organic compounds
Methyl 4-(4-bromoanilino)-2′,5-dioxo-5H-spiro[furan-2,3′-indoline]-3-carboxylate
aDepartment of Physics, Ethiraj College for Women (Autonomous), Chennai 600 008, India, bOrganic Chemistry Division, Central Leather Research Institute, Adyar, Chennai 600 020, India, and cDepartment of Physics, RKM Vivekananda College (Autonomous), Chennai 600 004, India
*Correspondence e-mail: ksethusankar@yahoo.co.in
In the title compound, C19H13BrN2O5, the spiro furan ring is almost planar with a maximum deviation of 0.034 (2) Å. The indole unit and the furan ring are normal to each other, making a dihedral angle of 87.82 (8) °. The molecular structure is stabilized by an intramolecular N—H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, molecules are linked via pairs of N—H⋯O hydrogen bonds, forming inversion dimers enclosing R22(8) ring motifs.
CCDC reference: 982248
Related literature
For applications of oxindoles, see: Akai et al. (2004); Gallagher et al. (1985); Tokunaga et al. (2001); Zaveri et al. (2004). For applications of tetrahydrofurans, see: Garzino et al. (2000). For a related structure, see: Gangadharan et al. (2013). For the length of a C—Br single bond, see: Koşar et al. (2006). For resonance structure in a carboxylate group, see: Merlino (1971); Varghese et al. (1986). For graph-set notation, see: Bernstein et al. (1995).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2008); cell SAINT (Bruker, 2008); data reduction: SAINT; 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, 2012); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).
Supporting information
CCDC reference: 982248
10.1107/S1600536814001329/su2688sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536814001329/su2688Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536814001329/su2688Isup3.cml
Isatin (1 mmol), p-bromoaniline (1 mmol), and dimethyl acetylene dicarboxylate (DMAD; 1 mmol) were stirred at room temperature in methanol in the presence of Triethylamine (20 mol %) for 4 hrs. The solid formed was filtered and recrystallized from methanol to afford the title compound as a pure yellow solid (85% yield).
The hydrogen atoms were located in difference electron density maps. The H-atoms of the amine groups were refined with distance restraints of N—H = 0.89 (2) Å with Uiso(H) = 1.2Ueq(N). The C bound H atoms were included in calculated positions and treated as riding atoms: C—H = 0.93 and 0.96 Å for CH and CH3 H atoms, respectively, with Uiso(H) = 1.5Ueq(C-methyl) and = 1.2Ueq(C) for other H atoms.
The indole template is generally recognized as an important structure in medicinal chemistry. In particular oxindoles are important constituents of drugs (Akai et al., 2004). The Oxindole motif is present in the anti-Parkinson's drug ropinirole (Gallagher et al., 1985), in non-opioid receptor ligands (Zaveri et al., 2004) and in growth hormone secretagogues (Tokunaga et al., 2001). Tetrahydrofuran is a common motif which can be found in numerous natural products such as polyether antibiotics,
and (Garzino et al., 2000).The five- (N1/C1–C8) and six- (C1–C6) membered rings in the indole unit are coplanar, making a dihedral angle of 1.50 (9)°. The indole moiety is orthogonal to the furan ring as indicated by the dihedral angle of 87.82 (8)°. The benzene ring is bisectionally oriented to the furan ring with a dihedral angle 37.54 (10)°. The bond lengths and angles are comparable with those in a similar structure (Gangadharan et al., 2013). In addition, the C–Br bond distance of 1.896 (2) Å, is slightly shorter than the value reported for the C–Br single bond (1.961 (3) Å; Koşar et al., 2006). The C15–C16–C17–Br1 torsion angle of 177.77 (14) ° indicates that the bromine atom is antiperiplanar to the benzene ring.
The keto O atoms O3 and O1 deviate from the furan and indoline rings by 0.130 (1) Å and 0.043 (1) Å, respectively. The sum of the bond angles around the nitrogen atoms N1 [359.9 (44) °] and N2 [360.0 (49) °] suggests sp2 ═ C12–O4–C13 group (Merlino, 1971). This feature is commonly observed in carboxyl ester groups of the substituents in various compounds where the average distances are 1.340 Å and 1.447 Å, respectively (Varghese et al., 1986). The molecular structure is stabilized by an intramolecular N—H···O hydrogen bond which generates an S(6) ring motif (Table 1).
The significant difference in length of the C12–O4 = 1.338 (2) Å and C13–O4 = 1.442 (2) Å bonds is attributed to partial contribution from O-–C=O+–C resonance structure of the O3In the crystal, molecules are linked via pairs of N-H···O hydrogen bonds forming inversion dimers enclosing R22(8) ring motifs (Bernstein et al., 1995; Table 1 and Fig. 2).
For applications of oxindoles, see: Akai et al. (2004); Gallagher et al. (1985); Tokunaga et al. (2001); Zaveri et al. (2004). For applications of tetrahydrofurans, see: Garzino et al. (2000). For a related structure, see: Gangadharan et al. (2013). For the length of a C—Br single bond, see: Koşar et al. (2006). For resonance structure in a carboxylate group, see: Merlino (1971); Varghese et al. (1986). For graph-set notation, see: Bernstein et al. (1995).
Data collection: APEX2 (Bruker, 2008); cell
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, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).C19H13BrN2O5 | Z = 2 |
Mr = 429.21 | F(000) = 432 |
Triclinic, P1 | Dx = 1.660 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.845 (5) Å | Cell parameters from 3611 reflections |
b = 8.365 (5) Å | θ = 2.5–30.7° |
c = 13.703 (5) Å | µ = 2.43 mm−1 |
α = 81.565 (5)° | T = 296 K |
β = 81.944 (5)° | Block, yellow |
γ = 76.183 (5)° | 0.30 × 0.25 × 0.20 mm |
V = 858.6 (8) Å3 |
Bruker SMART APEXII area-detector diffractometer | 5243 independent reflections |
Radiation source: fine-focus sealed tube | 3611 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.032 |
ω and φ scans | θmax = 30.7°, θmin = 2.5° |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | h = −11→11 |
Tmin = 0.487, Tmax = 0.615 | k = −10→11 |
19580 measured reflections | l = −19→19 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.034 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.095 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0509P)2 + 0.0269P] where P = (Fo2 + 2Fc2)/3 |
5243 reflections | (Δ/σ)max = 0.001 |
251 parameters | Δρmax = 0.30 e Å−3 |
0 restraints | Δρmin = −0.31 e Å−3 |
C19H13BrN2O5 | γ = 76.183 (5)° |
Mr = 429.21 | V = 858.6 (8) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.845 (5) Å | Mo Kα radiation |
b = 8.365 (5) Å | µ = 2.43 mm−1 |
c = 13.703 (5) Å | T = 296 K |
α = 81.565 (5)° | 0.30 × 0.25 × 0.20 mm |
β = 81.944 (5)° |
Bruker SMART APEXII area-detector diffractometer | 5243 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | 3611 reflections with I > 2σ(I) |
Tmin = 0.487, Tmax = 0.615 | Rint = 0.032 |
19580 measured reflections |
R[F2 > 2σ(F2)] = 0.034 | 0 restraints |
wR(F2) = 0.095 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | Δρmax = 0.30 e Å−3 |
5243 reflections | Δρmin = −0.31 e Å−3 |
251 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. |
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 | ||
C1 | −0.4990 (3) | 0.6472 (2) | 0.90768 (17) | 0.0504 (5) | |
H1 | −0.5215 | 0.6959 | 0.9664 | 0.060* | |
C2 | −0.6306 (3) | 0.6597 (3) | 0.8475 (2) | 0.0582 (6) | |
H2 | −0.7443 | 0.7179 | 0.8665 | 0.070* | |
C3 | −0.5985 (3) | 0.5890 (2) | 0.76091 (18) | 0.0558 (6) | |
H3 | −0.6902 | 0.5995 | 0.7225 | 0.067* | |
C4 | −0.4295 (3) | 0.5013 (2) | 0.72958 (16) | 0.0466 (5) | |
H4 | −0.4066 | 0.4538 | 0.6705 | 0.056* | |
C5 | −0.2984 (2) | 0.48741 (19) | 0.78896 (13) | 0.0364 (4) | |
C6 | −0.3335 (2) | 0.5594 (2) | 0.87638 (13) | 0.0380 (4) | |
C7 | −0.0421 (2) | 0.4317 (2) | 0.87382 (12) | 0.0337 (4) | |
C8 | −0.1067 (2) | 0.40203 (19) | 0.77657 (12) | 0.0332 (3) | |
C9 | 0.0787 (2) | 0.3804 (2) | 0.62970 (13) | 0.0370 (4) | |
C10 | 0.0397 (2) | 0.2139 (2) | 0.66609 (12) | 0.0340 (4) | |
C11 | −0.0593 (2) | 0.22549 (19) | 0.75528 (12) | 0.0329 (3) | |
C12 | −0.0965 (2) | 0.0843 (2) | 0.82184 (12) | 0.0334 (3) | |
C13 | −0.2248 (3) | −0.0121 (2) | 0.97751 (15) | 0.0555 (5) | |
H13A | −0.3023 | −0.0637 | 0.9511 | 0.083* | |
H13B | −0.2802 | 0.0271 | 1.0392 | 0.083* | |
H13C | −0.1165 | −0.0913 | 0.9885 | 0.083* | |
C14 | 0.2003 (2) | 0.0426 (2) | 0.53099 (13) | 0.0366 (4) | |
C15 | 0.3175 (3) | −0.1104 (2) | 0.52758 (14) | 0.0429 (4) | |
H15 | 0.3302 | −0.1848 | 0.5850 | 0.052* | |
C16 | 0.4145 (3) | −0.1526 (2) | 0.44021 (14) | 0.0424 (4) | |
H16 | 0.4923 | −0.2554 | 0.4381 | 0.051* | |
C17 | 0.3960 (2) | −0.0425 (2) | 0.35616 (13) | 0.0389 (4) | |
C18 | 0.2789 (3) | 0.1086 (2) | 0.35738 (13) | 0.0426 (4) | |
H18 | 0.2666 | 0.1819 | 0.2995 | 0.051* | |
C19 | 0.1797 (3) | 0.1509 (2) | 0.44496 (13) | 0.0418 (4) | |
H19 | 0.0990 | 0.2523 | 0.4461 | 0.050* | |
N1 | −0.1789 (2) | 0.52477 (18) | 0.92420 (11) | 0.0400 (3) | |
N2 | 0.1045 (2) | 0.07406 (19) | 0.62338 (12) | 0.0440 (4) | |
O1 | 0.10713 (17) | 0.37852 (16) | 0.89603 (10) | 0.0427 (3) | |
O2 | −0.01219 (16) | 0.48646 (14) | 0.69475 (9) | 0.0378 (3) | |
O3 | 0.17429 (19) | 0.42333 (17) | 0.56122 (10) | 0.0513 (3) | |
O4 | −0.18764 (17) | 0.12567 (14) | 0.90801 (9) | 0.0405 (3) | |
O5 | −0.04501 (18) | −0.05806 (15) | 0.80338 (10) | 0.0458 (3) | |
Br1 | 0.53764 (3) | −0.10026 (3) | 0.237127 (14) | 0.05583 (10) | |
H1A | −0.171 (3) | 0.566 (3) | 0.9820 (18) | 0.067* | |
H2A | 0.077 (3) | −0.004 (3) | 0.6630 (19) | 0.067* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0486 (12) | 0.0401 (10) | 0.0558 (12) | −0.0017 (9) | 0.0012 (10) | −0.0043 (9) |
C2 | 0.0434 (12) | 0.0434 (11) | 0.0796 (17) | −0.0040 (9) | −0.0056 (11) | 0.0091 (11) |
C3 | 0.0466 (12) | 0.0486 (11) | 0.0721 (16) | −0.0154 (9) | −0.0230 (11) | 0.0164 (11) |
C4 | 0.0535 (12) | 0.0409 (10) | 0.0489 (11) | −0.0160 (9) | −0.0179 (9) | 0.0048 (8) |
C5 | 0.0427 (10) | 0.0273 (8) | 0.0390 (9) | −0.0086 (7) | −0.0089 (8) | 0.0025 (7) |
C6 | 0.0418 (10) | 0.0294 (8) | 0.0403 (9) | −0.0062 (7) | −0.0032 (8) | −0.0003 (7) |
C7 | 0.0426 (10) | 0.0303 (8) | 0.0296 (8) | −0.0098 (7) | −0.0047 (7) | −0.0048 (6) |
C8 | 0.0411 (9) | 0.0319 (8) | 0.0280 (8) | −0.0107 (7) | −0.0057 (7) | −0.0025 (6) |
C9 | 0.0434 (10) | 0.0384 (9) | 0.0314 (8) | −0.0120 (8) | −0.0064 (7) | −0.0039 (7) |
C10 | 0.0407 (9) | 0.0334 (8) | 0.0296 (8) | −0.0093 (7) | −0.0061 (7) | −0.0054 (6) |
C11 | 0.0398 (9) | 0.0312 (8) | 0.0289 (8) | −0.0074 (7) | −0.0071 (7) | −0.0045 (6) |
C12 | 0.0368 (9) | 0.0335 (8) | 0.0307 (8) | −0.0076 (7) | −0.0073 (7) | −0.0029 (6) |
C13 | 0.0698 (14) | 0.0489 (11) | 0.0409 (11) | −0.0155 (10) | 0.0080 (10) | 0.0075 (9) |
C14 | 0.0447 (10) | 0.0385 (9) | 0.0296 (8) | −0.0141 (8) | −0.0013 (7) | −0.0081 (7) |
C15 | 0.0595 (12) | 0.0342 (9) | 0.0328 (9) | −0.0087 (8) | −0.0039 (8) | −0.0008 (7) |
C16 | 0.0509 (11) | 0.0354 (9) | 0.0377 (10) | −0.0039 (8) | −0.0019 (8) | −0.0062 (7) |
C17 | 0.0456 (10) | 0.0425 (9) | 0.0322 (9) | −0.0163 (8) | −0.0016 (7) | −0.0082 (7) |
C18 | 0.0604 (12) | 0.0399 (9) | 0.0303 (9) | −0.0163 (9) | −0.0104 (8) | 0.0000 (7) |
C19 | 0.0538 (11) | 0.0357 (9) | 0.0360 (9) | −0.0053 (8) | −0.0120 (8) | −0.0060 (7) |
N1 | 0.0453 (9) | 0.0400 (8) | 0.0351 (8) | −0.0048 (7) | −0.0057 (7) | −0.0123 (6) |
N2 | 0.0628 (11) | 0.0354 (8) | 0.0331 (8) | −0.0137 (7) | 0.0063 (7) | −0.0081 (6) |
O1 | 0.0403 (7) | 0.0487 (7) | 0.0402 (7) | −0.0053 (6) | −0.0085 (6) | −0.0126 (6) |
O2 | 0.0499 (7) | 0.0329 (6) | 0.0316 (6) | −0.0140 (5) | −0.0012 (5) | −0.0026 (5) |
O3 | 0.0622 (9) | 0.0502 (8) | 0.0425 (8) | −0.0225 (7) | 0.0098 (7) | −0.0068 (6) |
O4 | 0.0508 (8) | 0.0346 (6) | 0.0330 (6) | −0.0081 (5) | 0.0012 (5) | −0.0020 (5) |
O5 | 0.0613 (9) | 0.0318 (6) | 0.0423 (7) | −0.0088 (6) | −0.0003 (6) | −0.0056 (5) |
Br1 | 0.06364 (16) | 0.06784 (16) | 0.03773 (12) | −0.02209 (11) | 0.00927 (9) | −0.01359 (9) |
C1—C6 | 1.375 (3) | C11—C12 | 1.444 (2) |
C1—C2 | 1.386 (3) | C12—O5 | 1.214 (2) |
C1—H1 | 0.9300 | C12—O4 | 1.338 (2) |
C2—C3 | 1.368 (3) | C13—O4 | 1.442 (2) |
C2—H2 | 0.9300 | C13—H13A | 0.9600 |
C3—C4 | 1.396 (3) | C13—H13B | 0.9600 |
C3—H3 | 0.9300 | C13—H13C | 0.9600 |
C4—C5 | 1.372 (3) | C14—C19 | 1.381 (2) |
C4—H4 | 0.9300 | C14—C15 | 1.389 (3) |
C5—C6 | 1.383 (2) | C14—N2 | 1.405 (2) |
C5—C8 | 1.501 (3) | C15—C16 | 1.370 (3) |
C6—N1 | 1.409 (2) | C15—H15 | 0.9300 |
C7—O1 | 1.213 (2) | C16—C17 | 1.366 (3) |
C7—N1 | 1.336 (2) | C16—H16 | 0.9300 |
C7—C8 | 1.563 (2) | C17—C18 | 1.375 (3) |
C8—O2 | 1.446 (2) | C17—Br1 | 1.8962 (19) |
C8—C11 | 1.496 (2) | C18—C19 | 1.379 (3) |
C9—O3 | 1.185 (2) | C18—H18 | 0.9300 |
C9—O2 | 1.357 (2) | C19—H19 | 0.9300 |
C9—C10 | 1.497 (2) | N1—H1A | 0.92 (2) |
C10—N2 | 1.343 (2) | N2—H2A | 0.84 (3) |
C10—C11 | 1.356 (2) | ||
C6—C1—C2 | 116.7 (2) | O5—C12—O4 | 123.21 (16) |
C6—C1—H1 | 121.7 | O5—C12—C11 | 123.72 (16) |
C2—C1—H1 | 121.7 | O4—C12—C11 | 113.02 (14) |
C3—C2—C1 | 122.0 (2) | O4—C13—H13A | 109.5 |
C3—C2—H2 | 119.0 | O4—C13—H13B | 109.5 |
C1—C2—H2 | 119.0 | H13A—C13—H13B | 109.5 |
C2—C3—C4 | 120.7 (2) | O4—C13—H13C | 109.5 |
C2—C3—H3 | 119.6 | H13A—C13—H13C | 109.5 |
C4—C3—H3 | 119.6 | H13B—C13—H13C | 109.5 |
C5—C4—C3 | 117.7 (2) | C19—C14—C15 | 119.37 (17) |
C5—C4—H4 | 121.1 | C19—C14—N2 | 124.10 (16) |
C3—C4—H4 | 121.1 | C15—C14—N2 | 116.49 (16) |
C4—C5—C6 | 120.74 (18) | C16—C15—C14 | 120.46 (17) |
C4—C5—C8 | 130.56 (18) | C16—C15—H15 | 119.8 |
C6—C5—C8 | 108.70 (14) | C14—C15—H15 | 119.8 |
C1—C6—C5 | 122.12 (17) | C17—C16—C15 | 119.54 (17) |
C1—C6—N1 | 128.20 (18) | C17—C16—H16 | 120.2 |
C5—C6—N1 | 109.67 (15) | C15—C16—H16 | 120.2 |
O1—C7—N1 | 128.24 (15) | C16—C17—C18 | 121.04 (18) |
O1—C7—C8 | 124.32 (15) | C16—C17—Br1 | 118.82 (14) |
N1—C7—C8 | 107.43 (15) | C18—C17—Br1 | 120.13 (14) |
O2—C8—C11 | 103.78 (14) | C17—C18—C19 | 119.60 (16) |
O2—C8—C5 | 110.91 (13) | C17—C18—H18 | 120.2 |
C11—C8—C5 | 118.36 (14) | C19—C18—H18 | 120.2 |
O2—C8—C7 | 106.91 (13) | C18—C19—C14 | 119.96 (17) |
C11—C8—C7 | 114.63 (13) | C18—C19—H19 | 120.0 |
C5—C8—C7 | 101.94 (14) | C14—C19—H19 | 120.0 |
O3—C9—O2 | 121.60 (16) | C7—N1—C6 | 112.18 (15) |
O3—C9—C10 | 130.94 (17) | C7—N1—H1A | 123.8 (14) |
O2—C9—C10 | 107.37 (15) | C6—N1—H1A | 123.9 (14) |
N2—C10—C11 | 125.71 (16) | C10—N2—C14 | 132.62 (16) |
N2—C10—C9 | 126.41 (17) | C10—N2—H2A | 107.5 (17) |
C11—C10—C9 | 107.60 (14) | C14—N2—H2A | 119.9 (17) |
C10—C11—C12 | 123.83 (15) | C9—O2—C8 | 111.32 (13) |
C10—C11—C8 | 109.57 (14) | C12—O4—C13 | 114.86 (14) |
C12—C11—C8 | 126.35 (15) | ||
C6—C1—C2—C3 | −0.2 (3) | C7—C8—C11—C10 | −120.97 (16) |
C1—C2—C3—C4 | −0.3 (3) | O2—C8—C11—C12 | 169.66 (15) |
C2—C3—C4—C5 | 0.6 (3) | C5—C8—C11—C12 | −67.0 (2) |
C3—C4—C5—C6 | −0.4 (3) | C7—C8—C11—C12 | 53.4 (2) |
C3—C4—C5—C8 | 179.71 (16) | C10—C11—C12—O5 | −1.3 (3) |
C2—C1—C6—C5 | 0.4 (3) | C8—C11—C12—O5 | −174.99 (16) |
C2—C1—C6—N1 | −178.36 (18) | C10—C11—C12—O4 | 176.09 (15) |
C4—C5—C6—C1 | −0.1 (3) | C8—C11—C12—O4 | 2.4 (2) |
C8—C5—C6—C1 | 179.81 (16) | C19—C14—C15—C16 | 1.3 (3) |
C4—C5—C6—N1 | 178.90 (16) | N2—C14—C15—C16 | 179.03 (17) |
C8—C5—C6—N1 | −1.22 (19) | C14—C15—C16—C17 | 0.3 (3) |
C4—C5—C8—O2 | 68.7 (2) | C15—C16—C17—C18 | −1.4 (3) |
C6—C5—C8—O2 | −111.21 (15) | C15—C16—C17—Br1 | 177.77 (14) |
C4—C5—C8—C11 | −51.1 (3) | C16—C17—C18—C19 | 0.7 (3) |
C6—C5—C8—C11 | 129.05 (16) | Br1—C17—C18—C19 | −178.39 (13) |
C4—C5—C8—C7 | −177.83 (18) | C17—C18—C19—C14 | 0.9 (3) |
C6—C5—C8—C7 | 2.31 (17) | C15—C14—C19—C18 | −1.9 (3) |
O1—C7—C8—O2 | −65.7 (2) | N2—C14—C19—C18 | −179.48 (17) |
N1—C7—C8—O2 | 113.77 (15) | O1—C7—N1—C6 | −178.44 (17) |
O1—C7—C8—C11 | 48.8 (2) | C8—C7—N1—C6 | 2.16 (19) |
N1—C7—C8—C11 | −131.82 (16) | C1—C6—N1—C7 | 178.22 (18) |
O1—C7—C8—C5 | 177.89 (16) | C5—C6—N1—C7 | −0.7 (2) |
N1—C7—C8—C5 | −2.69 (17) | C11—C10—N2—C14 | 176.41 (18) |
O3—C9—C10—N2 | −2.8 (3) | C9—C10—N2—C14 | −10.5 (3) |
O2—C9—C10—N2 | −179.46 (16) | C19—C14—N2—C10 | −33.1 (3) |
O3—C9—C10—C11 | 171.27 (19) | C15—C14—N2—C10 | 149.3 (2) |
O2—C9—C10—C11 | −5.36 (18) | O3—C9—O2—C8 | −174.71 (15) |
N2—C10—C11—C12 | 5.7 (3) | C10—C9—O2—C8 | 2.31 (17) |
C9—C10—C11—C12 | −168.42 (15) | C11—C8—O2—C9 | 1.26 (17) |
N2—C10—C11—C8 | −179.68 (17) | C5—C8—O2—C9 | −126.86 (14) |
C9—C10—C11—C8 | 6.16 (18) | C7—C8—O2—C9 | 122.79 (14) |
O2—C8—C11—C10 | −4.75 (17) | O5—C12—O4—C13 | −1.4 (2) |
C5—C8—C11—C10 | 118.62 (17) | C11—C12—O4—C13 | −178.89 (16) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···O5 | 0.84 (2) | 2.06 (3) | 2.773 (3) | 143 (2) |
N1—H1A···O1i | 0.92 (2) | 1.96 (2) | 2.869 (3) | 168 (2) |
Symmetry code: (i) −x, −y+1, −z+2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···O5 | 0.84 (2) | 2.06 (3) | 2.773 (3) | 143 (2) |
N1—H1A···O1i | 0.92 (2) | 1.96 (2) | 2.869 (3) | 168 (2) |
Symmetry code: (i) −x, −y+1, −z+2. |
Acknowledgements
The authors thank Dr Babu Varghese, SAIF, IIT, Chennai, India, for the data collection.
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
The indole template is generally recognized as an important structure in medicinal chemistry. In particular oxindoles are important constituents of drugs (Akai et al., 2004). The Oxindole motif is present in the anti-Parkinson's drug ropinirole (Gallagher et al., 1985), in non-opioid receptor ligands (Zaveri et al., 2004) and in growth hormone secretagogues (Tokunaga et al., 2001). Tetrahydrofuran is a common motif which can be found in numerous natural products such as polyether antibiotics, nucleosides and lignans (Garzino et al., 2000).
The five- (N1/C1–C8) and six- (C1–C6) membered rings in the indole unit are coplanar, making a dihedral angle of 1.50 (9)°. The indole moiety is orthogonal to the furan ring as indicated by the dihedral angle of 87.82 (8)°. The benzene ring is bisectionally oriented to the furan ring with a dihedral angle 37.54 (10)°. The bond lengths and angles are comparable with those in a similar structure (Gangadharan et al., 2013). In addition, the C–Br bond distance of 1.896 (2) Å, is slightly shorter than the value reported for the C–Br single bond (1.961 (3) Å; Koşar et al., 2006). The C15–C16–C17–Br1 torsion angle of 177.77 (14) ° indicates that the bromine atom is antiperiplanar to the benzene ring.
The keto O atoms O3 and O1 deviate from the furan and indoline rings by 0.130 (1) Å and 0.043 (1) Å, respectively. The sum of the bond angles around the nitrogen atoms N1 [359.9 (44) °] and N2 [360.0 (49) °] suggests sp2 hybridization. The significant difference in length of the C12–O4 = 1.338 (2) Å and C13–O4 = 1.442 (2) Å bonds is attributed to partial contribution from O-–C=O+–C resonance structure of the O3═ C12–O4–C13 group (Merlino, 1971). This feature is commonly observed in carboxyl ester groups of the substituents in various compounds where the average distances are 1.340 Å and 1.447 Å, respectively (Varghese et al., 1986). The molecular structure is stabilized by an intramolecular N—H···O hydrogen bond which generates an S(6) ring motif (Table 1).
In the crystal, molecules are linked via pairs of N-H···O hydrogen bonds forming inversion dimers enclosing R22(8) ring motifs (Bernstein et al., 1995; Table 1 and Fig. 2).