PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2009 November 1; 65(Pt 11): o2965.
Published online 2009 October 31. doi:  10.1107/S160053680904402X
PMCID: PMC2971007

3,19-Diacetyl-12-nitro­methyl-14-deoxy­andrographolide

Abstract

In the crystal of the title compound, C24H33NO9, inter­molecular C—H(...)O hydrogen bonds link the mol­ecules.

Related literature

For general background, see: Thunuguntla et al. (2004 [triangle]). For bond-length data, see: Allen et al. (1987 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-o2965-scheme1.jpg

Experimental

Crystal data

  • C24H33NO9
  • M r = 479.51
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o2965-efi1.jpg
  • a = 10.533 (2) Å
  • b = 12.756 (3) Å
  • c = 10.659 (2) Å
  • β = 117.04 (3)°
  • V = 1275.6 (4) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.10 mm−1
  • T = 293 K
  • 0.30 × 0.20 × 0.20 mm

Data collection

  • Enraf–Nonius CAD-4 diffractometer
  • Absorption correction: none
  • 2565 measured reflections
  • 2431 independent reflections
  • 1945 reflections with I > 2σ(I)
  • R int = 0.024
  • 3 standard reflections every 200 reflections intensity decay: 1%

Refinement

  • R[F 2 > 2σ(F 2)] = 0.072
  • wR(F 2) = 0.199
  • S = 1.00
  • 2431 reflections
  • 302 parameters
  • 14 restraints
  • H-atom parameters constrained
  • Δρmax = 0.69 e Å−3
  • Δρmin = −0.48 e Å−3

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

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680904402X/hb5144sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053680904402X/hb5144Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Experimental

Andrographolide (15 g) and nitromethane (20 ml) in dry methanol were stired in the presence of sodium methoxide at room temperature for 3 h. After confirming the completion of reaction, the mixture was washed with brine. The organic phase was evaporated in vacuo, and the residue was recrystallized by ethyl acrtate. The product (10 g) and acetic anhydride (20 ml) was refluxed for 10 min. After confirming the completion of reaction, the mixture was washed with brine. The organic phase was evaporated in vacuo to afford corresponding product by flash chromatography. Colourless blocks of (I) were recrystallised from ethyl acetate.

Refinement

The H atoms were positioned geometrically (C—H = 0.93–0.97Å) and refined as riding with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(methyl C).

The deepest difference hole is 0.12Å from the N atom and the highest difference peak is 0.18Å from atom O9.

Figures

Fig. 1.
The molecular structure of (I) showing 30% displacement ellipsoids.

Crystal data

C24H33NO9F(000) = 512
Mr = 479.51Dx = 1.248 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from 25 reflections
a = 10.533 (2) Åθ = 9–12°
b = 12.756 (3) ŵ = 0.10 mm1
c = 10.659 (2) ÅT = 293 K
β = 117.04 (3)°Block, colourless
V = 1275.6 (4) Å30.30 × 0.20 × 0.20 mm
Z = 2

Data collection

Enraf–Nonius CAD-4 diffractometerRint = 0.024
Radiation source: fine-focus sealed tubeθmax = 25.3°, θmin = 2.2°
graphiteh = −11→12
ω/2θ scansk = −15→0
2565 measured reflectionsl = −12→0
2431 independent reflections3 standard reflections every 200 reflections
1945 reflections with I > 2σ(I) intensity decay: 1%

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.072H-atom parameters constrained
wR(F2) = 0.199w = 1/[σ2(Fo2) + (0.1P)2 + 1.120P] where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max < 0.001
2431 reflectionsΔρmax = 0.69 e Å3
302 parametersΔρmin = −0.48 e Å3
14 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.063 (8)

Special details

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 > 2sigma(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)

xyzUiso*/Ueq
N0.7992 (9)−0.3512 (6)0.7140 (12)0.1177 (19)
O10.1814 (7)0.3398 (4)0.6418 (6)0.0915 (17)
C10.0804 (12)0.4065 (7)0.7867 (12)0.108 (3)
H1A0.07690.47280.74270.162*
H1B0.13870.41270.88660.162*
H1C−0.01430.38590.76790.162*
O20.1466 (6)0.2330 (3)0.7887 (5)0.0719 (13)
C20.1425 (7)0.3259 (5)0.7293 (8)0.0645 (16)
O3−0.1429 (6)−0.0145 (5)0.8828 (7)0.0935 (18)
C3−0.1806 (8)0.1612 (7)0.9391 (9)0.084 (2)
H3A−0.26680.13420.93650.126*
H3B−0.20330.21600.87040.126*
H3C−0.12070.18871.03120.126*
O40.0165 (4)0.1100 (3)0.9106 (4)0.0555 (10)
C4−0.1040 (7)0.0749 (5)0.9066 (6)0.0587 (15)
C50.1112 (7)0.0355 (5)0.8929 (6)0.0559 (14)
H5A0.0813−0.03500.90110.067*
H5B0.20700.04540.96810.067*
C60.1141 (6)0.0463 (5)0.7499 (5)0.0470 (12)
O50.3609 (8)−0.3524 (5)0.7817 (8)0.115 (2)
C70.1806 (6)−0.0527 (4)0.7167 (5)0.0424 (12)
H7A0.1659−0.04120.62010.051*
O60.4623 (8)−0.1819 (6)0.3207 (5)0.106 (2)
C80.3456 (6)−0.0689 (4)0.8036 (5)0.0456 (12)
O70.4337 (11)−0.3352 (6)0.4088 (7)0.145 (3)
O80.8651 (14)−0.3399 (8)0.6600 (15)0.218 (7)
C90.4175 (7)0.0340 (5)0.7949 (8)0.0644 (16)
H9A0.51870.02940.85800.077*
H9B0.40630.04200.69990.077*
O90.7740 (7)−0.4391 (5)0.7441 (9)0.1177 (19)
C100.3570 (7)0.1318 (5)0.8330 (8)0.0655 (17)
H10A0.37760.12800.93130.079*
H10B0.40380.19370.82090.079*
C110.2003 (7)0.1420 (4)0.7444 (7)0.0558 (14)
H11A0.18170.15270.64650.067*
C12−0.0425 (6)0.0581 (5)0.6332 (6)0.0596 (15)
H12A−0.04330.06590.54330.089*
H12B−0.08480.11880.65230.089*
H12C−0.0959−0.00320.63210.089*
C130.3944 (7)−0.0991 (5)0.9598 (6)0.0595 (15)
H13A0.3676−0.04471.00530.089*
H13B0.4961−0.10751.00660.089*
H13C0.3498−0.16370.96400.089*
C140.0996 (6)−0.1543 (4)0.7078 (6)0.0522 (13)
H14A−0.0017−0.14260.65050.063*
H14B0.1150−0.17430.80140.063*
C150.1489 (7)−0.2431 (5)0.6436 (7)0.0616 (16)
H15A0.1009−0.30750.64530.074*
H15B0.1234−0.22670.54620.074*
C160.3051 (6)−0.2581 (5)0.7227 (6)0.0524 (13)
C170.3904 (6)−0.1603 (4)0.7310 (6)0.0467 (12)
H17A0.3592−0.13790.63340.056*
C180.5504 (6)−0.1759 (5)0.7935 (6)0.0554 (13)
H18A0.5837−0.20950.88470.066*
H18B0.5959−0.10780.80860.066*
C190.5979 (6)−0.2425 (5)0.7016 (6)0.0526 (14)
H19A0.5479−0.30980.68360.063*
C200.5592 (6)−0.1911 (5)0.5610 (6)0.0524 (13)
C210.4825 (11)−0.2478 (8)0.4296 (8)0.087 (2)
C220.5278 (9)−0.0844 (7)0.3765 (9)0.088 (2)
H22A0.4587−0.02790.34150.105*
H22B0.6036−0.07010.35110.105*
C230.5853 (8)−0.0952 (6)0.5302 (8)0.0693 (17)
H23A0.6326−0.04280.59570.083*
C240.7548 (7)−0.2639 (5)0.7812 (8)0.0649 (16)
H24A0.7784−0.28300.87740.078*
H24B0.8072−0.20080.78380.078*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
N0.109 (3)0.059 (2)0.196 (6)0.008 (3)0.079 (4)−0.003 (3)
O10.128 (5)0.059 (3)0.100 (4)0.001 (3)0.062 (4)0.019 (3)
C10.147 (8)0.051 (4)0.152 (9)0.012 (5)0.090 (7)0.001 (5)
O20.112 (4)0.036 (2)0.090 (3)0.001 (2)0.066 (3)0.002 (2)
C20.068 (4)0.037 (3)0.083 (4)0.001 (3)0.030 (3)0.007 (3)
O30.114 (4)0.073 (3)0.120 (4)−0.029 (3)0.077 (4)−0.020 (3)
C30.072 (4)0.097 (6)0.093 (5)0.009 (4)0.046 (4)−0.015 (5)
O40.066 (2)0.047 (2)0.062 (2)−0.0022 (19)0.037 (2)−0.0078 (18)
C40.069 (4)0.061 (4)0.054 (3)−0.009 (3)0.035 (3)−0.007 (3)
C50.072 (4)0.055 (3)0.051 (3)0.006 (3)0.036 (3)−0.001 (3)
C60.061 (3)0.043 (3)0.040 (3)−0.001 (3)0.026 (2)0.000 (2)
O50.157 (6)0.081 (4)0.128 (5)0.010 (4)0.082 (5)0.007 (4)
C70.049 (3)0.044 (3)0.036 (2)−0.002 (2)0.021 (2)−0.001 (2)
O60.155 (6)0.095 (4)0.065 (3)−0.007 (4)0.048 (3)0.000 (3)
C80.051 (3)0.043 (3)0.044 (3)−0.002 (2)0.022 (2)−0.005 (2)
O70.241 (9)0.085 (5)0.084 (4)−0.049 (6)0.054 (5)−0.028 (4)
O80.294 (13)0.122 (7)0.410 (18)−0.038 (8)0.310 (15)−0.057 (9)
C90.062 (3)0.044 (3)0.092 (5)−0.008 (3)0.039 (3)−0.005 (3)
O90.109 (3)0.059 (2)0.196 (6)0.008 (3)0.079 (4)−0.003 (3)
C100.075 (4)0.038 (3)0.088 (5)−0.010 (3)0.040 (4)−0.011 (3)
C110.078 (4)0.036 (3)0.062 (3)0.002 (3)0.040 (3)0.000 (3)
C120.065 (3)0.058 (4)0.053 (3)0.008 (3)0.023 (3)0.002 (3)
C130.072 (4)0.060 (4)0.044 (3)0.009 (3)0.023 (3)−0.006 (3)
C140.053 (3)0.048 (3)0.061 (3)−0.003 (3)0.030 (3)−0.007 (3)
C150.059 (4)0.054 (4)0.073 (4)−0.010 (3)0.031 (3)−0.019 (3)
C160.065 (4)0.044 (3)0.056 (3)0.001 (3)0.034 (3)−0.007 (2)
C170.051 (3)0.045 (3)0.046 (3)0.003 (2)0.024 (2)−0.001 (2)
C180.056 (3)0.054 (3)0.054 (3)0.003 (3)0.023 (3)−0.003 (3)
C190.053 (3)0.045 (3)0.062 (3)0.004 (3)0.029 (3)0.001 (3)
C200.055 (3)0.044 (3)0.066 (3)0.007 (3)0.034 (3)0.001 (3)
C210.114 (6)0.082 (6)0.069 (5)−0.005 (5)0.044 (4)−0.006 (4)
C220.104 (6)0.083 (6)0.099 (5)0.020 (5)0.066 (5)0.033 (5)
C230.076 (4)0.059 (4)0.085 (5)0.003 (3)0.048 (4)0.000 (3)
C240.058 (4)0.047 (3)0.085 (4)0.006 (3)0.029 (3)0.005 (3)

Geometric parameters (Å, °)

N—O81.094 (10)C9—H9B0.9700
N—O91.228 (10)C10—C111.488 (9)
N—C241.508 (10)C10—H10A0.9700
O1—C21.190 (8)C10—H10B0.9700
C1—C21.492 (11)C11—H11A0.9800
C1—H1A0.9600C12—H12A0.9600
C1—H1B0.9600C12—H12B0.9600
C1—H1C0.9600C12—H12C0.9600
O2—C21.335 (7)C13—H13A0.9600
O2—C111.460 (7)C13—H13B0.9600
O3—C41.200 (8)C13—H13C0.9600
C3—C41.495 (10)C14—C151.531 (8)
C3—H3A0.9600C14—H14A0.9700
C3—H3B0.9600C14—H14B0.9700
C3—H3C0.9600C15—C161.481 (9)
O4—C41.327 (7)C15—H15A0.9700
O4—C51.451 (7)C15—H15B0.9700
C5—C61.544 (7)C16—C171.517 (8)
C5—H5A0.9700C17—C181.518 (7)
C5—H5B0.9700C17—H17A0.9800
C6—C111.538 (8)C18—C191.541 (8)
C6—C121.557 (8)C18—H18A0.9700
C6—C71.561 (8)C18—H18B0.9700
O5—C161.361 (9)C19—C241.500 (8)
C7—C141.530 (8)C19—C201.512 (8)
C7—C81.568 (7)C19—H19A0.9800
C7—H7A0.9800C20—C231.328 (9)
O6—C211.369 (10)C20—C211.452 (10)
O6—C221.416 (12)C22—C231.473 (11)
C8—C91.539 (8)C22—H22A0.9700
C8—C131.551 (8)C22—H22B0.9700
C8—C171.585 (7)C23—H23A0.9300
O7—C211.205 (12)C24—H24A0.9700
C9—C101.538 (9)C24—H24B0.9700
C9—H9A0.9700
O8—N—O9121.4 (10)C6—C12—H12A109.5
O8—N—C24124.1 (9)C6—C12—H12B109.5
O9—N—C24113.5 (9)H12A—C12—H12B109.5
C2—C1—H1A109.5C6—C12—H12C109.5
C2—C1—H1B109.5H12A—C12—H12C109.5
H1A—C1—H1B109.5H12B—C12—H12C109.5
C2—C1—H1C109.5C8—C13—H13A109.5
H1A—C1—H1C109.5C8—C13—H13B109.5
H1B—C1—H1C109.5H13A—C13—H13B109.5
C2—O2—C11119.1 (5)C8—C13—H13C109.5
O1—C2—O2123.8 (7)H13A—C13—H13C109.5
O1—C2—C1126.2 (7)H13B—C13—H13C109.5
O2—C2—C1110.1 (6)C7—C14—C15111.2 (5)
C4—C3—H3A109.5C7—C14—H14A109.4
C4—C3—H3B109.5C15—C14—H14A109.4
H3A—C3—H3B109.5C7—C14—H14B109.4
C4—C3—H3C109.5C15—C14—H14B109.4
H3A—C3—H3C109.5H14A—C14—H14B108.0
H3B—C3—H3C109.5C16—C15—C14110.9 (5)
C4—O4—C5118.6 (5)C16—C15—H15A109.5
O3—C4—O4123.9 (6)C14—C15—H15A109.5
O3—C4—C3125.5 (7)C16—C15—H15B109.5
O4—C4—C3110.7 (6)C14—C15—H15B109.5
O4—C5—C6113.2 (5)H15A—C15—H15B108.1
O4—C5—H5A108.9O5—C16—C15120.8 (6)
C6—C5—H5A108.9O5—C16—C17125.5 (6)
O4—C5—H5B108.9C15—C16—C17113.7 (5)
C6—C5—H5B108.9C16—C17—C18115.3 (5)
H5A—C5—H5B107.8C16—C17—C8109.5 (4)
C11—C6—C5112.6 (5)C18—C17—C8113.6 (4)
C11—C6—C12108.8 (5)C16—C17—H17A105.9
C5—C6—C12108.0 (4)C18—C17—H17A105.9
C11—C6—C7107.5 (4)C8—C17—H17A105.9
C5—C6—C7111.3 (4)C17—C18—C19114.2 (5)
C12—C6—C7108.6 (4)C17—C18—H18A108.7
C14—C7—C6113.9 (4)C19—C18—H18A108.7
C14—C7—C8111.2 (4)C17—C18—H18B108.7
C6—C7—C8117.7 (4)C19—C18—H18B108.7
C14—C7—H7A104.1H18A—C18—H18B107.6
C6—C7—H7A104.1C24—C19—C20111.7 (5)
C8—C7—H7A104.1C24—C19—C18109.5 (5)
C21—O6—C22109.0 (6)C20—C19—C18111.9 (5)
C9—C8—C13110.1 (5)C24—C19—H19A107.9
C9—C8—C7107.2 (4)C20—C19—H19A107.9
C13—C8—C7113.8 (4)C18—C19—H19A107.9
C9—C8—C17109.5 (4)C23—C20—C21107.9 (6)
C13—C8—C17108.3 (4)C23—C20—C19130.6 (6)
C7—C8—C17107.7 (4)C21—C20—C19121.5 (6)
C10—C9—C8113.7 (5)O7—C21—O6121.6 (8)
C10—C9—H9A108.8O7—C21—C20129.9 (8)
C8—C9—H9A108.8O6—C21—C20108.4 (7)
C10—C9—H9B108.8O6—C22—C23105.1 (6)
C8—C9—H9B108.8O6—C22—H22A110.7
H9A—C9—H9B107.7C23—C22—H22A110.7
C11—C10—C9112.1 (5)O6—C22—H22B110.7
C11—C10—H10A109.2C23—C22—H22B110.7
C9—C10—H10A109.2H22A—C22—H22B108.8
C11—C10—H10B109.2C20—C23—C22109.5 (7)
C9—C10—H10B109.2C20—C23—H23A125.2
H10A—C10—H10B107.9C22—C23—H23A125.2
O2—C11—C10110.2 (5)C19—C24—N111.5 (6)
O2—C11—C6107.2 (4)C19—C24—H24A109.3
C10—C11—C6114.2 (5)N—C24—H24A109.3
O2—C11—H11A108.4C19—C24—H24B109.3
C10—C11—H11A108.4N—C24—H24B109.3
C6—C11—H11A108.4H24A—C24—H24B108.0
C11—O2—C2—O1−0.7 (10)C7—C14—C15—C1655.1 (7)
C11—O2—C2—C1178.3 (7)C14—C15—C16—O5122.3 (7)
C5—O4—C4—O3−3.5 (9)C14—C15—C16—C17−57.0 (7)
C5—O4—C4—C3175.1 (5)O5—C16—C17—C188.8 (8)
C4—O4—C5—C6108.6 (6)C15—C16—C17—C18−172.0 (5)
O4—C5—C6—C1175.4 (6)O5—C16—C17—C8−120.8 (6)
O4—C5—C6—C12−44.7 (7)C15—C16—C17—C858.5 (6)
O4—C5—C6—C7−163.8 (4)C9—C8—C17—C16−172.8 (5)
C11—C6—C7—C14−175.9 (5)C13—C8—C17—C1667.1 (6)
C5—C6—C7—C1460.3 (6)C7—C8—C17—C16−56.5 (5)
C12—C6—C7—C14−58.4 (6)C9—C8—C17—C1856.7 (6)
C11—C6—C7—C851.4 (5)C13—C8—C17—C18−63.4 (6)
C5—C6—C7—C8−72.4 (6)C7—C8—C17—C18173.0 (4)
C12—C6—C7—C8168.9 (4)C16—C17—C18—C1967.9 (6)
C14—C7—C8—C9174.9 (5)C8—C17—C18—C19−164.6 (5)
C6—C7—C8—C9−51.2 (6)C17—C18—C19—C24−173.0 (5)
C14—C7—C8—C13−63.1 (6)C17—C18—C19—C2062.6 (7)
C6—C7—C8—C1370.8 (6)C24—C19—C20—C23−70.8 (8)
C14—C7—C8—C1757.1 (5)C18—C19—C20—C2352.4 (8)
C6—C7—C8—C17−169.0 (4)C24—C19—C20—C21108.2 (7)
C13—C8—C9—C10−73.4 (7)C18—C19—C20—C21−128.6 (7)
C7—C8—C9—C1050.9 (7)C22—O6—C21—O7178.3 (11)
C17—C8—C9—C10167.6 (5)C22—O6—C21—C202.0 (9)
C8—C9—C10—C11−56.1 (8)C23—C20—C21—O7−176.9 (12)
C2—O2—C11—C1089.9 (7)C19—C20—C21—O73.9 (16)
C2—O2—C11—C6−145.2 (5)C23—C20—C21—O6−0.9 (9)
C9—C10—C11—O2177.3 (5)C19—C20—C21—O6179.9 (6)
C9—C10—C11—C656.5 (7)C21—O6—C22—C23−2.2 (9)
C5—C6—C11—O2−51.7 (6)C21—C20—C23—C22−0.5 (8)
C12—C6—C11—O268.0 (6)C19—C20—C23—C22178.6 (6)
C7—C6—C11—O2−174.6 (5)O6—C22—C23—C201.7 (8)
C5—C6—C11—C1070.7 (6)C20—C19—C24—N−70.7 (7)
C12—C6—C11—C10−169.6 (5)C18—C19—C24—N164.7 (6)
C7—C6—C11—C10−52.3 (6)O8—N—C24—C19110.7 (14)
C6—C7—C14—C15167.4 (5)O9—N—C24—C19−80.2 (10)
C8—C7—C14—C15−56.9 (6)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C15—H15A···O8i0.972.593.312 (18)131
C22—H22A···O9ii0.972.473.388 (13)158
C22—H22B···O1iii0.972.513.301 (13)139
C24—H24B···O3iv0.972.563.376 (9)142

Symmetry codes: (i) x−1, y, z; (ii) −x+1, y+1/2, −z+1; (iii) −x+1, y−1/2, −z+1; (iv) x+1, y, z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB5144).

References

  • 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.
  • Enraf–Nonius (1989). CAD-4 Software Enraf–Nonius, Delft. The Netherlands.
  • Harms, K. & Wocadlo, S. (1995). XCAD4 University of Marburg, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Thunuguntla, S. S. R., Nyavanandi, V. K. & Nanduri, S. (2004). Tetrahedron Lett.45, 9357–9360.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography