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1.  3β-Chloro-6-[2-(2-cyano­acet­yl)hydrazin-1-yl­idene]-5α-cholestane 
The asymmetric unit of the title compound, C30H48ClN3O, contains two mol­ecules, A and B. 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 mol­ecule B, the cyano group is disordered over two orientations with refined site-occupancies of 0.593 (8) and 0.407 (8). An intra­molecular C—H⋯N inter­action forms an S(10) ring in both mol­ecules. In the crystal, mol­ecules are linked by N—H⋯O, C—H⋯O and C—H⋯N inter­actions, resulting is chains propagating along the a-axis direction.
doi:10.1107/S1600536812009336
PMCID: PMC3344016  PMID: 22589925
2.  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
3.  (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
4.  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
5.  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
6.  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
7.  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
8.  (20S*,24S*)-25-Hy­droxy-20,24-ep­oxy-A-homo-4-oxadammaran-3-one (Chrysura) isolated from the leaves of Walsura chrysogyne  
The title dammarane triterpenoid, C30H50O4, assigned the name chrysura, was isolated from an ethyl acetate extract of Walsura chrysogyne leaves (Meliaceae). It has 20S*,24S* relative stereochemistry and an oxepanone ring with two methyl groups at position 4. The two cyclo­hexane rings adopt chair conformations. The cyclo­pentane and tetra­hydro­furan rings have envelope conformations; their mean planes make a dihedral angle of 13.1 (3)°, indicating that the rings are only slightly tilted with respect to each other. There is an intra­molecular C—H⋯O hydrogen bond in the mol­ecule, which forms S(6) and S(7) ring motifs. In the crystal, mol­ecules are linked via O—H⋯O and C—H⋯O hydrogen bonds, forming chains propagating along [001] which stack along the b-axis direction.
doi:10.1107/S1600536811047337
PMCID: PMC3238949  PMID: 22199798
9.  (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
10.  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
11.  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
12.  3,28-Diacet­oxy-29-bromo­betulin 
In the title mol­ecule, C34H53BrO4, all the cyclo­hexane rings adopt chair conformations, while the cyclo­pentane ring adopts an envelope conformation. In the crystal, weak inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into corrugated sheets parallel to the ab plane.
doi:10.1107/S1600536809027640
PMCID: PMC2977272  PMID: 21583658
13.  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
14.  cis-3-Methyl-1-phenyl-8a,9,10,11,12,12a,12b-hexa­hydro-1H,3bH-pyrazolo[3,4:2′,3′]pyrano[4′,5′,6′-kl]xanthene 
The asymmetric unit of the title compound, C23H22N2O2, contains two independent mol­ecules, A and B. The cyclo­hexane ring of mol­ecule B is disordered, with occupancies for the major and minor conformers of 0.570 (9) and 0.430 (9), respectively. The cyclo­hexane ring adopts a boat conformation in mol­ecule A and in the major conformer of mol­ecule B, and a chair conformation in the minor conformer of mol­ecule B. In both independent mol­ecules, one of the dihydro­pyran rings adopts a boat conformation while the other is in a half-chair conformation. The dihedral angle between the pyrazole and phenyl rings is 16.0 (1)° in mol­ecule A and 12.9 (1)° in mol­ecule B. The crystal packing is stabilized by C—H⋯O and C—H⋯N inter­molecular hydrogen bonds.
doi:10.1107/S1600536807065348
PMCID: PMC2915303  PMID: 21200811
15.  Cholest-5-en-7-one 
In the deca­hydro­phenanthrenone ring system of the title compound, C27H44O, the two cyclo­hexane rings adopt chair conformations, whereas the cyclo­hexene ring adopts an envelope conformation. The cyclo­pentane ring is twisted. In the crystal structure, mol­ecules are stacked along the a axis, but no significant inter­molecular inter­actions are observed.
doi:10.1107/S1600536810021598
PMCID: PMC3007018  PMID: 21587894
16.  (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
17.  Betulin 3,28-di-O-tosyl­ate 
The title compound, C44H62O6S2 {systematic name: (1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-5a,5b,8,8,11a-penta­methyl-1-(prop-1-en-2-yl)-3a-[(tos­yloxy)meth­yl]icosa­hydro-1H-cyclo­penta­[a]chrysen-9-yl 4-methyl­benzene­sulfonate}, was obtained by tosyl­ation of naturally occurring betulin. All the cyclo­hexane rings adopt chair conformations and the cyclo­pentane ring adopts a twisted envelope conformation, with the C atom bearing the tosyl­methyl substituent forming the flap. In the crystal, mol­ecules form a three-dimensional network through multiple weak C—H⋯O hydrogen bonds.
doi:10.1107/S1600536814016602
PMCID: PMC4158509  PMID: 25249923
crystal structure; hydrogen bonding; betulin 3,28-di-O-tosyl­ate; natural product
18.  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
19.  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
20.  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
21.  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
22.  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
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.  2-Bromo-4-chloro-6-(cyclo­pentyl­imino­meth­yl)phenol 
All atoms of the title mol­ecule, C12H13BrClNO, except the C and H atoms of the cyclo­pentane methyl­ene groups lie on a crystallographic mirror plane. The cyclo­pentane ring adopts an envelope conformation and an intra­molecular O—H⋯N hydrogen bond is observed. In the crystal, mol­ecules are stacked along the b axis by π–π inter­actions [centroid–centroid distance = 3.6424 (11) Å].
doi:10.1107/S1600536809039142
PMCID: PMC2971220  PMID: 21578219
25.  3-tert-Butyl-2-oxo-1-oxaspiro­[4.5]dec-3-en-4-yl 4-chloro­benzoate 
The title tetronic acid derivative, C20H23ClO4, which is a spiro­diclofen analogue, has two crystallographically independent mol­ecules in the asymmetric unit (Z′ = 2). The cyclo­hexane rings in the respective mol­ecules A and B adopt chair conformations [four C atoms are planar with mean deviations of 0.013 (2) and 0.001 (2) Å, and the flap positions deviate by 0.653 (4) and −0.663 (3) Å (mol­ecule A) and 0.642 (4) and −0.643 (5) Å (mol­ecule B) from the plane]. The furan ring makes dihedral angles of 86.9 (1) (mol­ecule A) and 85.4 (1)° (mol­ecule B) with the respective benzene rings.
doi:10.1107/S1600536811034684
PMCID: PMC3201220  PMID: 22058828

Results 1-25 (164964)