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1.  (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
2.  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
3.  Ethyl 2-(4-meth­oxy­phen­yl)-1-[3-(2-oxopyrrolidin-1-yl)prop­yl]-1H-benzimidazole-5-carboxyl­ate 
The asymmetric unit of the title compound, C24H27N3O4, contains two mol­ecules, A and B. The benzimidazole rings are essentially planar [maximum deviations = 0.0144 (10) and 0.0311 (8) Å in A and B, respectively]. The dihedral angle between the benzimidazole mean plane and its attached benzene ring is 36.90 (5) ° for mol­ecule A and 51.40 (5) ° for mol­ecule B. In both mol­ecules, the pyrrolidine ring adopts an envelope conformation with a C atom as the flap. In molecule B, the flap C atom is disordered over two positions in a 0.711 (6):0.289 (6) ratio. In the crystal, C—H⋯O inter­actions link the mol­ecules, generating [100] chains. The crystal packing also features weak π–π inter­actions between the imidazole and benzene rings [centroid–centroid distances = 3.8007 (7) and 3.8086 (7) Å] and between the benzene rings [centroid–centroid distance = 3.7001 (7) Å] and C—H⋯π inter­actions involving the benzene rings.
doi:10.1107/S1600536811055966
PMCID: PMC3275001  PMID: 22346946
4.  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
5.  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
6.  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
7.  3-Cyclo­pentyl­sulfonyl-5-fluoro-2-methyl-1-benzofuran 
There are two independent mol­ecules, A and B, in the asymmetric unit of the title compound, C14H15FO3S, in each of which the cyclo­pentyl ring adopts an envelope conformation. The benzofuran units in each mol­ecule are essentially planar, with mean deviations from the least-squares plane defined by the nine constituent ring atoms of 0.009 (2) Å for mol­ecule A and 0.013 (2) Å for mol­ecule B. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds. In the cyclo­pentyl ring of mol­ecule B, one C atom is disordered over two positions with site-occupancy factors of 0.60 (2) and 0.40 (2).
doi:10.1107/S1600536811021222
PMCID: PMC3152135  PMID: 21837086
8.  7′-Phenyl-1′,3′,5′,6′,7′,7a’-hexa­hydro­dipiro[acenaphthyl­ene-1,5′-pyrrolo­[1,2-c]thia­zole-6′,2′′-indane]-2,1′′(1H)-dione 
In the title compound, C31H23NO2S, the pyrrolidine ring adopts an envelope conformation (with the spiro C atom as the flap), while the thia­zolidine ring and the two cyclo­pentane rings adopt twisted conformations. The mean plane through the hexa­hydro­pyrrolo­[1,2-c]thia­zole ring [r.m.s deviation = 0.400 (1) Å] forms dihedral angles of 76.83 (4), 80.70 (5) and 79.00 (4)° with the benzene ring and the mean planes of the dihydro­acenaphthyl­ene and the dihydro­indene rings, respectively. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds into sheets lying parallel to the bc plane. One of the ketone O atoms accepts three such bonds. Weak C—H⋯π inter­actions are also observed.
doi:10.1107/S1600536812013293
PMCID: PMC3344191  PMID: 22606194
9.  Crystal structures of (±)-(1SR,5SR,6SR,7SR,10SR,11SR,13RS,14SR)-13-hy­droxy-7-meth­oxy­meth­oxy-11,15,18,18-tetra­methyl-3-oxo-2,4-dioxa­tetra­cyclo­[12.3.1.01,5.06,11]octa­dec-15-en-10-yl benzoate, its 13-epimer and 13-one derivative 
In the title three compounds, the ring conformations of tetra­cycles are similar; each tetra­cycle adopts essentially planar, chair, half-chair and chair–chair forms. In the crystals, mol­ecules are linked into similar chains by inter­molecular hydrogen bonds.
The title compounds, C29H38O8·0.25C5H12, (A), C29H38O8, (B), and C29H36O8, (C), are tetra­cyclic benzoates possessing a taxane skeleton with a fused dioxolane ring as the core structure. In the asymmetric unit of (A), there are two independent benzoate mol­ecules (A and A′) and a half mol­ecule of solvent pentane disordered about an inversion center. The mol­ecular conformations of (A), (B) and (C) are similar except for the flexible meth­oxy­meth­oxy group. The cyclo­hexane, cyclo­hexene and central cyclo­octane rings adopt chair, half-chair and chair–chair (extended crown) forms, respectively. The dioxolane rings are essentially planar, while the dioxolane ring of A′ is slightly twisted from the mean plane. In the crystal of (A), inter­molecular O—H⋯O, C—H⋯O and C—H⋯π inter­actions link the independent benzoates alternately, forming a chain structure. In the crystals of (B) and (C), mol­ecules are linked through O—H⋯O and C—H⋯π inter­actions, and C—H⋯O hydrogen bonds, respectively, into similar chains. Further, weak inter­molecular C—H⋯O inter­actions connect the chains into a three-dimensional network in (A) and a sheet in (B), whereas no other interactions are observed for (C).
doi:10.1107/S2056989015006854
PMCID: PMC4420046  PMID: 25995857
crystal structure; hydrogen bonds; taxane skeleton; paclitaxel
10.  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
11.  Lup-20(29)-en-28-ol-3-one (betulone) 
The asymmetric unit of the title compound, C30H48O2, contains two independent mol­ecules, the main difference between them being that the isopropenyl group is rotated by approximately 180°. In each mol­ecule, the fused six-membered rings have chair–chair–chair–chair conformations and the cyclo­pentane ring adopts an envelope conformation with the C atom bearing the hy­droxy­methyl group as the flap. All ring junctions are trans-fused. With the exception of one of the methyl groups adjacent to the C=O group, all the methyl groups are in axial positions. The isopropenyl group is equatorial and the hy­droxy­methyl group is in an axial orientation. In the crystal, weak C—H⋯O inter­actions link the mol­ecules into chains along [010]. Weak intra­molecular C—H⋯O hydrogen bonds are also observed but the hy­droxy groups are not involved in hydrogen bonds.
doi:10.1107/S1600536813011008
PMCID: PMC3648317  PMID: 23723937
12.  4-Amino-8-cyclo­pent­yloxy-7-meth­oxy-2H-chromen-2-one monohydrate 
The asymmetric unit of the title compound, C15H17NO4·H2O, contains two organic mol­ecules with marginal differences between them and two water molecules. The chromine rings in both mol­ecules are essentially planar, with maximum deviations of 0.012 (2) and 0.060 (2) Å. The five-membered cyclo­pentane rings adopt envelope conformations in both mol­ecules. In the crystal, the components are linked by N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds, resulting in a three-dimensional network.
doi:10.1107/S160053681201450X
PMCID: PMC3344523  PMID: 22590285
13.  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
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.  (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
16.  (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
17.  5-[(E)-(2,6-Dichloro­benzyl­idene)amino]-2-hy­droxy­benzoic acid 
There are two geometrically different mol­ecules in the asymmetric unit of the title compound, C14H9Cl2NO3. The 5-amino-2-hy­droxy­benzoic acid units [r.m.s. deviations of 0.0323 and 0.0414 Å] and 2,6-dichloro­benzaldehyde groups [r.m.s. deviations of 0.0285 and 0.0226 Å] are roughly planar and oriented at dihedral angles of 11.69 (13) and 83.12 (6)° in the two mol­ecules. An intra­molecular O—H⋯O hydrogen bond completes an S(6) ring motif in each mol­ecule. The two mol­ecules form dimers with each other through inter­molecular O—H⋯N and C—H⋯O hydrogen bonds, completing an R 2 2(8) ring motif. The dimers are inter­linked via inter­molecular O—H⋯N and C—H⋯O hydrogen bonds, forming polymeric sheets.
doi:10.1107/S160053681004136X
PMCID: PMC3009312  PMID: 21589097
18.  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
19.  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
20.  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
21.  Pseudoaglycone of Spinosyn A 
The title compound [systematic name: 9-ethyl-13-hy­droxy-14-methyl-2-(3,4,5-trimeth­oxy-6-methyl­tetra­hydro-2H-pyran-2-yl­oxy)-3,3a,5b,6,9,10,11,12,13,14,16a,16b-dodeca­hydro-1H-as-indaceno[3,2-d][1]oxacyclo­dodecine-7,15(2H,5aH)-dione], C33H50O9, was obtained by hydrolysis of Spinosyn A. The fused cyclo­pentene ring adopts a twisted conformation, while the fused cyclo­hexene and cyclo­pentane rings are in envelope conformations with the same C atom at the flaps. In the crystal, mol­ecules are linked by O—H⋯O and C—H⋯O hydrogen bonds into a layer parallel to the ab plane.
doi:10.1107/S1600536812028851
PMCID: PMC3414943  PMID: 22904930
22.  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
23.  (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
24.  Ferrocene-1-carbaldehyde 4-ethyl­thio­semi­carbazone 
The asymmetric unit of title compound, [Fe(C5H5)(C9H12N3S)], contains two crystallographically independent mol­ecules, A and B. The two cyclo­penta­dienyl (Cp) rings are parallel to each other in both mol­ecules, forming dihedral angles of 2.3 (3) and 1.0 (3)°, respectively, and adopt an eclipsed conformation. The mean plane of the semicarbazone group is twisted slightly away from the attached Cp ring in both mol­ecules, the dihedral angles between the mean plane and the Cp ring being 15.3 (2) and 10.8 (2)°. The ethyl group in mol­ecule A is coplanar with the mean plane of the semicarbazone group [C—N—C—C torsion angle = −175.2 (4)°], whereas it is nearly perpendicular in mol­ecule B [C—N—C—C torsion angle = 84.8 (6)°]. In the crystal structure, inter­molecular N—H⋯S hydrogen bonds link the mol­ecules into dimers. These dimers are further linked into chains via inter­molecular C—H⋯S hydrogen bonds. The crystal studied was a non-merohedral twin with a refined ratio of the twin components of 0.265 (2):0.735 (2).
doi:10.1107/S1600536810018209
PMCID: PMC2979492  PMID: 21579333
25.  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

Results 1-25 (513355)