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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

(4R*,5R*)-2-(4-Meth­­oxy­phen­yl)-1,3-dioxolane-4,5-dicarboxamide

aSchool of Pharmaceutical Science, Nanjing University of Technolgy, Xinmofan Road No. 5 Nanjing, Nanjing 210009, People's Republic of China, bXinchang Pharmaceutical Factory, Zhejiang Medicine Co. Ltd, Xinchang 312500, People's Republic of China, and cCollege of Materials Science and, Engineering, Nanjing University of Technology, Xinmofan Road No. 5 Nanjing, Nanjing 210009, People's Republic of China
*Correspondence e-mail: ludingqiang@126.com

(Received 9 January 2012; accepted 19 January 2012; online 4 February 2012)

In the title compound, C12H14N2O5, the five-membered 1,3-dioxolane ring has a twisted conformation. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into a two-dimensional network lying parallel to the ab plane. There are also C—H⋯π inter­actions present in the crystal structure.

Related literature

For the importantce of (2S,3S)-diethyl-2,3-O-alkyl­tartrate analogues in the synthesis of platinum complexes with anti­tumor activity, see: Kim et al. (1994[Kim, D. K., Kim, G., Gam, J. S., Cho, Y. B. & Park, J. G. (1994). J. Med. Chem. 37, 1471-1485.]), and for their importance as inter­mediates in organic synthesis, see: Pandey et al. (1997[Pandey, G., Hajra, S., Ghorai, M. K. & Kumar, K. R. (1997). J. Org. Chem. 62, 5966-5973.]). For the synthesis of the title compound, see: Ates-Alagoz & Buyukbingol (2001[Ates-Alagoz, Z. & Buyukbingol, E. (2001). Heterocycl. Commun. 7, 455-460.]). For standard bond lengths, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]).

[Scheme 1]

Experimental

Crystal data
  • C12H14N2O5

  • Mr = 266.25

  • Orthorhombic, P 21 21 21

  • a = 6.9620 (14) Å

  • b = 10.727 (2) Å

  • c = 16.932 (3) Å

  • V = 1264.5 (4) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.11 mm−1

  • T = 293 K

  • 0.20 × 0.20 × 0.10 mm

Data collection
  • Enraf–Nonius CAD-4 diffractometer

  • Absorption correction: ψ scan (North et al., 1968[North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351-359.]) Tmin = 0.978, Tmax = 0.989

  • 2615 measured reflections

  • 2297 independent reflections

  • 1939 reflections with I > 2σ(I)

  • Rint = 0.035

  • 3 standard reflections every 200 reflections intensity decay: 1%

Refinement
  • R[F2 > 2σ(F2)] = 0.041

  • wR(F2) = 0.135

  • S = 1.00

  • 2297 reflections

  • 173 parameters

  • H-atom parameters constrained

  • Δρmax = 0.16 e Å−3

  • Δρmin = −0.16 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

Cg2 is the centroid of the C2–C7 ring.

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1A⋯O1i 0.86 2.21 3.063 (3) 174
N1—H1B⋯O5ii 0.86 2.22 2.994 (4) 149
N2—H2A⋯O4iii 0.86 2.13 2.984 (4) 169
C7—H7A⋯O4iv 0.93 2.57 3.491 (4) 170
C9—H9ACg2v 0.98 2.83 3.737 (3) 154
Symmetry codes: (i) x, y-1, z; (ii) x+1, y, z; (iii) [-x, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]; (iv) x, y+1, z; (v) [-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}].

Data collection: CAD-4 Software (Enraf–Nonius, 1989[Enraf-Nonius (1989). CAD-4 Software. Enraf-Nonius, Delft, The Netherlands.]); cell refinement: CAD-4 Software; data reduction: XCAD4 (Harms & Wocadlo, 1995[Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.]); 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: PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

Antitumor platinum drugs are some of the most effective anticancer agents currently available. (2S,3S)-Diethyl-2,3-O-alkyltartrate analogues are starting materials for the synthesis of platinum complexes with antitumor activity (Kim et al., 1994), and are also important intermediates in organic synthesis (Pandey et al., 1997). As part of our studies of the synthesis and characterization of such compounds, we herein report on the crystal structure of the title compound.

The molecular structure of the title compound is shown in Fig. 1. The bond lengths (Allen et al., 1987) and angles are within normal ranges. The five-membered 1,3-dioxolane ring (O2,O3,C8-C10) has a twisted conformation on bond O2-C8.

In the crystal, intermolecular N—H···O and C—H···O hydrogen bonds link the molecules to form two-dimensional networks lieing parallel to the ab plane (Table 1 and Fig 2). There are also C-H···π interactions present in the crystal structure (Table 1).

Related literature top

For the importantce of (2S,3S)-diethyl-2,3-O-alkyltartrate analogues in the synthesis of platinum complexes with antitumor activity, see: Kim et al. (1994), and for their importance as intermediates in organic synthesis, see: Pandey et al. (1997). For the synthesis of the title compound, see: Ates-Alagoz & Buyukbingol (2001). For standard bond lengths, see: Allen et al. (1987).

Experimental top

The title compound was synthesized according to the published procedure (Ates-Alagoz & Buyukbingol, 2001). A mixture of (2S,3S)-diethyltartrate (500 mg, 2.43 mmol), 4-methoxybenzaldehyde (331 mg, 2.43 mmol), anhydrous copper(II) sulfate (776 mg, 2.86 mmol), and one drop of methane sulfonic acid in anhydrous toluene (8 ml) was stirred at room temperature for 8 h. Anhydrous Magnesium sulfate (30 mg) was added to the reaction mixture, which was then stirred for a further 20 min. Then a colourless precipitate was obtained by evaporation and dried in vacuo (Yield 83%). The obtained colourless product (654 mg, 2 mmol) was dissolved in 40 ml anhydrous ethanol, then a current of dry ammonia (dried by calcium cholride) was passed into the reaction mixture at room temperature for 4 h. The reaction mixture was then filtered and the resulting product was evaporated to dryness. Pure compound was obtained by crystallization from ethanol. Block-like yellow crystals of the title compound, suitable for X-ray diffraction, were obatined by slow evaporation of a solution in methanol after four weeks.

Refinement top

The NH and C-bound H-atoms were included in calculated positions and treated as riding atoms: N-H = 0.86 Å, C-H = 0.93, 0.98 and 0.96 Å for CH(aromatic), CH(methine), and CH3 H-atoms, respectively, with Uiso(H) = k × Ueq(C,N), where k = 1.5 for CH3 H-atoms, and k = 1.2 for all other H-atoms. In the final cycles of refinement, in the absence of significant anomalous scattering effects, 945 Friedel pairs were merged and Δf " set to zero.

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing the atom-numbering and displacement ellipsoids drawn at the 30% probability level.
[Figure 2] Fig. 2. The crystal packing diagram of the title compound viewed along the a axis, with the N-H···O and C-H···O hydrogen bonds shown as dashed lines.
(4R*,5R*)-2-(4-Methoxyphenyl)-1,3-dioxolane-4,5-dicarboxamide top
Crystal data top
C12H14N2O5F(000) = 560
Mr = 266.25Dx = 1.399 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 25 reflections
a = 6.9620 (14) Åθ = 9–12°
b = 10.727 (2) ŵ = 0.11 mm1
c = 16.932 (3) ÅT = 293 K
V = 1264.5 (4) Å3Block, yellow
Z = 40.20 × 0.20 × 0.10 mm
Data collection top
Enraf–Nonius CAD-4
diffractometer
1939 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.035
Graphite monochromatorθmax = 25.3°, θmin = 2.3°
ω/2θ scansh = 08
Absorption correction: ψ scan
(North et al., 1968)
k = 012
Tmin = 0.978, Tmax = 0.989l = 2020
2615 measured reflections3 standard reflections every 200 reflections
2297 independent reflections intensity decay: 1%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.041H-atom parameters constrained
wR(F2) = 0.135 w = 1/[σ2(Fo2) + (0.098P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max < 0.001
2297 reflectionsΔρmax = 0.16 e Å3
173 parametersΔρmin = 0.16 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.024 (5)
Crystal data top
C12H14N2O5V = 1264.5 (4) Å3
Mr = 266.25Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 6.9620 (14) ŵ = 0.11 mm1
b = 10.727 (2) ÅT = 293 K
c = 16.932 (3) Å0.20 × 0.20 × 0.10 mm
Data collection top
Enraf–Nonius CAD-4
diffractometer
1939 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.035
Tmin = 0.978, Tmax = 0.9893 standard reflections every 200 reflections
2615 measured reflections intensity decay: 1%
2297 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0410 restraints
wR(F2) = 0.135H-atom parameters constrained
S = 1.00Δρmax = 0.16 e Å3
2297 reflectionsΔρmin = 0.16 e Å3
173 parameters
Special details top

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
O10.7648 (3)0.69904 (17)0.91700 (13)0.0480 (5)
N10.6002 (4)0.0645 (2)0.84147 (17)0.0547 (7)
H1A0.64830.13290.85910.066*
H1B0.67460.00500.82660.066*
C10.9569 (4)0.7107 (3)0.9441 (2)0.0572 (8)
H1C0.99330.79700.94410.086*
H1D1.04100.66490.90980.086*
H1E0.96650.67810.99680.086*
O20.4731 (3)0.17224 (15)0.81276 (11)0.0394 (5)
C20.6867 (4)0.5817 (2)0.91351 (15)0.0369 (6)
N20.0220 (4)0.2673 (2)0.76177 (16)0.0544 (7)
H2A0.10360.28650.72560.065*
H2B0.04320.32490.78480.065*
O30.2168 (3)0.23134 (17)0.88371 (11)0.0417 (5)
C30.7876 (4)0.4738 (3)0.93091 (17)0.0436 (7)
H3A0.91460.47760.94770.052*
O40.2966 (3)0.13078 (18)0.85712 (14)0.0524 (6)
C40.6951 (4)0.3598 (3)0.92277 (17)0.0440 (7)
H4A0.76170.28700.93480.053*
O50.0843 (3)0.0617 (2)0.75178 (15)0.0587 (6)
C50.5076 (4)0.3515 (2)0.89740 (15)0.0383 (6)
C60.4100 (4)0.4611 (3)0.88108 (18)0.0439 (7)
H6A0.28290.45740.86430.053*
C70.4980 (4)0.5755 (3)0.88927 (17)0.0449 (6)
H7A0.43020.64820.87850.054*
C80.4199 (4)0.2252 (3)0.88635 (16)0.0394 (6)
H8A0.46010.17010.92940.047*
C90.3416 (4)0.0725 (2)0.80307 (15)0.0358 (6)
H9A0.31700.06120.74650.043*
C100.1557 (4)0.1216 (2)0.84279 (16)0.0389 (6)
H10A0.10770.06000.88070.047*
C110.4124 (4)0.0509 (2)0.83725 (17)0.0404 (7)
C120.0032 (4)0.1493 (2)0.78190 (16)0.0413 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0442 (11)0.0306 (10)0.0693 (13)0.0077 (9)0.0037 (9)0.0019 (9)
N10.0415 (14)0.0295 (12)0.093 (2)0.0034 (11)0.0067 (13)0.0148 (14)
C10.0528 (19)0.0486 (17)0.070 (2)0.0190 (15)0.0076 (16)0.0023 (16)
O20.0413 (11)0.0243 (9)0.0527 (10)0.0038 (8)0.0054 (8)0.0005 (8)
C20.0417 (15)0.0281 (12)0.0409 (13)0.0032 (12)0.0013 (12)0.0011 (11)
N20.0564 (16)0.0378 (13)0.0689 (16)0.0055 (12)0.0172 (14)0.0031 (12)
O30.0378 (10)0.0356 (10)0.0516 (11)0.0051 (8)0.0018 (8)0.0084 (8)
C30.0383 (15)0.0389 (15)0.0537 (16)0.0010 (13)0.0111 (13)0.0007 (12)
O40.0461 (12)0.0288 (10)0.0824 (14)0.0100 (9)0.0044 (11)0.0089 (10)
C40.0453 (16)0.0313 (14)0.0554 (16)0.0033 (13)0.0119 (13)0.0029 (12)
O50.0483 (11)0.0446 (12)0.0833 (16)0.0088 (11)0.0161 (11)0.0066 (11)
C50.0448 (15)0.0303 (12)0.0398 (13)0.0030 (13)0.0042 (12)0.0002 (10)
C60.0374 (14)0.0341 (14)0.0601 (17)0.0025 (12)0.0069 (13)0.0002 (12)
C70.0414 (15)0.0285 (12)0.0647 (17)0.0025 (13)0.0014 (15)0.0017 (12)
C80.0439 (15)0.0314 (13)0.0428 (14)0.0021 (12)0.0029 (12)0.0058 (12)
C90.0380 (13)0.0281 (12)0.0413 (13)0.0038 (12)0.0020 (12)0.0024 (11)
C100.0408 (15)0.0274 (13)0.0484 (14)0.0065 (11)0.0033 (13)0.0015 (11)
C110.0412 (15)0.0261 (13)0.0541 (16)0.0052 (12)0.0042 (13)0.0018 (11)
C120.0329 (12)0.0352 (14)0.0557 (16)0.0010 (13)0.0008 (13)0.0032 (12)
Geometric parameters (Å, º) top
O1—C21.373 (3)C3—C41.388 (4)
O1—C11.420 (4)C3—H3A0.9300
N1—C111.317 (4)O4—C111.224 (3)
N1—H1A0.8600C4—C51.378 (4)
N1—H1B0.8600C4—H4A0.9300
C1—H1C0.9600O5—C121.230 (3)
C1—H1D0.9600C5—C61.386 (4)
C1—H1E0.9600C5—C81.498 (4)
O2—C91.417 (3)C6—C71.378 (4)
O2—C81.419 (3)C6—H6A0.9300
C2—C71.378 (4)C7—H7A0.9300
C2—C31.386 (4)C8—H8A0.9800
N2—C121.323 (4)C9—C111.527 (4)
N2—H2A0.8600C9—C101.551 (4)
N2—H2B0.8600C9—H9A0.9800
O3—C81.416 (3)C10—C121.509 (4)
O3—C101.430 (3)C10—H10A0.9800
C2—O1—C1117.9 (2)C5—C6—H6A119.4
C11—N1—H1A120.0C6—C7—C2119.8 (3)
C11—N1—H1B120.0C6—C7—H7A120.1
H1A—N1—H1B120.0C2—C7—H7A120.1
O1—C1—H1C109.5O3—C8—O2104.6 (2)
O1—C1—H1D109.5O3—C8—C5111.7 (2)
H1C—C1—H1D109.5O2—C8—C5111.4 (2)
O1—C1—H1E109.5O3—C8—H8A109.7
H1C—C1—H1E109.5O2—C8—H8A109.7
H1D—C1—H1E109.5C5—C8—H8A109.7
C9—O2—C8103.63 (19)O2—C9—C11113.7 (2)
O1—C2—C7115.7 (2)O2—C9—C10103.43 (19)
O1—C2—C3123.8 (2)C11—C9—C10113.6 (2)
C7—C2—C3120.4 (3)O2—C9—H9A108.6
C12—N2—H2A120.0C11—C9—H9A108.6
C12—N2—H2B120.0C10—C9—H9A108.6
H2A—N2—H2B120.0O3—C10—C12112.2 (2)
C8—O3—C10105.9 (2)O3—C10—C9104.0 (2)
C2—C3—C4118.6 (3)C12—C10—C9110.9 (2)
C2—C3—H3A120.7O3—C10—H10A109.9
C4—C3—H3A120.7C12—C10—H10A109.9
C5—C4—C3121.8 (3)C9—C10—H10A109.9
C5—C4—H4A119.1O4—C11—N1124.1 (3)
C3—C4—H4A119.1O4—C11—C9119.9 (2)
C4—C5—C6118.2 (3)N1—C11—C9115.9 (2)
C4—C5—C8118.9 (2)O5—C12—N2123.9 (3)
C6—C5—C8122.9 (2)O5—C12—C10118.8 (2)
C7—C6—C5121.2 (3)N2—C12—C10117.2 (2)
C7—C6—H6A119.4
C1—O1—C2—C7178.0 (3)C4—C5—C8—O281.2 (3)
C1—O1—C2—C33.5 (4)C6—C5—C8—O296.9 (3)
O1—C2—C3—C4177.9 (3)C8—O2—C9—C1190.3 (3)
C7—C2—C3—C40.5 (4)C8—O2—C9—C1033.4 (2)
C2—C3—C4—C50.5 (4)C8—O3—C10—C12135.0 (2)
C3—C4—C5—C61.1 (4)C8—O3—C10—C915.0 (3)
C3—C4—C5—C8177.2 (3)O2—C9—C10—O311.4 (3)
C4—C5—C6—C70.5 (4)C11—C9—C10—O3112.3 (2)
C8—C5—C6—C7177.6 (3)O2—C9—C10—C12109.4 (2)
C5—C6—C7—C20.5 (4)C11—C9—C10—C12126.9 (2)
O1—C2—C7—C6177.5 (3)O2—C9—C11—O4155.4 (3)
C3—C2—C7—C61.0 (4)C10—C9—C11—O437.5 (4)
C10—O3—C8—O236.7 (3)O2—C9—C11—N126.2 (4)
C10—O3—C8—C5157.3 (2)C10—C9—C11—N1144.1 (3)
C9—O2—C8—O344.4 (2)O3—C10—C12—O5168.2 (3)
C9—O2—C8—C5165.1 (2)C9—C10—C12—O576.0 (3)
C4—C5—C8—O3162.3 (2)O3—C10—C12—N214.7 (4)
C6—C5—C8—O319.6 (4)C9—C10—C12—N2101.1 (3)
Hydrogen-bond geometry (Å, º) top
Cg2 is the centroid of the C2–C7 ring.
D—H···AD—HH···AD···AD—H···A
N1—H1A···O1i0.862.213.063 (3)174
N1—H1B···O5ii0.862.222.994 (4)149
N2—H2A···O4iii0.862.132.984 (4)169
C7—H7A···O4iv0.932.573.491 (4)170
C9—H9A···Cg2v0.982.833.737 (3)154
Symmetry codes: (i) x, y1, z; (ii) x+1, y, z; (iii) x, y+1/2, z+3/2; (iv) x, y+1, z; (v) x+1, y1/2, z+3/2.

Experimental details

Crystal data
Chemical formulaC12H14N2O5
Mr266.25
Crystal system, space groupOrthorhombic, P212121
Temperature (K)293
a, b, c (Å)6.9620 (14), 10.727 (2), 16.932 (3)
V3)1264.5 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.11
Crystal size (mm)0.20 × 0.20 × 0.10
Data collection
DiffractometerEnraf–Nonius CAD-4
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.978, 0.989
No. of measured, independent and
observed [I > 2σ(I)] reflections
2615, 2297, 1939
Rint0.035
(sin θ/λ)max1)0.601
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.041, 0.135, 1.00
No. of reflections2297
No. of parameters173
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.16, 0.16

Computer programs: CAD-4 Software (Enraf–Nonius, 1989), XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
Cg2 is the centroid of the C2–C7 ring.
D—H···AD—HH···AD···AD—H···A
N1—H1A···O1i0.862.213.063 (3)174
N1—H1B···O5ii0.862.222.994 (4)149
N2—H2A···O4iii0.862.132.984 (4)169
C7—H7A···O4iv0.932.573.491 (4)170
C9—H9A···Cg2v0.982.833.737 (3)154
Symmetry codes: (i) x, y1, z; (ii) x+1, y, z; (iii) x, y+1/2, z+3/2; (iv) x, y+1, z; (v) x+1, y1/2, z+3/2.
 

Acknowledgements

The authors thank Liu Bo Nian from Nanjing University of Technology for useful discussions and the Center of Testing and Analysis, Nanjing University, for their support.

References

First citationAllen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19.  CrossRef Web of Science Google Scholar
First citationAtes-Alagoz, Z. & Buyukbingol, E. (2001). Heterocycl. Commun. 7, 455–460.  CAS Google Scholar
First citationEnraf–Nonius (1989). CAD-4 Software. Enraf–Nonius, Delft, The Netherlands.  Google Scholar
First citationHarms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.  Google Scholar
First citationKim, D. K., Kim, G., Gam, J. S., Cho, Y. B. & Park, J. G. (1994). J. Med. Chem. 37, 1471–1485.  CrossRef CAS PubMed Web of Science Google Scholar
First citationNorth, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359.  CrossRef IUCr Journals Web of Science Google Scholar
First citationPandey, G., Hajra, S., Ghorai, M. K. & Kumar, K. R. (1997). J. Org. Chem. 62, 5966–5973.  CSD CrossRef CAS Web of Science Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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