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1.  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
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.  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
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.  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
6.  (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
7.  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
8.  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
9.  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
10.  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
11.  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
12.  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
13.  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
14.  Redetermination at 113 K of 2,2-tetra­methyl­ene-1,2-dihydro­quinazolin-4(3H)-one 
The title compound {systematic name: spiro­[cyclo­pentane-1,2′(1′H)-quinazolin]-4′(3′H)-one]}, C12H14N2O, has been reported previously [Klemm, Weakley, Gilbertson & Song (1998 ▶). J. Heterocycl Chem. 35, 1269–1273]. Its structure has been redetermined at 113 K with greater precision for all data. The mol­ecule is built up from two fused six-membered rings and one five-membered ring linked through a spiro C atom. The pyrimidine ring has an envelope conformation and the cyclopentane ring adopts a distorted boat form. There are inter­molecular N—H⋯O hydrogen bonds, which form a two-dimensional sheet parallel to the (001) plane.
doi:10.1107/S1600536807066706
PMCID: PMC2960329  PMID: 21201476
15.  4′-(4-Chlorophenyl)-1′-methyldispiro[indan-2,2′-pyrrolidine-3′,2′′-indan]-1,3,1′′-trione 
In the title compound, C27H20ClNO3, the two cyclo­pentane rings adopt envelope conformations. The pyrrolidine ring also adopts an envelope conformation (with the spiro C atom as the flap) and its least-squares plane (fitted to five atoms) makes dihedral angles of 66.50 (9), 77.36 (8) and 73.76 (8)° with the chloro­benzene ring and the two 2,3-dihydro-1H-indene ring systems, respectively. The mol­ecular conformation is stabilized by an intra­molecular C—H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds into chains running parallel to the [001] direction.
doi:10.1107/S1600536811033642
PMCID: PMC3200810  PMID: 22064509
16.  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
17.  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
18.  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
19.  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
20.  (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
21.  5-Cyclo­pentyl-2-(3-fluoro­phen­yl)-3-methyl­sulfinyl-1-benzofuran 
In the title compound, C20H19FO2S, the benzofuran fragment is essentially planar, with a largest deviation from the mean plane of 0.026 (2) Å. The benzene ring makes a dihedral angle of 30.72 (12)° with this plane. The cyclo­pentyl group adopts an envelope conformation, with the α-C atom as the flap. This atom is disordered over two sites with occupancy factors of 0.803 (16) and 0.197 (16). In the crystal, mol­ecules are linked by weak C—H⋯O, C—H⋯π and C—F⋯π [3.257 (3) Å] inter­actions.
doi:10.1107/S1600536812025482
PMCID: PMC3393297  PMID: 22807854
22.  cis-Cyclo­heptane-1,2-diol 
The title compound, C7H14O2, is a vicinal diol derived from cyclo­heptane with cis-orientated hydr­oxy groups. The mol­ecules shows no non-crystallographic symmetry. The O—C—C—O torsion angles of both mol­ecules present in the asymmetric unit [−66.4 (2) and −66.9 (2)°] are similar to those in trans-configured cyclo­hexane derivatives (including pyran­oses) as well as rac-trans-cyclo­heptane-1,2-diol, but smaller than those in trans-configured cyclo­pentane derivatives (including furan­oses). In the crystal structure, O—H⋯O hydrogen bonds furnish the formation of sheets parallel to [110].
doi:10.1107/S160053680905051X
PMCID: PMC2971971  PMID: 21578965
23.  5-Cyclo­pentyl-2-(4-methyl­phen­yl)-3-methyl­sulfinyl-1-benzofuran 
In the title compound, C21H22O2S, the cyclo­pentyl ring adopts an envelope conformation with the flap atom connected to the benzofuran residue. The benzofuran unit is essentially planar, with a mean deviation from the least-squares plane defined by the nine constituent ring atoms of 0.008 (2) Å. In the crystal, mol­ecules are linked via pairs of C—H⋯π inter­actions, forming inversion dimers. In the ring of the 4-methyl­phenyl group, four C atoms and their attached H atoms are disordered over two sets of sites, with site-ccupancy factors of 0.899 (5) and 0.10.
doi:10.1107/S1600536812042249
PMCID: PMC3515229  PMID: 23284449
24.  Ferrocene-1-carbaldehyde thio­semi­carbazone 
The asymmetric unit of the title compound, [Fe(C5H5)(C7H8N3S)], consists of two crystallographically independent mol­ecules, A and B. The cyclo­penta­dienyl (Cp) rings in both mol­ecules adopt an eclipsed conformation and are parallel to each other, forming dihedral angles of 2.5 (3) and 1.1 (3)°, respectively. The mean plane of the semicarbazone group is coplanar with the attached Cp ring in mol­ecule A, whereas it is twisted away in mol­ecule B. In the crystal structure, inter­molecular N—H⋯S hydrogen bonds link the mol­ecules into two-dimensional planes parallel to the ab plane. The structure is further consolidated by C—H⋯π inter­actions.
doi:10.1107/S1600536810017605
PMCID: PMC2979593  PMID: 21579319
25.  2-Amino-4-(2-chloro­phen­yl)-7,7-di­methyl-5-oxo-5,6,7,8-tetra­hydro-4H-chromene-3-carbonitrile hemihydrate 
The asymmetric unit of the title compound, C18H17ClN2O2·0.5H2O, contains two organic mol­ecules and one solvent water mol­ecule. In each organic mol­ecule, the cyclo­hexene ring adopts an envelope conformation with the C atom connecting the two methyl groups on the flap; the 4H-pyran ring is nearly planar [maximum deviation = 0.113 (3) Å in one mol­ecule and 0.089 (3) Å in the other mol­ecule] and is approximately perpendicular to the chloro­phenyl ring [dihedral angle = 86.43 (15)° in one mol­ecule and 89.73 (15)° in the other mol­ecule]. Inter­molecular N—H⋯N, N—H⋯O, O—H⋯O and O—H⋯Cl hydrogen bonding is present in the crystal.
doi:10.1107/S1600536812003807
PMCID: PMC3297884  PMID: 22412687

Results 1-25 (315858)