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1.  N-[(2-Chloro-8-methyl­quinolin-3-yl)meth­yl]-4-meth­oxy­aniline 
In the title compound, C18H17ClN2O, the quinoline ring system is essentially planar; the r.m.s. deviation for the non-H atoms is 0.04 Å with a maximum deviation from the mean plane of 0.026 (4) Å for the C atom bonded to the –CH2– group. The meth­oxy-substituted benzene ring forms a dihedral angle of 70.22 (4)° with this ring system. The crystal structure can be described as zigzag layers in which the quinoline ring systems are parallel to (011) and molecules are connected via inter­molecular N—H⋯N hydrogen bonds, forming chains along [100]. The crystal studied was an inversion twin with a 0.86 (5):0.14 (5) domain ratio.
PMCID: PMC3009236  PMID: 21589041
2.  Crystal structures of 2-meth­oxy­isoindoline-1,3-dione, 1,3-dioxoisoindolin-2-yl methyl carbonate and 1,3-dioxo-2,3-di­hydro-1H-benzo[de]isoquinolin-2-yl methyl carbonate: three anti­convulsant compounds 
In three potentially anti­convulsant compounds, of which two are isoindoline derivatives and one an iso­quinoline derivative, the central moiety is planar. In the crystals of all three compounds, there are C—H⋯O hydrogen bonds present linking the mol­ecules into two-dimensional slabs for the isoindoline derivatives, and into a three-dimensional framework for the iso­quinoline derivative.
The title compounds, C9H7NO3, (1), C10H7NO5, (2), and C14H9NO5, (3), are three potentially anti­convulsant compounds. Compounds (1) and (2) are isoindoline derivatives and (3) is an iso­quinoline derivative. Compounds (2) and (3) crystallize with two independent mol­ecules (A and B) in their asymmetric units. In all three cases, the isoindoline and benzoiso­quinoline moieties are planar [r.m.s. deviations are 0.021 Å for (1), 0.04 and 0.018 Å for (2), and 0.033 and 0.041 Å for (3)]. The substituents attached to the N atom are almost perpendicular to the mean planes of the heterocycles, with dihedral angles of 89.7 (3)° for the N—O—Cmeth­yl group in (1), 71.01 (4) and 80.00 (4)° for the N—O—C(=O)O—Cmeth­yl groups in (2), and 75.62 (14) and 74.13 (4)° for the same groups in (3). In the crystal of (1), there are unusual inter­molecular C=O⋯C contacts of 2.794 (1) and 2.873 (1) Å present in mol­ecules A and B, respectively. There are also C—H⋯O hydrogen bonds and π–π inter­actions [inter-centroid distance = 3.407 (3) Å] present, forming slabs lying parallel to (001). In the crystal of (2), the A and B mol­ecules are linked by C—H⋯O hydrogen bonds, forming slabs parallel to (10-1), which are in turn linked via a number of π–π inter­actions [the most significant centroid–centroid distances are 3.4202 (7) and 3.5445 (7) Å], forming a three-dimensional structure. In the crystal of (3), the A and B mol­ecules are linked via C—H⋯O hydrogen bonds, forming a three-dimensional structure, which is consolidated by π–π inter­actions [the most significant inter-centroid distances are 3.575 (3) and 3.578 (3) Å].
PMCID: PMC4257384  PMID: 25552964
crystal structure; anti­convulsant; isoindoline; iso­quinoline; indoline
3.  3-Meth­oxy-2-[(E)-(4-meth­oxy­phen­yl)imino­meth­yl]phenol 
The title compound, C15H15NO3, adopts the enol–imine tautomeric form. The two rings are twisted with respect to each other, making a dihedral angle of 44.08 (5)°. The 3-methoxy-2-[(E)-(4-methoxyphenyl)-iminomethyl]phenol unit is almost planar, the largest deviation from the mean plane being 0.047 (2) Å. Such a planar conformation might be related to the occurrence of an intra­molecular O—H⋯N hydrogen bond. In the crystal, inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into sheets parallel to (010). These sheets are inter­connected by weak C—H⋯π inter­actions.
PMCID: PMC3051687  PMID: 21523025
4.  Crystal structure of 2-chloro-3-(di­meth­oxy­meth­yl)-6-meth­oxy­quinoline 
The title compound, C13H14ClNO3, crystallizes with Z′ = 2 in the space group Pca21, but a search for possible additional crystallographic symmetry found none. However, the crystal structure exhibits pseudosymmetry as the two independent mol­ecules are related by an approximate but non-crystallographic inversion located close to (0.38, 0.26, 1/2) in the selected asymmetric unit, and the structure exhibits partial inversion twinning. The approximate inversion relationship between the two mol­ecules in the selected asymmetric unit is clearly shown by comparison of the relevant torsion angle in the two mol­ecules; the corresponding torsion angles have similar, although not identical magnitudes but with opposite signs. The mean planes of the quinoline rings in the two independent mol­ecules are almost parallel, with a dihedral angle of only 0.16 (3)° between them, and the mutual orientation of these rings permits significant π–π stacking inter­actions between them [centroid–centroid distances = 3.7579 (15) and 3.7923 (15) Å]. In addition, the bimolecular aggregates which are related by translation along [010] are linked by a further π–π stacking inter­action [centroid–centroid distance = 3.7898 (15) Å], so forming a π-stacked chain running parallel to [010]. However, there are no C—H⋯N hydrogen bonds in the structure nor, despite the number of independent aromatic rings, are there any C—H⋯π hydrogen bonds; hence there are no direction-specific inter­actions between adjacent π-stacked chains.
PMCID: PMC4420130  PMID: 25995951
crystal structure; quinolone; pseudosymmetry; twinning; π–π stacking inter­actions
5.  6-Chloro-3-[5-(3-meth­oxy-8-methyl-4-quinol­yl)-1-phenyl-4,5-dihydro-1H-pyrazol-3-yl]-2-methyl-4-phenyl­quinoline 
In the title compound, C36H29ClN4O, the dihydro­pyrazole ring adopts an envelope conformation. The two quinoline ring systems (r.m.s. deviations = 0.029 and 0.018 Å) are oriented at a dihedral angle of 71.43 (4)°. One of the quinoline rings makes a dihedral angle of 65.40 (7)° with the phenyl substituent. In the crystal, mol­ecules are linked into chains along the b axis by inter­molecular C—H⋯N hydrogen bonds. In addition, C—H⋯π and π–π [centroid–centroid distance = 3.7325 (8) Å] inter­actions are observed.
PMCID: PMC2971305  PMID: 21578276
6.  4-Hy­droxy-5-meth­oxy-N,1-dimethyl-2-oxo-N-[4-(tri­fluoro­meth­yl)phen­yl]-1,2-di­hydro­quinoline-3-carboxamide 
The title compound, C20H17F3N2O4, named tasquinimod, is a second-generation oral quinoline-3-carboxamide analogue, which is currently in phase III clinical trials for the treatment of metastatic prostate cancer. The quinoline unit is almost planar (r.m.s. deviation of fitted atoms = 0.0075 Å). The carboxamide side chain, substituted at position 3, is tilted by 88.07 (7)° to the quinoline plane. Both the methyl and carbonyl groups of this carboxamide side chain are in a syn conformation. The 4-(tri­fluoro­meth­yl)phenyl plane is inclined at 50.62 (17)° to the plane of the carboxamide side chain, and at 87.14 (4)° to the plane of the quinoline ring system. The 4-hy­droxy H atom acts as a double proton donor in an intra­molecular hydrogen bond to the 5-position meth­oxy O atom and in an inter­molecular contact to the 2-oxo group, generating a chain along [010] in the crystal structure.
PMCID: PMC3998412  PMID: 24765003
7.  (E)-4-(4-Hydr­oxy-3-methoxy­benzyl­idene­amino)-3-[1-(4-isobutyl­phen­yl)eth­yl]-1H-1,2,4-triazole-5(4H)-thione 
The asymmetric unit of the title compound, C22H26N4O2S, contains two crystallographically independent mol­ecules (A and B). The isobutyl unit of mol­ecule B is disordered over two orientations with refined occupancies of 0.785 (6) and 0.215 (6). In each mol­ecule, intra­molecular C—H⋯S hydrogen bonds generate S(6) ring motifs. The essentially planar 1,2,4-triazole rings [r.m.s. deviations of 0.004 (2) and 0.011 (2) Å, in A and B respectively] form dihedral angles of 85.86 (12), 8.38 (10)°, respectively, with the isobutyl-substituted phenyl ring and the 2-methoxy­phenol substituent in mol­ecule A [89.26 (13) and 2.46 (10)°, respectively, in B]. In the crystal structure, inter­molecular N—H⋯N and N—H⋯S hydrogen bonds link neighbouring mol­ecules, generating R 2 2(7) ring motifs. These molecules are further inter­connected into extended chains along [20] by inter­molecular O—H⋯O hydrogen bonds. The crystal structure is further stabilized by π–π [centroid-centroid distance = 3.6299 (13) Å] and C—H⋯π inter­actions. A short O⋯O contact of 2.781 (2) Å is also observed.
PMCID: PMC2980163  PMID: 21580185
8.  8-{[3-(3-Meth­oxy­phen­yl)-1,2,4-oxa­diazol-5-yl]meth­oxy}quinoline monohydrate 
In the title hydrate, C19H15N3O3·H2O, the three aromatic groups in the quinoline derivative are close to coplanar: the central oxa­diazole fragment makes dihedral angles of 15.7 (2)° with the benzene ring and 5.30 (14)° with the quinoline ring system. In the crystal, the organic mol­ecules are connected with water mol­ecules by pairs of O—H⋯N hydrogen bonds involving the quinoline and oxa­diazole N atoms. The mol­ecules form stacks along the a axis, neighboring mol­ecules within each stack being related by inversion and the shortest distance between the centroids of the oxa­diazole and pyridine rings being 3.500 (2) Å. Mol­ecules from neighboring stacks are linked by weak C—H⋯O hydrogen bonds, forming a three-dimensional structure.
PMCID: PMC3648286  PMID: 23723906
9.  7-Hy­droxy-6-meth­oxy-2H-chromen-2-one 
The title compound, C10H8O4, is one of the coumarins existing in Morinda citrifolia L (Noni). The chromenone ring system is approximately planar with a maximum deviation of 0.0208 (14) Å. The meth­oxy group does not deviate from this plane [C—O—C—C torsion angle = −1.5 (3)°], indicating that the whole mol­ecule is almost planar. In the crystal packing, inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into chains. These are further connected by C—H⋯O hydrogen bonds.
PMCID: PMC3007346  PMID: 21588426
10.  (E)-1-[2-Hy­droxy-4,6-bis­(meth­oxy­meth­oxy)phen­yl]-3-[3-meth­oxy-4-(meth­oxy­meth­oxy)phen­yl]prop-2-en-1-one 
The title compound, C22H26O9, crystallizes with two independent mol­ecules in the asymmetric unit in which the dihedral angles between the two benzene rings are 21.4 (2) and 5.1 (2)°. An intra­molecular O—H⋯O hydrogen bond occurs in each mol­ecule. Inter­molecular C—H⋯O hydrogen bonds stabilize the crystal structure.
PMCID: PMC3247344  PMID: 22219962
11.  Crystal structure of 2-[4-(4-chloro­phen­yl)-1-(4-meth­oxy­phen­yl)-2-oxoazetidin-3-yl]benzo[de]iso­quinoline-1,3-dione dimethyl sulfoxide monosolvate 
In the title solvated compound, C28H19N2O4·C2H6OS, the central β-lactam ring is almost planar (r.m.s. deviation = 0.002 Å). It makes dihedral angles of 1.92 (11), 83.23 (12) and 74.90 (10)° with the meth­oxy- and chloro­phenyl rings and the ring plane of the 1H-benzo[de]iso­quinoline-1,3(2H)-dione group [maximum deviation = 0.089 (1)], respectively. An intra­molecular C—H⋯O hydrogen bond closes an S(6) ring and helps to establish the near coplanarity of the β-lactam and meth­oxy­benzene rings. In the crystal, the components are linked by C—H⋯O hydrogen bonds, C—H⋯π inter­actions and aromatic π–π stacking inter­actions [centroid-to-centroid distances = 3.6166 (10) and 3.7159 (10) Å], resulting in a three-dimensional network, The dimethyl sulfoxide solvent mol­ecule is disordered over two sets of sites in a 0.847 (2):0.153 (2) ratio.
PMCID: PMC4384601  PMID: 25878867
crystal structure; β-lactam ring; 1H-benzo[de]iso­quinoline-1,3(2H)-dione group; disorder; azetidin-2-ones
12.  Crystal structure of methyl 6-meth­oxy-11-(4-meth­oxy­phen­yl)-16-methyl-14-phenyl-8,12-dioxa-14,15-di­aza­tetra­cyclo­[,7.013,17]hepta­deca-2(7),3,5,13(17),15-penta­ene-10-carboxyl­ate 
In the title compound, the pyran and pyrone rings adopt slightly distorted half-chair and envelope conformations, respectively. In the crystal, C—H⋯O and π–π inter­actions connect the mol­ecules, forming double layers that stack along the c-axis direction.
In the title compound, C30H28N2O6, the pyran ring adopts a slightly distorted half-chair conformation and the pyrone ring adopts an envelope conformation, with the C atom bearing the carboxyl­ate group as the flap. The pyrazole ring [maximum deviation = 0.002 (2) Å] forms a dihedral angle of 13.2 (1)° with the attached benzene ring. The near-planar atoms of the pyran ring and the pyrazole ring are close to coplanar, the dihedral angles between their mean planes being 6.4 (1)°. The dihedral angle between the pyrone ring and the benzene ring of the chromene unit is 10.7 (1)°. The mol­ecular conformation is stabilized by an intra­molecular C—H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, C—H⋯O inter­actions generate supra­molecular chains propagating in [100] and these are connected into double layers that stack along the c-axis direction by weak π–π inter­actions between pyrazole rings [centroid–centroid distance = 3.801 (1) Å].
PMCID: PMC4186142  PMID: 25309159
crystal structure; conformation; crystal packing; chromene
13.  Comparison of crystal structures of 4-(benzo[b]thio­phen-2-yl)-5-(3,4,5-tri­meth­oxy­phen­yl)-2H-1,2,3-triazole and 4-(benzo[b]thio­phen-2-yl)-2-methyl-5-(3,4,5-tri­meth­oxy­phen­yl)-2H-1,2,3-triazole 
In the crystal structure of (I), the mol­ecules are linked into chains by N—H⋯O hydrogen bonds with (5) ring motifs. After the N-methyl­ation of structure (I), no hydrogen-bonding inter­actions were observed for structure (II).
The title compound, C19H17N3O3S (I), was prepared by a [3 + 2]cyclo­addition azide condensation reaction using sodium azide and l-proline as a Lewis base catalyst. N-Methyl­ation of compound (I) using CH3I gave compound (II), C20H19N3O3S. The benzo­thio­phene ring systems in (I) and (II) are almost planar, with r.m.s deviations from the mean plane = 0.0205 (14) in (I) and 0.016 (2) Å in (II). In (I) and (II), the triazole rings make dihedral angles of 32.68 (5) and 10.43 (8)°, respectively, with the mean planes of the benzo­thio­phene ring systems. The trimeth­oxy phenyl rings make dihedral angles with the benzo­thio­phene rings of 38.48 (4) in (I) and 60.43 (5)° in (II). In the crystal of (I), the mol­ecules are linked into chains by N—H⋯O hydrogen bonds with R 2 1(5) ring motifs. After the N-methyl­ation of structure (I), no hydrogen-bonding inter­actions were observed for structure (II). The crystal structure of (II) has a minor component of disorder that corresponds to a 180° flip of the benzo­thio­phene ring system [occupancy ratio 0.9363 (14):0.0637 (14)].
PMCID: PMC4257340  PMID: 25484755
combretastatin A-4 analog; anti-cancer agent; triazole ring; hydrogen bonding; crystal structure
14.  1-{[(Cyclo­hexyl­oxy)carbon­yl]­oxy}ethyl 3-{[2′-(2-ethyl-2H-tetra­zol-5-yl)biphenyl-4-yl]meth­yl}-2-oxo-2,3-dihydro-1H-benzimidazole-4-carboxyl­ate 
In the title compound, C33H34N6O6, the dihydro­benzimidazol-2-one ring system is essentially planar (r.m.s. deviation = 0.021 Å). The cyclo­hexane ring adopts a chair conformation. In the 5-(biphenyl-2-yl)-2H-tetra­zole fragment, the tetra­zole ring is twisted away from the attached benzene ring by 35.73 (11)° and the two benzene rings form a dihedral angle of 68.00 (9)°. An intra­molecular C—H⋯O inter­action is observed. In the crystal, the mol­ecules are linked into a zigzag chain running along the b axis by inter­molecular N—H⋯O hydrogen bonds.
PMCID: PMC2983784  PMID: 21580794
15.  N-(4-Meth­oxy­phen­yl)-6-methyl-2-phenyl-5-{[4-(tri­fluoro­meth­yl)anilino]meth­yl}pyrimidin-4-amine 
The title compound, C26H23F3N4O, crystallizes with two symmetry-independent mol­ecules in the asymmetric unit, denoted A and B, which differ mainly in the rotation of the meth­oxy­phenyl ring. The –CF3 group of mol­ecule B is disordered by rotation, with the F atoms split over two sets of sites; the occupancy factor for the major component is 0.853 (4). The dihedral angles between the pyrimidine ring and the attached phenyl, meth­oxy­phenyl and tri­fluoro­methyl­phenyl rings are 8.1 (2), 37.5 (2) and 70.7 (2)°, respectively, in mol­ecule A, and 9.3 (2), 5.3 (2) and 79.7 (2)° in mol­ecule B. An intra­molecular N—H⋯N hydrogen bond occurs in each mol­ecule. In the crystal, two crystallographically independent mol­ecules associate into a dimer via a pair of N—H⋯N hydrogen bonds, with a resulting R 2 2(12) ring motif and π–π stacking inter­actions [centroid–centroid distance = 3.517 (4) Å] between the pyrimidine rings. For the A mol­ecules, there are inter­molecular C—H⋯O hydrogen bonds between an aryl C atom of meth­oxy­phenyl ring and a meth­oxy O atom of an adjacent mol­ecule. A similar inter­action is lacking in the B mol­ecules.
PMCID: PMC3885078  PMID: 24454254
16.  Crystal structure of (2E)-1-(4-hy­droxy-1-methyl-2-oxo-1,2-di­hydro­quinolin-3-yl)-3-(4-hy­droxy-3-meth­oxy­phen­yl)prop-2-en-1-one 
The crystal packing of the title compound features O—H⋯O hydrogen bonds, which form one-dimensional chains of mol­ecules further linked via π–π inter­actions.
In the title compound, C20H17NO5, the dihedral angle between the mean plane of the di­hydro­quinoline ring system (r.m.s. deviation = 0.003 Å) and the benzene ring is 1.83 (11)°. The almost planar conformation is a consequence of an intra­molecular O—H⋯O hydrogen bond and the E configuration about the central C=C bond. In the crystal structure, O—H⋯O hydrogen bonds generate chains of mol­ecules along the [10-1] direction. These chains are linked via π–π inter­actions [inter-centroid distances are in the range 3.6410 (16)–3.8663 (17) Å].
PMCID: PMC4438805  PMID: 26029406
crystal structure; 4-hy­droxy-1,2-di­hydro­quinolin-2(1H)-one; α,β-unsaturated ketones; hydrogen bonding; π–π inter­actions
17.  Triaqua­bis­{2-meth­oxy-6-[(phenyl­iminium­yl)meth­yl]phenolate-κO 1}manganese(II) dinitrate 
The crystal structure of the title compound, [Mn(C14H13NO2)2(H2O)3](NO3)2, is comprised of two Schiff base 2-meth­oxy-6-(N-phenyl­carboximido­yl)phenol (HL) ligands and three coordinated water mol­ecules. The MnII ion lies on a twofold axis that bis­ects one water O atom. The coordination sphere of the five-coordinate Mn atom is completed by the two monodentate HL ligands and three coordinated water mol­ecules binding through their O atoms, affording a distorted tetra­gonal–pyramidal geometry. In the phenolate ligands, the hy­droxy H atom transfers to the imine N atom. This H atom is also involved in an intra­molecular N—H⋯O hydrogen bond that imposes a nearly planar conformation on each ligand, with dihedral angles of 2.78 (3) and 2.43 (5)° between the aromatic rings of each ligand. In the crystal, mol­ecules are linked by inter­molecular O—H⋯O hydrogen bonds.
PMCID: PMC3120327  PMID: 21754686
18.  N-[(2-Hydr­oxy-1-naphthyl)(3-nitro­phenyl)meth­yl]acetamide 
The title compound, C19H16N2O4, is of inter­est as a precursor to biologically active substituted quinolines and related compounds. The dihedral angle between the naphthalene ring system and the benzene ring is 81.9 (1)°. The crystal structure is stabilized by N—H⋯O inter­molecular hydrogen bonds, linking the mol­ecules into pairs around a center of symmetry. The crystal structure is further stabilized by inter­molecular O—H⋯O hydrogen bonds, which link the mol­ecules into chains running along a axis. An intra­molecular C—H⋯O short contact is also present.
PMCID: PMC2968788  PMID: 21582451
19.  1-[2-(Carboxy­meth­oxy)phen­yl]-N-(4-chloro­phen­yl)methanimine oxide1  
In the title resonance conformer, C15H12ClNO4, the central C–N bond [1.297 (2) Å] has considerable double-bond character and the N–O bond [1.3215 (18) Å] indicates formal negative charge on the oxygen atom. Considerable deviations from co-planarity are evident in the mol­ecule, with both benzene rings twisted out of the central C–C–N–C plane [the dihedral angle formed between the rings = 81.99 (8)°]. Similarly, the carboxylic acid residue occupies a position almost normal to the plane of the benzene ring to which it is connected [C—C—O—C torsion angle = −78.42 (17)°]. The most prominent inter­molecular inter­actions involve the carboxylic acid the N+–O− residues with the O—H⋯O hydrogen bonds leading to helical supra­molecular chains along the b axis. These chains are connected into layers via C–H⋯Ocarbon­yl inter­actions and the layers are consolidated into the crystal structure by C–H⋯Cl contacts.
PMCID: PMC2980074  PMID: 21580149
20.  Ethyl 4-{[1-(2,4-dichloro­benz­yl)-1H-1,2,3-triazol-4-yl]meth­oxy}-8-(trifluoro­meth­yl)quinoline-3-carboxyl­ate 
In the title compound, C23H17Cl2F3N4O3, the triazole ring makes dihedral angles of 50.27 (6) and 82.78 (7)° with the quinoline ring system and the dichloro-substituted benzene ring. The dihedral angle between the quinoline and dichloro-substituted benzene rings is 38.17 (4)°. In the crystal, mol­ecules are linked via C—H⋯N, C—H⋯F and C—H⋯O hydrogen bonds into a three-dimensional network. The crystal is further consolidated by C—H⋯π contacts to the triazole ring and inversion-related π–π inter­actions between the benzene and pyridine rings of quinoline systems [centroid–centroid distance = 3.7037 (7) Å].
PMCID: PMC3470374  PMID: 23125787
21.  2-[6-(4-Chloro­phen­yl)imidazo[2,1-b][1,3]thia­zol-2-yl]-N′-[(E)-4-meth­oxy­benzyl­idene]acetohydrazide 
In the imidazo[2,1-b][1,3]thia­zole group of the title compound, C21H17ClN4O2S, the dihedral angle between the thia­zole and imidazole rings is 1.9 (2)°. The mean plane of this group makes dihedral angles of 5.5 (2) and 39.9 (2)° with the benzene rings of the chloro­phenyl and meth­oxy­phenyl groups, respectively. The dihedral angle between these two benzene rings is 34.4 (2)°. In the crystal, mol­ecules are connected to each other by inter­molecular N—H⋯O hydrogen bonds along the b axis, generating a C(4) chain. Weak C—H⋯π inter­actions also occur.
PMCID: PMC3050215  PMID: 21522689
22.  1-{6-Chloro-2-[(2-chloro-6-methyl­quinolin-3-yl)meth­oxy]-4-phenyl­quinolin-3-yl}ethanone 
In the title compound, C28H20Cl2N2O2, the 2-chloro­quinoline and 6-chloro­quinoline ring systems are twisted slightly, making a dihedral angle of 4.05 (3)°. The dihedral angle between the 2-quinoline ring system and the phenyl ring attached to it is 74.43 (5)°. In the crystal structure, a pair of inter­molecular C—H⋯O hydrogen bonds connect the mol­ecules, forming centrosymmetric dimers with R 2 2(16) motifs. The dimers are further consolidated by a C—H⋯π inter­action and a π–π stacking inter­action with a centroid–centroid distance of 3.6562 (10) Å.
PMCID: PMC3006731  PMID: 21587915
23.  6-(4-Chloro­phen­yl)-2-(4-meth­oxy­phen­yl)-6,7-dihydro-4H-pyrazolo­[5,1-c][1,4]oxazine 
In the title compound, C19H17ClN2O2, the pyrazole ring is almost planar with a maximum deviation of 0.009 (3) Å and makes a dihedral angle of 8.96 (9)° with the oxazine ring. The dihedral angles between the pyrazole ring and the chlorine- and meth­oxy-substituted benzene rings are 50.95 (8) and 13.24 (9)°, respectively. An inter­molecular C—H⋯N hydrogen bond links the mol­ecules into infinite chains along the a axis. The crystal structure is further stabilized by C—H⋯π inter­actions.
PMCID: PMC3212334  PMID: 22090991
24.  (E)-Methyl 3-(3,4-dimeth­oxy­phen­yl)-2-[(1,3-dioxoisoindolin-2-yl)meth­yl]acrylate 
In the title compound, C21H19NO6, the isoindole ring system is essentially planar [maximum deviation = 0.019 (2) Å for the N atom] and is oriented at a dihedral angle of 51.3 (1)° with respect to the benzene ring. The two meth­oxy groups are almost coplanar with the attached benzene ring [C—O—C—C = 3.7 (4) and 4.3 (4)°]. The mol­ecular conformation is stabilized by an intra­molecular C—H⋯O hydrogen bond, which generates an S(9) ring motif. In the crystal, mol­ecules are linked through bifurcated C—H⋯(O,O) hydrogen bonds having R 1 2(5) ring motifs, forming chains along the b-axis direction. The crystal packing is further stabilzed by π–π inter­actions [centriod–centroid distance = 3.463 (1) Å].
PMCID: PMC3344056  PMID: 22589965
25.  Crystal structure of (±)-(1SR,5SR,6SR,7SR,10SR,11SR,13SR)-13-benz­yloxy-7-meth­oxy­meth­oxy-11,15,18,18-tetra­methyl-3-oxo-2,4-dioxa­tetra­cyclo­[,5.06,11]octa­deca-14,16-dien-10-yl benzoate 
In the title compound, the ring conformations of the tetra­cycle are twist, chair, half-chair and chair–boat forms. In the crystal, inter­molecular C—H⋯O and C—H⋯π inter­actions link mol­ecules to construct a three-dimensional architecture.
In the title compound, C36H42O8, the dioxolane ring adopts a twist conformation; the two adjacent C atoms deviate alternately from the mean plane of other atoms by −0.287 (5) and 0.174 (5) Å. The cyclo­hexane, cyclo­hexa­diene and central cyclo­octane rings show chair, half-chair and boat–chair forms, respectively. As a result of the strained ring system, the tetra­subsituted olefin in the cyclo­hexa­diene is skewed from an ideal planar structure. In the crystal, C—H⋯O hydrogen bonds connect the mol­ecules into a sheet parallel to (100). The sheets are further linked by other weak C—H⋯O and C—H⋯π inter­actions, forming a three-dimensional network.
PMCID: PMC4420122  PMID: 25995863
crystal structure; hydrogen bonds; taxane skeleton; paclitaxel; hydrogen bonding; C—H⋯π inter­actions

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