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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 67| Part 9| September 2011| Pages o2269-o2270

2-Oxochromen-4-yl 4-(di­methyl­amino)­benzoate

aLaboratoire de Cristallographie et Physique Moléculaire, UFR SSMT, Université de Cocody 22 BP 582 Abidjan 22, Côte d'Ivoire, and bLaboratoire de Chimie Bio-organique et Phytochimie, Université de Ouagadougou 03 BP 7021 Ouagadougou 03, Burkina Faso
*Correspondence e-mail: abou_akoun@yahoo.fr

(Received 18 July 2011; accepted 1 August 2011; online 6 August 2011)

In the title mol­ecule, C18H15NO4, the benzoate ring is oriented at a dihedral angle of 43.43 (6)° with respect to the planar [maximum deviation = 0.038 (2) Å] chromene ring. The crystal structure features R22(12) centrosymetric dimers formed via C—H⋯O inter­actions and these dimeric aggregates are connected by C—H⋯π inter­actions.

Related literature

For the biological activity of coumarin derivatives, see: Ukhov et al. (2001[Ukhov, S. V., Kon'shin, M. E. & Odegova, T. F. (2001). Pharm. Chem. J. 35, 364-365.]); Abd Elhafez et al. (2003[Abd Elhafez, O. M., El Khrisy, E. A., Badria, F. & Fathy, A. M. (2003). J. Arch. Pharm. Res. 26, 686-696.]); Basanagouda et al. (2009[Basanagouda, M., Kulkarni, M. V., Sharma, D., Gupta, V. K., Sandhyarani, P. & Sasal, V. P. J. (2009). Chem. Sci. 121, 485-495.]); Liu et al. (2008[Liu, X., Dong, M., Chen, X., Jiang, M., Lv, X. & Zhou, J. (2008). Appl. Microbiol. Biotechnol. 78, 241-247.]); Trapkov et al. (1996[Trapkov, V. A., Parfenov, E. A. & Smirnov, L. D. (1996). Pharm. Chem. J. 30, 445-447.]); Vukovic et al. (2010[Vukovic, N., Sukdolak, S., Solujic, S. & Niciforovic, N. (2010). Arch. Pharm. Res. 33, 5-15.]); Emmanuel-Giota et al. (2001[Emmanuel-Giota, A. A., Fylaktakidou, K. C., Hadjipavlou-Litina, D. J., Litinas, K. E. & Nicolaides, D. N. J. (2001). Heterocycl. Chem. 38, 717-722.]); Hamdi & Dixneuf (2007[Hamdi, N. & Dixneuf, P. H. (2007). Topics in Heterocyclic Chemistry. Berlin, Heidelberg: Springer-Verlag.]); Wang et al. (2001[Wang, M., Wang, L., Li, Y. & Li, Q. (2001). Transition Met. Chem. 26, 307-310.]); Marchenko et al. (2006[Marchenko, M. M., Kopyl'chuk, G. P., Shmarakov, I. A., Ketsa, O. V. & Kushnir, V. M. (2006). Pharm. Chem. J. 40, 296-297.]). For hydrogen-bond graph-set 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.]).

[Scheme 1]

Experimental

Crystal data
  • C18H15NO4

  • Mr = 309.32

  • Triclinic, [P \overline 1]

  • a = 7.4939 (2) Å

  • b = 10.2361 (3) Å

  • c = 10.6620 (3) Å

  • α = 92.307 (3)°

  • β = 103.935 (1)°

  • γ = 109.852 (2)°

  • V = 739.92 (4) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.10 mm−1

  • T = 298 K

  • 0.50 × 0.40 × 0.30 mm

Data collection
  • Nonius KappaCCD diffractometer

  • 8424 measured reflections

  • 3590 independent reflections

  • 2897 reflections with I > 2σ(I)

  • Rint = 0.024

Refinement
  • R[F2 > 2σ(F2)] = 0.048

  • wR(F2) = 0.120

  • S = 0.98

  • 3585 reflections

  • 208 parameters

  • H-atom parameters constrained

  • Δρmax = 0.23 e Å−3

  • Δρmin = −0.20 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

Cg3 is the centroid of the C15–C18/C22/C23 ring.

D—H⋯A D—H H⋯A DA D—H⋯A
C9—H91⋯O8i 0.96 2.49 3.449 (2) 171
C7—H71⋯Cg3ii 0.95 2.84 3.429 (2) 121
C20—H202⋯Cg3iii 0.99 2.91 3.777 (2) 146
Symmetry codes: (i) -x, -y, -z-1; (ii) -x, -y+1, -z; (iii) -x+1, -y+1, -z+1.

Data collection: COLLECT (Nonius, 2001[Nonius (2001). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994[Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.]); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003[Betteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487.]); molecular graphics: PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]); software used to prepare material for publication: CRYSTALS.

Supporting information


Comment top

Coumarin constitutes one of the major classes of naturally occurring compounds, and interest in its chemistry continues unabated because of its usefulness as biologically active agents. It also represents the core structure of several molecules of pharmaceutical importance. Coumarin and its derivatives have been reported to serve as anti-bacterial (Ukhov et al., 2001; Abd Elhafez et al., 2003; Basanagouda et al., 2009; Liu et al., 2008), anti-oxidant (Trapkov et al., 1996; Vukovic et al., 2010), anti-inflammatory (Emmanuel-Giota et al., 2001; Hamdi & Dixneuf, 2007), anti-coagulant (Hamdi et al., 2007) and anti-tumour (Wang et al., 2001; Marchenko et al., 2006) agents. Therefore, the synthesis of new coumarin derivatives is of considerable interest. In order to study the influence of new substituents on the activity of the coumarin derivative, the title compound, (I), has been synthesized and in this paper, we present its molecular structure, Fig. 1.

In (I), the planar chromene ring system resulting from the two coupled rings (benzene and 3,6-dihydro-2H-pyran) is oriented with respect to the benzoate-benzene ring at a dihedral angle of 43.43 (6)°. Atoms O14, N19, C13 and C21 are 0.046 (1), 0.052 (1), 0.079 (2) and 0.077 (3) Å out of the plane of the benzoate-benzene ring, respectively, so, they are coplanar with this ring.

In the crystal structure, intermolecular C—H···O interactions (Table 1) link the molecules into centrosymmetric dimers through R22(12) ring motifs (Bernstein et al., 1995) (Fig. 2). Two weak C—H···π interactions formed between the H71 and H202 atoms and the centroid Cg3 of the benzoate-benzene ring (Table 1 and Fig. 3) further stabilize the structure.

Related literature top

For the biological activity of coumarin derivatives, see: Ukhov et al. (2001); Abd Elhafez et al. (2003); Basanagouda et al. (2009); Liu et al. (2008); Trapkov et al. (1996); Vukovic et al. (2010); Emmanuel-Giota et al. (2001); Hamdi & Dixneuf (2007); Wang et al. (2001); Marchenko et al. (2006). For hydrogen-bond graph-set motifs, see: Bernstein et al. (1995).

Experimental top

To a solution of 4.10-2 mole of paradimethylamino benzoyl chloride in 150 ml of dried tetrahydrofuran, was added 0.12 mole of dried triethylamine and 4.10-2 mole of 4-hydroxycoumarin by small portions over 30 min. The mixture was then refluxed for 3 h and poured in 300 ml of chloroform or dichloromethane. The solution was acidified with dilute hydrochloric acid until the pH was 2 or 3. The organic layer was extracted, washed with water, dried over MgSO4 and the solvent removed. The crude product was recrystallized in chloroform. Colourless crystals of the title compound are obtained in a good yield: 82.6%; M.pt. 445 K.

Refinement top

The H-atoms were placed at calculated positions and were included in the refinement in the riding model approximation with C—H in the range of 0.94–0.99 Å, and with Uiso(H) = 1.2–1.5Ueq(C).

Computing details top

Data collection: COLLECT (Nonius, 2001); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I) showing the atomic labeling scheme, with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as spheres of arbitrary radius.
[Figure 2] Fig. 2. Crystal packing, viewed in projection down the b axis, showing parallel centrosymmetric dimers. Dashed lines indicate hydrogen bonds. H atoms not involved in hydrogen bonds have been omitted for clarity.
[Figure 3] Fig. 3. Crystal packing, showing C—H···π stacking interactions. The green dots are centroids of rings. H atoms not involved in C—H···π interactions have been omitted for clarity.
2-Oxochromen-4-yl 4-(dimethylamino)benzoate top
Crystal data top
C18H15NO4Z = 2
Mr = 309.32F(000) = 324
Triclinic, P1Dx = 1.388 Mg m3
Hall symbol: -P 1Melting point: 445 K
a = 7.4939 (2) ÅMo Kα radiation, λ = 0.71073 Å
b = 10.2361 (3) ÅCell parameters from 8424 reflections
c = 10.6620 (3) Åθ = 2.0–28.7°
α = 92.307 (3)°µ = 0.10 mm1
β = 103.935 (1)°T = 298 K
γ = 109.852 (2)°Parallelepiped, colourless
V = 739.92 (4) Å30.50 × 0.40 × 0.30 mm
Data collection top
Nonius KappaCCD
diffractometer
2897 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.024
Graphite monochromatorθmax = 28.7°, θmin = 2.0°
ϕ and ω scansh = 99
8424 measured reflectionsk = 1313
3590 independent reflectionsl = 1414
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)] = 0.048Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.120H-atom parameters constrained
S = 0.98 Method = Modified Sheldrick w = 1/[σ2(F2) + (0.05P)2 + 0.22P],
where P = [max(Fo2,0) + 2Fc2]/3
3585 reflections(Δ/σ)max = 0.00023
208 parametersΔρmax = 0.23 e Å3
0 restraintsΔρmin = 0.20 e Å3
60 constraints
Crystal data top
C18H15NO4γ = 109.852 (2)°
Mr = 309.32V = 739.92 (4) Å3
Triclinic, P1Z = 2
a = 7.4939 (2) ÅMo Kα radiation
b = 10.2361 (3) ŵ = 0.10 mm1
c = 10.6620 (3) ÅT = 298 K
α = 92.307 (3)°0.50 × 0.40 × 0.30 mm
β = 103.935 (1)°
Data collection top
Nonius KappaCCD
diffractometer
2897 reflections with I > 2σ(I)
8424 measured reflectionsRint = 0.024
3590 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0480 restraints
wR(F2) = 0.120H-atom parameters constrained
S = 0.98Δρmax = 0.23 e Å3
3585 reflectionsΔρmin = 0.20 e Å3
208 parameters
Special details top

Refinement. The 5 reflections 1 0 0; 0 1 0; -1 0 1; 0 0 1; -1 1 1 have been measured with too low intensities. It might be caused by some systematical error, probably by shielding by a beam stop of these diffractions. They were not used in the refinement.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.16941 (15)0.34698 (9)0.00111 (8)0.0462
C20.13553 (19)0.27238 (13)0.11979 (11)0.0385
C30.16678 (17)0.14123 (12)0.10953 (12)0.0363
C40.12326 (18)0.05485 (13)0.22545 (12)0.0396
O50.05704 (15)0.09384 (10)0.34457 (9)0.0493
C60.0349 (2)0.22168 (15)0.35487 (13)0.0480
C70.0715 (2)0.31027 (14)0.23575 (13)0.0453
O80.0149 (2)0.24941 (13)0.46358 (10)0.0703
C90.1466 (2)0.07411 (14)0.22593 (15)0.0499
C100.2154 (2)0.11591 (15)0.10867 (16)0.0531
C110.2611 (2)0.03116 (15)0.00810 (15)0.0504
C120.2373 (2)0.09635 (14)0.00783 (13)0.0436
C130.26101 (19)0.49181 (13)0.02252 (12)0.0394
O140.31022 (19)0.56038 (11)0.06000 (10)0.0605
C150.29273 (18)0.54219 (12)0.15893 (11)0.0361
C160.40333 (19)0.68335 (13)0.20353 (12)0.0399
C170.4486 (2)0.73643 (14)0.33261 (13)0.0438
C180.38190 (19)0.64988 (14)0.42412 (12)0.0399
N190.42952 (19)0.70056 (13)0.55279 (11)0.0513
C200.3356 (3)0.61733 (19)0.64173 (14)0.0591
C210.5486 (4)0.8446 (2)0.59983 (17)0.0903
C220.2647 (2)0.50796 (14)0.37750 (12)0.0422
C230.22417 (19)0.45612 (13)0.24879 (12)0.0402
H710.05000.39630.24410.0557*
H910.11320.13200.30790.0600*
H1010.23290.20530.10620.0641*
H1110.30970.06050.09020.0601*
H1210.26730.15520.08750.0528*
H1610.44920.74420.14160.0485*
H1710.52650.83220.35940.0528*
H2010.38560.67020.72800.0885*
H2030.19300.59210.61210.0885*
H2020.36220.52860.64500.0885*
H2110.58370.85630.69320.1350*
H2130.47520.90460.56720.1350*
H2120.66550.87110.57080.1350*
H2210.21210.44660.43670.0519*
H2310.14840.35890.21930.0481*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0692 (6)0.0362 (5)0.0336 (4)0.0168 (4)0.0184 (4)0.0015 (4)
C20.0442 (7)0.0376 (6)0.0332 (6)0.0136 (5)0.0122 (5)0.0005 (5)
C30.0355 (6)0.0348 (6)0.0363 (6)0.0096 (5)0.0109 (5)0.0019 (5)
C40.0397 (6)0.0371 (6)0.0375 (6)0.0095 (5)0.0095 (5)0.0001 (5)
O50.0631 (6)0.0452 (5)0.0345 (5)0.0183 (5)0.0072 (4)0.0028 (4)
C60.0555 (8)0.0498 (8)0.0358 (6)0.0196 (6)0.0069 (6)0.0016 (6)
C70.0571 (8)0.0444 (7)0.0378 (6)0.0241 (6)0.0105 (6)0.0042 (5)
O80.1030 (10)0.0720 (8)0.0340 (5)0.0396 (7)0.0038 (5)0.0047 (5)
C90.0537 (8)0.0389 (7)0.0534 (8)0.0137 (6)0.0140 (6)0.0039 (6)
C100.0543 (8)0.0396 (7)0.0668 (9)0.0197 (6)0.0150 (7)0.0058 (6)
C110.0500 (8)0.0478 (8)0.0534 (8)0.0194 (6)0.0104 (6)0.0122 (6)
C120.0467 (7)0.0439 (7)0.0382 (6)0.0149 (6)0.0099 (5)0.0052 (5)
C130.0487 (7)0.0361 (6)0.0357 (6)0.0171 (5)0.0133 (5)0.0045 (5)
O140.0936 (8)0.0462 (6)0.0392 (5)0.0159 (5)0.0266 (5)0.0087 (4)
C150.0419 (6)0.0361 (6)0.0331 (6)0.0161 (5)0.0124 (5)0.0044 (5)
C160.0461 (7)0.0368 (6)0.0379 (6)0.0129 (5)0.0159 (5)0.0076 (5)
C170.0477 (7)0.0367 (6)0.0415 (7)0.0090 (5)0.0120 (5)0.0012 (5)
C180.0423 (7)0.0456 (7)0.0324 (6)0.0185 (5)0.0077 (5)0.0033 (5)
N190.0632 (8)0.0545 (7)0.0319 (5)0.0193 (6)0.0086 (5)0.0011 (5)
C200.0716 (10)0.0777 (11)0.0347 (7)0.0325 (9)0.0179 (7)0.0104 (7)
C210.1312 (19)0.0643 (11)0.0409 (9)0.0037 (11)0.0096 (10)0.0089 (8)
C220.0506 (7)0.0418 (7)0.0366 (6)0.0160 (6)0.0163 (5)0.0102 (5)
C230.0474 (7)0.0344 (6)0.0385 (6)0.0128 (5)0.0139 (5)0.0048 (5)
Geometric parameters (Å, º) top
O1—C21.3728 (14)C13—C151.4586 (16)
O1—C131.3885 (15)C15—C161.3937 (17)
C2—C31.4430 (17)C15—C231.3985 (17)
C2—C71.3373 (18)C16—C171.3762 (17)
C3—C41.3920 (16)C16—H1610.969
C3—C121.3958 (17)C17—C181.4110 (18)
C4—O51.3749 (15)C17—H1710.944
C4—C91.3892 (18)C18—N191.3637 (16)
O5—C61.3794 (17)C18—C221.4121 (18)
C6—C71.4425 (18)N19—C201.4490 (19)
C6—O81.2056 (16)N19—C211.433 (2)
C7—H710.952C20—H2010.967
C9—C101.376 (2)C20—H2030.976
C9—H910.965C20—H2020.994
C10—C111.388 (2)C21—H2110.958
C10—H1010.967C21—H2130.977
C11—C121.3764 (19)C21—H2120.956
C11—H1110.965C22—C231.3742 (17)
C12—H1210.954C22—H2210.965
C13—O141.1970 (15)C23—H2310.958
C2—O1—C13122.05 (10)C13—C15—C23123.81 (11)
O1—C2—C3113.36 (10)C16—C15—C23117.98 (11)
O1—C2—C7125.23 (12)C15—C16—C17121.34 (11)
C3—C2—C7121.35 (11)C15—C16—H161118.6
C2—C3—C4117.02 (11)C17—C16—H161120.1
C2—C3—C12124.46 (11)C16—C17—C18120.99 (12)
C4—C3—C12118.52 (12)C16—C17—H171118.8
C3—C4—O5121.54 (11)C18—C17—H171120.2
C3—C4—C9121.44 (12)C17—C18—N19121.52 (12)
O5—C4—C9117.02 (11)C17—C18—C22117.38 (11)
C4—O5—C6121.54 (10)N19—C18—C22121.10 (12)
O5—C6—C7117.73 (11)C18—N19—C20120.85 (12)
O5—C6—O8116.75 (12)C18—N19—C21120.98 (13)
C7—C6—O8125.52 (14)C20—N19—C21117.41 (13)
C6—C7—C2120.70 (12)N19—C20—H201109.4
C6—C7—H71116.9N19—C20—H203110.3
C2—C7—H71122.4H201—C20—H203109.8
C4—C9—C10118.74 (13)N19—C20—H202110.5
C4—C9—H91119.3H201—C20—H202109.5
C10—C9—H91121.9H203—C20—H202107.3
C9—C10—C11120.87 (13)N19—C21—H211108.5
C9—C10—H101120.4N19—C21—H213110.0
C11—C10—H101118.7H211—C21—H213109.9
C10—C11—C12120.06 (13)N19—C21—H212110.5
C10—C11—H111120.8H211—C21—H212109.4
C12—C11—H111119.2H213—C21—H212108.5
C3—C12—C11120.37 (12)C18—C22—C23120.82 (12)
C3—C12—H121118.8C18—C22—H221119.6
C11—C12—H121120.8C23—C22—H221119.6
O1—C13—O14122.43 (11)C15—C23—C22121.45 (12)
O1—C13—C15110.44 (10)C15—C23—H231118.7
O14—C13—C15127.08 (12)C22—C23—H231119.9
C13—C15—C16118.18 (11)
Hydrogen-bond geometry (Å, º) top
Cg3 is the centroid of the benzoate-benzene ring (C15–C18/C22/C23).
D—H···AD—HH···AD···AD—H···A
C9—H91···O8i0.962.493.449 (2)171
C7—H71···Cg3ii0.952.843.429 (2)121
C20—H202···Cg3iii0.992.913.777 (2)146
Symmetry codes: (i) x, y, z1; (ii) x, y+1, z; (iii) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC18H15NO4
Mr309.32
Crystal system, space groupTriclinic, P1
Temperature (K)298
a, b, c (Å)7.4939 (2), 10.2361 (3), 10.6620 (3)
α, β, γ (°)92.307 (3), 103.935 (1), 109.852 (2)
V3)739.92 (4)
Z2
Radiation typeMo Kα
µ (mm1)0.10
Crystal size (mm)0.50 × 0.40 × 0.30
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
8424, 3590, 2897
Rint0.024
(sin θ/λ)max1)0.676
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.048, 0.120, 0.98
No. of reflections3585
No. of parameters208
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.23, 0.20

Computer programs: COLLECT (Nonius, 2001), DENZO/SCALEPACK (Otwinowski & Minor, 1997), SIR92 (Altomare et al., 1994), CRYSTALS (Betteridge et al., 2003), PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
Cg3 is the centroid of the benzoate-benzene ring (C15–C18/C22/C23).
D—H···AD—HH···AD···AD—H···A
C9—H91···O8i0.962.493.449 (2)171
C7—H71···Cg3ii0.952.843.429 (2)121
C20—H202···Cg3iii0.992.913.777 (2)146
Symmetry codes: (i) x, y, z1; (ii) x, y+1, z; (iii) x+1, y+1, z+1.
 

Acknowledgements

We thank the Laboratoire de Physique des Inter­actions Ioniques and Spectropôle, Université de Provence, and the Université Paul Cézanne, Faculté des Sciences et Techniques de Saint Jérôme, Marseille, France, for the use of their diffractometer.

References

First citationAbd Elhafez, O. M., El Khrisy, E. A., Badria, F. & Fathy, A. M. (2003). J. Arch. Pharm. Res. 26, 686–696.  CAS Google Scholar
First citationAltomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.  CrossRef Web of Science IUCr Journals Google Scholar
First citationBasanagouda, M., Kulkarni, M. V., Sharma, D., Gupta, V. K., Sandhyarani, P. & Sasal, V. P. J. (2009). Chem. Sci. 121, 485–495.  CAS Google Scholar
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 Google Scholar
First citationBetteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487.  Web of Science CrossRef IUCr Journals Google Scholar
First citationEmmanuel-Giota, A. A., Fylaktakidou, K. C., Hadjipavlou-Litina, D. J., Litinas, K. E. & Nicolaides, D. N. J. (2001). Heterocycl. Chem. 38, 717–722.  CAS Google Scholar
First citationHamdi, N. & Dixneuf, P. H. (2007). Topics in Heterocyclic Chemistry. Berlin, Heidelberg: Springer-Verlag.  Google Scholar
First citationLiu, X., Dong, M., Chen, X., Jiang, M., Lv, X. & Zhou, J. (2008). Appl. Microbiol. Biotechnol. 78, 241–247.  Web of Science CrossRef PubMed CAS Google Scholar
First citationMarchenko, M. M., Kopyl'chuk, G. P., Shmarakov, I. A., Ketsa, O. V. & Kushnir, V. M. (2006). Pharm. Chem. J. 40, 296–297.  CrossRef CAS Google Scholar
First citationNonius (2001). COLLECT. Nonius BV, Delft, The Netherlands.  Google Scholar
First citationOtwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.  Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationTrapkov, V. A., Parfenov, E. A. & Smirnov, L. D. (1996). Pharm. Chem. J. 30, 445–447.  CrossRef Google Scholar
First citationUkhov, S. V., Kon'shin, M. E. & Odegova, T. F. (2001). Pharm. Chem. J. 35, 364–365.  CrossRef CAS Google Scholar
First citationVukovic, N., Sukdolak, S., Solujic, S. & Niciforovic, N. (2010). Arch. Pharm. Res. 33, 5–15.  Web of Science CrossRef CAS PubMed Google Scholar
First citationWang, M., Wang, L., Li, Y. & Li, Q. (2001). Transition Met. Chem. 26, 307–310.  Web of Science CrossRef CAS Google Scholar

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Volume 67| Part 9| September 2011| Pages o2269-o2270
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