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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.  (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
3.  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
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.  (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
7.  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
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-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
10.  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
11.  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
12.  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
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.  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
15.  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
16.  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
17.  Spiro­[cyclo­pentane-1,2′(1′H)-pyrido[2,3-d]pyrimidin]-4′(3′H)-one 
The title compound, C11H13N2O, was obtained by cyclo­condensation of 2-amino­pyridine-3-carbonitrile with cyclo­penta­none. The mol­ecule is built up from two fused six-membered rings and one five-membered ring linked through a spiro C atom. Both the pyrimidine and the cyclo­pentane rings adopt envelope conformations. In the crystal structure, mol­ecules are linked by inter­molecular N—H⋯O hydrogen bonds.
doi:10.1107/S1600536810027479
PMCID: PMC3008029  PMID: 21588651
18.  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
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.  (1β,2α,3α,7α,11α,13β)-1,3,7,11-Tetra­acet­oxy-2,13-bis­(benz­yloxy)-21-methyl-19,21-secohetisan-19-al hemi­hydrate 
In the crystal structure of the title compound, C43H46NO13·0.5H2O, the mol­ecule assumes a U-shaped conformation, the terminal benzene rings being approximately parallel and partially overlapped with each other. The mol­ecule contains eight alicyclic and heterocyclic rings. The cyclo­hexane rings adopt chair conformations, the other three six-membered carbocyclic rings form a bicyclo­[2.2.2]octane system with a boat conformation for each six-membered ring, the six-membered heterocyclic ring has a chair conformation and both of the five-membered rings have envelope conformations. The solvent water mol­ecule links with the organic mol­ecule via classic O—H⋯O and weak C—H⋯O hydrogen bonding in the crystal structure.
doi:10.1107/S1600536809018315
PMCID: PMC2969740  PMID: 21583273
21.  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
22.  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
23.  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
24.  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
25.  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

Results 1-25 (113240)