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1.  Crystal structure of 2-(1,3-dioxoindan-2-yl)iso­quinoline-1,3,4-trione 
In the title iso­quinoline-1,3,4-trione derivative, C18H9NO5, the five-membered ring of the indane fragment adopts an envelope conformation with the nitro­gen-substituted C atom being the flap. The planes of the indane benzene ring and the iso­quinoline-1,3,4-trione ring make a dihedral angle of 82.06 (6)°. In the crystal, mol­ecules are linked into chains extending along the bc plane via C—H⋯O hydrogen-bonding inter­actions, enclosing R 2 2(8) and R 2 2(10) loops. The chains are further connected by π–π stacking inter­ations, with centroid-to-centroid distances of 3.9050 (7) Å, forming layers parallel to the b axis.
doi:10.1107/S2056989014025997
PMCID: PMC4331915
crystal structure; iso­quinoline-1,3,4-trione derivative; synthesis; hydrogen bonding; pharmacological properties
2.  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
3.  9-(3,4-Dimeth­oxy­phen­yl)-3,3,6,6-tetra­methyl-4,5,6,9-tetra­hydro-3H-xanthene-1,8(2H,7H)-dione 
The asymmetric unit of the title xanthene compound, C25H30O5, contains two mol­ecules in which the pyran ring and the dimeth­oxy­phenyl ring are nearly perpendicular to one another [dihedral angles = 86.81 (8) and 84.45 (9)°]. One of the meth­oxy groups in one mol­ecule is twisted away from the phenyl ring [C—O—C—C torsion angle = −103.40 (16)°]. The pyran ring adopts a boat conformation whereas the two fused cyclo­hexane rings adopt envelope conformations in both mol­ecules. In the crystal, mol­ecules are linked into a three-dimensional network by C—H⋯O hydrogen bonds.
doi:10.1107/S1600536811023014
PMCID: PMC3152024  PMID: 21837111
4.  2-Methyl-5-nitro-1H-benzimidazole monohydrate 
In the title compound, C8H7N3O2·H2O, the 2-methyl-5-nitro-1H-benzimidazole mol­ecule, excluding the methyl H atoms, is approximately planar, with a maximum deviation of 0.137 (1) Å. The crystal structure is stabilized by water mol­ecules via N—H⋯O(water), O(water)—H⋯O and O(water)—H⋯N hydrogen bonds, forming sheets parallel to the (100) plane. A short inter­molecular contact between the benzene and imidazole rings, with a centroid–centroid distance of 3.6419 (10) Å, indicates a π–π inter­action.
doi:10.1107/S1600536811019027
PMCID: PMC3120310  PMID: 21754885
5.  Cholest-5-ene 
The asymmetric unit of the title compound, C27H46, contains two crytallographically independent cholest-5-ene mol­ecules (A and B). In each mol­ecule, the three six-membered rings are all in chair conformations, while the five-membered ring is in a twist conformation. The terminal isopropyl group of mol­ecule A has a (−)-gauche conformation, whereas that of mol­ecule B has a (+)-gauche conformation. No significant inter­molecular inter­actions are observed in the crystal structure.
doi:10.1107/S1600536811016783
PMCID: PMC3120455  PMID: 21754760
6.  N,N′-Bis(3β-acet­oxy-5α-cholest-6-yl­idene)hydrazine 
The asymmetric unit of the title compound, C58H96N2O4, contains two crystallographically independent mol­ecules. All cyclohexane rings are in chair conformations, while the furan ring is in an envelope conformation in one mol­ecule and a twist conformation in the other. Two acetaldehyde and one isobutane groups are disordered over two orientations with refined site occupancies of 0.940 (4):0.060 (4) and 0.791 (7):0.209 (7), respectively. In the crystal, mol­ecules are stacked along the a axis through van der Waals inter­actions.
doi:10.1107/S1600536811003254
PMCID: PMC3051532  PMID: 21523172
7.  5-[(E)-(2-Hy­droxy­benzyl­idene)amino]-1H-1,3-benzimidazole-2(3H)-thione 
There are two mol­ecules in the asymmetric unit of the title compound, C14H11N3OS. In each, the benzimidazole ring system is essentially planar, with maximum deviations of 0.010 (2) and 0.006 (2) Å, and makes dihedral angles of 8.70 (9) and 13.75 (8)°, respectively, with the hy­droxy-substituted benzene rings. Each mol­ecule adopts an E configuration about the central C=N double bond. In the crystal, the two independent mol­ecules are connected via inter­molecular N—H⋯S hydrogen bonds, forming dimers. Furthermore, the dimers are connected by N—H⋯O hydrogen bonds into mol­ecular ribbons along the c axis. There is an intra­molecular O—H⋯N hydrogen bond in each mol­ecule, which generates an S(6) ring motif.
doi:10.1107/S160053681005172X
PMCID: PMC3050258  PMID: 21522653
8.  Cyclo­hexane-1,3-diyl bis­(N-phenyl­carbamate) 
The asymmetric unit of the title compound, C20H22N2O4, comprises two crystallographically independent mol­ecules (A and B) with slightly different geometries. The dihedral angle between the two terminal phenyl rings is 61.7 (1)° in mol­ecule A and 29.6 (1)° in B. The cyclo­hexane rings adopt chair conformations. In the crystal packing, inter­molecular N—H⋯O hydrogen bonds inter­connect adjacent mol­ecules into a ladder-like structure along the c axis incorporating R 2 2(20) ring motifs. The crystal packing is further stabilized by weak inter­molecular C—H⋯π inter­actions.
doi:10.1107/S1600536810033817
PMCID: PMC3008041  PMID: 21588737
9.  2-(4-Methyl­cyclo­hex-3-en­yl)propan-2-yl N-phenyl­carbamate 
In the title carbamate compound, C17H23NO2, one of the Csp 3 atoms of the cyclo­hexene ring is disordered over two sites with refined occupancies of 0.55 (2) and 0.45 (2), both disorder components resulting in half-boat conformations. The mean plane through the carbamate unit is inclined at inter­planar angles of 14.80 (13), 18.30 (17) and 24.0 (2)°, respectively, with respect to the phenyl ring, and the major and minor disorder component cyclo­hexene rings. In the crystal structure, adjacent mol­ecules are linked into chains along [001] via inter­molecular N—H⋯O hydrogen bonds. The crystal structure is further stabilized by weak inter­molecular C—H⋯π inter­actions.
doi:10.1107/S1600536810025080
PMCID: PMC3007260  PMID: 21588225
10.  2,2,4-Trimethyl-7-nitro-2,3-dihydro-1H-1,5-benzodiazepin-5-ium perchlorate 
In the title mol­ecular salt, C12H16N3O2 +·ClO4 −, the nitro group is close to being coplanar with the benzene ring [dihedral angle = 8.1 (3)°]. The seven-membered ring has a maximum deviation of 0.502 (3) Å at the C atom between the dimethyl- and methyl-substituted C atoms. In the crystal, the components are linked into infinite sheets lying parallel to the bc plane by N—H⋯O and C—H⋯O hydrogen bonds. A short O⋯N contact of 2.896 (4) Å occurs within the sheets and a short O⋯O contact of 2.608 (4) Å occurs between the sheets.
doi:10.1107/S1600536810024475
PMCID: PMC3006776  PMID: 21588044
11.  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
12.  11H-Indeno­[1,2-b]quinoxalin-11-one 
In the title compound, C15H8N2O, the fused ring system is approximately planar, with a maximum deviation of 0.039 (1) Å. In the crystal, weak inter­molecular C—H⋯O inter­actions help to establish the packing.
doi:10.1107/S1600536810019252
PMCID: PMC2979415  PMID: 21579556
13.  A second monoclinic polymorph of 3β-chloro­cholest-5-ene 
The title compound, C27H45Cl, is a second monoclinic polymorph which crystallizes in the space group P21 with four crystallographically independent mol­ecules in the asymmetric unit. The structure was previously reported [Bernal et al. (1940 ▶). Philos. Trans. R. Soc. London Ser. B, 239, 135–182; Vani & Vijayan (1979 ▶). Mol. Cryst. Liq. Cryst. 51, 253–264], also in the space group P21, but with two unique mol­ecules in the asymmetric unit. As in the previously reported structures, rings A and C in the mol­ecule adopt chair conformations with half-chair conformations for rings B and D. The ring junctions B–C and C–D are trans, whereas the junction A–B is quasi-trans. In the crystal structure, mol­ecules are arranged in a head-to-tail fashion along a and are stacked along the b axis.
doi:10.1107/S1600536810015722
PMCID: PMC2979588  PMID: 21579355
14.  3β-Chloro­cholest-5-en-7-one 
The title compound, C27H43ClO, is a steroid derivative composed of a saturated carbon fused-ring framework with an alkyl side chain. The A and C rings have chair conformations and the B and D rings assume half-chair conformations. The cholesterol side chain is fully extended with a gauche, trans conformation of the terminal methyl groups. In the crystal structure, the molecules are aligned in an antiparallel fashion, forming alternate layers. These layers are then linked via C—H⋯O hydrogen bonds, forming a three-dimensional network.
doi:10.1107/S1600536810006380
PMCID: PMC2983643  PMID: 21580431
15.  Redetermination of ethyl (3a-cis)-3a,8b-dihydr­oxy-2-methyl-4-oxo-3a,8b-dihydro-4H-indeno[1,2-b]furan-3-carboxyl­ate monohydrate 
The crystal structure of the title compound, C15H14O6·H2O, has been redetermined from single-crystal X-ray data. The structure was originally determined by Peet et al. [J. Heterocycl. Chem. (1995), 32, 33–41] but the atomic coordinates were not reported or deposited in the Cambridge Structural Database. The ethyl substituent is disordered over two sites with refined occupancies of 0.815 (6) and 0.185 (6). The indeno group is almost planar [maximum deviation 0.0922 (14) Å] and makes an angle of 68.81 (4)° with the furan ring. The fused ring molecules are assembled in pairs by intermolecular O—H⋯O hydrogen bonds. The resulting dimers are also hydrogen bonded to the water molecules, forming double-stranded chains running along the a axis.
doi:10.1107/S1600536809039403
PMCID: PMC2971414  PMID: 21578232

Results 1-15 (15)