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ISSN: 2056-9890

Indomethacin methyl ester

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aDepartment of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, England, and Pfizer Institute for Pharmaceutical Materials Science, bInstitute of Chemical and Engineering Sciences, Ayer Rajah Crescent, Block 28, Unit 02-08, Singapore 139959, and Pfizer Institute for Pharmaceutical Materials Science, and cCambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, England
*Correspondence e-mail: avt21@cam.ac.uk

(Received 30 January 2004; accepted 26 February 2004; online 6 March 2004)

The cystal structure of the title compound [systematic name: methyl 1-(4-chloro­benzoyl)-5-methoxy-2-methyl-1H-indole-3-acetate], C20H18ClNO4, exhibits a short axis similar to another indomethacin analogue. Also observed in the structure is a packing of mol­ecules influenced by weak C—H⋯O hydrogen bonds.

Comment

As part of an investigation into the crystallization of pharmaceutical compounds, the crystal structures of indomethacin derivatives are of interest. Numerous studies have been reported on various crystal structures of the drug indomethacin (γ-form: Kistenmacher & Marsh, 1972[Kistenmacher, T. J. & Marsh, R. E. (1972). J. Am. Chem. Soc. 94, 1340-1345.]; α-form: Chen et al., 2002[Chen, X., Morris, K. R., Griesser, U. J., Byrn, S. R. & Stowell, J. G. (2002). J. Am. Chem. Soc. 124, 15012-15019.]; t-butanol and methanol solvates: Joshi et al., 1998[Joshi, V., Stowell, J. G. & Byrn, S. R. (1998). Mol. Cryst. Liq. Cryst. 313, 265-270.]). In contrast, the structure of its methyl ester, (I[link]), has not been reported to date. We report here its crystal structure and describe the intermolecular interactions involved.

[Scheme 1]

The asymmetric unit of (I[link]) comprises one mol­ecule (Fig. 1[link]). Although the crystal structure of the indomethacin methyl ester differs significantly from that of the parent carboxyl­ic acid, it bears some similarity to the structure of another indomethacin derivative, iodo­indomethacin (Loll et al., 1996[Loll, P. J., Garavito, R. M., Carrell, C. J. & Carrell, H. L. (1996). Acta Cryst. C52, 455-457.]). Both crystal structures exhibit a relatively short axis [4.8326 (1) Å for the methyl ester derivative versus 4.7250 (10) Å for the iodo derivative]. In addition, both crystal structures show a halogen contact to a carbonyl O atom [Cl1⋯O4 = 3.575 (2) Å versus I1⋯O4 = 3.162 (5) Å].

In the absence of the carboxyl­ic acid group of indomethacin, no strong O—H⋯O hydrogen bonding can be expected in the crystal structure of the methyl ester. Instead, C—H⋯O hydrogen bonds form a three-dimensional supramolecular network, as shown in Fig. 2[link]. Hydro­gen-bond distances and angles are provided in Table 1[link].

[Figure 1]
Figure 1
Molecular unit showing displacement ellipsoids at the 50% probability level.
[Figure 2]
Figure 2
Projection on to (010), showing the packing involving C—H⋯O interactions. The intermolecular C9—H9A⋯O4(x, y − 1, z) hydrogen bond projects parallel to the b axis.

Experimental

Indomethacin and an­hydrous benzene­sulfonic acid were obtained from Sigma–Aldrich and were used as received. Indomethacin (130 mg, 0.364 mmol) and benzen­sulfonic acid (115 mg, 0.727 mmol) were dissolved in methanol with heating. Crystals precipitated as the solution cooled to room temperature and were immediately isolated and dried.

Crystal data
  • C20H18ClNO4

  • Mr = 371.82

  • Monoclinic, P21/n

  • a = 19.0206 (5) Å

  • b = 4.8326 (1) Å

  • c = 19.3092 (8) Å

  • β = 97.739 (1)°

  • V = 1758.72 (9) Å3

  • Z = 4

  • Dx = 1.404 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 6724 reflections

  • θ = 1.0–25.0°

  • μ = 0.24 mm−1

  • T = 180 (2) K

  • Needle, yellow

  • 0.46 × 0.07 × 0.05 mm

Data collection
  • Nonius KappaCCD diffractometer

  • ω and φ scans

  • Absorption correction: multi-scan (SORTAV; Blessing, 1995[Blessing, R. H. (1995). Acta Cryst. A51, 33-38.]) Tmin = 0.946, Tmax = 0.985

  • 10 009 measured reflections

  • 3086 independent reflections

  • 2410 reflections with I > 2σ(I)

  • Rint = 0.035

  • θmax = 25.0°

  • h = −22 → 22

  • k = −5 → 5

  • l = −22 → 23

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.047

  • wR(F2) = 0.117

  • S = 1.04

  • 3086 reflections

  • 238 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(Fo2) + (0.0481P)2 + 1.0445P] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max = 0.002

  • Δρmax = 0.31 e Å−3

  • Δρmin = −0.39 e Å−3

Table 1
Hydrogen-bonding geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C18—H18⋯O1i 0.95 2.34 3.260 (3) 162
C3—H3⋯O1ii 0.95 2.59 3.480 (3) 156
C9—H9A⋯O4iii 0.99 2.62 3.565 (3) 160
C15—H15⋯O2iv 0.95 2.48 3.419 (2) 170
Symmetry codes: (i) 2-x,1-y,2-z; (ii) 2-x,-y,2-z; (iii) x,y-1,z; (iv) [{\script{5\over 2}}-x,y-{\script{1\over 2}},{\script{3\over 2}}-z].

All H atoms were placed geometrically and treated using a riding model. The Uiso values for methyl H atoms were fixed at 1.5Ueq of the carrier atom. For all other H atoms, Uiso(H) = 1.2Ueq(carrier atom). The C—H distances of methyl groups were fixed at 0.98 Å; all other C—H distances were fixed at 0.95 Å.

Data collection: COLLECT (Nonius, 1998[Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: HKL DENZO (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXL97 and SHELXS97. University of Göttingen, Germany.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXL97 and SHELXS97. University of Göttingen, Germany.]); molecular graphics: XP (Sheldrick, 1993[Sheldrick, G. M. (1993). XP. University of Göttingen, Germany.]) and DIAMOND (Brandenburg, 1999[Brandenburg, K. (1999). DIAMOND. Version 2.1c. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: SHELXL97.

Supporting information


Computing details top

Data collection: Collect (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997b); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: XP (Sheldrick, 1993) and Diamond (Brandenburg, 1999); software used to prepare material for publication: SHELXL97.

Methyl [1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indol-3-ylmethyl]acetate top
Crystal data top
C20H18ClNO4Dx = 1.404 Mg m3
Mr = 371.82Melting point: not measured K
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 19.0206 (5) ÅCell parameters from 6724 reflections
b = 4.8326 (1) Åθ = 1.0–25.0°
c = 19.3092 (8) ŵ = 0.24 mm1
β = 97.739 (1)°T = 180 K
V = 1758.72 (9) Å3Needle, yellow
Z = 40.46 × 0.07 × 0.05 mm
F(000) = 776
Data collection top
Nonius KappaCCD
diffractometer
3086 independent reflections
Radiation source: fine-focus sealed tube2410 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.035
ω and φ scansθmax = 25.0°, θmin = 3.6°
Absorption correction: multi-scan
Sortav (Blessing, 1995)
h = 2222
Tmin = 0.946, Tmax = 0.985k = 55
10009 measured reflectionsl = 2223
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)] = 0.047Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.117H-atom parameters constrained
S = 1.04 w = 1/[σ2(Fo2) + (0.0481P)2 + 1.0445P]
where P = (Fo2 + 2Fc2)/3
3086 reflections(Δ/σ)max = 0.002
238 parametersΔρmax = 0.31 e Å3
0 restraintsΔρmin = 0.39 e Å3
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
Cl10.65787 (4)0.17803 (18)0.86754 (4)0.0706 (3)
O10.98228 (10)0.2360 (4)0.95373 (9)0.0550 (5)
O21.24396 (8)0.8532 (3)0.84051 (8)0.0436 (4)
O31.09430 (9)0.0986 (3)0.56653 (8)0.0458 (4)
O41.02616 (11)0.3946 (4)0.61588 (9)0.0613 (5)
N11.00383 (9)0.2127 (3)0.84188 (9)0.0299 (4)
C10.96165 (12)0.1665 (5)0.89405 (11)0.0355 (5)
C20.88813 (12)0.0526 (5)0.87820 (11)0.0354 (5)
C30.86722 (13)0.1409 (5)0.92464 (12)0.0431 (6)
H30.90130.21960.95960.052*
C40.79675 (14)0.2190 (5)0.92002 (13)0.0498 (7)
H40.78240.35540.95070.060*
C50.74766 (13)0.0969 (5)0.87051 (13)0.0451 (6)
C60.76742 (13)0.0955 (5)0.82406 (13)0.0451 (6)
H60.73290.17790.79010.054*
C70.83837 (12)0.1670 (5)0.82758 (12)0.0404 (6)
H70.85290.29530.79500.049*
C80.95660 (12)0.1570 (5)0.75198 (12)0.0377 (5)
H8A0.97610.26280.71560.057*
H8B0.91130.07390.73230.057*
H8C0.94910.28060.79050.057*
C91.09125 (12)0.0424 (4)0.68596 (10)0.0335 (5)
H9A1.07560.15230.67920.040*
H9B1.14380.04340.69310.040*
C101.06587 (12)0.2015 (4)0.62062 (11)0.0339 (5)
C111.00736 (11)0.0656 (4)0.77853 (10)0.0307 (5)
C121.26800 (13)1.0394 (5)0.89591 (13)0.0465 (6)
H12A1.31221.12750.88660.070*
H12B1.27650.93710.94010.070*
H12C1.23181.18150.89910.070*
C131.06544 (11)0.1519 (4)0.75071 (10)0.0302 (5)
C141.10167 (11)0.3605 (4)0.79639 (10)0.0286 (5)
C151.16259 (11)0.5171 (4)0.79317 (11)0.0321 (5)
H151.18950.49550.75550.039*
C161.18318 (11)0.7055 (4)0.84620 (11)0.0325 (5)
C171.14376 (11)0.7377 (4)0.90166 (11)0.0332 (5)
H171.15860.86890.93730.040*
C181.08335 (11)0.5814 (4)0.90559 (11)0.0332 (5)
H181.05640.60380.94320.040*
C191.06351 (11)0.3918 (4)0.85293 (10)0.0289 (5)
C201.07509 (17)0.2359 (7)0.50019 (13)0.0614 (8)
H20A1.09960.14700.46460.092*
H20B1.08900.43110.50450.092*
H20C1.02370.22270.48650.092*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0484 (4)0.0997 (6)0.0658 (5)0.0277 (4)0.0158 (3)0.0150 (4)
O10.0611 (11)0.0762 (13)0.0302 (10)0.0255 (10)0.0156 (8)0.0075 (9)
O20.0426 (10)0.0463 (10)0.0448 (10)0.0091 (7)0.0166 (8)0.0041 (7)
O30.0578 (11)0.0550 (10)0.0263 (8)0.0105 (8)0.0117 (7)0.0011 (7)
O40.0880 (14)0.0593 (12)0.0367 (10)0.0352 (11)0.0081 (9)0.0053 (8)
N10.0325 (10)0.0326 (10)0.0253 (9)0.0025 (7)0.0065 (7)0.0004 (7)
C10.0416 (13)0.0373 (12)0.0291 (12)0.0008 (10)0.0097 (10)0.0004 (9)
C20.0394 (13)0.0363 (12)0.0324 (12)0.0015 (10)0.0124 (10)0.0048 (10)
C30.0472 (14)0.0451 (14)0.0381 (13)0.0045 (11)0.0096 (11)0.0023 (11)
C40.0604 (17)0.0491 (15)0.0429 (15)0.0159 (12)0.0181 (13)0.0009 (12)
C50.0420 (14)0.0543 (15)0.0408 (14)0.0127 (11)0.0123 (11)0.0147 (12)
C60.0422 (14)0.0513 (15)0.0414 (14)0.0002 (11)0.0043 (11)0.0049 (11)
C70.0424 (14)0.0411 (13)0.0392 (14)0.0013 (10)0.0109 (11)0.0019 (10)
C80.0403 (13)0.0369 (12)0.0358 (13)0.0031 (10)0.0046 (10)0.0046 (10)
C90.0419 (13)0.0329 (12)0.0265 (11)0.0082 (9)0.0075 (9)0.0016 (9)
C100.0385 (12)0.0353 (13)0.0286 (12)0.0004 (10)0.0067 (10)0.0044 (9)
C110.0369 (12)0.0286 (11)0.0261 (11)0.0074 (9)0.0028 (9)0.0009 (8)
C120.0437 (14)0.0465 (14)0.0492 (15)0.0077 (11)0.0063 (12)0.0006 (12)
C130.0385 (12)0.0286 (11)0.0234 (11)0.0089 (9)0.0035 (9)0.0019 (8)
C140.0335 (12)0.0297 (11)0.0231 (11)0.0083 (9)0.0054 (9)0.0042 (8)
C150.0363 (12)0.0338 (12)0.0284 (12)0.0093 (9)0.0124 (9)0.0041 (9)
C160.0340 (12)0.0313 (12)0.0332 (12)0.0033 (9)0.0078 (9)0.0065 (9)
C170.0394 (12)0.0317 (11)0.0291 (12)0.0008 (9)0.0063 (10)0.0016 (9)
C180.0380 (12)0.0361 (12)0.0272 (11)0.0026 (9)0.0104 (9)0.0012 (9)
C190.0318 (11)0.0293 (11)0.0260 (11)0.0039 (8)0.0054 (9)0.0028 (9)
C200.078 (2)0.081 (2)0.0256 (13)0.0024 (16)0.0099 (13)0.0064 (13)
Geometric parameters (Å, º) top
Cl1—C51.746 (2)C8—H8B0.9800
O1—C11.214 (3)C8—H8C0.9800
O2—C161.376 (3)C9—C131.500 (3)
O2—C121.425 (3)C9—C101.501 (3)
O3—C101.335 (3)C9—H9A0.9900
O3—C201.445 (3)C9—H9B0.9900
O4—C101.196 (3)C11—C131.357 (3)
N1—C11.388 (3)C12—H12A0.9800
N1—C191.420 (3)C12—H12B0.9800
N1—C111.424 (3)C12—H12C0.9800
C1—C21.496 (3)C13—C141.451 (3)
C2—C71.381 (3)C14—C151.393 (3)
C2—C31.390 (3)C14—C191.398 (3)
C3—C41.384 (3)C15—C161.386 (3)
C3—H30.9500C15—H150.9500
C4—C51.376 (4)C16—C171.396 (3)
C4—H40.9500C17—C181.386 (3)
C5—C61.379 (4)C17—H170.9500
C6—C71.386 (3)C18—C191.383 (3)
C6—H60.9500C18—H180.9500
C7—H70.9500C20—H20A0.9800
C8—C111.490 (3)C20—H20B0.9800
C8—H8A0.9800C20—H20C0.9800
C16—O2—C12117.11 (17)O4—C10—C9126.3 (2)
C10—O3—C20116.21 (19)O3—C10—C9110.39 (18)
C1—N1—C19121.17 (17)C13—C11—N1108.76 (18)
C1—N1—C11129.92 (18)C13—C11—C8127.59 (19)
C19—N1—C11107.69 (16)N1—C11—C8123.55 (18)
O1—C1—N1120.0 (2)O2—C12—H12A109.5
O1—C1—C2118.03 (19)O2—C12—H12B109.5
N1—C1—C2121.79 (19)H12A—C12—H12B109.5
C7—C2—C3119.8 (2)O2—C12—H12C109.5
C7—C2—C1122.0 (2)H12A—C12—H12C109.5
C3—C2—C1117.2 (2)H12B—C12—H12C109.5
C4—C3—C2120.0 (2)C11—C13—C14108.55 (18)
C4—C3—H3120.0C11—C13—C9126.6 (2)
C2—C3—H3120.0C14—C13—C9124.73 (19)
C5—C4—C3119.2 (2)C15—C14—C19119.89 (19)
C5—C4—H4120.4C15—C14—C13132.90 (19)
C3—C4—H4120.4C19—C14—C13107.21 (18)
C4—C5—C6121.5 (2)C16—C15—C14118.56 (18)
C4—C5—Cl1119.7 (2)C16—C15—H15120.7
C6—C5—Cl1118.8 (2)C14—C15—H15120.7
C5—C6—C7119.0 (2)O2—C16—C15116.01 (18)
C5—C6—H6120.5O2—C16—C17123.2 (2)
C7—C6—H6120.5C15—C16—C17120.8 (2)
C2—C7—C6120.3 (2)C18—C17—C16121.1 (2)
C2—C7—H7119.8C18—C17—H17119.5
C6—C7—H7119.8C16—C17—H17119.5
C11—C8—H8A109.5C19—C18—C17117.84 (19)
C11—C8—H8B109.5C19—C18—H18121.1
H8A—C8—H8B109.5C17—C18—H18121.1
C11—C8—H8C109.5C18—C19—C14121.80 (19)
H8A—C8—H8C109.5C18—C19—N1130.35 (19)
H8B—C8—H8C109.5C14—C19—N1107.77 (17)
C13—C9—C10114.56 (17)O3—C20—H20A109.5
C13—C9—H9A108.6O3—C20—H20B109.5
C10—C9—H9A108.6H20A—C20—H20B109.5
C13—C9—H9B108.6O3—C20—H20C109.5
C10—C9—H9B108.6H20A—C20—H20C109.5
H9A—C9—H9B107.6H20B—C20—H20C109.5
O4—C10—O3123.3 (2)
C19—N1—C1—O113.8 (3)N1—C11—C13—C9176.99 (18)
C11—N1—C1—O1152.0 (2)C8—C11—C13—C90.6 (3)
C19—N1—C1—C2161.21 (19)C10—C9—C13—C1194.3 (3)
C11—N1—C1—C233.0 (3)C10—C9—C13—C1489.3 (2)
O1—C1—C2—C7123.7 (2)C11—C13—C14—C15179.5 (2)
N1—C1—C2—C751.4 (3)C9—C13—C14—C153.5 (3)
O1—C1—C2—C344.9 (3)C11—C13—C14—C190.9 (2)
N1—C1—C2—C3140.0 (2)C9—C13—C14—C19176.05 (18)
C7—C2—C3—C40.1 (3)C19—C14—C15—C161.1 (3)
C1—C2—C3—C4169.0 (2)C13—C14—C15—C16179.3 (2)
C2—C3—C4—C52.0 (4)C12—O2—C16—C15177.32 (19)
C3—C4—C5—C61.9 (4)C12—O2—C16—C172.3 (3)
C3—C4—C5—Cl1176.15 (19)C14—C15—C16—O2179.62 (18)
C4—C5—C6—C70.0 (4)C14—C15—C16—C170.0 (3)
Cl1—C5—C6—C7178.05 (18)O2—C16—C17—C18179.13 (19)
C3—C2—C7—C61.8 (3)C15—C16—C17—C180.5 (3)
C1—C2—C7—C6166.5 (2)C16—C17—C18—C190.2 (3)
C5—C6—C7—C21.8 (4)C17—C18—C19—C141.4 (3)
C20—O3—C10—O40.6 (3)C17—C18—C19—N1177.6 (2)
C20—O3—C10—C9179.1 (2)C15—C14—C19—C181.9 (3)
C13—C9—C10—O42.9 (3)C13—C14—C19—C18178.48 (19)
C13—C9—C10—O3176.79 (19)C15—C14—C19—N1178.81 (17)
C1—N1—C11—C13168.3 (2)C13—C14—C19—N11.5 (2)
C19—N1—C11—C131.1 (2)C1—N1—C19—C1813.2 (3)
C1—N1—C11—C88.3 (3)C11—N1—C19—C18178.2 (2)
C19—N1—C11—C8175.50 (19)C1—N1—C19—C14170.21 (18)
N1—C11—C13—C140.1 (2)C11—N1—C19—C141.6 (2)
C8—C11—C13—C14176.28 (19)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C18—H18···O1i0.952.343.260 (3)162
C3—H3···O1ii0.952.593.480 (3)156
C9—H9A···O4iii0.992.623.565 (3)160
C15—H15···O2iv0.952.483.419 (2)170
Symmetry codes: (i) x+2, y+1, z+2; (ii) x+2, y, z+2; (iii) x, y1, z; (iv) x+5/2, y1/2, z+3/2.
 

Acknowledgements

The authors are grateful for funding from the Pfizer Institute for Pharmaceutical Materials Science at the University of Cambridge. We thank Dr J. E. Davies for the data collection.

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