chain motif along the ac plane.
In the title compound, C21H21BrClNO4, the dihydropyridine ring adopts a flattened boat conformation. The 3-bromo-5-chloro-2-hydroxyphenyl ring forms a dihedral angles of 84.44 (7)° with the dihydropyridine mean plane. The molecular conformation is stabilized by an intramolecular O—H⋯O hydrogen bond, with an S(8) ring motif. In the crystal, O—H⋯O and C—H⋯O hydrogen bonds link the molecules, forming a three-dimensional network.
The title compound, C14H11N3O3, adopts an E or trans configuration with respect to the C=N bond. In the molecule there is an intramolecular O—H⋯N hydrogen bond involving the hydroxy substituent at the 2-positon of the naphthalene ring and the adjacent methyleneamino N atom. The molecule is roughly planar, the dihedral angle between the naphthalene and imidazolidine-2,4-dione mean planes being 8.4 (1)°. In the crystal, pairs of N—H⋯O hydrogen bonds link molecules into inversion dimers. These dimers are futher linked via C—H⋯O interactions, forming a three-dimensional network.
The seven-membered ring of the title compound, C12H12N2O3, which is fused with the phenylene ring, adopts a boat-shaped conformation (with the methine C atom as the prow and the phenylene C atoms as the stern); the H atom on the methine linkage exists in an axial position. The five-membered ring that is fused with the seven-membered ring adopts an envelope conformation (with the C atom bearing the hydroxy substituent representing the flap) [the deviation from the plane defined by the other four atoms is 0.200 (7) Å in one molecule and 0.627 (5) Å in the other]. The two independent molecules are disposed about a pseudo center of inversion and are connected by a pair of N—H⋯O hydrogen bonds. Adjacent dimers are linked by a pair of O—H⋯O hydrogen bonds, generating a chain running along the b axis.
The title compound is a new aminocoumarin derivative, C17H13NO4, and was synthesized by the condensation of 2-aminophenol and 3-acetyl-4-hydroxycoumarin. An intramolecular N—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, the molecules are linked into chains extending in the  direction by O—H⋯O hydrogen bonds. There is also a π–π stacking interaction between the bicyclic coumarin fragment and the phenol ring [centroid–centroid distance = 3.7510 (14) Å], and these ring systems form between them a dihedral angle of 53.3 (2)°. Intermolecular hydrogen bond C—H⋯O hydrogen bonding is also observed in the interconnection of the crystal packing.
In the title compound, C11H11NO4S·H2O, the five-membered thiazolidine ring is nearly planar, with a maximum deviation of 0.010 (2) Å. The dihedral angle between the thiazolidine and benzene rings is 49.16 (9)°. Intermolecular O—H⋯O and N—H⋯O hydrogen bonding is present in the crystal structure.
The title compound, C15H22O4, an eremophilane sesquiternoid, was isolated from the roots of Ligularia virgaurea. Both six-membered rings (A and B) adopt chair conformations and the five-membered ring is almost planar (r.m.s. deviation = 0.016 Å). The two methyl and two hydroxy groups adopt a syn conformation and the A/B ring junction is cis-fused. An intramolecular O—H⋯O hydrogen bond generates an S(6) ring. In the crystal, O—H⋯O hydrogen bonds link the molecules into  chains.