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

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ISSN: 2056-9890

(1E,4Z,6E)-5-Hy­dr­oxy-1,7-bis­­(2-meth­­oxy­phen­yl)-1,4,6-hepta­trien-3-one

aFaculty of Pharmacy, The University of Sydney, NSW 2006, Australia
*Correspondence e-mail: yiliang.zhao@sydney.edu.au

(Received 23 May 2011; accepted 23 June 2011; online 2 July 2011)

In the title compound, C21H20O4, the central hepta­trienone unit is approximately planar, with a maximum atomic deviation of 0.1121 (11) Å; the two benzene rings are twisted with respect to the hepta­trienone mean plane by 2.73 (5) and 29.31 (4)°. The mol­ecule exists in the enol form and the hy­droxy group forms an intra­molecular hydrogen bond with the neighboring carbonyl group. Weak inter­molecular C—H⋯O hydrogen bonding is present in the crystal structure.

Related literature

For potential applications of curcumin and its derivatives in medicine, see: Reddy & Lokesh (1992[Reddy, A. C. & Lokesh, B. R. (1992). Mol. Cell. Biochem. 111, 117-124.]); Sreejayan Rao (1997[Sreejayan Rao, M. N. (1997). J. Pharm. Pharmacol. 49, 105-107.]); Narlawar et al. (2008[Narlawar, R., Pickhardt, M., Leuchtenberger, S., Baumann, K., Krause, S., Dyrks, T., Weggen, S., Mandelkow, E. & Schmidt, B. (2008). ChemMedChem, 3, 165-172.]); Qiu et al. (2010[Qiu, X., Du, Y., Lou, B., Zuo, Y., Shao, W., Huo, Y., Huang, J., Yu, Y., Zhou, B., Du, J., Fu, H. & Bu, X. (2010). J. Med. Chem. 53, 8260-8273.]). For the tautomerism of curcumin and its analogues, see: Gunasekaran et al. (2008[Gunasekaran, S., Natarajan, R. K., Natarajan, S. & Rathikha, R. (2008). Asian J. Chem. 20, 2903-2913.]).

[Scheme 1]

Experimental

Crystal data
  • C21H20O4

  • Mr = 336.37

  • Triclinic, [P \overline 1]

  • a = 7.3234 (11) Å

  • b = 7.7960 (12) Å

  • c = 16.897 (3) Å

  • α = 96.819 (3)°

  • β = 95.641 (3)°

  • γ = 115.520 (2)°

  • V = 852.3 (2) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 150 K

  • 0.30 × 0.20 × 0.20 mm

Data collection
  • Bruker SMART APEXII CCD diffractometer

  • 5805 measured reflections

  • 2998 independent reflections

  • 2238 reflections with I > 2σ(I)

  • Rint = 0.022

Refinement
  • R[F2 > 2σ(F2)] = 0.044

  • wR(F2) = 0.120

  • S = 1.05

  • 2998 reflections

  • 229 parameters

  • H-atom parameters constrained

  • Δρmax = 0.19 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
O3—H3′⋯O2 0.82 1.77 2.5003 (18) 147
C5—H5⋯O2i 0.93 2.45 3.351 (2) 162
C8—H8⋯O2i 0.93 2.49 3.413 (2) 169
Symmetry code: (i) -x+2, -y+2, -z+1.

Data collection: APEX2 (Bruker, 2008[Bruker (2008). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2008[Bruker (2008). APEX2 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: ORTEP-3 for Windows (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]); software used to prepare material for publication: SHELXL97 and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Comment top

The title compound is a derivative of curcumin. The curcumin and its derivatives have potent applications in the medicine field (Reddy & Lokesh, 1992; Sreejayan Rao, 1997; Narlawar et al., 2008; Qiu et al., 2010). We synthesized non-natural curcumin analogs in order to increase the NF-κB inhibitory activity and reduce the cell toxicity.

The molecular structure of the compound is showing in Fig. 1. The bond lengths indicate the electron delocalization in the molecular structure. The central heptatrienone unit is approximately planar with the maximum atomic deviation of -0.1121 (11) Å; the two benzene rings are twisted with respect to the heptatrienone mean plane at 2.73 (5) and 29.31 (4)°, respectively. In the solution, curcumin and its non-natural analogs exist as ketol-enol tautomeric forms (Gunasekaran et al., 2008). In the crystal, the title compound exists as an enol form, the hydroxy group forms an intra-molecular hydrogen bond to the neighboring carbonyl group.

Weak intermolecular C—H···O hydrogen bonding is present in the crystal structure (Table 1).

Related literature top

For potential applications of curcumin and its derivatives in the medicine fields, see: Reddy & Lokesh (1992); Sreejayan et al. (1997); Narlawar et al. (2008); Qiu et al. (2010). For the tautomerism of curcumin and its analogues, see: Gunasekaran et al. (2008).

Experimental top

In a dry three-necked flask, 1.03 ml acetylacetone (10 mmol) and 0.488 g boron oxide (3.5 mmol) were dissolved in 10 ml e thyl acetate and heated to 75°C for 1 h. Methoxybenzaldehyde (2.84 ml, 20 mmol) and tributylborate (4.8 ml, 20 mmol) were mixed with 10 ml e thyl acetate, stirred for 45 min and then added to the solution.

The mixture was heated to 100°C for 1 h, then n-butylamine (1.54 ml, 15 mmol) dissolved in 15 ml e thyl acetate was added dropwise over a period of 90 min. The reaction was stirred for 18 h at 85°C, cooled to 60°C, then 4M HCl solution (5 ml) was added and the mixture stirred at 60°C for 1 h.

The reaction mixture was cooled to ambient temperature, the organic layer was separated and the aqueous layer was extracted with ethyl acetate (3 × 100 ml). The combined organic layers were washed with 100 ml of brine, dried over anhydrous Na2SO4 and evaporated in vacuo.

The crude compound was purified by flash column chromatography, using 4% ethyl acetate in petroleum ether to give the title compound as a yellow solid (0.35 g, 5%). Single crystals suitable for X-ray data collection were obtained by slow evaporation of an ethyl acetate:petroleum ether (2:8) solution.

Refinement top

H atoms were placed in calculated positions with O—H = 0.82, C—H = 0.93 to 0.96 Å, and were refined in a riding mode with Uiso(H) = 1.2Ueq(C) for aromatic H atoms and 1.5Ueq(C,O) for the others.

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1999); software used to prepare material for publication: SHELXL97 and publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound with 50% probability displacement ellipsoids for non-H atoms.
(1E,4Z,6E)-5-Hydroxy-1,7-bis(2-methoxyphenyl)-1,4,6- heptatrien-3-one top
Crystal data top
C21H20O4Z = 2
Mr = 336.37F(000) = 356
Triclinic, P1Dx = 1.311 Mg m3
Hall symbol: -P 1Melting point: 397(2) K
a = 7.3234 (11) ÅMo Kα radiation, λ = 0.71073 Å
b = 7.7960 (12) ÅCell parameters from 500 reflections
c = 16.897 (3) Åθ = 1.1–28.2°
α = 96.819 (3)°µ = 0.09 mm1
β = 95.641 (3)°T = 150 K
γ = 115.520 (2)°Block, yellow
V = 852.3 (2) Å30.30 × 0.20 × 0.20 mm
Data collection top
Bruker SMART APEXII CCD
diffractometer
2238 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube, Bruker K760Rint = 0.022
Graphite monochromatorθmax = 25.2°, θmin = 2.5°
ω scansh = 88
5805 measured reflectionsk = 79
2998 independent reflectionsl = 2020
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)] = 0.044Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.120H-atom parameters constrained
S = 1.05 w = 1/[σ2(Fo2) + (0.0634P)2 + 0.0684P]
where P = (Fo2 + 2Fc2)/3
2998 reflections(Δ/σ)max = 0.009
229 parametersΔρmax = 0.19 e Å3
0 restraintsΔρmin = 0.24 e Å3
Crystal data top
C21H20O4γ = 115.520 (2)°
Mr = 336.37V = 852.3 (2) Å3
Triclinic, P1Z = 2
a = 7.3234 (11) ÅMo Kα radiation
b = 7.7960 (12) ŵ = 0.09 mm1
c = 16.897 (3) ÅT = 150 K
α = 96.819 (3)°0.30 × 0.20 × 0.20 mm
β = 95.641 (3)°
Data collection top
Bruker SMART APEXII CCD
diffractometer
2238 reflections with I > 2σ(I)
5805 measured reflectionsRint = 0.022
2998 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0440 restraints
wR(F2) = 0.120H-atom parameters constrained
S = 1.05Δρmax = 0.19 e Å3
2998 reflectionsΔρmin = 0.24 e Å3
229 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
C10.6037 (2)0.3920 (3)0.64590 (10)0.0297 (4)
C20.5514 (3)0.3937 (3)0.72270 (10)0.0344 (4)
H20.49290.27930.74280.041*
C30.5873 (3)0.5672 (3)0.76908 (10)0.0354 (5)
H30.55240.56870.82050.042*
C40.6743 (3)0.7384 (3)0.74013 (10)0.0338 (4)
H40.69640.85410.77160.041*
C50.7279 (2)0.7363 (3)0.66415 (9)0.0297 (4)
H50.78770.85180.64500.036*
C60.6946 (2)0.5643 (2)0.61529 (9)0.0268 (4)
C70.7506 (2)0.5582 (2)0.53473 (9)0.0281 (4)
H70.71750.43650.50580.034*
C80.8438 (2)0.7075 (3)0.49809 (10)0.0304 (4)
H80.88200.83070.52660.036*
C90.8905 (2)0.6913 (3)0.41590 (9)0.0280 (4)
C100.8584 (2)0.5123 (2)0.37012 (9)0.0272 (4)
H100.81220.40230.39370.033*
C110.8942 (2)0.4988 (2)0.29240 (9)0.0268 (4)
C120.8535 (2)0.3168 (2)0.24370 (9)0.0283 (4)
H120.81550.20920.26870.034*
C130.8668 (2)0.2926 (3)0.16534 (9)0.0281 (4)
H130.90860.40200.14150.034*
C140.8221 (2)0.1110 (2)0.11348 (9)0.0264 (4)
C150.8139 (2)0.0505 (2)0.14426 (10)0.0293 (4)
H150.84430.04060.19990.035*
C160.7621 (2)0.2245 (3)0.09447 (10)0.0315 (4)
H160.75700.33020.11630.038*
C170.7178 (3)0.2390 (3)0.01173 (10)0.0348 (4)
H170.68110.35590.02210.042*
C180.7274 (3)0.0814 (3)0.02129 (10)0.0335 (4)
H180.69750.09300.07700.040*
C190.7815 (2)0.0937 (2)0.02861 (9)0.0275 (4)
C200.4696 (3)0.0470 (3)0.62014 (13)0.0528 (6)
H20A0.54600.04550.66940.079*
H20B0.45740.05500.57880.079*
H20C0.33530.02840.62900.079*
C210.7528 (3)0.2469 (3)0.08326 (9)0.0361 (4)
H21A0.84250.20870.11010.054*
H21B0.77220.37140.09380.054*
H21C0.61290.15390.10300.054*
O10.57382 (19)0.22818 (18)0.59524 (7)0.0404 (3)
O20.95885 (19)0.84396 (17)0.38537 (7)0.0373 (3)
O30.96478 (19)0.65274 (18)0.25677 (7)0.0355 (3)
H3'0.98010.74820.28830.053*
O40.79859 (17)0.25673 (17)0.00178 (6)0.0335 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0299 (9)0.0292 (10)0.0291 (9)0.0131 (8)0.0038 (7)0.0041 (8)
C20.0337 (10)0.0361 (11)0.0333 (10)0.0132 (8)0.0080 (7)0.0138 (8)
C30.0332 (9)0.0475 (13)0.0250 (9)0.0171 (9)0.0072 (7)0.0067 (8)
C40.0335 (9)0.0356 (11)0.0288 (9)0.0142 (8)0.0035 (7)0.0010 (8)
C50.0314 (9)0.0268 (10)0.0273 (9)0.0102 (8)0.0047 (7)0.0027 (7)
C60.0269 (8)0.0258 (10)0.0261 (9)0.0108 (7)0.0030 (7)0.0040 (7)
C70.0315 (9)0.0241 (10)0.0258 (9)0.0110 (8)0.0033 (7)0.0003 (7)
C80.0383 (10)0.0222 (10)0.0258 (9)0.0102 (8)0.0059 (7)0.0008 (7)
C90.0288 (9)0.0245 (10)0.0270 (9)0.0085 (7)0.0045 (7)0.0046 (7)
C100.0312 (9)0.0234 (9)0.0245 (8)0.0100 (7)0.0046 (7)0.0042 (7)
C110.0262 (8)0.0236 (9)0.0282 (9)0.0091 (7)0.0032 (7)0.0052 (7)
C120.0313 (9)0.0241 (10)0.0287 (9)0.0113 (8)0.0066 (7)0.0049 (7)
C130.0287 (9)0.0260 (10)0.0283 (9)0.0107 (7)0.0063 (7)0.0052 (7)
C140.0243 (8)0.0281 (10)0.0264 (9)0.0113 (7)0.0065 (6)0.0035 (7)
C150.0287 (9)0.0302 (10)0.0283 (9)0.0122 (8)0.0067 (7)0.0048 (7)
C160.0328 (9)0.0268 (10)0.0371 (10)0.0143 (8)0.0099 (7)0.0066 (8)
C170.0365 (10)0.0283 (11)0.0361 (10)0.0133 (8)0.0079 (8)0.0028 (8)
C180.0383 (10)0.0351 (11)0.0254 (9)0.0157 (8)0.0063 (7)0.0005 (8)
C190.0262 (8)0.0263 (10)0.0299 (9)0.0109 (7)0.0076 (7)0.0061 (7)
C200.0698 (14)0.0275 (12)0.0646 (14)0.0198 (11)0.0241 (11)0.0186 (10)
C210.0405 (10)0.0443 (12)0.0284 (9)0.0212 (9)0.0099 (8)0.0125 (8)
O10.0556 (8)0.0249 (7)0.0414 (7)0.0157 (6)0.0178 (6)0.0098 (6)
O20.0537 (8)0.0227 (7)0.0312 (7)0.0114 (6)0.0141 (6)0.0051 (5)
O30.0508 (8)0.0248 (7)0.0288 (6)0.0138 (6)0.0124 (6)0.0052 (5)
O40.0454 (7)0.0302 (7)0.0265 (6)0.0177 (6)0.0079 (5)0.0065 (5)
Geometric parameters (Å, º) top
C1—O11.369 (2)C12—H120.9300
C1—C21.389 (2)C13—C141.460 (2)
C1—C61.406 (2)C13—H130.9300
C2—C31.384 (3)C14—C151.398 (2)
C2—H20.9300C14—C191.414 (2)
C3—C41.382 (3)C15—C161.384 (2)
C3—H30.9300C15—H150.9300
C4—C51.380 (2)C16—C171.384 (2)
C4—H40.9300C16—H160.9300
C5—C61.398 (2)C17—C181.386 (2)
C5—H50.9300C17—H170.9300
C6—C71.461 (2)C18—C191.388 (3)
C7—C81.332 (2)C18—H180.9300
C7—H70.9300C19—O41.359 (2)
C8—C91.466 (2)C20—O11.425 (2)
C8—H80.9300C20—H20A0.9600
C9—O21.271 (2)C20—H20B0.9600
C9—C101.424 (2)C20—H20C0.9600
C10—C111.365 (2)C21—O41.4283 (18)
C10—H100.9300C21—H21A0.9600
C11—O31.3297 (19)C21—H21B0.9600
C11—C121.445 (2)C21—H21C0.9600
C12—C131.334 (2)O3—H3'0.8200
O1—C1—C2123.87 (16)C12—C13—C14126.25 (16)
O1—C1—C6115.31 (14)C12—C13—H13116.9
C2—C1—C6120.82 (16)C14—C13—H13116.9
C3—C2—C1119.36 (17)C15—C14—C19117.82 (15)
C3—C2—H2120.3C15—C14—C13122.64 (14)
C1—C2—H2120.3C19—C14—C13119.53 (15)
C4—C3—C2121.01 (16)C16—C15—C14121.97 (15)
C4—C3—H3119.5C16—C15—H15119.0
C2—C3—H3119.5C14—C15—H15119.0
C5—C4—C3119.41 (17)C17—C16—C15119.04 (16)
C5—C4—H4120.3C17—C16—H16120.5
C3—C4—H4120.3C15—C16—H16120.5
C4—C5—C6121.47 (16)C16—C17—C18120.78 (17)
C4—C5—H5119.3C16—C17—H17119.6
C6—C5—H5119.3C18—C17—H17119.6
C5—C6—C1117.92 (15)C17—C18—C19120.17 (16)
C5—C6—C7122.55 (15)C17—C18—H18119.9
C1—C6—C7119.53 (15)C19—C18—H18119.9
C8—C7—C6127.18 (16)O4—C19—C18124.39 (15)
C8—C7—H7116.4O4—C19—C14115.44 (14)
C6—C7—H7116.4C18—C19—C14120.18 (16)
C7—C8—C9124.57 (16)O1—C20—H20A109.5
C7—C8—H8117.7O1—C20—H20B109.5
C9—C8—H8117.7H20A—C20—H20B109.5
O2—C9—C10120.10 (14)O1—C20—H20C109.5
O2—C9—C8117.60 (15)H20A—C20—H20C109.5
C10—C9—C8122.29 (15)H20B—C20—H20C109.5
C11—C10—C9121.33 (15)O4—C21—H21A109.5
C11—C10—H10119.3O4—C21—H21B109.5
C9—C10—H10119.3H21A—C21—H21B109.5
O3—C11—C10121.55 (15)O4—C21—H21C109.5
O3—C11—C12116.30 (14)H21A—C21—H21C109.5
C10—C11—C12122.14 (15)H21B—C21—H21C109.5
C13—C12—C11124.44 (16)C1—O1—C20118.23 (14)
C13—C12—H12117.8C11—O3—H3'109.5
C11—C12—H12117.8C19—O4—C21118.11 (13)
O1—C1—C2—C3179.73 (15)O3—C11—C12—C135.5 (2)
C6—C1—C2—C30.8 (2)C10—C11—C12—C13173.19 (15)
C1—C2—C3—C40.0 (3)C11—C12—C13—C14178.32 (15)
C2—C3—C4—C50.7 (2)C12—C13—C14—C1518.2 (3)
C3—C4—C5—C60.6 (2)C12—C13—C14—C19160.64 (15)
C4—C5—C6—C10.1 (2)C19—C14—C15—C161.9 (2)
C4—C5—C6—C7179.81 (14)C13—C14—C15—C16176.95 (14)
O1—C1—C6—C5179.67 (14)C14—C15—C16—C170.3 (2)
C2—C1—C6—C50.8 (2)C15—C16—C17—C180.8 (2)
O1—C1—C6—C70.4 (2)C16—C17—C18—C190.1 (3)
C2—C1—C6—C7179.11 (15)C17—C18—C19—O4178.77 (14)
C5—C6—C7—C82.5 (3)C17—C18—C19—C141.6 (2)
C1—C6—C7—C8177.40 (16)C15—C14—C19—O4177.76 (13)
C6—C7—C8—C9178.05 (15)C13—C14—C19—O43.3 (2)
C7—C8—C9—O2172.23 (16)C15—C14—C19—C182.6 (2)
C7—C8—C9—C106.7 (3)C13—C14—C19—C18176.36 (15)
O2—C9—C10—C111.9 (2)C2—C1—O1—C204.7 (2)
C8—C9—C10—C11177.04 (14)C6—C1—O1—C20175.74 (15)
C9—C10—C11—O31.5 (2)C18—C19—O4—C211.7 (2)
C9—C10—C11—C12177.04 (14)C14—C19—O4—C21177.93 (13)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O20.821.772.5003 (18)147
C5—H5···O2i0.932.453.351 (2)162
C8—H8···O2i0.932.493.413 (2)169
Symmetry code: (i) x+2, y+2, z+1.

Experimental details

Crystal data
Chemical formulaC21H20O4
Mr336.37
Crystal system, space groupTriclinic, P1
Temperature (K)150
a, b, c (Å)7.3234 (11), 7.7960 (12), 16.897 (3)
α, β, γ (°)96.819 (3), 95.641 (3), 115.520 (2)
V3)852.3 (2)
Z2
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.30 × 0.20 × 0.20
Data collection
DiffractometerBruker SMART APEXII CCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
5805, 2998, 2238
Rint0.022
(sin θ/λ)max1)0.599
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.044, 0.120, 1.05
No. of reflections2998
No. of parameters229
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.19, 0.24

Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1999), SHELXL97 and publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3'···O20.821.772.5003 (18)147
C5—H5···O2i0.932.453.351 (2)162
C8—H8···O2i0.932.493.413 (2)169
Symmetry code: (i) x+2, y+2, z+1.
 

Acknowledgements

The authors would like to thank the Clive and Vera Ramaciotti Foundation for a generous equipment gift, and the National Health and Medical Research Council for funding.

References

First citationBruker (2008). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals Google Scholar
First citationGunasekaran, S., Natarajan, R. K., Natarajan, S. & Rathikha, R. (2008). Asian J. Chem. 20, 2903–2913.  CAS Google Scholar
First citationNarlawar, R., Pickhardt, M., Leuchtenberger, S., Baumann, K., Krause, S., Dyrks, T., Weggen, S., Mandelkow, E. & Schmidt, B. (2008). ChemMedChem, 3, 165–172.  Web of Science CrossRef PubMed CAS Google Scholar
First citationQiu, X., Du, Y., Lou, B., Zuo, Y., Shao, W., Huo, Y., Huang, J., Yu, Y., Zhou, B., Du, J., Fu, H. & Bu, X. (2010). J. Med. Chem. 53, 8260–8273.  Web of Science CrossRef CAS PubMed Google Scholar
First citationReddy, A. C. & Lokesh, B. R. (1992). Mol. Cell. Biochem. 111, 117–124.  PubMed 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 citationSreejayan Rao, M. N. (1997). J. Pharm. Pharmacol. 49, 105–107.  PubMed Web of Science Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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