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Acta Crystallogr Sect E Struct Rep Online. 2009 November 1; 65(Pt 11): o2796.
Published online 2009 October 17. doi:  10.1107/S1600536809041567
PMCID: PMC2971097

tert-Butyl 3-[2,2-bis­(ethoxy­carbon­yl)vin­yl]-2-bromo­methyl-1H-indole-1-carboxyl­ate

Abstract

In the title compound, C22H26BrNO6, the indole ring system is planar [maximum deviation 0.029 (2) Å]. The tert-butyl bound carboxyl­ate group forms a dihedral angle of 17.54 (8)° with the indole ring system. In the crystal, mol­ecules are linked into centrosymmetric R 2 2(10) dimers by paired C—H(...)O hydrogen bonds.

Related literature

For general background to indoles, see: Gribble (1996 [triangle]); Jing-Ru et al. (2007 [triangle]); Ximenes et al. (2005 [triangle]). For hybridization, see: Beddoes et al. (1986 [triangle]). For hydrogen-bond motifs, see: Bernstein et al. (1995 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-o2796-scheme1.jpg

Experimental

Crystal data

  • C22H26BrNO6
  • M r = 480.35
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o2796-efi1.jpg
  • a = 10.8682 (3) Å
  • b = 11.1094 (4) Å
  • c = 11.5699 (6) Å
  • α = 111.984 (3)°
  • β = 105.841 (2)°
  • γ = 106.926 (2)°
  • V = 1118.51 (9) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 1.88 mm−1
  • T = 293 K
  • 0.30 × 0.25 × 0.20 mm

Data collection

  • Bruker Kappa APEXII area-detector diffractometer
  • Absorption correction: multi-scan (SADABS, Sheldrick, 2001 [triangle]) T min = 0.603, T max = 0.706
  • 32165 measured reflections
  • 8669 independent reflections
  • 5490 reflections with I > 2σ(I)
  • R int = 0.028

Refinement

  • R[F 2 > 2σ(F 2)] = 0.040
  • wR(F 2) = 0.114
  • S = 1.01
  • 8669 reflections
  • 271 parameters
  • 1 restraint
  • H-atom parameters constrained
  • Δρmax = 0.29 e Å−3
  • Δρmin = −0.60 e Å−3

Data collection: APEX2 (Bruker, 2004 [triangle]); cell refinement: SAINT (Bruker, 2004 [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, 1997 [triangle]); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809041567/ci2911sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809041567/ci2911Isup2.hkl

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

Acknowledgments

MT thanks Dr Babu Varghese, SAIF, IIT-Madras, Chennai, India, for his help with the data collection.

supplementary crystallographic information

Comment

Indole is a common motif for a drug target and, as such, the development of new diversity-tolerant routes to this previleged biological scaffold continues to be of significant benefit (Gribble et al., 1996) and forms the basis of a wide variety of drugs, including the anti-inflammatory agent indomethacin, reserpine (exploited as hypotensive agent) and sumatriptan (used for the treatment of magraine). The indole derivatives are the effective inhibitors of myeloperoxidase(MPO)-chlorinating activity (Ximenes et al., 2005). Indole-3-carbinol has emerged as a promising chemopreventive agent due to its in vivo efficacy in prostate cancer cells of various animal models (Jing-Ru et al., 2007).

The indole ring system of the title molecule (Fig.1) is planar and the bromomethyl group is oriented at an angle of 74.98 (8)°. The tert butyl carboxylate group substituted at N1 of the indole ring is in an extended conformation [N1–C10–O1–C11 = 176.24 (16)°]. Both ethoxycarbonyl groups adopt extended conformations as can be seen from torsion angles C16–C17–O3–C18 [-179.61 (16)°], C17–O3–C18–C19 [-156.5 (2)°], C16–C20–O5–C21 [179.18 (14)°] and C20–O5–C21–C22 [-177.9 (2)°]. The sum of bond angles around N1 [360.0 (4)°] indicates that atom N1 exhibits sp2 hybridization (Beddoes et al., 1986).

The crystal structure is stabilized by C–H···O hydrogen bonds. The molecules form centrosymmetric R22(10) dimers through paired C18–H18A···O4 hydrogen bonds (Fig. 2) (Bernstein et al., 1995).

Experimental

A solution of tert-butyl 3-(2,2-di(ethoxycarbonyl)vinyl)-2-methyl-1H-indole- 1-carboxylate (2 g, 4.98 mmol) in dry carbon tetrachloride (80 ml), azobis(isobutyronitrile)(AIBN) (0.07 g) and finely powdered N-bromosuccinimide(NBS) (0.93 g, 5.23 mmol) were added and refluxed for 2 h. Then, the reaction mixture was cooled to room temperature. The floated succinimide was filtered off and washed with carbon tetrachloride (10 ml). The combined filtrate was concentrated in vacuo to afford the title compound (1.91 g, 80%) as colourless crystals.

Refinement

H atoms were positioned geometrically (C-H = 0.93–0.97 Å) and allowed to ride on their parent atoms, with Uiso(H) = 1.5Ueq(C) for methyl H and 1.2Ueq(C) for other H atoms. The C18–C19 bond distance was restrained to 1.50 (5) Å.

Figures

Fig. 1.
The molecular structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity.
Fig. 2.
A view of the crystal packing of molecules, showing C–H···O interactions (dashed lines), leading to dimer formation.

Crystal data

C22H26BrNO6Z = 2
Mr = 480.35F(000) = 496
Triclinic, P1Dx = 1.426 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 10.8682 (3) ÅCell parameters from 8669 reflections
b = 11.1094 (4) Åθ = 2.1–33.8°
c = 11.5699 (6) ŵ = 1.88 mm1
α = 111.984 (3)°T = 293 K
β = 105.841 (2)°Block, colourless
γ = 106.926 (2)°0.30 × 0.25 × 0.20 mm
V = 1118.51 (9) Å3

Data collection

Bruker Kappa APEXII area-detector diffractometer8669 independent reflections
Radiation source: fine-focus sealed tube5490 reflections with I > 2σ(I)
graphiteRint = 0.028
ω and [var phi] scansθmax = 33.8°, θmin = 2.1°
Absorption correction: multi-scan (SADABS, Sheldrick, 2001)h = −17→16
Tmin = 0.603, Tmax = 0.706k = −16→17
32165 measured reflectionsl = −17→17

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)] = 0.040Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.114H-atom parameters constrained
S = 1.01w = 1/[σ2(Fo2) + (0.0566P)2 + 0.1525P] where P = (Fo2 + 2Fc2)/3
8669 reflections(Δ/σ)max = 0.001
271 parametersΔρmax = 0.29 e Å3
1 restraintΔρmin = −0.60 e Å3

Special details

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)

xyzUiso*/Ueq
C20.09184 (16)0.74325 (17)1.16827 (16)0.0342 (3)
C30.07086 (19)0.8044 (2)1.28578 (19)0.0441 (4)
H30.13580.83071.37250.053*
C4−0.0521 (2)0.8242 (2)1.2671 (2)0.0537 (5)
H4−0.06940.86591.34350.064*
C5−0.14938 (19)0.7836 (2)1.1379 (2)0.0528 (5)
H5−0.22990.79971.12930.063*
C6−0.12946 (17)0.7201 (2)1.0217 (2)0.0427 (4)
H6−0.19660.69090.93490.051*
C7−0.00584 (15)0.70013 (16)1.03705 (17)0.0341 (3)
C80.04611 (15)0.63561 (16)0.94006 (16)0.0328 (3)
C90.17083 (15)0.63964 (16)1.01285 (15)0.0323 (3)
C100.31912 (16)0.73467 (18)1.26701 (16)0.0365 (3)
C110.51726 (16)0.67167 (19)1.32235 (17)0.0391 (3)
C120.5566 (2)0.5718 (3)1.2261 (2)0.0578 (5)
H12A0.48290.47471.17910.087*
H12B0.64480.57601.27820.087*
H12C0.56710.60101.15980.087*
C130.4815 (2)0.6177 (3)1.4162 (2)0.0565 (5)
H13A0.44950.67841.47160.085*
H13B0.56470.61991.47520.085*
H13C0.40740.52021.36160.085*
C140.6292 (2)0.8251 (2)1.3980 (2)0.0603 (5)
H14A0.64020.85601.33280.090*
H14B0.71800.83161.45170.090*
H14C0.60090.88611.45820.090*
C15−0.02203 (15)0.56833 (17)0.78999 (16)0.0361 (3)
H15−0.02460.47880.74070.043*
C16−0.08096 (15)0.62017 (18)0.71535 (16)0.0367 (3)
C17−0.06921 (18)0.76980 (19)0.77787 (18)0.0425 (4)
C18−0.1952 (2)0.9111 (2)0.8069 (3)0.0658 (6)
H18A−0.11470.97700.89660.079*
H18B−0.18640.95050.74600.079*
C19−0.3273 (3)0.8959 (3)0.8200 (4)0.1028 (11)
H19A−0.40620.81720.73550.154*
H19B−0.33670.98370.83870.154*
H19C−0.32620.87660.89440.154*
C20−0.14814 (17)0.5379 (2)0.56162 (18)0.0428 (4)
C21−0.2390 (2)0.3118 (2)0.36364 (19)0.0571 (5)
H21A−0.17870.34800.32450.069*
H21B−0.32990.31220.32470.069*
C22−0.2597 (4)0.1643 (3)0.3329 (3)0.0913 (9)
H22A−0.16880.16470.36880.137*
H22B−0.30730.10090.23470.137*
H22C−0.31650.13110.37500.137*
C230.26606 (17)0.59735 (18)0.95525 (16)0.0373 (3)
H23A0.21400.53620.85580.045*
H23B0.29970.54230.99290.045*
N10.20188 (13)0.70606 (14)1.15357 (13)0.0331 (3)
O10.38397 (12)0.65566 (13)1.22367 (11)0.0397 (2)
O20.34760 (15)0.81621 (16)1.38221 (13)0.0570 (4)
O3−0.19532 (13)0.77004 (13)0.75104 (14)0.0476 (3)
O40.04207 (15)0.87474 (16)0.84512 (19)0.0707 (4)
O5−0.17187 (14)0.40133 (14)0.51266 (12)0.0483 (3)
O6−0.17445 (18)0.59307 (18)0.49278 (15)0.0668 (4)
Br10.429587 (19)0.76941 (2)0.99976 (2)0.05385 (8)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C20.0370 (7)0.0337 (8)0.0387 (8)0.0197 (6)0.0174 (6)0.0204 (7)
C30.0481 (9)0.0488 (10)0.0408 (9)0.0256 (8)0.0221 (8)0.0219 (8)
C40.0559 (10)0.0622 (12)0.0581 (12)0.0346 (10)0.0359 (10)0.0291 (10)
C50.0445 (9)0.0635 (12)0.0712 (13)0.0335 (9)0.0335 (9)0.0392 (11)
C60.0344 (7)0.0478 (10)0.0531 (10)0.0204 (7)0.0174 (7)0.0311 (8)
C70.0342 (7)0.0320 (7)0.0414 (8)0.0164 (6)0.0152 (6)0.0224 (7)
C80.0346 (7)0.0316 (7)0.0334 (7)0.0160 (6)0.0114 (6)0.0184 (6)
C90.0361 (7)0.0323 (7)0.0299 (7)0.0182 (6)0.0112 (6)0.0163 (6)
C100.0384 (7)0.0385 (8)0.0335 (8)0.0202 (7)0.0123 (6)0.0185 (7)
C110.0334 (7)0.0500 (10)0.0342 (8)0.0223 (7)0.0086 (6)0.0221 (7)
C120.0541 (10)0.0722 (14)0.0528 (11)0.0435 (10)0.0189 (9)0.0271 (10)
C130.0495 (10)0.0813 (15)0.0576 (12)0.0335 (10)0.0208 (9)0.0497 (11)
C140.0430 (9)0.0559 (12)0.0664 (14)0.0151 (9)0.0151 (9)0.0268 (11)
C150.0340 (7)0.0369 (8)0.0340 (8)0.0155 (6)0.0096 (6)0.0181 (7)
C160.0311 (7)0.0401 (8)0.0356 (8)0.0142 (6)0.0084 (6)0.0209 (7)
C170.0402 (8)0.0410 (9)0.0419 (9)0.0148 (7)0.0079 (7)0.0256 (8)
C180.0744 (14)0.0448 (11)0.0804 (16)0.0348 (11)0.0287 (12)0.0297 (11)
C190.0846 (18)0.0762 (19)0.129 (3)0.0495 (16)0.0475 (19)0.0222 (18)
C200.0338 (7)0.0545 (11)0.0392 (9)0.0184 (7)0.0104 (7)0.0268 (8)
C210.0551 (10)0.0651 (13)0.0308 (9)0.0161 (10)0.0135 (8)0.0163 (9)
C220.129 (3)0.0657 (16)0.0488 (14)0.0332 (17)0.0320 (15)0.0117 (12)
C230.0413 (7)0.0407 (8)0.0314 (8)0.0238 (7)0.0135 (6)0.0164 (7)
N10.0359 (6)0.0358 (7)0.0297 (6)0.0204 (5)0.0115 (5)0.0165 (5)
O10.0410 (5)0.0488 (7)0.0298 (5)0.0282 (5)0.0088 (5)0.0179 (5)
O20.0569 (7)0.0709 (9)0.0311 (6)0.0389 (7)0.0105 (6)0.0118 (6)
O30.0427 (6)0.0366 (6)0.0566 (8)0.0189 (5)0.0121 (6)0.0220 (6)
O40.0441 (7)0.0440 (8)0.0922 (12)0.0081 (6)0.0071 (8)0.0281 (8)
O50.0547 (7)0.0486 (7)0.0314 (6)0.0190 (6)0.0119 (5)0.0178 (6)
O60.0823 (10)0.0742 (10)0.0452 (8)0.0385 (9)0.0118 (7)0.0387 (8)
Br10.05092 (11)0.05899 (14)0.05578 (13)0.02350 (9)0.02807 (10)0.02914 (10)

Geometric parameters (Å, °)

C2—C31.389 (2)C14—H14A0.96
C2—C71.393 (2)C14—H14B0.96
C2—N11.4057 (17)C14—H14C0.96
C3—C41.390 (2)C15—C161.331 (2)
C3—H30.93C15—H150.93
C4—C51.383 (3)C16—C201.489 (2)
C4—H40.93C16—C171.493 (2)
C5—C61.374 (3)C17—O41.189 (2)
C5—H50.93C17—O31.321 (2)
C6—C71.399 (2)C18—C191.452 (3)
C6—H60.93C18—O31.454 (2)
C7—C81.439 (2)C18—H18A0.97
C8—C91.365 (2)C18—H18B0.97
C8—C151.458 (2)C19—H19A0.96
C9—N11.4017 (19)C19—H19B0.96
C9—C231.4701 (19)C19—H19C0.96
C10—O21.183 (2)C20—O61.198 (2)
C10—O11.3199 (18)C20—O51.318 (2)
C10—N11.409 (2)C21—O51.450 (2)
C11—O11.4929 (17)C21—C221.471 (4)
C11—C141.498 (3)C21—H21A0.97
C11—C121.504 (2)C21—H21B0.97
C11—C131.507 (2)C22—H22A0.96
C12—H12A0.96C22—H22B0.96
C12—H12B0.96C22—H22C0.96
C12—H12C0.96C23—Br11.9654 (17)
C13—H13A0.96C23—H23A0.97
C13—H13B0.96C23—H23B0.97
C13—H13C0.96
C3—C2—C7122.51 (14)H14B—C14—H14C109.5
C3—C2—N1129.77 (15)C16—C15—C8127.53 (15)
C7—C2—N1107.63 (12)C16—C15—H15116.2
C2—C3—C4116.62 (17)C8—C15—H15116.2
C2—C3—H3121.7C15—C16—C20121.44 (15)
C4—C3—H3121.7C15—C16—C17122.82 (15)
C5—C4—C3121.64 (17)C20—C16—C17115.34 (14)
C5—C4—H4119.2O4—C17—O3125.11 (17)
C3—C4—H4119.2O4—C17—C16122.78 (16)
C6—C5—C4121.34 (15)O3—C17—C16112.10 (14)
C6—C5—H5119.3C19—C18—O3109.1 (2)
C4—C5—H5119.3C19—C18—H18A109.9
C5—C6—C7118.48 (17)O3—C18—H18A109.9
C5—C6—H6120.8C19—C18—H18B109.9
C7—C6—H6120.8O3—C18—H18B109.9
C2—C7—C6119.38 (14)H18A—C18—H18B108.3
C2—C7—C8107.57 (12)C18—C19—H19A109.5
C6—C7—C8133.01 (15)C18—C19—H19B109.5
C9—C8—C7107.60 (13)H19A—C19—H19B109.5
C9—C8—C15124.17 (13)C18—C19—H19C109.5
C7—C8—C15128.12 (13)H19A—C19—H19C109.5
C8—C9—N1109.10 (12)H19B—C19—H19C109.5
C8—C9—C23125.35 (14)O6—C20—O5125.09 (17)
N1—C9—C23125.16 (13)O6—C20—C16122.46 (18)
O2—C10—O1127.84 (15)O5—C20—C16112.44 (14)
O2—C10—N1122.20 (14)O5—C21—C22107.12 (18)
O1—C10—N1109.93 (13)O5—C21—H21A110.3
O1—C11—C14110.16 (14)C22—C21—H21A110.3
O1—C11—C12101.60 (13)O5—C21—H21B110.3
C14—C11—C12111.45 (16)C22—C21—H21B110.3
O1—C11—C13108.63 (13)H21A—C21—H21B108.5
C14—C11—C13113.56 (17)C21—C22—H22A109.5
C12—C11—C13110.76 (17)C21—C22—H22B109.5
C11—C12—H12A109.5H22A—C22—H22B109.5
C11—C12—H12B109.5C21—C22—H22C109.5
H12A—C12—H12B109.5H22A—C22—H22C109.5
C11—C12—H12C109.5H22B—C22—H22C109.5
H12A—C12—H12C109.5C9—C23—Br1110.47 (11)
H12B—C12—H12C109.5C9—C23—H23A109.6
C11—C13—H13A109.5Br1—C23—H23A109.6
C11—C13—H13B109.5C9—C23—H23B109.6
H13A—C13—H13B109.5Br1—C23—H23B109.6
C11—C13—H13C109.5H23A—C23—H23B108.1
H13A—C13—H13C109.5C9—N1—C2108.08 (12)
H13B—C13—H13C109.5C9—N1—C10129.37 (12)
C11—C14—H14A109.5C2—N1—C10122.55 (13)
C11—C14—H14B109.5C10—O1—C11120.94 (12)
H14A—C14—H14B109.5C17—O3—C18116.27 (15)
C11—C14—H14C109.5C20—O5—C21116.52 (15)
H14A—C14—H14C109.5
C7—C2—C3—C4−1.5 (3)C17—C16—C20—O69.1 (2)
N1—C2—C3—C4−177.75 (17)C15—C16—C20—O515.1 (2)
C2—C3—C4—C50.7 (3)C17—C16—C20—O5−171.97 (14)
C3—C4—C5—C60.8 (3)C8—C9—C23—Br1101.19 (16)
C4—C5—C6—C7−1.6 (3)N1—C9—C23—Br1−70.93 (17)
C3—C2—C7—C60.8 (2)C8—C9—N1—C20.55 (17)
N1—C2—C7—C6177.74 (14)C23—C9—N1—C2173.76 (14)
C3—C2—C7—C8−177.20 (15)C8—C9—N1—C10−179.59 (15)
N1—C2—C7—C8−0.23 (17)C23—C9—N1—C10−6.4 (3)
C5—C6—C7—C20.8 (2)C3—C2—N1—C9176.49 (17)
C5—C6—C7—C8178.15 (17)C7—C2—N1—C9−0.18 (17)
C2—C7—C8—C90.57 (17)C3—C2—N1—C10−3.4 (3)
C6—C7—C8—C9−177.01 (17)C7—C2—N1—C10179.95 (14)
C2—C7—C8—C15176.90 (15)O2—C10—N1—C9164.58 (17)
C6—C7—C8—C15−0.7 (3)O1—C10—N1—C9−17.1 (2)
C7—C8—C9—N1−0.68 (17)O2—C10—N1—C2−15.6 (3)
C15—C8—C9—N1−177.20 (14)O1—C10—N1—C2162.71 (14)
C7—C8—C9—C23−173.88 (15)O2—C10—O1—C11−5.6 (3)
C15—C8—C9—C239.6 (2)N1—C10—O1—C11176.24 (13)
C9—C8—C15—C16−136.69 (17)C14—C11—O1—C10−57.2 (2)
C7—C8—C15—C1647.5 (3)C12—C11—O1—C10−175.45 (16)
C8—C15—C16—C20−179.46 (14)C13—C11—O1—C1067.7 (2)
C8—C15—C16—C178.1 (3)O4—C17—O3—C181.3 (3)
C15—C16—C17—O457.9 (3)C16—C17—O3—C18−179.61 (16)
C20—C16—C17—O4−115.0 (2)C19—C18—O3—C17−156.5 (2)
C15—C16—C17—O3−121.20 (17)O6—C20—O5—C21−1.9 (3)
C20—C16—C17—O365.95 (19)C16—C20—O5—C21179.18 (14)
C15—C16—C20—O6−163.84 (17)C22—C21—O5—C20−177.9 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C18—H18A···O4i0.972.563.392 (3)144

Symmetry codes: (i) −x, −y+2, −z+2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CI2911).

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