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1.  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
2.  (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
3.  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
4.  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
5.  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
6.  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
7.  (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
8.  [2,6-Bis(biphenyl-4-yl)-4-hy­droxy-4-(pyridin-2-yl)cyclo­hexane-1,3-di­yl]bis­[(pyridin-2-yl)methanone]–butan-2-one (1/1) 
In the title solvate, C47H37N3O3·C4H8O, the cyclo­hexane ring adopts a chair conformation and the plane through its near coplanar atoms forms dihedral angles of 82.58 (7), 89.27 (7), 60.30 (8), 54.54 (7) and 72.03 (7)°, respectively, with the three pyridine rings and the two attached benzene rings. The rings of the biphenyl units are twisted from each other, making dihedral angles of 35.27 (7) and 45.41 (7)°. All the rings are in equatorial orientations in the cyclo­hexane ring, except for the C=O-bonded pyridine ring in position 1, which is axial. Intra­molecular O—H⋯N and C—H⋯O hydrogen bonds form one S(5) and three S(6) ring motifs. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds into a chain along the c axis. The crystal structure also features weak C—H⋯π inter­actions and aromatic π–π stacking [centroid–centroid distances = 3.5856 (10) and 3.7090 (9) Å].
doi:10.1107/S1600536812019241
PMCID: PMC3379237  PMID: 22719435
9.  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
10.  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
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.  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
13.  (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
14.  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
15.  16-[(E)-Benzyl­idene]-13-hy­droxy-4-methyl-2-phenyl-4,14-diaza­penta­cyclo-[12.3.1.01,5.05,13.07,12]octa­deca-7(12),8,10-triene-6,17-dione 
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 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.
doi:10.1107/S1600536810020271
PMCID: PMC3006797  PMID: 21587787
16.  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
17.  Crystal structure of (±)-(4RS,5RS,7SR)-4-[(1RS,2RS,3RS,6RS)-3-benzo­yloxy-2-(2-hy­droxy­ethyl)-6-meth­oxy­meth­oxy-2-methyl­cyclo­hex­yl]-8,10,10-trimethyl-2-oxo-1,3-dioxa­spiro­[4.5]dec-8-en-7-yl benzoate benzene monosolvate 
In the title compound, the ring conformations of the tricycles are in an envelope, a half-chair and a chair. In the crystal, inter­molecular O—H⋯O and C—H⋯O hydrogen bonds and C—H⋯π inter­actions link the mol­ecules into a three-dimensional architecture.
In the title compound, C36H44O10·C6H6, the dioxolane ring adopts an envelope conformation with the C atom bonded to the H atom as the flap, while the cyclo­hexene and cyclo­hexane rings are in half-chair and chair conformations, respectively. In the crystal, a pair of O—H⋯O hydrogen bonds with an R 2 2(26) graph-set motif connect the benzoate mol­ecules into an inversion dimer. The dimers are linked by a weak C—H⋯O inter­action into a tape structure along [01-1]. The benzene mol­ecule links the tapes through C—H⋯O and C—H⋯π inter­actions, forming a sheet parallel to (100).
doi:10.1107/S2056989014026048
PMCID: PMC4331859
crystal structure; hydrogen bonds; taxane skeleton; paclitaxel
18.  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
19.  1β,15α-Dihy­droxy-16α,17-ep­oxy­pregn-4-ene-3,20-dione 
The title mol­ecule, C21H28O5, is composed of three six-membered rings (A/B/C) and a five-membered ring (D). Ring A adopts a 1α-sofa conformation, while rings B and C adopt chair conformations. Cyclo­pentane ring D adopts a 14α-envelope conformation. In the crystal, O—H⋯O hydrogen bonds lead to the formation of ribbons running along the a axis. The structure is further consolidated by C—H⋯O inter­actions, which link the molecules head-to-tail into ribbons along the a axis.
doi:10.1107/S1600536813005023
PMCID: PMC3588417  PMID: 23476615
20.  4a-Hy­droxy-9-(2-meth­oxy­phen­yl)-4,4a,5,6,7,8,9,9a-octa­hydro-3H-xanthene-1,8(2H)-dione 
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.
doi:10.1107/S1600536810050191
PMCID: PMC3050262  PMID: 21522746
21.  (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
22.  (3aR,8bR)-3a,8b-Dihy­droxy-2-methyl­sulfanyl-3-nitro-1-phenyl-1,8b-di­hydro­indeno[1,2-b]pyrrol-4(3aH)-one 
In the title compound, C18H14N2O5, the pyrrolidine ring adopts a shallow envelope conformation, with the C atom bearing the OH group (and remote from the N atom) displaced by 0.257 (2) Å from the other atoms. The cyclo­pentane ring has a twisted conformation about the C—C bond bearing one =O and one —OH grouping. The dihedral angle between the five-membered rings (all atoms) is 65.54 (9)° and the OH groups lie to the same side of the ring-junction. The mol­ecular structure features a weak intra­molecular O—H⋯O bond and a possible C—H⋯π inter­action. In the crystal, the mol­ecules are linked into [010] chains by O—H⋯O hydrogen bonds. Weak C—H⋯O bonds connect the chains into (100) sheets.
doi:10.1107/S1600536813029577
PMCID: PMC3885043  PMID: 24454219
23.  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
24.  2-[(1R*,4R*)-1,4-Dihy­droxy­cyclo­hex­yl]acetic acid 
The title compound, C8H14O4, is an isolation product of the aerial parts of Senecio desfontanei. The acetic acid group is oriented at a dihedral angle of 48.03 (9)° with respect to the basal plane of the cyclo­hexane-1,4-diol chair. An intra­molecular O—H⋯O hydrogen bond generates an S(6) ring with an envelope conformation. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds, resulting in R 3 3(20) ring motifs and C(2) O—H⋯O—H⋯O—H⋯ chains. Overall, a three-dimensional polymeric network arises. A C—H⋯O contact is also present.
doi:10.1107/S1600536811010397
PMCID: PMC3100032  PMID: 21754231
25.  9α-Hy­droxy-12-{[4-(4-hy­droxy­phen­yl)piperazin-1-yl]meth­yl}-4,8-dimethyl-3,14-dioxatri­cyclo­[9.3.0.02,4]tetra­dec-7-en-13-one 
The title compound, C25H34N2O5, was synthesized from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methylen-3, 14-dioxa-tri­cyclo­[9.3.0.02,4]tetra­dec-7-en-13-one), which in turn was isolated from the chloro­form extract of the aerial parts of Anvillea radiata. The mol­ecule comprises a ten-membered ring fused to a five-membered ring with an additional ep­oxy ring system fused to the ten-membered ring. The five-membered ring also carries a 4-hy­droxy­phenyl-piperazin-1-ylmethyl substituent. The ten-membered ring adopts an approximate chair–chair conformation, while the piperazine ring displays a chair conformation and the five-membered ring shows an envelope conformation with the C atom closest to the hy­droxy group forming the flap. Two C atoms in the phenyl ring and the O atom of the hydroxyl group are disordered over two sites, with an occupancy ratio of 0.53 (5):0.47 (5). An intra­molecular O—H⋯N hydrogen-bond stabilizes the mol­ecular conformation. In the crystal, C—H⋯O hydrogen bonds link the mol­ecules into zigzag chains running along the a-axis direction.
doi:10.1107/S1600536814007430
PMCID: PMC4011210  PMID: 24860343

Results 1-25 (147909)