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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 66| Part 11| November 2010| Pages o2947-o2948

6-Iso­propyl-5-meth­­oxy-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidin-7(6H)-one

aInstitute of Medicinal Chemistry, Hubei Medical University, Shiyan 442000, People's Republic of China, and bCenter of Oncology, People's Hospital affiliated with Hubei Medical University, Shi Yan 442000, People's Republic of China
*Correspondence e-mail: zken710@yahoo.com.cn

(Received 9 October 2010; accepted 16 October 2010; online 30 October 2010)

In the title compound, C14H15N5O2, the whole mol­ecule apart from the terminal C atoms of the isopropyl group is located on a crystallographic mirror plane. An intra­molecular C—H⋯N hydrogen-bonding inter­action may stabilize the mol­ecular conformation. The crystal packing features weak slipped ππ inter­actions between the pyrimidine and the phenyl rings of symmetry-related mol­ecules [centroid–centroid distance = 3.746 (1)Å, slippage of 1.574 Å].

Related literature

Fpr the biological activity of 8-aza­guanine derivatives, see: Roblin et al. (1945[Roblin, R. O., Lampen, J. O., English, J. P., Cole, Q. P. & Vaughan, J. R. (1945). J. Am. Chem. Soc. 67, 290-294.]); Ding et al. (2004[Ding, M. W., Xu, S. Z. & Zhao, J. F. (2004). J. Org. Chem. 69, 8366-8371.]); Mitchell et al. (1950[Mitchell, J. H., Skipper, H. E. & Bennett, L. L. (1950). Cancer Res. 10, 647-649.]); Levine et al. (1963[Levine, R. J., Hall, T. C. & Harris, C. A. (1963). Cancer (N. Y.), 16, 269-272.]); Montgomery et al. (1962[Montgomery, J. A., Schabel, F. M. & Skipper, H. E. (1962). Cancer Res. 22, 504-509.]); Yamamoto et al. (1967[Yamamoto, I., Inoki, R., Tamari, Y. & Iwatsubo, K. (1967). Jpn J. Pharmacol. 17, 140-142.]); Bariana (1971[Bariana, D. S. (1971). J. Med. Chem. 14, 535-543.]); Holland et al. (1975[Holland, A., Jackson, D., Chaplen, P., Lunt, E., Marshall, S., Pain, C. L. & Wooldridge, K. R. H. (1975). Eur. J. Med. Chem. 10, 447-449.]). For related structures, see: Chen & Shi (2006[Chen, X.-B. & Shi, D.-Q. (2006). Acta Cryst. E62, o4780-o4782.]); Ferguson et al. (1998[Ferguson, G., Low, J. N., Nogueras, M., Cobo, J., Lopez, M. D., Quijano, M. L. & Sanchez, A. (1998). Acta Cryst. C54, IUC9800031.]); Li et al. (2004[Li, M., Wen, L. R., Fu, W. J., Hu, F. Z. & Yang, H. Z. (2004). Chin. J. Struct. Chem. 23, 11-14.]); Maldonado et al. (2006[Maldonado, C. R., Quirós, M. & Salas, J. M. (2006). Acta Cryst. C62, o489-o491.]); Wang et al. (2006[Wang, H.-M., Zeng, X.-H., Hu, Z.-Q., Li, G.-H. & Tian, J.-H. (2006). Acta Cryst. E62, o5038-o5040.]); Xiao & Shi (2007[Xiao, L.-X. & Shi, D.-Q. (2007). Acta Cryst. E63, o2843.]); Zeng et al. (2006[Zeng, X.-H., Wang, H.-M., Ding, M.-W. & He, H.-W. (2006). Acta Cryst. E62, o1888-o1890.], 2009[Zeng, X.-H., Liu, X.-L., Deng, S.-H., Chen, P. & Wang, H.-M. (2009). Acta Cryst. E65, o2583-o2584.]); Zhao, Hu et al. (2005[Zhao, J.-F., Hu, Y.-G., Ding, M.-W. & He, H.-W. (2005). Acta Cryst. E61, o2791-o2792.]); Zhao, Wang & Ding (2005[Zhao, J. F., Wang, C. G. & Ding, M. W. (2005). Chin. J. Struct. Chem. 24, 439-444.]); Zhao, Xie et al. (2005[Zhao, J. F., Xie, C., Ding, M. W. & He, H. W. (2005). Chem. Lett. 34, 1020-1022.]).

[Scheme 1]

Experimental

Crystal data
  • C14H15N5O2

  • Mr = 285.31

  • Orthorhombic, P n m a

  • a = 14.921 (2) Å

  • b = 6.7989 (11) Å

  • c = 13.839 (2) Å

  • V = 1404.0 (4) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.10 mm−1

  • T = 298 K

  • 0.16 × 0.12 × 0.10 mm

Data collection
  • Bruker SMART CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) Tmin = 0.985, Tmax = 0.991

  • 7422 measured reflections

  • 1418 independent reflections

  • 1045 reflections with I > 2σ(I)

  • Rint = 0.039

Refinement
  • R[F2 > 2σ(F2)] = 0.065

  • wR(F2) = 0.185

  • S = 1.07

  • 1418 reflections

  • 125 parameters

  • H-atom parameters constrained

  • Δρmax = 0.23 e Å−3

  • Δρmin = −0.29 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C2—H2⋯N4 0.93 2.37 3.021 (4) 127

Data collection: SMART (Bruker, 2001[Bruker (2001). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2001[Bruker (2001). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; 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: ORTEPIII (Burnett & Johnson, 1996[Burnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA.]), ORTEP-3 for Windows (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]).

Supporting information


Comment top

The derivatives of heterocycles containing 8-azaguanine system, which are well known bioisosteres of guanine, are of great importance because of their remarkable biological properties, such as antimicrobial or antifungal activities (Roblin et al., 1945; Ding et al., 2004), encephaloma cell inhibitor (Mitchell et al., 1950; Levine et al., 1963), antileukemie (Montgomery et al., 1962), hypersusceptibility inhibitor and acesodyne activities (Yamamoto et al., 1967; Bariana, 1971; Holland et al., 1975).

In recent years, Zhao's group succeeded in synthesizing the derivatives of 8-azaguanine via aza-Wittig reaction of beta-ethoxycarbonyl iminophosphorane with aromatic isocyanates (Zhao, Xie et al., 2005). As a continuation of the quest for new biologically active derivatives of 8-azaguanine, the title compound, (I), was obtained from beta-ethoxycarbonyl iminophosphorane with aliphatic isocyanate, and structurally characterized.

In the title compound, C14H15N5O2, the whole molecule but the terminal C atoms of the isopropyl group is located in a mirror plane and is then perfectly planar (Fig. 1). The bond lengths and angles in the triazolopyrimidinone moiety are in good agreement with those observed for closely related structures (Zhao, Hu et al., 2005; Zhao, Wang & Ding, 2005). the triazolopyrimidine ring system is perfectly coplanar (Chen & Shi, 2006; Ferguson et al., 1998; Li et al., 2004; Maldonado et al., 2006; Wang et al., 2006; Xiao & Shi, 2007; Zeng et al., 2009).

The molecules are packed along the b axis with weak slippest ππ interaction between the pyrimidin and the phenyl rings of symmetry related molecules (Centroid to centroid distance= 3.746 (1)Å, interplanar distance= 3.399 Å with a slippage of 1.574 Å).

Related literature top

Fpr the biological activity of 8-azaguanine derivatives, see: Roblin et al. (1945); Ding et al. (2004); Mitchell et al. (1950); Levine et al. (1963); Montgomery et al. (1962); Yamamoto et al. (1967); Bariana (1971); Holland et al. (1975). For related structures, see: Chen & Shi (2006); Ferguson et al. (1998); Li et al. (2004); Maldonado et al. (2006); Wang et al. (2006); Xiao & Shi (2007); Zeng et al. (2006, 2009); Zhao, Hu et al. (2005); Zhao, Wang & Ding (2005); Zhao, Xie et al. (2005).

Experimental top

To the solution of carbodiimide prepared according to Zeng et al. (2006) in a mixed solvent (CH2Cl2/MeOH,1:4 v/v, 15 ml) was added a fresh prepared solution of Na/MeOH (0.1 g/2 ml). After stirring the reaction mixture for 6 h, the solvent was removed under reduced pressure and the residue was recrystallized from EtOH to give the title compound (I) in 89% yield (m.p. 471 K). Elemental analysis: calculated for C14H15N5O2: C, 58.94; H, 5.30; N, 24.55%. Found: C, 57.62; H, 5.72; N, 24.01%. Crystals suitable for X-ray diffraction study were obtained by recrystallization from hexane and dichloromethane (1:3 v/v) at room temperature.

Refinement top

All H atoms attached to C atoms and N atom were fixed geometrically and treated as riding with C—H = 0.98 Å (methine), 0.96 Å (methyl) or 0.93 Å (aromatic) with Uiso(H) = 1.2Ueq(C) or Uiso(H) = 1.5Ueq(Cmethyl).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1999) and PLATON (Spek, 2009); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. View of the molecule of showing the atom-labeling scheme. Displacement ellipsoids are drawn at the 30% probability level. H-atoms are reprsented as small spheres of arbitrary radii. [Symmetry code: (i) -x-1/2, y+1/2, z-1/2].
[Figure 2] Fig. 2. Packing view showing the stacking of the molecules along the b axis. H atoms have been omitted for clarity.
6-Isopropyl-5-methoxy-3-phenyl-3H-1,2,3-triazolo[4,5- d]pyrimidin-7(6H)-one top
Crystal data top
C14H15N5O2F(000) = 600
Mr = 285.31Dx = 1.350 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 982 reflections
a = 14.921 (2) Åθ = 2.9–20.5°
b = 6.7989 (11) ŵ = 0.10 mm1
c = 13.839 (2) ÅT = 298 K
V = 1404.0 (4) Å3Block, colourless
Z = 40.16 × 0.12 × 0.10 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer
1418 independent reflections
Radiation source: fine-focus sealed tube1045 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.039
ϕ and ω scansθmax = 25.5°, θmin = 2.0°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2008)
h = 1718
Tmin = 0.985, Tmax = 0.991k = 88
7422 measured reflectionsl = 1316
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)] = 0.065Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.185H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.0883P)2 + 0.4734P]
where P = (Fo2 + 2Fc2)/3
1418 reflections(Δ/σ)max < 0.001
125 parametersΔρmax = 0.23 e Å3
0 restraintsΔρmin = 0.29 e Å3
Crystal data top
C14H15N5O2V = 1404.0 (4) Å3
Mr = 285.31Z = 4
Orthorhombic, PnmaMo Kα radiation
a = 14.921 (2) ŵ = 0.10 mm1
b = 6.7989 (11) ÅT = 298 K
c = 13.839 (2) Å0.16 × 0.12 × 0.10 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer
1418 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2008)
1045 reflections with I > 2σ(I)
Tmin = 0.985, Tmax = 0.991Rint = 0.039
7422 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0650 restraints
wR(F2) = 0.185H-atom parameters constrained
S = 1.07Δρmax = 0.23 e Å3
1418 reflectionsΔρmin = 0.29 e Å3
125 parameters
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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*/UeqOcc. (<1)
O10.36483 (19)0.25000.3850 (3)0.1092 (13)
O20.24610 (18)0.25000.6874 (2)0.0829 (9)
N10.06296 (18)0.25000.41475 (18)0.0507 (7)
N20.0868 (3)0.25000.3193 (2)0.0843 (12)
N30.1730 (3)0.25000.3126 (2)0.0908 (12)
N40.14519 (17)0.25000.5659 (2)0.0495 (7)
N50.30395 (19)0.25000.5368 (3)0.0629 (9)
C10.0298 (2)0.25000.4402 (2)0.0462 (8)
C20.0554 (2)0.25000.5362 (2)0.0546 (9)
H20.01240.25000.58480.065*
C30.1452 (2)0.25000.5591 (3)0.0599 (10)
H30.16260.25000.62360.072*
C40.2092 (3)0.25000.4886 (3)0.0630 (10)
H40.26970.25000.50490.076*
C50.1835 (3)0.25000.3938 (3)0.0672 (11)
H50.22700.25000.34570.081*
C60.0949 (3)0.25000.3683 (3)0.0580 (10)
H60.07830.25000.30350.070*
C70.1382 (2)0.25000.4688 (2)0.0464 (8)
C80.2070 (2)0.25000.4039 (3)0.0608 (10)
C90.2979 (3)0.25000.4346 (3)0.0721 (11)
C100.2277 (2)0.25000.5942 (3)0.0589 (9)
C110.3973 (3)0.25000.5789 (4)0.0879 (14)
H110.43380.25000.52000.105*
C120.4225 (2)0.0624 (6)0.6212 (3)0.1210 (15)
H12A0.48610.05990.63190.181*
H12B0.40630.04210.57800.181*
H12C0.39190.04540.68160.181*
C130.1714 (3)0.25000.7534 (3)0.1016 (17)
H13A0.19330.25000.81860.152*
H13B0.13560.13470.74270.152*0.50
H13C0.13560.36530.74270.152*0.50
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0561 (19)0.156 (3)0.115 (3)0.0000.0314 (18)0.000
O20.0545 (17)0.125 (3)0.0687 (18)0.0000.0150 (14)0.000
N10.0539 (18)0.0584 (17)0.0399 (14)0.0000.0009 (13)0.000
N20.075 (2)0.131 (3)0.0470 (19)0.0000.0067 (17)0.000
N30.074 (3)0.142 (4)0.056 (2)0.0000.0142 (18)0.000
N40.0419 (16)0.0507 (16)0.0559 (18)0.0000.0071 (12)0.000
N50.0365 (16)0.0593 (19)0.093 (2)0.0000.0019 (15)0.000
C10.050 (2)0.0395 (17)0.0485 (19)0.0000.0052 (15)0.000
C20.043 (2)0.066 (2)0.055 (2)0.0000.0077 (16)0.000
C30.052 (2)0.065 (2)0.063 (2)0.0000.0000 (17)0.000
C40.047 (2)0.060 (2)0.082 (3)0.0000.0074 (19)0.000
C50.054 (2)0.064 (2)0.083 (3)0.0000.030 (2)0.000
C60.067 (3)0.056 (2)0.051 (2)0.0000.0148 (18)0.000
C70.048 (2)0.0419 (18)0.0497 (19)0.0000.0003 (15)0.000
C80.050 (2)0.072 (2)0.060 (2)0.0000.0094 (17)0.000
C90.060 (3)0.078 (3)0.078 (3)0.0000.016 (2)0.000
C100.055 (2)0.055 (2)0.067 (2)0.0000.0120 (19)0.000
C110.045 (2)0.086 (3)0.133 (4)0.0000.013 (2)0.000
C120.082 (2)0.118 (3)0.163 (4)0.011 (2)0.034 (2)0.043 (3)
C130.079 (3)0.172 (5)0.054 (2)0.0000.016 (2)0.000
Geometric parameters (Å, º) top
O1—C91.212 (5)C3—H30.9300
O2—C101.319 (4)C4—C51.367 (6)
O2—C131.441 (5)C4—H40.9300
N1—C71.350 (4)C5—C61.369 (5)
N1—N21.368 (4)C5—H50.9300
N1—C11.428 (4)C6—H60.9300
N2—N31.290 (5)C7—C81.364 (5)
N3—C81.360 (5)C8—C91.421 (5)
N4—C101.293 (4)C11—C12i1.453 (4)
N4—C71.348 (4)C11—C121.453 (4)
N5—C101.387 (5)C11—H110.9800
N5—C91.418 (5)C12—H12A0.9600
N5—C111.510 (5)C12—H12B0.9600
C1—C21.382 (5)C12—H12C0.9600
C1—C61.391 (4)C13—H13A0.9600
C2—C31.377 (5)C13—H13B0.9600
C2—H20.9300C13—H13C0.9600
C3—C41.365 (5)
C10—O2—C13117.3 (3)N4—C7—C8126.8 (3)
C7—N1—N2108.6 (3)N1—C7—C8105.1 (3)
C7—N1—C1132.0 (3)N3—C8—C7109.4 (3)
N2—N1—C1119.4 (3)N3—C8—C9129.3 (4)
N3—N2—N1109.2 (3)C7—C8—C9121.4 (4)
N2—N3—C8107.8 (3)O1—C9—N5120.8 (4)
C10—N4—C7112.0 (3)O1—C9—C8128.1 (4)
C10—N5—C9121.2 (3)N5—C9—C8111.1 (3)
C10—N5—C11122.4 (4)N4—C10—O2119.6 (3)
C9—N5—C11116.4 (3)N4—C10—N5127.5 (4)
C2—C1—C6119.6 (3)O2—C10—N5112.9 (3)
C2—C1—N1120.4 (3)C12i—C11—C12122.8 (5)
C6—C1—N1120.0 (3)C12i—C11—N5113.2 (2)
C3—C2—C1119.4 (3)C12—C11—N5113.2 (2)
C3—C2—H2120.3C12i—C11—H11101.0
C1—C2—H2120.3C12—C11—H11101.0
C4—C3—C2121.1 (4)N5—C11—H11101.0
C4—C3—H3119.5C11—C12—H12A109.5
C2—C3—H3119.5C11—C12—H12B109.5
C3—C4—C5119.3 (4)H12A—C12—H12B109.5
C3—C4—H4120.3C11—C12—H12C109.5
C5—C4—H4120.3H12A—C12—H12C109.5
C4—C5—C6121.2 (3)H12B—C12—H12C109.5
C4—C5—H5119.4O2—C13—H13A109.5
C6—C5—H5119.4O2—C13—H13B109.5
C5—C6—C1119.4 (3)H13A—C13—H13B109.5
C5—C6—H6120.3O2—C13—H13C109.5
C1—C6—H6120.3H13A—C13—H13C109.5
N4—C7—N1128.1 (3)H13B—C13—H13C109.5
Symmetry code: (i) x, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2···N40.932.373.021 (4)127
C6—H6···N20.932.472.794 (5)100
C11—H11···O10.982.132.727 (7)117
C12—H12C···O20.962.583.065 (5)111

Experimental details

Crystal data
Chemical formulaC14H15N5O2
Mr285.31
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)298
a, b, c (Å)14.921 (2), 6.7989 (11), 13.839 (2)
V3)1404.0 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.10
Crystal size (mm)0.16 × 0.12 × 0.10
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2008)
Tmin, Tmax0.985, 0.991
No. of measured, independent and
observed [I > 2σ(I)] reflections
7422, 1418, 1045
Rint0.039
(sin θ/λ)max1)0.606
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.065, 0.185, 1.07
No. of reflections1418
No. of parameters125
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.23, 0.29

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1999) and PLATON (Spek, 2009), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2···N40.932.373.021 (4)127.3
C6—H6···N20.932.472.794 (5)100.3
C11—H11···O10.982.132.727 (7)117.4
C12—H12C···O20.962.583.065 (5)111.3
 

Acknowledgements

We gratefully acknowledge financial support of this work by the National Basic Research Program of China (2003CB114400), the National Natural Science Foundation of China (20372023, 20102001), the Educational Commission of Hubei Province (grant Nos. B200624004, B20092412), the Shiyan Municipal Science and Technology Bureau (grant No. 20061835) and Hubei Medical University (grant Nos. 2007QDJ15, 2007ZQB19, 2007ZQB20).

References

First citationBariana, D. S. (1971). J. Med. Chem. 14, 535–543.  PubMed Web of Science
First citationBruker (2001). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationBurnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA.
First citationChen, X.-B. & Shi, D.-Q. (2006). Acta Cryst. E62, o4780–o4782.  Web of Science CSD CrossRef IUCr Journals
First citationDing, M. W., Xu, S. Z. & Zhao, J. F. (2004). J. Org. Chem. 69, 8366–8371.  Web of Science CrossRef PubMed CAS
First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals
First citationFerguson, G., Low, J. N., Nogueras, M., Cobo, J., Lopez, M. D., Quijano, M. L. & Sanchez, A. (1998). Acta Cryst. C54, IUC9800031.  CrossRef IUCr Journals
First citationHolland, A., Jackson, D., Chaplen, P., Lunt, E., Marshall, S., Pain, C. L. & Wooldridge, K. R. H. (1975). Eur. J. Med. Chem. 10, 447–449.  CAS
First citationLevine, R. J., Hall, T. C. & Harris, C. A. (1963). Cancer (N. Y.), 16, 269–272.  CrossRef CAS
First citationLi, M., Wen, L. R., Fu, W. J., Hu, F. Z. & Yang, H. Z. (2004). Chin. J. Struct. Chem. 23, 11–14.
First citationMaldonado, C. R., Quirós, M. & Salas, J. M. (2006). Acta Cryst. C62, o489–o491.  Web of Science CSD CrossRef CAS IUCr Journals
First citationMitchell, J. H., Skipper, H. E. & Bennett, L. L. (1950). Cancer Res. 10, 647–649.  CAS
First citationMontgomery, J. A., Schabel, F. M. & Skipper, H. E. (1962). Cancer Res. 22, 504–509.  PubMed CAS Web of Science
First citationRoblin, R. O., Lampen, J. O., English, J. P., Cole, Q. P. & Vaughan, J. R. (1945). J. Am. Chem. Soc. 67, 290–294.  CrossRef CAS Web of Science
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals
First citationWang, H.-M., Zeng, X.-H., Hu, Z.-Q., Li, G.-H. & Tian, J.-H. (2006). Acta Cryst. E62, o5038–o5040.  Web of Science CSD CrossRef IUCr Journals
First citationXiao, L.-X. & Shi, D.-Q. (2007). Acta Cryst. E63, o2843.  Web of Science CSD CrossRef IUCr Journals
First citationYamamoto, I., Inoki, R., Tamari, Y. & Iwatsubo, K. (1967). Jpn J. Pharmacol. 17, 140–142.  CrossRef CAS PubMed Web of Science
First citationZeng, X.-H., Liu, X.-L., Deng, S.-H., Chen, P. & Wang, H.-M. (2009). Acta Cryst. E65, o2583–o2584.  Web of Science CSD CrossRef IUCr Journals
First citationZeng, X.-H., Wang, H.-M., Ding, M.-W. & He, H.-W. (2006). Acta Cryst. E62, o1888–o1890.  Web of Science CSD CrossRef IUCr Journals
First citationZhao, J.-F., Hu, Y.-G., Ding, M.-W. & He, H.-W. (2005). Acta Cryst. E61, o2791–o2792.  Web of Science CSD CrossRef IUCr Journals
First citationZhao, J. F., Wang, C. G. & Ding, M. W. (2005). Chin. J. Struct. Chem. 24, 439–444.  Web of Science CrossRef CAS
First citationZhao, J. F., Xie, C., Ding, M. W. & He, H. W. (2005). Chem. Lett. 34, 1020–1022.  Web of Science CrossRef

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Volume 66| Part 11| November 2010| Pages o2947-o2948
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