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1.  Pinnatane A from the bark of Walsura pinnata Hassk 
In the mol­ecule of pinnatane A, C30H48O3, isolated from the bark of Walsura pinnata Hassk, the four cyclo­hexane rings adopt chair conformations; the carboxyl and hydr­oxy substituents occupy axial positions. The cyclo­hexene ring is envelope-shaped. Adjacent mol­ecules are linked by O—H⋯O hydrogen bonds into a chain running along the c axis.
doi:10.1107/S1600536809015955
PMCID: PMC2969541  PMID: 21583174
2.  3-Oxoolean-1-en-28-oic acid–n-hexa­ne–water (4/1/1) from the bark of Walsura pinnata Hassk 
3-Oxoolean-1-en-28-oic acid, isolated from the bark of Walsura pinnata Hassk, crystallized from n-hexane as an n-hexane 0.25-solvent 0.25-hydrate, C30H46O3·0.25C6H14·0.25H2O. There are two independent mol­ecules in the asymmetric unit of the title compound. The three six-membered cyclo­hexane rings in each mol­ecule adopt chair conformations and the carboxyl substituent occupies an axial/equatorial position. The two independent mol­ecules are linked by a pair of O—Hcarbox­yl⋯O hydrogen bonds into a dimer. The n-hexane mol­ecule is disordered about a twofold rotation axis and the water mol­ecule lies on a twofold rotation axis. In addition, the cyclo­hexone carbonyl group of one of the independent mol­ecules is disordered over two sites with occupancies of 0.75 and 0.25.
doi:10.1107/S1600536809015086
PMCID: PMC2977831  PMID: 21583968
3.  Absolute configuration of isoeichlerialactone 
The title seco-dammarane triterpenoid, C27H42O4 (systematic name: 3-{(3S,3aR,5aR,6S,7S,9aR,9bR)-6,9a,9b-trimethyl-3-[(R)-2-methyl-5-oxotetra­hydro­furan-2-yl]-7-(prop-1-en-2-yl)dodeca­hydro-1H-cyclo­penta­[a]naphthalen-6-yl}propanoic acid), has been isolated for the first time from the seeds of Aglaia forbesii. The mol­ecule has three fused rings and all rings are in trans-fused. The two cyclo­hexane rings are in standard chair conformations and the cyclo­pentane ring adopts an envelope conformation. Its absolute configuration was determined by the refinement of the Flack parameter to 0.26 (17). In the crystal, mol­ecules are linked into chains along [010] by O—H⋯O hydrogen bonds.
doi:10.1107/S1600536810009499
PMCID: PMC2984085  PMID: 21580698
4.  (20S)-24,25-Dihydr­oxy-20,24-ep­oxy-3,4-secodammar-4(28)-en-3-oic acid from Aglaia smithii  
The title compound, C30H50O5, was isolated from the bark of Aglaia smithii. There are two independent mol­ecules in the asymmetric unit that differ in the orientation of the isopropenyl group attached to the cyclo­hexane ring. The cyclo­hexane rings in both mol­ecules adopt chair conformations, whereas the cyclo­pentane and tetra­hydro­furan rings adopt envelope conformations. The independent mol­ecules are linked into a layer parallel to (010) by O—H⋯O hydrogen bonds.
doi:10.1107/S1600536810002072
PMCID: PMC2979682  PMID: 21579834
5.  3-epi-Dammarenediol II 1.075 hydrate: a dammarane triterpene from the bark of Aglaia eximia  
The title dammarane tritepene, 3α,20(S)-dihy­droxy­dammar-24-ene, which crystallized out in a hydrated form, C30H52O2.1.075H2O, was isolated from the Aglaia eximia bark. The three cyclo­hexane rings adopt chair conformations. The cyclo­pentane has an envelope conformation with the quaternary C at position 14 as the flap atom with the maximum deviation of 0.288 (2) Å. The methyl­heptene side chain is disordered over two positions with 0.505 (1):0.495 (1) site occupancies and is axially attached with an (+)-syn-clinal conformation. The hydroxyl group at position 3 of dammarane is in a different conformation to the corresponding hydroxyl in Dammarenediol II. In the crystal, the dammarane and water mol­ecules are linked by ODammarane—H⋯Owater and Owater—H⋯ODammarane hydrogen bonds into a three-dimensional network.
doi:10.1107/S1600536812040366
PMCID: PMC3515193  PMID: 23284420
6.  (3S,12R,20S,24R)-20,24-Ep­oxy­dammarane-3,12,25-triol 
In the title mol­ecule, C30H52O4, the three six-membered rings are in chair conformations, the cyclo­pentane ring is in an envelope form and the tetra­hydro­furan ring has a conformation inter­mediate between half-chair and sofa. In the crystal, mol­ecules are linked by inter­molecular O—H⋯O hydrogen bonds into helical chains along [100]. Two intra­molecular O—H⋯O hydrogen bonds are also present. One C atom of the tetrahydrofuran ring and its attached H atoms are equally disordered over two sets of sites.
doi:10.1107/S1600536811028418
PMCID: PMC3213554  PMID: 22091131
7.  (1S,3′S,3a′R,6′S)-6′-(2-Chloro­phen­yl)-3′-[(2R,3S)-1-(4-meth­oxy­phen­yl)-4-oxo-3-phenyl­azetidin-2-yl]-2-oxo-3′,3′a,4′,6′-tetra­hydro-2H,2′H-spiro­[ace­naphthyl­ene-1,1′-pyrrolo­[1,2-c][1,3]thia­zole]-2′,2′-dicarbo­nitrile 
The mol­ecular conformation of the title compound, C41H29ClN4O3S, is stabilized by intra­molecular C—H⋯O and C—H⋯Cl hydrogen bonds. The thia­zole ring adopts an envelope conformation with the N atom as the flap, while the pyrrolidine ring has a twisted conformation on the N—C bond involving the spiro C atom. The β la­ctam ring makes dihedral angles of 39.74 (15) and 16.21 (16)° with the mean planes of the thia­zole and pyrrolidine rings, respectively. The thia­zole ring mean plane makes dihedral angles of 23.79 (13) and 70.88 (13) ° with the pyrrolidine and cyclo­pentane rings, respectively, while the pyrrolidine ring makes a dihedral angle of 85.63 (13)° with the cyclo­pentane ring. The O atom attached to the β la­ctam ring deviates from its mean plane by 0.040 (2) Å, while the O atom attached to the cyclo­pentane ring deviates from its mean plane by 0.132 (2) Å. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming chains along [010], and C—H⋯π and π-π inter­actions [centroid-centroid distance = 3.6928 (17) Å].
doi:10.1107/S1600536813009276
PMCID: PMC3648279  PMID: 23723899
8.  Absolute configuration of methyl isoeichlerialactone 
The title compound, C28H44O4·0.56H2O, is a co-crystal of methyl isoeichlerialactone monohydrate as the major component and methyl isoeichlerialactone as the minor component in a 0.55778 (3):0.44222 (3) ratio. The conformations of both components are identical except for that of the –COOCH3 group of the methyl propanoate side chain on the cyclo­hexane ring which is positionally disordered over two orientations. The mol­ecule of methyl isoeichlerialactone has three fused rings and all rings are trans-fused. The two cyclo­hexane rings are in standard chair conformations and the cyclo­pentane ring adopts an envelope conformation. In the crystal, weak C—H⋯O inter­actions link methyl isoeichlerialactone mol­ecules into screw chains along [010]. The crystal structure is further stabilized by O—H⋯O hydrogen bonds and weak C—H⋯O inter­actions.
doi:10.1107/S1600536810018295
PMCID: PMC3007061  PMID: 21587839
9.  Methyl 7,8-diacet­oxy-11-oxo-5-(2-oxo­pyrrolidin-1-yl)-7,9-epoxy­cyclo­penta­[4,5]pyrido[1,2-a]quinoline-10-carboxyl­ate sesquihydrate 
The title compound, C26H28N2O9·1.5H2O, the product of an acid-catalysed Wagner–Meerwein skeletal rearrangement, crystallizes as a sesquihydrate with the O atom of one of the two independent water mol­ecules occupying a special position on a twofold axis. The organic mol­ecule comprises a fused penta­cyclic system containing two five-membered rings (cyclo­pentane and tetra­hydro­furan) and three six-membered rings (piperidinone, tetra­hydro­pyridine and benzene). The five-membered rings have the usual envelope conformations, and the central six-membered piperidinone and tetra­hydro­pyridine rings adopt boat and sofa conformations, respectively. In the crystal, there are three independent O—H⋯O hydrogen bonds, which link the organic mol­ecules and water mol­ecules into complex two-tier layers parallel to (001). The layers are further linked into a three-dimensional framework by attractive inter­molecular carbon­yl–carbonyl inter­actions.
doi:10.1107/S160053680905363X
PMCID: PMC2980137  PMID: 21580091
10.  Triamcinolone acetonide acetate 
In the crystal structure of the title compound [systematic name: 2-(4b-fluoro-5-hy­droxy-4a,6a,8,8-tetra­methyl-2-oxo-2,4a,4b,5,6,6a,9a,10,10a,10b,11,12-dodeca­hydro-7,9-dioxa­penta­leno[2,1-a]phenanthren-6b-yl)-2-oxoethyl acetate], C26H33FO7, the mol­ecules are connected by inter­molecular O—H⋯O hydrogen bonds into an infinite supra­molecular chain along the b axis. The mol­ecular framework consists of five condensed rings, including three six-membered rings and two five-membered rings. The cyclo­hexa-2,5-dienone ring is nearly planar [maximum deviation = 0.013 (3) Å], while the cyclo­hexane rings adopt chair conformations. The two five-membered rings, viz. cyclo­pentane and 1,3-dioxolane, display envelope conformations.
doi:10.1107/S1600536811000316
PMCID: PMC3051574  PMID: 21523039
11.  3β-Acet­oxy-19-hy­droxy-Δ5-pregnen-20-one 
In the title compound, C23H34O4, the C/D and D/E rings are trans fused and the A/B ring possesses an anti fusion. The two cyclo­hexane rings adopt a chair conformation while the cyclo­hexene ring exhibits a half-chair conformation. The cyclo­pentane ring displays an envelope conformation with the C atom bearing the methyl group as the flap. In the crystal, the mol­ecules are linked by O—H⋯O hydrogen bonds, forming chains along the b axis.
doi:10.1107/S1600536813002493
PMCID: PMC3569832  PMID: 23424578
12.  3β-Acet­oxy-5α-cholestan-6-one 2-cyano­acetyl­hydrazone 
The asymmetric unit of the title compound, C32H51N3O3, consists of two crystallographically independent mol­ecules, A and B; the 2-methyl­pentane group of mol­ecule A and the propane group of mol­ecule B are each disordered over two sets of sites, with refined site-occupancies of 0.825 (5):0.175 (5) and 0.630 (18):0.370 (18), respectively. In both mol­ecules, the three cyclo­hexane rings in the steroid fused ring systems adopt chair conformations while the cyclo­pentane rings adopt envelope and twist conformations in mol­ecules A and B, respectively. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds link the two independent mol­ecules together, generating R 2 1(7) and R 2 2(8) ring motifs.
doi:10.1107/S1600536812001432
PMCID: PMC3275224  PMID: 22347080
13.  6-Amino-5-(1-amino-2,2-dicyano­vin­yl)-3,3a,4,5-tetra­hydro-2H-indene-4-spiro-1′-cyclo­pentane-3a,7-dicarbonitrile–thio­phene-2-carbaldehyde (1/0.5) 
In each of the two independent indene-4-spiro­pentane mol­ecules in the asymmetric unit of the title 2:1 adduct, C19H18N6·0.5C5H4OS, the cyclo­hexene ring adopts a half-chair conformation and the cyclo­pentene and cyclo­pentane rings adopt envelope conformations. The mean plane through the cyclo­hexene/cyclo­pentene fused system is aligned at a dihedral angle of 77.9 (1)° with respect to the mean plane through the cyclo­pentane ring in one mol­ecule and 87.0 (1)° in the other. In the crystal, adjacent indene-4-spiro­pentane mol­ecules are linked by N—H⋯N hydrogen bonds into a three-dimensional network. The spaces within the network are occupied by the thio­phene-2-carbaldehyde mol­ecules. The thio­phene-2-carbaldehyde unit is disordered over two positions of equal occupancy. The crystal studied was found to be a non-morohedral twin with two minor twin components of 18.4 and 9.7%.
doi:10.1107/S1600536810034434
PMCID: PMC2983394  PMID: 21587485
14.  17βH-Periplogenin, a cardiac aglycone from the root bark of Periploca sepium Bunge 
The title compound {systematic name: 4-[(3S,5S,8R,9S,10R,13R,14S,17S)-3,5,14-trihy­droxy-10,13-dimethyl­hexa­deca­hydro-1H-cyclo­penta­[a]phenanthren-17-yl]furan-2(5H)-one}, C23H34O5, was isolated from the roots of Periploca sepium Bunge, a famous Chinese traditional herbal medicine. The three six-membered rings adopt chair conformations, the cyclo­pentane ring displays an approximate envelope conformation (with the C atom bearing the methyl substituent at the flap) and the five-membered lactone ring adopts an essentially planar [maximum deviation of 0.004 (8) Å] conformation. In the crystal, mol­ecules are linked into helical chains along [010] by O—H⋯O hydrogen bonds and weak C—H⋯O inter­actions. Two intra­molecular O—H⋯O hydrogen bonds are also present.
doi:10.1107/S1600536812018521
PMCID: PMC3379196  PMID: 22719394
15.  3β-Chloro-5α-cholestan-6-one 
The asymmetric unit of the title compound, C27H45ClO, consists of two crystallographically independent mol­ecules. In both mol­ecules, the three cyclo­hexane rings in the steroid fused-ring systems adopt chair conformations, while the cyclo­pentane ring adopts a half-chair conformation in one mol­ecule and an envelope conformation in the other. In the crystal, the mol­ecules are linked into a two-dimensional network by weak C—H⋯O hydrogen bonds. The crystal studied is a nonmerohedral twin with a refined ratio of twin components of 0.264 (3):0.736 (3).
doi:10.1107/S1600536812012482
PMCID: PMC3344147  PMID: 22606150
16.  Absolute configuration of vouaca­pen-5α-ol 
The title compound, C20H30O2, {systematic name: (4aR,6aS,7R,11aS,11bR)-4,4,7,11b-tetra­methyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca­hydro­phenanthro[3,2-b]furan-4a-ol}, is a cas­sane furan­oditerpene which was isolated from the roots of Caesalpinia pulcherrima. The absolute configurations at positions 4a, 6a, 7, 11a and 11b are R, S, R, S and R, respectively. The mol­ecule has four-fused rings consisting of three cyclo­hexane rings and one furan ring. The three cyclo­hexane rings are trans-fused. Two cyclo­hexane rings are in chair conformations, while the third is in an envelope conformation. In the crystal structure, the mol­ecules are linked by inter­molecular O—H⋯O hydrogen bonds into a zigzag chain along the a axis. A short O⋯O contact [3.0398 (14) Å] is also present.
doi:10.1107/S1600536810029557
PMCID: PMC3007238  PMID: 21588448
17.  4′-(4-Fluoro­phen­yl)-1′-methyl­dispiro­[indane-2,2′-pyrrolidine-3′,2′′-indane]-1,3,1′′-trione methanol hemisolvate 
The asymmetric unit of the title compound, C29H24FNO5·0.5CH3OH, contains two independent mol­ecules and a one methanol solvent mol­ecule. The methanol mol­ecule is O—H⋯O hydrogen bonded to one of the independent mol­ecules. The pyrrolidine rings in both mol­ecules adopt half-chair conformations, while the cyclo­pentane rings within the indane groups are in flattened envelope conformations, with the spiro C atoms forming the flaps. The benzene rings of the indane ring systems form a dihedral angle of 35.06 (7)° in one independent mol­ecule and 31.16 (8)° in the other. The fluoro-substituted benzene ring forms dihedral angles of 65.35 (6) and 85.87 (7)° with the indane group benzene rings in one mol­ecule, and 72.78 (8) and 77.27 (8)° in the other. In each mol­ecule, a weak intra­molecular C—H⋯O hydrogen bond forms an S(6) ring motif. In the crystal, weak C—H⋯O, C—H⋯N and C—H⋯F hydrogen bonds link the mol­ecules into a three-dimensional network.
doi:10.1107/S1600536813009987
PMCID: PMC3648276  PMID: 23723896
18.  14,15-Didehydro­hellebrigenin 
The title compound, C24H30O5, is the didehydro product of the steroid hellebrigenin (systematic name: 3β,5,14-trihy­droxy-19-oxo-5β-bufa-20,22-dienolide). It consists of three cyclo­hexane rings (A, B and C), a five-membered ring (D) and a six-membered lactone ring (E). The stereochemistry of the ring junctions are A/B cis, B/C trans and C/D cis. Cyclo­hexane rings A, B and C have normal chair conformations. The five-membered ring D with the C=C bond adopts an envelope conformation. Lactone ring E is essentially planar with a mean derivation of 0.006 (4) Å and is β-oriented at the C atom of ring D to which it is attached. There is an O—H⋯O hydrogen bond in the mol­ecule involving the hy­droxy groups. In the crystal, O—H⋯O hydrogen bonds link the mol­ecules into chains propagating along [010]. The chains are linked by C—H⋯O contacts into a three-dimensional network.
doi:10.1107/S1600536812018570
PMCID: PMC3379221  PMID: 22719419
19.  5α-Hy­droxy­eudesm-4(15),11(13)-dien-8β,12-olide 
The title compound, C15H20O3, a sesquiterpene lactone, was isolated from the aerial parts of Carpesium minus Hemsl. (Compositae). The mol­ecule is composed of three rings, with the two cyclo­hexane rings in chair conformations and the cyclo­pentane ring adopting a twist conformation. The A/B ring junction is trans-fused. The absolute configuration shown has been arbitrarily assigned. In the crystal, mol­ecules are linked into [100] chains by O—H⋯O hydrogen bonds.
doi:10.1107/S1600536812012470
PMCID: PMC3344144  PMID: 22606147
20.  3-Mesityl-2-oxo-1-oxaspiro­[4.4]non-3-en-4-yl 4-chloro­benzoate 
The title compound, C24H23ClO4, is a potent insecticide and miticide. The five-membered cyclo­pentane ring displays an envelope conformation with the atom at the flap position 0.611 (2) Å out of the mean plane formed by the other four atoms. The furan ring makes dihedral angles of 71.3 (2) and 81.9 (2)°, respectively, with the 2,4,6-trimethyl­phenyl and 4-chloro­phenyl rings. The dihedral angle between the two benzene rings is 76.6 (1)°. In the crystal, mol­ecules are linked through weak inter­molecular C—H⋯O hydrogen bonds, forming chains running along the c axis.
doi:10.1107/S1600536809006503
PMCID: PMC2969026  PMID: 21582443
21.  1-Deacet­oxy-1-oxocaesalmin 
The title compound, C24H30O7, is a diterpenoid isolated from the seeds of Caesalpinia minax. It consists of two cyclo­hexane rings (A and B), one unsaturated six-membered ring (C) and one furan ring (D). The stereochemistry of the ring junctures is A/B trans and B/C trans. Rings A and B have normal chair conformations while C adopts a twisted half-chair conformation due to fusion to the furan ring which is planar [r.m.s. deviation = 0.0009 (2) Å]. In the crystal, hydroxyl O—H⋯Ocarbon­yl hydrogen bonds link the mol­ecules into a chain structure extending along the a-axis direction.
doi:10.1107/S1600536814011040
PMCID: PMC4051044  PMID: 24940245
22.  (20S)-Dammar-24-ene-3β,20-diol monohydrate from the bark of Aglaia exima (Meliaceae) 
In the title compound {systematic name: (1R,2R,5R,7R,10R,11R,14S,15R)-14-[(2S)-2-hy­droxy-6-methyl­hept-5-en-2-yl]-2,6,6,10,11-penta­methyl­tetra­cyclo­[8.7.0.02,7.011,15]hepta­decan-5-ol monohydrate}, C30H52O2·H2O, the three fused cyclo­hexane rings adopt chair conformations and the hy­droxy substituent of one of these occupies an axial position. The fused cyclo­pentane ring adopts an envelope conformation (with the flap atom being the C atom bearing the methyl group) and the 3-methyl­but-2-enyl portion of its substituent is disordered over three sets of sites in a 0.413 (7):0.250 (7):0.337 (7) ratio. The O atoms of both water mol­ecules occupy special positions of 2 site symmetry. In the crystal, Os—H⋯Ow and Ow—H⋯Os (s = steroid and w = water) hydrogen bonds link hy­droxy groups and water mol­ecules, forming a three-dimensional network. The crystal studied was found to be a non-merohedral twin with a 0.518 (1):0.482 (1) component ratio.
doi:10.1107/S1600536812034976
PMCID: PMC3435729  PMID: 22969600
23.  4′-(4-Bromo­phen­yl)-1′-methyl­dispiro­[acenaphthyl­ene-1,2′-pyrrolidine-3′,2′′-indane]-2,1′′(1H)-dione 
In the title compound, C30H22BrNO2, the cyclo­pentane ring of the dihydro­acenaphthyl­ene group and the pyrrolidine ring are both in envelope conformations with the spiro C atom and N atom, respectively, as the flap atom. The cyclo­pentane ring of the indane group adopts a half-chair conformation. A weak intra­molecular C—H⋯O hydrogen bond forms an S(8) ring motif. The naphthalene ring system of the dihydro­acenaphthyl­ene group forms dihedral angles of 41.76 (6) and 42.17 (6)° with the benzene ring of the bromo­phenyl group and the benzene ring of the indane group, respectively. The dihedral angle between the two benzene rings is 83.92 (7)°. In the crystal, mol­ecules are linked by weak C—H⋯O and C—H⋯N hydrogen bonds into a two-dimensional network parallel to the ac plane. Weak C—H⋯π inter­actions are also observed.
doi:10.1107/S1600536812014213
PMCID: PMC3344476  PMID: 22590238
24.  Crystal structure of hydro­cortisone 17-butyrate 
In the title compound, C25H36O6, the two central cyclo­hexane rings exhibit a chair conformation. The terminal cyclo­hexene and cyclo­pentane rings are in half-chair and envelope conformations (with the C atom bearing the methyl substit­uent as the flap), respectively. The methyl group of the butyrate chain is disordered over two orientations, with a refined occupancy ratio of 0.742 (6):0.258 (6). Intra­molecular O—H⋯O and C—H⋯O hydrogen bonds are observed. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds into chains running parallel to the a axis.
doi:10.1107/S1600536814023903
PMCID: PMC4257404  PMID: 25553020
crystal structure; hydro­cortisone derivative; hydrogen bonds; pharmacological activity
25.  Crystal structure of (R)-6′-bromo-3,3-dimethyl-3′,4′-di­hydro-2′H-spiro­[cyclo­hexane-1,3′-1,2,4-benzo­thia­diazine] 1′,1′-dioxide 
In the title compound, the mean plane of the cyclo­hexane ring is almost normal to the benzene ring and to the mean plane of the 1,2,4-thia­diazinane ring. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds, forming chains along [10], which are in turn linked via C—H⋯π inter­actions, forming sheets parallel to (010).
In the title compound, C14H19BrN2O2S, the 1,2,4-thia­diazinane ring adopts an envelope conformation with the N atom (attached to the sulfonyl group) as the flap, while the cyclo­hexane ring adopts a chair conformation. The mean plane of the cyclo­hexane ring is almost normal to the benzene ring and the mean plane of the 1,2,4-thia­diazinane ring, making dihedral angles of 70.4 (2) and 71.43 (19)°, respectively. Furthermore, the dihedral angle between the benzene ring and the mean plane of the 1,2,4-thia­diazinane ring is 4.91 (18)°. The mol­ecular structure is stabilized by an intra­molecular C—H⋯O hydrogen bond, which encloses an S(6) ring motif. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds into chains along [10-1], forming a C(6) graph-set motif. These chains are inter­connected via C—H⋯π inter­actions, leading to chains along [-101], so finally forming sheets parallel to (010).
doi:10.1107/S1600536814022417
PMCID: PMC4257282  PMID: 25484745
crystal structure; benzo­thia­diazine; hydrogen bonding; chirality

Results 1-25 (144781)