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): o2854–o2855.
Published online 2009 October 28. doi:  10.1107/S1600536809043190
PMCID: PMC2971156

Ethyl 2-(4-benzoyl-2,5-dimethyl­phen­oxy)acetate

Abstract

The title compound, C19H20O4, was synthesized via a Fries rearrangement of hydr­oxy benzophenone. The dihedral angle between the least-squares planes of the two benzene rings is 69.04 (11)°. The mol­ecular structure displays an intra­molecular non-classical C—H(...)O hydrogen bond.

Related literature

hydr­oxy benzophenones may obtained from natural products, see: Henry et al. (1999 [triangle]); Vidya et al. (2003 [triangle]); Cuesta-Rubio et al. (2002 [triangle]) and by synthetic methods, see: Hsieh et al. (2003 [triangle]); Revesz et al. (2004 [triangle]); Schlitzer et al. (2002 [triangle]). For their biological activity, see: Jiri et al. (1991 [triangle]); Palomer et al. (2000 [triangle], 2002 [triangle]); Palaska et al. (2002 [triangle]); Khanum et al. (2004a [triangle],b [triangle]). Benzophenone analogues with nitro substituents exhibit significant in vivo antitumor activity and they have been reported to show activity as immunomodulators, see: Leonard (1997 [triangle]). Nitro benzophenone derivatives show strong cytotoxic activity while the corresponding aminobenzophenone derivatives show weak activity, see: Kumazawa et al. (1997 [triangle]). For the antimicobial activity of benzophenone derivatives, see: Selvi et al. (2003 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-o2854-scheme1.jpg

Experimental

Crystal data

  • C19H20O4
  • M r = 312.35
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o2854-efi1.jpg
  • a = 8.148 (4) Å
  • b = 8.635 (4) Å
  • c = 13.029 (7) Å
  • α = 84.054 (8)°
  • β = 81.176 (8)°
  • γ = 66.559 (7)°
  • V = 830.2 (7) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.09 mm−1
  • T = 295 K
  • 0.21 × 0.20 × 0.10 mm

Data collection

  • Bruker SMART CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 2004 [triangle]) T min = 0.982, T max = 0.991
  • 8847 measured reflections
  • 3391 independent reflections
  • 2630 reflections with I > 2σ(I)
  • R int = 0.025

Refinement

  • R[F 2 > 2σ(F 2)] = 0.057
  • wR(F 2) = 0.173
  • S = 1.05
  • 3391 reflections
  • 209 parameters
  • H-atom parameters constrained
  • Δρmax = 0.36 e Å−3
  • Δρmin = −0.25 e Å−3

Data collection: SMART (Bruker, 2001 [triangle]); cell refinement: SAINT (Bruker, 2001 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 (Farrugia, 1999 [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/S1600536809043190/rk2174sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809043190/rk2174Isup2.hkl

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

Acknowledgments

The authors thank Professor T. N Guru Row and Miss Brinda Selvaraj, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, for the data collection.

supplementary crystallographic information

Comment

Hydroxy benzophenones are achieved from natural products (Henry et al., 1999; Vidya et al., 2003; Cuesta-Rubio et al., 2002) as well as by synthetic methods (Hsieh et al., 2003; Schlitzer et al., 2002; Revesz et al., 2004). The great importance of these substances is essentially due to the diverse biological and chemical properties they acquire. Benzophenone analogues possess a high analgesic (Jiri et al., 1991) efficacy and also endowed with anti-inflammatory property (Palomer et al., 2000; Palomer et al., 2002; Palaska et al., 2002; Khanum et al., 2004a,b).

Benzophenone analogues with nitro substituent exhibit significant in vivo antitumor activity and they have been reported to show activity as immunomodulators (Leonard, 1997). Based on these report, in vitro and in vivo studies of a series of novel nitro- and amino-substituted benzophenones have been investigated as potential anticancer agents. Nitro benzophenone derivative showed strong cytotoxic activity while the corresponding aminobenzophenone derivatives showed weak activity (Kumazawa et al., 1997). Besides benzophenone derivatives endowed with anti-microbial activity, for instance isoprenylated benzophenone, at its lower concentration of 500 to 1000 p.p.m. inhibits aflatoxin production in Aspergillus flavus, relatively greater than inhibition growth of the fungus - Selvi et al., (2003).

The molecular structure of title compound is shown on Fig.1. The dihedral angle between least-squares planes (two phenyl rings) is 69.04 (11)°. The intramolecular non-classical C–H···O hydrogen bond (Table 1) is observed.

Experimental

2,5-Dimethyl phenyl benzoate was synthesized from 2,5-dimethyl phenol and benzoyl chloride in presence of 10% sodium hydroxide. 4-Hydroxy-2,5-dimethyl benzophenone was achieved from 2,5-dimethyl phenyl benzoate by Fries rearrangement.

In a typical procedure, a mixture of 4-hydroxy-2,5-dimethylbenzophenone (4.5 g, 0.02 mol) and ethylchloroacetate (2.4 g, 0.02 mol) in dry acetone (60 ml) and anhydrous potassium carbonate (2.8 g, 0.02 mol) was refluxed for 6 h then cooled and the solvent removed under reduced pressure. The residual mass was triturated with ice water to remove potassium carbonate and extracted with ether (3 × 50ml) and the ether layer was washed with 10% sodium hydroxide solution (3 × 30ml) followed by water (3 × 30ml) and then dried over anhydrous sodium sulfate and evaporated to dryness to get crude solid, which on recrystallization with ethanol gave 4-benzoyl-2,5-dimethyl phenoxy ethyl acetate.

M.p. 329 K; IR (Nujol): 1740 (ester, C═O), 1665 cm-1 (C═O). 1H NMR (CDCl3): δ 1.2 (t, J=7 Hz, 3H, CH3 of ester), 2.2-2.3 (d, 6H, 2Ar-CH3), 4.25 (q, J=6 Hz, 2H, CH2 of ester), 4.45 (s, 2H, OCH2), 7.2-7.8 (bm, 7H, Ar–H); Anal. Cal. for C19H20O4: C, 72.61%; H, 6.36%. Found: C, 72.29%; H, 6.15%.

Refinement

All H atoms were positioned at calculated positions with C–H = 0.93Å for aromatic H, 0.97Å for methylene H and 0.96Å for methyl H, and refined using a riding model with Uiso(H) = 1.5Ueq(C) for methyl H and Uiso(H) = 1.2Ueq(C) for other.

Figures

Fig. 1.
The asymmetric unit of the title compound with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as a small spheres of arbitrary radius.

Crystal data

C19H20O4Z = 2
Mr = 312.35F(000) = 332
Triclinic, P1Dx = 1.250 Mg m3
Hall symbol: -P 1Melting point: 329 K
a = 8.148 (4) ÅMo Kα radiation, λ = 0.71073 Å
b = 8.635 (4) ÅCell parameters from 3391 reflections
c = 13.029 (7) Åθ = 1.6–26.4°
α = 84.054 (8)°µ = 0.09 mm1
β = 81.176 (8)°T = 295 K
γ = 66.559 (7)°Plate, colourless
V = 830.2 (7) Å30.21 × 0.20 × 0.10 mm

Data collection

Bruker SMART CCD diffractometer3391 independent reflections
Radiation source: fine-focus sealed tube2630 reflections with I > 2σ(I)
graphiteRint = 0.025
ω and [var phi] scansθmax = 26.4°, θmin = 1.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)h = −10→10
Tmin = 0.982, Tmax = 0.991k = −10→10
8847 measured reflectionsl = −16→16

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.057Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.173H-atom parameters constrained
S = 1.05w = 1/[σ2(Fo2) + (0.0848P)2 + 0.2822P] where P = (Fo2 + 2Fc2)/3
3391 reflections(Δ/σ)max < 0.001
209 parametersΔρmax = 0.36 e Å3
0 restraintsΔρmin = −0.25 e Å3

Special details

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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)

xyzUiso*/Ueq
O10.4354 (3)0.82563 (19)0.84149 (12)0.0691 (5)
O20.14909 (19)1.14174 (17)0.41431 (11)0.0546 (4)
O30.1127 (2)1.37122 (19)0.24885 (14)0.0715 (5)
O40.1339 (2)1.16785 (19)0.14867 (12)0.0662 (5)
C10.4303 (3)0.5733 (2)0.79154 (15)0.0462 (5)
C20.5409 (3)0.4695 (3)0.86317 (18)0.0642 (6)
H20.60730.51040.89670.077*
C30.5525 (4)0.3051 (3)0.8849 (2)0.0760 (7)
H30.62760.23560.93240.091*
C40.4536 (4)0.2448 (3)0.8364 (2)0.0731 (7)
H40.46110.13470.85160.088*
C50.3435 (4)0.3461 (3)0.7654 (2)0.0667 (6)
H50.27610.30470.73310.080*
C60.3327 (3)0.5103 (3)0.74180 (17)0.0537 (5)
H60.26000.57800.69270.064*
C70.4101 (3)0.7530 (2)0.77353 (15)0.0476 (5)
C80.3509 (2)0.8461 (2)0.67388 (15)0.0425 (4)
C90.4344 (2)0.7866 (2)0.57555 (14)0.0413 (4)
C100.3660 (2)0.8849 (2)0.48841 (14)0.0432 (4)
H100.41930.84660.42250.052*
C110.2199 (2)1.0389 (2)0.49763 (15)0.0437 (4)
C120.1369 (2)1.1014 (2)0.59520 (16)0.0449 (4)
C130.2055 (3)1.0032 (2)0.68133 (15)0.0457 (4)
H130.15311.04300.74700.055*
C140.6014 (3)0.6268 (2)0.56025 (16)0.0490 (5)
H14A0.63690.60930.48720.074*
H14B0.57650.53260.59350.074*
H14C0.69700.63680.59020.074*
C15−0.0212 (3)1.2694 (2)0.60437 (19)0.0596 (6)
H15A−0.04841.31740.53620.089*
H15B0.00861.34460.64030.089*
H15C−0.12411.25320.64250.089*
C160.2201 (3)1.0816 (3)0.31397 (16)0.0523 (5)
H16A0.18470.99040.30290.063*
H16B0.35071.03880.30620.063*
C170.1474 (3)1.2266 (3)0.23580 (17)0.0519 (5)
C180.0828 (4)1.2910 (3)0.06180 (19)0.0752 (7)
H18A0.18341.32120.03220.090*
H18B−0.01731.39270.08560.090*
C190.0308 (5)1.2153 (4)−0.0163 (2)0.0967 (10)
H19A−0.00371.2947−0.07420.145*
H19B−0.06891.18600.01360.145*
H19C0.13101.1153−0.03980.145*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.1070 (13)0.0530 (9)0.0549 (9)−0.0327 (9)−0.0290 (9)−0.0015 (7)
O20.0530 (8)0.0449 (8)0.0511 (8)−0.0028 (6)−0.0123 (6)0.0043 (6)
O30.0911 (12)0.0458 (9)0.0748 (11)−0.0189 (8)−0.0288 (9)0.0057 (8)
O40.0907 (12)0.0566 (9)0.0522 (9)−0.0281 (8)−0.0194 (8)0.0076 (7)
C10.0514 (11)0.0412 (10)0.0429 (10)−0.0149 (8)−0.0053 (8)−0.0019 (8)
C20.0795 (16)0.0530 (12)0.0612 (13)−0.0237 (11)−0.0233 (12)0.0062 (10)
C30.0950 (19)0.0504 (13)0.0734 (16)−0.0189 (13)−0.0212 (14)0.0142 (11)
C40.0944 (19)0.0442 (12)0.0723 (16)−0.0254 (12)0.0105 (14)−0.0030 (11)
C50.0800 (16)0.0592 (13)0.0688 (15)−0.0373 (12)0.0026 (12)−0.0127 (11)
C60.0568 (12)0.0522 (11)0.0534 (12)−0.0226 (10)−0.0058 (9)−0.0036 (9)
C70.0524 (11)0.0426 (10)0.0468 (11)−0.0158 (9)−0.0092 (9)−0.0043 (8)
C80.0451 (10)0.0354 (9)0.0472 (10)−0.0142 (8)−0.0103 (8)−0.0026 (7)
C90.0379 (9)0.0346 (9)0.0494 (10)−0.0105 (7)−0.0088 (8)−0.0029 (7)
C100.0412 (10)0.0391 (9)0.0437 (10)−0.0088 (8)−0.0064 (8)−0.0038 (8)
C110.0412 (9)0.0384 (9)0.0489 (11)−0.0118 (8)−0.0113 (8)0.0027 (8)
C120.0402 (9)0.0350 (9)0.0552 (11)−0.0092 (8)−0.0066 (8)−0.0044 (8)
C130.0491 (10)0.0374 (9)0.0473 (10)−0.0132 (8)−0.0018 (8)−0.0084 (8)
C140.0439 (10)0.0415 (10)0.0532 (11)−0.0060 (8)−0.0095 (8)−0.0038 (8)
C150.0524 (12)0.0397 (10)0.0711 (14)−0.0017 (9)−0.0052 (10)−0.0056 (10)
C160.0562 (12)0.0454 (10)0.0509 (12)−0.0142 (9)−0.0131 (9)0.0035 (9)
C170.0492 (11)0.0502 (11)0.0550 (12)−0.0166 (9)−0.0143 (9)0.0045 (9)
C180.103 (2)0.0683 (15)0.0531 (13)−0.0326 (15)−0.0191 (13)0.0145 (11)
C190.130 (3)0.108 (2)0.0701 (18)−0.061 (2)−0.0400 (18)0.0194 (16)

Geometric parameters (Å, °)

O1—C71.222 (2)C9—C141.508 (2)
O2—C111.373 (2)C10—C111.389 (3)
O2—C161.408 (3)C10—H100.9300
O3—C171.190 (3)C11—C121.397 (3)
O4—C171.327 (3)C12—C131.382 (3)
O4—C181.459 (3)C12—C151.510 (3)
C1—C61.387 (3)C13—H130.9300
C1—C21.389 (3)C14—H14A0.9600
C1—C71.491 (3)C14—H14B0.9600
C2—C31.387 (3)C14—H14C0.9600
C2—H20.9300C15—H15A0.9600
C3—C41.370 (4)C15—H15B0.9600
C3—H30.9300C15—H15C0.9600
C4—C51.375 (4)C16—C171.512 (3)
C4—H40.9300C16—H16A0.9700
C5—C61.390 (3)C16—H16B0.9700
C5—H50.9300C18—C191.461 (4)
C6—H60.9300C18—H18A0.9700
C7—C81.494 (3)C18—H18B0.9700
C8—C91.400 (3)C19—H19A0.9600
C8—C131.402 (3)C19—H19B0.9600
C9—C101.392 (3)C19—H19C0.9600
C11—O2—C16117.92 (15)C11—C12—C15120.57 (18)
C17—O4—C18116.19 (18)C12—C13—C8122.77 (18)
C6—C1—C2119.25 (19)C12—C13—H13118.6
C6—C1—C7120.90 (18)C8—C13—H13118.6
C2—C1—C7119.76 (18)C9—C14—H14A109.5
C3—C2—C1120.2 (2)C9—C14—H14B109.5
C3—C2—H2119.9H14A—C14—H14B109.5
C1—C2—H2119.9C9—C14—H14C109.5
C4—C3—C2120.1 (2)H14A—C14—H14C109.5
C4—C3—H3119.9H14B—C14—H14C109.5
C2—C3—H3119.9C12—C15—H15A109.5
C3—C4—C5120.3 (2)C12—C15—H15B109.5
C3—C4—H4119.8H15A—C15—H15B109.5
C5—C4—H4119.8C12—C15—H15C109.5
C4—C5—C6120.1 (2)H15A—C15—H15C109.5
C4—C5—H5119.9H15B—C15—H15C109.5
C6—C5—H5119.9O2—C16—C17108.12 (16)
C1—C6—C5120.0 (2)O2—C16—H16A110.1
C1—C6—H6120.0C17—C16—H16A110.1
C5—C6—H6120.0O2—C16—H16B110.1
O1—C7—C1120.15 (18)C17—C16—H16B110.1
O1—C7—C8120.08 (17)H16A—C16—H16B108.4
C1—C7—C8119.71 (16)O3—C17—O4124.87 (19)
C9—C8—C13119.31 (17)O3—C17—C16125.4 (2)
C9—C8—C7123.67 (16)O4—C17—C16109.72 (18)
C13—C8—C7117.01 (17)O4—C18—C19108.2 (2)
C10—C9—C8118.21 (16)O4—C18—H18A110.1
C10—C9—C14118.84 (17)C19—C18—H18A110.1
C8—C9—C14122.83 (16)O4—C18—H18B110.1
C11—C10—C9121.49 (17)C19—C18—H18B110.1
C11—C10—H10119.3H18A—C18—H18B108.4
C9—C10—H10119.3C18—C19—H19A109.5
O2—C11—C10123.79 (17)C18—C19—H19B109.5
O2—C11—C12115.21 (16)H19A—C19—H19B109.5
C10—C11—C12120.99 (17)C18—C19—H19C109.5
C13—C12—C11117.21 (16)H19A—C19—H19C109.5
C13—C12—C15122.22 (18)H19B—C19—H19C109.5
C6—C1—C2—C3−0.3 (4)C8—C9—C10—C110.6 (3)
C7—C1—C2—C3176.3 (2)C14—C9—C10—C11−175.62 (17)
C1—C2—C3—C4−0.6 (4)C16—O2—C11—C104.9 (3)
C2—C3—C4—C50.5 (4)C16—O2—C11—C12−176.40 (17)
C3—C4—C5—C60.4 (4)C9—C10—C11—O2179.02 (17)
C2—C1—C6—C51.3 (3)C9—C10—C11—C120.4 (3)
C7—C1—C6—C5−175.3 (2)O2—C11—C12—C13−179.07 (16)
C4—C5—C6—C1−1.3 (3)C10—C11—C12—C13−0.4 (3)
C6—C1—C7—O1151.5 (2)O2—C11—C12—C151.0 (3)
C2—C1—C7—O1−25.1 (3)C10—C11—C12—C15179.66 (18)
C6—C1—C7—C8−25.8 (3)C11—C12—C13—C8−0.7 (3)
C2—C1—C7—C8157.6 (2)C15—C12—C13—C8179.29 (18)
O1—C7—C8—C9130.0 (2)C9—C8—C13—C121.7 (3)
C1—C7—C8—C9−52.7 (3)C7—C8—C13—C12−179.52 (17)
O1—C7—C8—C13−48.7 (3)C11—O2—C16—C17−169.54 (16)
C1—C7—C8—C13128.6 (2)C18—O4—C17—O33.8 (3)
C13—C8—C9—C10−1.6 (3)C18—O4—C17—C16−174.0 (2)
C7—C8—C9—C10179.72 (16)O2—C16—C17—O332.4 (3)
C13—C8—C9—C14174.45 (17)O2—C16—C17—O4−149.82 (18)
C7—C8—C9—C14−4.3 (3)C17—O4—C18—C19−165.9 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C15—H15A···O20.962.282.751 (3)110

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RK2174).

References

  • Bruker (2001). SMART and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Cuesta-Rubio, O., Frontana-Uribe, B. A., Ramirez-Apan, T. & Cardenas, J. (2002). J. Biosci.57, 372–380. [PubMed]
  • Farrugia, L. J. (1999). J. Appl. Cryst.32, 837–838.
  • Henry, G. E., Jacobs, H., Carrington, C. M. S., McLean, S. & Reynolds, W. F. (1999). Tetrahedron, 55, 1581–1596.
  • Hsieh, H. P., Liou, J. P., Lin, Y. T., Mahindroo, N., Chang, J. Y., Yang, Y. N., Chern, S. S., Tan, U. K., Chang, C. W., Chen, T. W., Lin, C. H., Chang, Y. Y. & Wang, C. C. (2003). Bioorg. Med. Chem. Lett.13, 101–105. [PubMed]
  • Jiri, J., Miroslav, P., Josef, P. & Stanislav, W. (1991). Csech CS, 271, 185.
  • Khanum, S. A., Shashikanth, S. & Deepak, A. V. (2004a). Bioorg. Chem.32, 211–222. [PubMed]
  • Khanum, S. A., Venu, T. D., Shashikanth, S. & Firdouse, A. (2004b). Bioorg. Med. Chem. Lett.14, 5351–5355. [PubMed]
  • Kumazawa, E., Hirotani, K., Burford, S. C., Kawagoe, K., Miwa, T., Mitsul, I. & Ejima, A. (1997). Chem. Pharm. Bull.45, 1470–1474. [PubMed]
  • Leonard, D. M. (1997). J. Med. Chem.40, 2971–2990. [PubMed]
  • Palaska, E., Sahin, G., Kelicen, P., Durllu, N. T. & Altinok, G. (2002). Farmaco, 57, 101–107. [PubMed]
  • Palomer, A., Pascual, J., Cabre, M., Borras, L., Gonzalez, G., Aparici, M., Carabaza, A., Cabre, F., Garcia, M. L. & Mauleon, D. (2002). Bioorg. Med. Chem. Lett.12, 533–537. [PubMed]
  • Palomer, A., Perez, J. J., Navea, S., Llorens, O., Pascual, J., Garcia, M. L. & Mauleon, D. M. (2000). Med. Chem.43, 2280–2284. [PubMed]
  • Revesz, L., Blum, F. E., Di Padova, E., Buhl, T. R., Feifel, H., Gram, P., Hiestand, U., Manning, U. & Rucklin, G. (2004). Bioorg. Med. Chem. Lett.14, 3601–3605. [PubMed]
  • Schlitzer, M., Bohm, M. & Sattler, I. (2002). Bioorg. Med. Chem. Lett.10, 615–635. [PubMed]
  • Selvi, A. T., Joseph, G. S. & Jayaprakasha, G. K. (2003). Food Microbiol.20, 455–460.
  • Sheldrick, G. M. (2004). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Vidya, R., Eggen, M., Georg, G. I. & Himes, R. H. (2003). Bioorg. Med. Chem. Lett.13, 757–760. [PubMed]

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