organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 69| Part 1| January 2013| Pages o88-o89

2,2,7,7-Tetra­methyl-1,2,3,4,5,6,7,8-octa­hydro­acridine-1,8-dione

aDepartment of Chemistry, Howard University, 525 College Street NW, Washington, DC 20059, USA, bDepartment of Physics, Faculty of Sciences, Erciyes University, 38039 Kayseri, Turkey, and cHacettepe University, Faculty of Pharmacy, Dept. of Pharmaceutical Chemistry, 06100 Sihhiye-Ankara, Turkey
*Correspondence e-mail: rbutcher99@yahoo.com

(Received 14 November 2012; accepted 29 November 2012; online 15 December 2012)

The whole molecule of the title compound, C17H21NO2, is generated by twofold rotational symmetry. The N atom and the C and H atoms in position 4 of the pyridine ring lie on the twofold axis. The cyclohexene ring has a sofa conformation with the CH2 C atom adjacent to the dimethyl-substituted C atom displaced by 0.5949 (16) Å from the mean plane of the other five C atoms. In the crystal, weak C—H⋯O inter­actions link the mol­ecules into chains parallel to the a axis. In addition, ππ stacking inter­actions [centroid–centroid distance = 3.8444 (7) Å] contribute to the stabilization of the crystal structure.

Related literature

For background to potassium channels and biological functions and physiological roles, see: Horiuchi et al. (2001[Horiuchi, T., Dietrich, H. H., Tsugane, S. & Dacey, R. G. Jr (2001). Stroke, 32, 218-224.]); Crestanello et al. (2000[Crestanello, J. A., Doliba, N. M., Babsky, A. M., Doliba, N. M., Niibori, K., Osbakken, M. D. & Whitman, G. J. (2000). J. Surg. Res. 94, 116-123.]). For biological properties of 1,4-dihydro­pyridines (DHP), see: Simşek et al. (2004[Simşek, R., Ozkan, M., Kismetli, E., Uma, S. & Safak, C. (2004). Il Farmaco, 59, 939-943.]); Fincan et al. (2012[Fincan, G. S. Ö., Gündüz, M. G., Vural, I. M., Şimşek, R., Sarioğlu, Y. & Şafak, C. (2012). Med. Chem. Res. 21, 1817-1824.]); Gündüz et al. (2009[Gündüz, M. G., Doğan, A. E., Şimşek, R., Erol, K. & Şafak, C. (2009). Med. Chem. Res. 18, 317-325.]); Pyrko (2008[Pyrko, A. N. (2008). Russ. J. Org. Chem. 44, 1215-1224.]); Li et al. (2010[Li, T., Feng, X., Yao, C., Yu, C., Jiang, B. & Tu, S. (2010). Bioorg. Med. Chem. Lett. 21, 453-455.]). For geometric analysis, see: Cremer & Pople (1975[Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354-1358.]). For a description of the Cambridge Structural Database, see: Allen (2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]). For hydrogen-bond motifs, see: Bernstein et al. (1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]). For similar structures, see: El-Khouly et al. (2012[El-Khouly, A., Öztürk Yildirim, S., Butcher, R. J., Şimsek, R. & Şafak, C. (2012). Acta Cryst. E68, o3337.]); Öztürk Yildirim et al. (2012[Öztürk Yildirim, S., Butcher, R. J., El-Khouly, A., Safak, C. & Şimsek, R. (2012). Acta Cryst. E68, o3365-o3366.], 2013[Öztürk Yildirim, S., Butcher, R. J., Gündüz, M. G., El-Khouly, A., Şimşek, R. & Şafak, C. (2013). Acta Cryst. E69, o40-o41.]); Gündüz et al. (2012[Gündüz, M. G., Butcher, R. J., Öztürk Yildirim, S., El-Khouly, A., Şafak, C. & Şimşek, R. (2012). Acta Cryst. E68, o3404-o3405.]).

[Scheme 1]

Experimental

Crystal data
  • C17H21NO2

  • Mr = 271.35

  • Tetragonal, P 43 22

  • a = 9.99077 (19) Å

  • c = 14.5063 (4) Å

  • V = 1447.95 (6) Å3

  • Z = 4

  • Cu Kα radiation

  • μ = 0.64 mm−1

  • T = 123 K

  • 0.50 × 0.30 × 0.25 mm

Data collection
  • Agilent Xcalibur (Ruby, Gemini) diffractometer

  • Absorption correction: multi-scan [CrysAlis RED (Agilent, 2011[Agilent (2011). CrysAlis PRO and CrysAlis RED. Agilent Technologies, Yarnton, England.]), based on expressions derived by Clark & Reid (1995[Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897.])] Tmin = 0.740, Tmax = 0.856

  • 3055 measured reflections

  • 1452 independent reflections

  • 1349 reflections with I > 2σ(I)

  • Rint = 0.030

Refinement
  • R[F2 > 2σ(F2)] = 0.043

  • wR(F2) = 0.122

  • S = 1.09

  • 1452 reflections

  • 94 parameters

  • H-atom parameters constrained

  • Δρmax = 0.16 e Å−3

  • Δρmin = −0.24 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C2—H2B⋯O1i 0.99 2.52 3.415 (2) 151
Symmetry code: (i) [-y+1, x, z-{\script{1\over 4}}].

Data collection: CrysAlis PRO (Agilent, 2011[Agilent (2011). CrysAlis PRO and CrysAlis RED. Agilent Technologies, Yarnton, England.]); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

Potassium channels play an important role in cell function in both excitable and non-excitable cells. Potassium channel openers, which open vascular potassium channels, have the potential to restrain or prevent contractile responses to excitatory stimuli or clamp the vessel in a relaxed condition. Their vasorelaxant effect is due to an increase in the potassium efflux through opening plasmalemmal potassium channels, which reduce calcium release from intracellular sources (Horiuchi et al., 2001; Crestanello et al., 2000). It is well known that 1,4-dihydropyridine (DHP) and its bicyclo (quinoline) and tricyclo (acridine) analogs are a well known group of calcium channel blockers that are established in the clinic as having vasodilator and anti-hypertensive functions. Potassium channel opener activities of these compounds are well known (Simşek et al., 2004; Fincan et al., 2012; Gündüz et al., 2009; Pyrko, 2008; Li et al., 2010).

The molecular structure of (I) is shown in Fig. 1. The asymmetric unit consists of one half of the molecule and the complete molecule is generated from the asymmetric unit by a twofold axis which passes through the N1 and C7 atoms. The keto bond distance (C5—O1) is 1.215 (2) Å and is comparable with those in similar structures obtained from the Cambrige Crystallographic Database (Allen, 2002).The deviation of atom C3 from the mean plane passing through C1, C2, C4, C5, C6 is 0.595 (2) Å. The dihedral angle between the mean planes of C1, C2, C5 and C6 and C1i, C2i, C5i and C6i (related by 2-fold axis) is 6.02 (3)°. The π conjugation along N1/C1/C6/C7/C6i/C1i [N1—C1 = 1.3423 (18) Å, N1—C1i = 1.3423 (18) Å, C1—C6 = 1.409 (2) Å, C6—C7 = 1.3861 (17) Å, C7—C6i = 1.3861 (17) Å and C1i—C6i = 1.409 (2) Å, symmetry code: (i) = y, x, -z + 5/4] indicates the strong aromaticity in the central ring, which makes all the atoms of the ring lie almost in a plane with the maximum deviation being -0.017 (1) Å for C1. This planarity of the central ring is further supported by the zero value for the puckering amplitude of this ring (Cremer & Pople, 1975). The unique cyclohexene ring (C1–C6) is in a sofa conformation with puckering parameters (Cremer & Pople, 1975) of QT = 0.435 (2) Å, θ = 48.8 (2)° and ϕ = 123.7 (3)°, respectively. The values of the bond lengths and bond angles are comparable with those of the related structures previously reported (El-Khouly et al., 2012; Öztürk Yildirim et al., 2012, 2013; Gündüz, et al., 2012).

Molecules of (I) are linked to each other via weak intermolecular C—H···O hydrogen bonds forming D motifs (Bernstein et al., 1995) as chains parallel to the a axis (Table 1, Fig. 2). In the crystal, weak π-π stacking interactions also contribute to the stabilization: [Cg1···Cg1ii (symmetry code: (ii) = 1 - y, x, -1/4 + z) = 3.844 (7) Å; where Cg1 is the centroid of the N1/C1/C6/C7/C6i/C1i (symmetry code: (i) = y, x, -z + 5/4) ring].

Related literature top

For background to potassium channels and biological functions and physiological roles, see: Horiuchi et al. (2001); Crestanello et al. (2000). For biological properties of 1,4-dihydropyridines (DHP), see: Simşek et al. (2004); Fincan et al. (2012); Gündüz et al. (2009); Pyrko (2008); Li et al. (2010). For geometric analysis, see: Cremer & Pople (1975). For a description of the Cambridge Structural Database, see: Allen (2002). For hydrogen-bond motifs, see: Bernstein et al. (1995). For similar structures, see: El-Khouly et al. (2012); Öztürk Yildirim et al. (2012,2013); Gündüz et al. (2012).

Experimental top

A mixture of paraformaldehyde (1.0 mmol), 4,4-dimethyl-1,3-cyclohexanedione (2.0 mmol) and 1 mL of glacial acetic acid was refluxed in 5 mL of methanol for 8 h. Ammonium acetate (5.0 mmol) was then added and reflux was continued until the reaction was completed (monitored by TLC). The mixture was evaporated under reduced pressure, the residue was treated with 5 mL of water and 20 mL of dichloromethane. The dichloromethane extract was dried over sodium sulfate and evaporated to give the desired product. Pure crystals suitable for X-ray structure analysis were obtained by slow evaporation method using methanol as a solvent.

Refinement top

H atoms bonded to C atoms were positioned geometrically and treated as riding with C—H = 0.95–0.99 Å and Uiso(H) = 1.2Ueq(C) for H, and C—H = 0.98 Å and Uiso(H) = 1.5Ueq(C) for methyl H. The crystal is a racemic twin with a BASF value of 0.3 (4).

Computing details top

Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing 30% probability displacement ellipsoids and the atom-numbering scheme. H atoms are drawn as spheres of arbitrary radii. Unlabelled atoms are related to labelled counterparts by the two-fold axis
[Figure 2] Fig. 2. Crystal packing of (I) viewed along the a axis showing the three dimensional network. Dashed lines indicate the C—H···O interactions.
2,2,7,7-Tetramethyl-1,2,3,4,5,6,7,8-octahydroacridine-1,8-dione top
Crystal data top
C17H21NO2Dx = 1.245 Mg m3
Mr = 271.35Cu Kα radiation, λ = 1.54184 Å
Tetragonal, P4322Cell parameters from 1551 reflections
Hall symbol: P 4cw 2cθ = 3.0–75.1°
a = 9.99077 (19) ŵ = 0.64 mm1
c = 14.5063 (4) ÅT = 123 K
V = 1447.95 (6) Å3Block, colorless
Z = 40.50 × 0.30 × 0.25 mm
F(000) = 584
Data collection top
Agilent Xcalibur (Ruby, Gemini)
diffractometer
1452 independent reflections
Radiation source: Enhance (Cu) X-ray Source1349 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.030
Detector resolution: 10.5081 pixels mm-1θmax = 75.3°, θmin = 4.4°
ω scansh = 1112
Absorption correction: multi-scan
[CrysAlis RED (Agilent, 2011), based on expressions derived by Clark & Reid (1995)]
k = 127
Tmin = 0.740, Tmax = 0.856l = 1218
3055 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.043Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.122H-atom parameters constrained
S = 1.09 w = 1/[σ2(Fo2) + (0.0749P)2 + 0.0669P]
where P = (Fo2 + 2Fc2)/3
1452 reflections(Δ/σ)max < 0.001
94 parametersΔρmax = 0.16 e Å3
0 restraintsΔρmin = 0.24 e Å3
Crystal data top
C17H21NO2Z = 4
Mr = 271.35Cu Kα radiation
Tetragonal, P4322µ = 0.64 mm1
a = 9.99077 (19) ÅT = 123 K
c = 14.5063 (4) Å0.50 × 0.30 × 0.25 mm
V = 1447.95 (6) Å3
Data collection top
Agilent Xcalibur (Ruby, Gemini)
diffractometer
1452 independent reflections
Absorption correction: multi-scan
[CrysAlis RED (Agilent, 2011), based on expressions derived by Clark & Reid (1995)]
1349 reflections with I > 2σ(I)
Tmin = 0.740, Tmax = 0.856Rint = 0.030
3055 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0430 restraints
wR(F2) = 0.122H-atom parameters constrained
S = 1.09Δρmax = 0.16 e Å3
1452 reflectionsΔρmin = 0.24 e Å3
94 parameters
Special details top

Experimental. Absorption correction: CrysAlis RED, (Agilent, 2011) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. (Clark & Reid, 1995).

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.54930 (12)0.19920 (12)0.62530 (9)0.0345 (3)
N10.66208 (13)0.66208 (13)0.62500.0259 (4)
C10.69529 (15)0.53223 (15)0.61859 (10)0.0231 (3)
C20.84076 (15)0.49870 (18)0.60647 (12)0.0288 (4)
H2A0.89570.56490.64030.035*
H2B0.86430.50490.54030.035*
C30.87361 (17)0.35818 (18)0.64155 (11)0.0297 (4)
H3A0.86710.35790.70960.036*
H3B0.96740.33680.62510.036*
C40.78234 (16)0.24795 (17)0.60323 (11)0.0254 (4)
C50.63570 (16)0.28413 (16)0.61821 (11)0.0240 (3)
C60.59904 (15)0.42923 (15)0.62063 (10)0.0218 (3)
C70.46519 (15)0.46519 (15)0.62500.0223 (4)
H7A0.39800.39800.62500.027*
C80.79805 (17)0.23165 (17)0.49808 (12)0.0319 (4)
H8A0.73070.16850.47520.048*
H8B0.88770.19740.48420.048*
H8C0.78560.31860.46800.048*
C90.8130 (2)0.1153 (2)0.65133 (18)0.0458 (6)
H9A0.75590.04480.62570.069*
H9B0.79550.12420.71750.069*
H9C0.90720.09200.64160.069*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0283 (6)0.0225 (5)0.0527 (8)0.0016 (5)0.0096 (6)0.0026 (6)
N10.0238 (6)0.0238 (6)0.0300 (9)0.0034 (7)0.0020 (6)0.0020 (6)
C10.0220 (7)0.0265 (8)0.0209 (7)0.0006 (7)0.0003 (6)0.0011 (6)
C20.0202 (7)0.0309 (9)0.0352 (8)0.0030 (6)0.0014 (6)0.0046 (7)
C30.0222 (7)0.0388 (9)0.0283 (8)0.0035 (7)0.0034 (7)0.0007 (7)
C40.0222 (8)0.0251 (7)0.0288 (8)0.0040 (6)0.0006 (6)0.0038 (6)
C50.0233 (8)0.0229 (8)0.0257 (7)0.0013 (6)0.0033 (7)0.0031 (6)
C60.0229 (7)0.0227 (7)0.0197 (7)0.0001 (6)0.0007 (6)0.0020 (6)
C70.0213 (6)0.0213 (6)0.0243 (10)0.0026 (8)0.0004 (6)0.0004 (6)
C80.0263 (8)0.0357 (9)0.0338 (9)0.0008 (7)0.0036 (7)0.0065 (8)
C90.0353 (10)0.0389 (10)0.0631 (13)0.0080 (8)0.0002 (9)0.0204 (10)
Geometric parameters (Å, º) top
O1—C51.215 (2)C4—C91.528 (2)
N1—C11.3423 (18)C4—C81.542 (2)
N1—C1i1.3423 (18)C5—C61.496 (2)
C1—C61.409 (2)C6—C71.3861 (17)
C1—C21.502 (2)C7—C6i1.3861 (17)
C2—C31.529 (2)C7—H7A0.9500
C2—H2A0.9900C8—H8A0.9800
C2—H2B0.9900C8—H8B0.9800
C3—C41.534 (2)C8—H8C0.9800
C3—H3A0.9900C9—H9A0.9800
C3—H3B0.9900C9—H9B0.9800
C4—C51.525 (2)C9—H9C0.9800
C1—N1—C1i118.85 (19)O1—C5—C6120.07 (15)
N1—C1—C6122.40 (14)O1—C5—C4121.96 (15)
N1—C1—C2117.57 (14)C6—C5—C4117.93 (13)
C6—C1—C2120.01 (14)C7—C6—C1118.05 (15)
C1—C2—C3111.93 (14)C7—C6—C5119.24 (14)
C1—C2—H2A109.2C1—C6—C5122.71 (14)
C3—C2—H2A109.2C6i—C7—C6120.1 (2)
C1—C2—H2B109.2C6i—C7—H7A119.9
C3—C2—H2B109.2C6—C7—H7A119.9
H2A—C2—H2B107.9C4—C8—H8A109.5
C2—C3—C4114.27 (13)C4—C8—H8B109.5
C2—C3—H3A108.7H8A—C8—H8B109.5
C4—C3—H3A108.7C4—C8—H8C109.5
C2—C3—H3B108.7H8A—C8—H8C109.5
C4—C3—H3B108.7H8B—C8—H8C109.5
H3A—C3—H3B107.6C4—C9—H9A109.5
C5—C4—C9109.45 (15)C4—C9—H9B109.5
C5—C4—C3110.45 (13)H9A—C9—H9B109.5
C9—C4—C3109.74 (15)C4—C9—H9C109.5
C5—C4—C8105.29 (13)H9A—C9—H9C109.5
C9—C4—C8109.85 (16)H9B—C9—H9C109.5
C3—C4—C8111.95 (14)
C1i—N1—C1—C61.60 (11)C3—C4—C5—C629.2 (2)
C1i—N1—C1—C2176.83 (16)C8—C4—C5—C691.81 (16)
N1—C1—C2—C3154.89 (12)N1—C1—C6—C73.1 (2)
C6—C1—C2—C326.6 (2)C2—C1—C6—C7175.25 (13)
C1—C2—C3—C451.52 (19)N1—C1—C6—C5176.91 (12)
C2—C3—C4—C552.49 (18)C2—C1—C6—C54.7 (2)
C2—C3—C4—C9173.25 (15)O1—C5—C6—C74.2 (2)
C2—C3—C4—C864.49 (18)C4—C5—C6—C7173.69 (12)
C9—C4—C5—O132.0 (2)O1—C5—C6—C1175.89 (15)
C3—C4—C5—O1152.98 (16)C4—C5—C6—C16.3 (2)
C8—C4—C5—O185.99 (19)C1—C6—C7—C6i1.48 (10)
C9—C4—C5—C6150.15 (17)C5—C6—C7—C6i178.57 (16)
Symmetry code: (i) y, x, z+5/4.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2B···O1ii0.992.523.415 (2)151
Symmetry code: (ii) y+1, x, z1/4.

Experimental details

Crystal data
Chemical formulaC17H21NO2
Mr271.35
Crystal system, space groupTetragonal, P4322
Temperature (K)123
a, c (Å)9.99077 (19), 14.5063 (4)
V3)1447.95 (6)
Z4
Radiation typeCu Kα
µ (mm1)0.64
Crystal size (mm)0.50 × 0.30 × 0.25
Data collection
DiffractometerAgilent Xcalibur (Ruby, Gemini)
diffractometer
Absorption correctionMulti-scan
[CrysAlis RED (Agilent, 2011), based on expressions derived by Clark & Reid (1995)]
Tmin, Tmax0.740, 0.856
No. of measured, independent and
observed [I > 2σ(I)] reflections
3055, 1452, 1349
Rint0.030
(sin θ/λ)max1)0.627
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.043, 0.122, 1.09
No. of reflections1452
No. of parameters94
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.16, 0.24

Computer programs: CrysAlis PRO (Agilent, 2011), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2B···O1i0.992.523.415 (2)151
Symmetry code: (i) y+1, x, z1/4.
 

Acknowledgements

RJB acknowledges the NSF–MRI program (grant No. CHE-0619278) for funds to purchase the diffractometer.

References

First citationAgilent (2011). CrysAlis PRO and CrysAlis RED. Agilent Technologies, Yarnton, England.
First citationAllen, F. H. (2002). Acta Cryst. B58, 380–388.  Web of Science CrossRef CAS IUCr Journals
First citationBernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573.  CrossRef CAS Web of Science
First citationClark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887–897.  CrossRef CAS Web of Science IUCr Journals
First citationCremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358.  CrossRef CAS Web of Science
First citationCrestanello, J. A., Doliba, N. M., Babsky, A. M., Doliba, N. M., Niibori, K., Osbakken, M. D. & Whitman, G. J. (2000). J. Surg. Res. 94, 116–123.  Web of Science CrossRef PubMed CAS
First citationEl-Khouly, A., Öztürk Yildirim, S., Butcher, R. J., Şimsek, R. & Şafak, C. (2012). Acta Cryst. E68, o3337.  CSD CrossRef IUCr Journals
First citationFincan, G. S. Ö., Gündüz, M. G., Vural, I. M., Şimşek, R., Sarioğlu, Y. & Şafak, C. (2012). Med. Chem. Res. 21, 1817–1824.  Web of Science CrossRef CAS
First citationGündüz, M. G., Butcher, R. J., Öztürk Yildirim, S., El-Khouly, A., Şafak, C. & Şimşek, R. (2012). Acta Cryst. E68, o3404–o3405.  CSD CrossRef IUCr Journals
First citationGündüz, M. G., Doğan, A. E., Şimşek, R., Erol, K. & Şafak, C. (2009). Med. Chem. Res. 18, 317–325.
First citationHoriuchi, T., Dietrich, H. H., Tsugane, S. & Dacey, R. G. Jr (2001). Stroke, 32, 218–224.  CrossRef PubMed CAS
First citationLi, T., Feng, X., Yao, C., Yu, C., Jiang, B. & Tu, S. (2010). Bioorg. Med. Chem. Lett. 21, 453–455.  Web of Science CSD CrossRef PubMed
First citationÖztürk Yildirim, S., Butcher, R. J., El-Khouly, A., Safak, C. & Şimsek, R. (2012). Acta Cryst. E68, o3365–o3366.  CSD CrossRef IUCr Journals
First citationÖztürk Yildirim, S., Butcher, R. J., Gündüz, M. G., El-Khouly, A., Şimşek, R. & Şafak, C. (2013). Acta Cryst. E69, o40–o41.  CSD CrossRef IUCr Journals
First citationPyrko, A. N. (2008). Russ. J. Org. Chem. 44, 1215–1224.  Web of Science CrossRef CAS
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationSimşek, R., Ozkan, M., Kismetli, E., Uma, S. & Safak, C. (2004). Il Farmaco, 59, 939–943.  PubMed

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Volume 69| Part 1| January 2013| Pages o88-o89
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