organic compounds
Ethyl 3,3,3-trifluoro-2-hydroxy-2-(5-methoxy-1H-indol-3-yl)propionate
aTashkent Chemical–Technological Institute, Navoi St. 32, Tashkent 100011, Uzbekistan, bInstitute of Bioorganic Chemistry, Mirzo-Ulugbek St. 83, Tashkent 100125, Uzbekistan, cA.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova St. 28, Moscow 119991, Russian Federation, and dNational University of Uzbekistan named by Mirzo Ulugbek, Chemical Faculty, Vuzgorodok, Tashkent 100123, Uzbekistan
*Correspondence e-mail: zuhra_kadirova@yahoo.com
In the title compound, C14H14F3NO4, the 3,3,3-trifluoropyruvate fragment has a syn configuration and is noncoplanar with the indole plane [dihedral angle = 84.87 (5)°]. In the crystal, molecules form inversion-related dimers via pairs of intermolecular O—H⋯O hydrogen bonds. These dimers are connected by intermolecular N—H⋯O=C(CF3) hydrogen bonds to form a two-dimensional network structure.
Related literature
For background on the synthesis and activity of trifluoropyruvates of indole, see: Nakamura et al. (2008); Abid et al. (2008). For the crystal structures of related compounds, see: Choudhury et al. (2004); Abid et al. (2008).
Experimental
Crystal data
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Refinement
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Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell CrysAlis PRO; data reduction: CrysAlis PRO; 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, 1997); software used to prepare material for publication: publCIF (Westrip, 2010).
Supporting information
10.1107/S1600536811021489/pk2322sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811021489/pk2322Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536811021489/pk2322Isup3.cml
A solution of 0.170 g (0.001 mol) of ethyl 3,3,3-trifluoropyruvate in 10 ml of ether was added to a solution of 0.147 g (0.001 mol) of 5-methoxyindole in 10 ml ether, and stirred at room temperature for 24 h. The reaction was monitored by TLC. The reaction mixture was then evaporated under reduced pressure and the residue was purified by δ 1.11 (3H, t, CH3); 4.22 (2H, q, CH2, JCH3—CH2 7,2 Hz); 3.72 (3H, s, O—CH3), 6.78 (1H, d, aromatic, J6–5 = 6.9 Hz), 7.17 (1H, s, aromatic), 7.32 (1H, d, aromatic), 7.37 (2H, s. br., OH, CH), 11.58 (1H, s. br., NH); 19F NMR (dmso-d6): 3.01 (s, CF3); MS (m/z 317).
on silica gel (chloroform/ethylacetate=9:1); yield: 0.150 g (47%). The compound was crystallized from ethanolic solution by slow evaporation, giving colorless prism crystals suitable for X-ray 1H NMR (300 MHz, dmso-d6):Hydrogen atoms of the NH, OH and hydrogens attached to carbon (except CMe) were located in difference Fourier maps and fully refined (including Uiso). Methyl hydrogens were included using a riding model with Uiso(H) values of 1.5 Ueq(CMe).
Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell
CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); 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, 1997); software used to prepare material for publication: publCIF (Westrip, 2010).C14H14F3NO4 | F(000) = 656 |
Mr = 317.26 | Dx = 1.456 Mg m−3 |
Monoclinic, P21/n | Cu Kα radiation, λ = 1.54178 Å |
Hall symbol: -P 2yn | Cell parameters from 2319 reflections |
a = 9.6277 (4) Å | θ = 5.5–75.5° |
b = 15.9760 (6) Å | µ = 1.15 mm−1 |
c = 9.9738 (4) Å | T = 293 K |
β = 109.314 (5)° | Block, colourless |
V = 1447.75 (10) Å3 | 0.55 × 0.45 × 0.40 mm |
Z = 4 |
Oxford Diffraction Xcalibur Ruby CCD diffractometer | 2911 independent reflections |
Radiation source: fine-focus sealed tube | 2319 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.018 |
Detector resolution: 10.2576 pixels mm-1 | θmax = 75.9°, θmin = 5.5° |
ω scans | h = −11→12 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | k = −19→13 |
Tmin = 0.782, Tmax = 1.000 | l = −12→12 |
5738 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.040 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.116 | w = 1/[σ2(Fo2) + (0.0607P)2 + 0.1918P] where P = (Fo2 + 2Fc2)/3 |
S = 1.06 | (Δ/σ)max < 0.001 |
2911 reflections | Δρmax = 0.20 e Å−3 |
234 parameters | Δρmin = −0.14 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0092 (10) |
C14H14F3NO4 | V = 1447.75 (10) Å3 |
Mr = 317.26 | Z = 4 |
Monoclinic, P21/n | Cu Kα radiation |
a = 9.6277 (4) Å | µ = 1.15 mm−1 |
b = 15.9760 (6) Å | T = 293 K |
c = 9.9738 (4) Å | 0.55 × 0.45 × 0.40 mm |
β = 109.314 (5)° |
Oxford Diffraction Xcalibur Ruby CCD diffractometer | 2911 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | 2319 reflections with I > 2σ(I) |
Tmin = 0.782, Tmax = 1.000 | Rint = 0.018 |
5738 measured reflections |
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.116 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | Δρmax = 0.20 e Å−3 |
2911 reflections | Δρmin = −0.14 e Å−3 |
234 parameters |
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. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
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. |
x | y | z | Uiso*/Ueq | ||
F1 | 0.24919 (15) | 0.21987 (8) | 0.04081 (14) | 0.0900 (4) | |
F2 | 0.24512 (15) | 0.09413 (9) | −0.03770 (13) | 0.0863 (4) | |
F3 | 0.42514 (12) | 0.13538 (8) | 0.14198 (14) | 0.0805 (4) | |
O1 | −0.16538 (14) | 0.08409 (10) | 0.51949 (16) | 0.0773 (4) | |
O2 | 0.04297 (12) | 0.12631 (7) | 0.09810 (13) | 0.0566 (3) | |
O3 | 0.12118 (13) | −0.03385 (7) | 0.13702 (13) | 0.0622 (3) | |
O4 | 0.34902 (11) | −0.00327 (7) | 0.27903 (12) | 0.0535 (3) | |
N1 | 0.34543 (16) | 0.23072 (9) | 0.50886 (17) | 0.0590 (4) | |
C1 | 0.22216 (17) | 0.19773 (10) | 0.53026 (18) | 0.0524 (4) | |
C2 | 0.1720 (2) | 0.20300 (11) | 0.6458 (2) | 0.0627 (5) | |
C3 | 0.0439 (2) | 0.16245 (13) | 0.6367 (2) | 0.0658 (5) | |
C4 | −0.03659 (18) | 0.11812 (11) | 0.5139 (2) | 0.0596 (4) | |
C5 | 0.01333 (17) | 0.11079 (10) | 0.40028 (19) | 0.0528 (4) | |
C6 | 0.14673 (16) | 0.15055 (9) | 0.40867 (17) | 0.0476 (4) | |
C7 | 0.23112 (16) | 0.15638 (9) | 0.31430 (17) | 0.0479 (4) | |
C8 | 0.34965 (18) | 0.20619 (10) | 0.3800 (2) | 0.0556 (4) | |
C9 | 0.19239 (16) | 0.11127 (9) | 0.17494 (17) | 0.0475 (4) | |
C10 | 0.21565 (15) | 0.01523 (9) | 0.19510 (16) | 0.0461 (4) | |
C11 | 0.3900 (2) | −0.09195 (11) | 0.2897 (2) | 0.0639 (5) | |
C12 | 0.4403 (3) | −0.11618 (14) | 0.1696 (3) | 0.0826 (6) | |
H12A | 0.4697 | −0.1739 | 0.1794 | 0.124* | |
H12B | 0.5223 | −0.0818 | 0.1702 | 0.124* | |
H12C | 0.3613 | −0.1085 | 0.0817 | 0.124* | |
C13 | 0.2798 (2) | 0.14066 (12) | 0.0805 (2) | 0.0645 (5) | |
C14 | −0.2605 (2) | 0.04673 (16) | 0.3932 (2) | 0.0810 (6) | |
H14A | −0.3506 | 0.0303 | 0.4073 | 0.122* | |
H14B | −0.2137 | −0.0017 | 0.3703 | 0.122* | |
H14C | −0.2815 | 0.0863 | 0.3166 | 0.122* | |
H1A | 0.403 (2) | 0.2684 (13) | 0.559 (2) | 0.066 (6)* | |
H2A | 0.222 (2) | 0.2317 (15) | 0.724 (2) | 0.079 (6)* | |
H2B | 0.009 (2) | 0.0882 (16) | 0.045 (2) | 0.079 (7)* | |
H3A | 0.007 (2) | 0.1646 (14) | 0.715 (2) | 0.075 (6)* | |
H5A | −0.0408 (19) | 0.0778 (12) | 0.3176 (19) | 0.056 (5)* | |
H8A | 0.430 (2) | 0.2217 (12) | 0.3467 (19) | 0.059 (5)* | |
H11A | 0.304 (2) | −0.1242 (13) | 0.292 (2) | 0.068 (6)* | |
H11B | 0.473 (3) | −0.0959 (14) | 0.378 (2) | 0.079 (6)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
F1 | 0.1020 (9) | 0.0653 (7) | 0.0962 (9) | −0.0066 (6) | 0.0240 (7) | 0.0318 (6) |
F2 | 0.0997 (9) | 0.0956 (10) | 0.0691 (7) | −0.0147 (7) | 0.0352 (6) | −0.0033 (6) |
F3 | 0.0560 (6) | 0.0923 (9) | 0.0963 (8) | −0.0088 (6) | 0.0292 (6) | 0.0143 (7) |
O1 | 0.0549 (7) | 0.0862 (10) | 0.0964 (10) | −0.0112 (7) | 0.0323 (7) | −0.0175 (8) |
O2 | 0.0429 (6) | 0.0470 (6) | 0.0639 (7) | 0.0081 (5) | −0.0037 (5) | −0.0038 (6) |
O3 | 0.0518 (6) | 0.0471 (6) | 0.0710 (7) | −0.0071 (5) | −0.0022 (5) | 0.0011 (5) |
O4 | 0.0387 (5) | 0.0429 (6) | 0.0696 (7) | 0.0059 (4) | 0.0053 (5) | 0.0037 (5) |
N1 | 0.0492 (7) | 0.0435 (7) | 0.0687 (9) | −0.0106 (6) | −0.0014 (7) | −0.0051 (6) |
C1 | 0.0448 (8) | 0.0369 (7) | 0.0645 (10) | 0.0019 (6) | 0.0032 (7) | −0.0040 (7) |
C2 | 0.0611 (10) | 0.0519 (10) | 0.0645 (11) | 0.0052 (8) | 0.0066 (9) | −0.0157 (8) |
C3 | 0.0611 (10) | 0.0628 (11) | 0.0724 (12) | 0.0074 (9) | 0.0204 (9) | −0.0139 (9) |
C4 | 0.0469 (8) | 0.0525 (9) | 0.0774 (11) | 0.0031 (7) | 0.0179 (8) | −0.0085 (8) |
C5 | 0.0420 (8) | 0.0442 (8) | 0.0648 (10) | −0.0021 (6) | 0.0076 (7) | −0.0100 (7) |
C6 | 0.0408 (7) | 0.0331 (7) | 0.0600 (9) | 0.0026 (6) | 0.0049 (6) | −0.0033 (6) |
C7 | 0.0404 (7) | 0.0358 (7) | 0.0594 (9) | 0.0005 (6) | 0.0055 (6) | 0.0032 (6) |
C8 | 0.0437 (8) | 0.0459 (9) | 0.0673 (10) | −0.0053 (7) | 0.0050 (7) | 0.0068 (7) |
C9 | 0.0365 (7) | 0.0415 (8) | 0.0563 (9) | 0.0015 (6) | 0.0042 (6) | 0.0038 (6) |
C10 | 0.0390 (7) | 0.0426 (8) | 0.0515 (8) | 0.0001 (6) | 0.0079 (6) | 0.0010 (6) |
C11 | 0.0521 (9) | 0.0459 (9) | 0.0860 (13) | 0.0096 (8) | 0.0125 (9) | 0.0074 (9) |
C12 | 0.0726 (13) | 0.0660 (12) | 0.1059 (17) | 0.0106 (10) | 0.0249 (12) | −0.0157 (12) |
C13 | 0.0636 (10) | 0.0580 (10) | 0.0664 (11) | −0.0046 (8) | 0.0139 (8) | 0.0111 (9) |
C14 | 0.0487 (10) | 0.0883 (15) | 0.1008 (16) | −0.0144 (10) | 0.0176 (10) | −0.0043 (12) |
F1—C13 | 1.330 (2) | C4—C5 | 1.375 (3) |
F2—C13 | 1.339 (2) | C5—C6 | 1.410 (2) |
F3—C13 | 1.332 (2) | C5—H5A | 0.972 (18) |
O1—C4 | 1.372 (2) | C6—C7 | 1.436 (2) |
O1—C14 | 1.421 (3) | C7—C8 | 1.367 (2) |
O2—C9 | 1.4090 (17) | C7—C9 | 1.499 (2) |
O2—H2B | 0.80 (2) | C8—H8A | 0.974 (18) |
O3—C10 | 1.1954 (18) | C9—C13 | 1.530 (3) |
O4—C10 | 1.3137 (17) | C9—C10 | 1.554 (2) |
O4—C11 | 1.465 (2) | C11—C12 | 1.484 (3) |
N1—C8 | 1.357 (2) | C11—H11A | 0.98 (2) |
N1—C1 | 1.378 (2) | C11—H11B | 0.98 (2) |
N1—H1A | 0.86 (2) | C12—H12A | 0.9600 |
C1—C2 | 1.391 (3) | C12—H12B | 0.9600 |
C1—C6 | 1.408 (2) | C12—H12C | 0.9600 |
C2—C3 | 1.369 (3) | C14—H14A | 0.9600 |
C2—H2A | 0.90 (2) | C14—H14B | 0.9600 |
C3—C4 | 1.405 (3) | C14—H14C | 0.9600 |
C3—H3A | 0.97 (2) | ||
C4—O1—C14 | 117.18 (16) | C7—C9—C13 | 113.86 (13) |
C9—O2—H2B | 110.4 (17) | O2—C9—C10 | 108.44 (12) |
C10—O4—C11 | 116.54 (13) | C7—C9—C10 | 111.95 (13) |
C8—N1—C1 | 109.48 (14) | C13—C9—C10 | 107.31 (14) |
C8—N1—H1A | 122.4 (13) | O3—C10—O4 | 126.01 (14) |
C1—N1—H1A | 127.1 (13) | O3—C10—C9 | 122.07 (13) |
N1—C1—C2 | 131.13 (16) | O4—C10—C9 | 111.91 (12) |
N1—C1—C6 | 107.25 (16) | O4—C11—C12 | 110.23 (17) |
C2—C1—C6 | 121.60 (16) | O4—C11—H11A | 107.4 (12) |
C3—C2—C1 | 117.93 (17) | C12—C11—H11A | 112.8 (12) |
C3—C2—H2A | 120.9 (14) | O4—C11—H11B | 104.3 (13) |
C1—C2—H2A | 121.2 (14) | C12—C11—H11B | 109.3 (13) |
C2—C3—C4 | 121.43 (19) | H11A—C11—H11B | 112.5 (17) |
C2—C3—H3A | 119.9 (13) | C11—C12—H12A | 109.5 |
C4—C3—H3A | 118.6 (13) | C11—C12—H12B | 109.5 |
O1—C4—C5 | 124.53 (16) | H12A—C12—H12B | 109.5 |
O1—C4—C3 | 114.21 (18) | C11—C12—H12C | 109.5 |
C5—C4—C3 | 121.26 (17) | H12A—C12—H12C | 109.5 |
C4—C5—C6 | 118.20 (15) | H12B—C12—H12C | 109.5 |
C4—C5—H5A | 120.7 (11) | F1—C13—F3 | 107.05 (16) |
C6—C5—H5A | 121.1 (11) | F1—C13—F2 | 107.46 (16) |
C1—C6—C5 | 119.49 (16) | F3—C13—F2 | 106.77 (17) |
C1—C6—C7 | 106.70 (14) | F1—C13—C9 | 111.24 (17) |
C5—C6—C7 | 133.81 (15) | F3—C13—C9 | 113.91 (15) |
C8—C7—C6 | 106.71 (15) | F2—C13—C9 | 110.11 (15) |
C8—C7—C9 | 129.49 (16) | O1—C14—H14A | 109.5 |
C6—C7—C9 | 123.74 (13) | O1—C14—H14B | 109.5 |
N1—C8—C7 | 109.86 (16) | H14A—C14—H14B | 109.5 |
N1—C8—H8A | 121.8 (11) | O1—C14—H14C | 109.5 |
C7—C8—H8A | 128.3 (11) | H14A—C14—H14C | 109.5 |
O2—C9—C7 | 108.57 (13) | H14B—C14—H14C | 109.5 |
O2—C9—C13 | 106.46 (13) | ||
C8—N1—C1—C2 | 178.10 (17) | C8—C7—C9—O2 | −133.00 (17) |
C8—N1—C1—C6 | 0.03 (18) | C6—C7—C9—O2 | 50.01 (18) |
N1—C1—C2—C3 | −179.49 (18) | C8—C7—C9—C13 | −14.6 (2) |
C6—C1—C2—C3 | −1.7 (3) | C6—C7—C9—C13 | 168.40 (14) |
C1—C2—C3—C4 | −1.2 (3) | C8—C7—C9—C10 | 107.32 (18) |
C14—O1—C4—C5 | −7.2 (3) | C6—C7—C9—C10 | −69.67 (18) |
C14—O1—C4—C3 | 172.94 (18) | C11—O4—C10—O3 | 7.0 (3) |
C2—C3—C4—O1 | −177.34 (18) | C11—O4—C10—C9 | −171.67 (15) |
C2—C3—C4—C5 | 2.8 (3) | O2—C9—C10—O3 | 8.1 (2) |
O1—C4—C5—C6 | 178.83 (16) | C7—C9—C10—O3 | 127.84 (17) |
C3—C4—C5—C6 | −1.3 (3) | C13—C9—C10—O3 | −106.54 (18) |
N1—C1—C6—C5 | −178.63 (14) | O2—C9—C10—O4 | −173.15 (13) |
C2—C1—C6—C5 | 3.1 (2) | C7—C9—C10—O4 | −53.40 (18) |
N1—C1—C6—C7 | 0.41 (17) | C13—C9—C10—O4 | 72.22 (17) |
C2—C1—C6—C7 | −177.88 (14) | C10—O4—C11—C12 | 83.2 (2) |
C4—C5—C6—C1 | −1.5 (2) | O2—C9—C13—F1 | 54.98 (18) |
C4—C5—C6—C7 | 179.74 (16) | C7—C9—C13—F1 | −64.61 (19) |
C1—C6—C7—C8 | −0.69 (17) | C10—C9—C13—F1 | 170.92 (14) |
C5—C6—C7—C8 | 178.15 (17) | O2—C9—C13—F3 | 176.06 (15) |
C1—C6—C7—C9 | 176.89 (13) | C7—C9—C13—F3 | 56.5 (2) |
C5—C6—C7—C9 | −4.3 (3) | C10—C9—C13—F3 | −67.99 (19) |
C1—N1—C8—C7 | −0.48 (19) | O2—C9—C13—F2 | −64.04 (18) |
C6—C7—C8—N1 | 0.73 (18) | C7—C9—C13—F2 | 176.37 (13) |
C9—C7—C8—N1 | −176.66 (14) | C10—C9—C13—F2 | 51.91 (18) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O2i | 0.86 (2) | 2.11 (2) | 2.9166 (18) | 156.8 (18) |
O2—H2B···O3ii | 0.80 (2) | 2.03 (2) | 2.7798 (17) | 156 (2) |
Symmetry codes: (i) x+1/2, −y+1/2, z+1/2; (ii) −x, −y, −z. |
Experimental details
Crystal data | |
Chemical formula | C14H14F3NO4 |
Mr | 317.26 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 293 |
a, b, c (Å) | 9.6277 (4), 15.9760 (6), 9.9738 (4) |
β (°) | 109.314 (5) |
V (Å3) | 1447.75 (10) |
Z | 4 |
Radiation type | Cu Kα |
µ (mm−1) | 1.15 |
Crystal size (mm) | 0.55 × 0.45 × 0.40 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur Ruby CCD diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) |
Tmin, Tmax | 0.782, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5738, 2911, 2319 |
Rint | 0.018 |
(sin θ/λ)max (Å−1) | 0.629 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.116, 1.06 |
No. of reflections | 2911 |
No. of parameters | 234 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.20, −0.14 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), publCIF (Westrip, 2010).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O2i | 0.86 (2) | 2.11 (2) | 2.9166 (18) | 156.8 (18) |
O2—H2B···O3ii | 0.80 (2) | 2.03 (2) | 2.7798 (17) | 156 (2) |
Symmetry codes: (i) x+1/2, −y+1/2, z+1/2; (ii) −x, −y, −z. |
Acknowledgements
This work was supported by the Grant of Fundamental Research of the Center of Science and Technology, Republic of Uzbekistan (grant No. F3-142).
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3,3,3-Trifluoropyruvates have been used as efficient fluorinated building blocks in the synthesis of some biologically active trifluoromethylated compounds owing to the unique properties of the trifluoromethyl group, such as high electronegativity, electron density, steric hindrance and its hydrophobic character. The incorporation of a tertiary α-trifluoromethyl alcohol stereocenter (CF3C*(OH)R1R2) into heterocycles could provide novel drug candidates with unusual biological activities as a result of the presence of the chiral tertiary α-trifluoromethyl alcohol functionality (Nakamura et al. 2008, Abid et al., 2008).
In this study we synthesized the 3,3,3-trifluoropyruvate derivative of indole, which is an analogue of indole alkaloids. The molecular structure is shown in Fig. 1.
The compound crystallizes as a racemate and the carboxy- and hydroxy- groups are syn to each other (torsion angle O2—C9—C10—O3 = 8.1 (2)°. The 3,3,3-trifluoropyruvate fragment is non-coplanar to the plane of the indole [torsion angles C8—C7—C9—C10, C6—C7—C9—C10, C6—C7—C9—O2, C8—C7—C9—O2 are 107.3 (2)°, -69.7 (2)°, 50.0 (2)°, and -133.0 (2)°, respectively)]. The methoxy-, hydroxy- and trifluoromethyl groups deviate from the indole plane by 0.061 (2), 0.854 (1) and 0.165 (2) Å, respectively. The bond distances C—C and C—N in the indole group are in the range 1.369–1.435 Å and 1.358–1.379 Å, respectively. Due to the concurrent influence of electron-withdrawing groups in the 3,3,3-trifluoropyruvate fragment, the EtO(O)C—C(O)CF3 bond is elongated slightly to 1.554 (2) Å.
The fluorine does not readily accept hydrogen bonds and hence behaves differently from chlorine and bromine, but a signifcant number of compounds pack via weak interactions involving organic fluorine (Choudhury et al., 2004) and generate different packing motifs via F···F, C—H···F and C—F···π interactions. In the presence of a strong acceptor such as C=O, the C—H···O interaction takes priority over C—H···F. The molecules form inversion-related dimers via pairs of intermolecular O—H···O hydrogen bonds. These dimers are connected by intermolecular N—H···O═C(CF3) hydrogen bonds to form a two-dimensional network structure.