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In the title compound, C18H13NO4, both the indole and benzo­furan moieties are nearly planar, and are in an equatorial configuration relative to each other. The O atom of the acetyl group is involved in a weak intramolecular C—H...O hydrogen bond with the indole, and a stronger intermolecular O—H...O hydrogen bond with the hydroxy group, which stabilize the molecular and crystal-packing structures.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801016324/na6100sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801016324/na6100Isup2.hkl
Contains datablock I

CCDC reference: 176021

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.005 Å
  • R factor = 0.072
  • wR factor = 0.174
  • Data-to-parameter ratio = 11.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry








Comment top

1H-indole-2,3-dione (isatin) derivatives have been of interest owing to their biological activities (Bieck et al., 1993), and their photo-induced reactions with alkenes giving the corresponding spirooxetanes have been investigated intensively (Xue et al., 2000). Our interest on the ring-opening reaction of such spirooxetane derivatives led us to the title compound (I) which was obtained by acid catalysed ring-opening reaction of a spiroxetane derivative. An X-ray crystallographic structure analysis of (I) was undertaken to confirm the 3-(heteroaryl)indole structure of this novel product.

The C9 atom is the chiral center atom of the title compound (I). The bond lengths and bond angles in the title compound (Table 1) show normal values (Allen et al., 1987). These values, especially those within the indole and benzofuran moieties, agree with those of the related structure previously studied (Usman et al., 2001). The indole moiety is almost planar with an angle of 2.3 (2)° between the pyrrolidine and benzene rings. The benzofuran moiety is also planar with an angle of 1.2 (2)° between the furan and benzene rings. The indole and benzofuran moieties make a dihedral angle of 75.3 (2)° between themselves corresponding to an equatorial configuration. The attached acetyl group at N1 atom makes a dihedral angle of 6.8 (2)° with the indole moiety.

In the title structure, the O4 atom of the acetyl group is involved in intra- and intermolecular hydrogen bonds. The intramolecular C—H···O interaction forms a six-membered closed ring of O4—C17—N1—C11—C12—H12A. The molecules are stacked into columns nearly along the c axis. The stronger intermolecular O—H···O interaction interconnects the O4 atoms with the hydrogen atom of the hydroxy group between the two molecules of the adjacent molecular columns. (see Table 2) This interaction as well as van der Waals interactions stabilize the molecular and packing structure in the crystal.

Experimental top

The title compound (I) was prepared by hydrochloric-acid-catalysed ring-opening reaction of syn-1-Acetyl-5'a-hydro-spiro[3H-indole-3,2'](2a'H)oxeto[2,3-b] benzofuran-2(1H)-one in benzene solution. Single crystals suitable for an X-ray diffraction were obtained by slow evaporation from a mixture of petroleum ether–acetone solution.

Refinement top

After checking their presence in the difference map, all H-atoms were geometrically fixed and allowed to ride on the parent C atoms and refined isotropically. Owing to a not-so-good quality of the crystals and a large fraction of weak data at higher angles, the R[F2>2σ(F2)] value is rather high and the completeness is less than 0.96, even though the 2θ maximum was limited to 50°.

Computing details top

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL, PARST (Nardelli, 1995) and PLATON (Spek, 1990).

Figures top
[Figure 1] Fig. 1. The structure of (I) showing 50% probability displacement ellipsoids and the atom-numbering scheme.
[Figure 2] Fig. 2. Packing diagram of the structure (I) viewed down the c axis.
1-Acetyl-1,2-dihydro-3-hydroxy-3-(benzofuran-3-yl)-2-oxo-(3H)indole top
Crystal data top
C18H13NO4F(000) = 320
Mr = 307.29Dx = 1.417 Mg m3
Triclinic, P1Melting point: 383K K
a = 7.5900 (6) ÅMo Kα radiation, λ = 0.71073 Å
b = 9.6858 (8) ÅCell parameters from 2226 reflections
c = 10.4040 (9) Åθ = 2.0–29.5°
α = 74.141 (2)°µ = 0.10 mm1
β = 83.650 (2)°T = 293 K
γ = 78.772 (2)°Block, colorless
V = 720.3 (1) Å30.36 × 0.24 × 0.18 mm
Z = 2
Data collection top
Siemens SMART CCD area detector
diffractometer
2421 independent reflections
Radiation source: fine-focus sealed tube1233 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.091
Detector resolution: 8.33 pixels mm-1θmax = 25.0°, θmin = 2.0°
ω scansh = 98
Absorption correction: empirical (using intensity measurements)
SADABS (Sheldrick, 1996)
k = 1110
Tmin = 0.965, Tmax = 0.982l = 1210
3999 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.072H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.174 w = 1/[σ2(Fo2) + (0.039P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.86(Δ/σ)max < 0.001
2421 reflectionsΔρmax = 0.30 e Å3
214 parametersΔρmin = 0.31 e Å3
0 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.133 (14)
Crystal data top
C18H13NO4γ = 78.772 (2)°
Mr = 307.29V = 720.3 (1) Å3
Triclinic, P1Z = 2
a = 7.5900 (6) ÅMo Kα radiation
b = 9.6858 (8) ŵ = 0.10 mm1
c = 10.4040 (9) ÅT = 293 K
α = 74.141 (2)°0.36 × 0.24 × 0.18 mm
β = 83.650 (2)°
Data collection top
Siemens SMART CCD area detector
diffractometer
2421 independent reflections
Absorption correction: empirical (using intensity measurements)
SADABS (Sheldrick, 1996)
1233 reflections with I > 2σ(I)
Tmin = 0.965, Tmax = 0.982Rint = 0.091
3999 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0720 restraints
wR(F2) = 0.174H atoms treated by a mixture of independent and constrained refinement
S = 0.86Δρmax = 0.30 e Å3
2421 reflectionsΔρmin = 0.31 e Å3
214 parameters
Special details top

Experimental. The data collection covered over a hemisphere of reciprocal space by a combination of three sets of exposures; each set had a different ϕ angle (0, 88 and 180°) for the crystal and each exposure of 10 s covered 0.3° in ω. The crystal-to-detector distance was 4 cm and the detector swing angle was -35°. Crystal decay was monitored by repeating fifty initial frames at the end of data collection and analysing the intensity of duplicate reflections, and was found to be negligible.

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
O11.0255 (3)0.3011 (3)1.0070 (3)0.0569 (8)
O20.4559 (3)0.3894 (3)0.8736 (3)0.0524 (8)
O30.6435 (4)0.1983 (3)0.7059 (3)0.0546 (8)
O40.7760 (4)0.4837 (3)0.3466 (3)0.0630 (8)
N10.7128 (4)0.4195 (3)0.5713 (3)0.0392 (7)
C10.9184 (5)0.3920 (4)0.9110 (4)0.0506 (10)
H1A0.94510.48030.85750.061*
C20.9391 (5)0.1833 (4)1.0637 (4)0.0430 (9)
C31.0016 (5)0.0626 (4)1.1637 (4)0.0504 (10)
H3A1.10980.05361.20200.061*
C40.8961 (5)0.0433 (4)1.2039 (4)0.0507 (10)
H4A0.93390.12691.27050.061*
C50.7330 (5)0.0281 (4)1.1466 (4)0.0528 (10)
H5A0.66370.10131.17700.063*
C60.6719 (5)0.0930 (4)1.0462 (4)0.0468 (10)
H6A0.56360.10211.00820.056*
C70.7794 (5)0.2016 (3)1.0034 (3)0.0387 (9)
C80.7680 (4)0.3392 (3)0.9021 (3)0.0380 (9)
C90.6267 (5)0.4061 (3)0.8034 (3)0.0399 (9)
C100.6608 (4)0.3223 (4)0.6925 (3)0.0373 (9)
C110.6940 (4)0.5627 (3)0.5910 (3)0.0373 (9)
C120.7191 (5)0.6924 (4)0.4996 (4)0.0508 (10)
H12A0.75540.69590.41060.061*
C130.6877 (5)0.8172 (4)0.5461 (4)0.0535 (11)
H13A0.70260.90570.48640.064*
C140.6362 (5)0.8138 (4)0.6761 (4)0.0533 (11)
H14A0.61470.89960.70350.064*
C150.6154 (5)0.6839 (4)0.7678 (4)0.0507 (10)
H15A0.58390.68090.85740.061*
C160.6420 (4)0.5586 (3)0.7243 (3)0.0385 (9)
C170.7630 (5)0.3847 (4)0.4477 (4)0.0447 (9)
C180.7987 (6)0.2292 (4)0.4452 (4)0.0650 (12)
H18A0.87360.17320.51650.097*
H18B0.85880.22010.36090.097*
H18C0.68690.19380.45640.097*
H2A0.359 (5)0.447 (3)0.818 (4)0.056 (11)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0574 (17)0.0555 (16)0.067 (2)0.0260 (13)0.0204 (15)0.0133 (13)
O20.0431 (15)0.0678 (18)0.0403 (17)0.0134 (13)0.0023 (13)0.0030 (13)
O30.079 (2)0.0406 (15)0.0519 (18)0.0261 (13)0.0107 (15)0.0112 (12)
O40.082 (2)0.0761 (19)0.0350 (17)0.0253 (16)0.0035 (15)0.0157 (15)
N10.0486 (18)0.0426 (17)0.0289 (17)0.0168 (14)0.0009 (14)0.0080 (13)
C10.059 (2)0.046 (2)0.052 (3)0.0161 (19)0.018 (2)0.0096 (18)
C20.049 (2)0.046 (2)0.040 (2)0.0130 (17)0.0072 (18)0.0168 (17)
C30.057 (2)0.055 (2)0.041 (2)0.003 (2)0.017 (2)0.0135 (18)
C40.065 (3)0.044 (2)0.037 (2)0.0015 (19)0.004 (2)0.0043 (17)
C50.059 (2)0.050 (2)0.046 (2)0.0138 (19)0.000 (2)0.0052 (18)
C60.049 (2)0.047 (2)0.044 (2)0.0167 (17)0.0023 (19)0.0073 (18)
C70.048 (2)0.0396 (19)0.031 (2)0.0094 (16)0.0061 (17)0.0104 (15)
C80.045 (2)0.044 (2)0.030 (2)0.0149 (17)0.0035 (16)0.0123 (15)
C90.049 (2)0.046 (2)0.026 (2)0.0151 (17)0.0042 (17)0.0089 (16)
C100.0347 (19)0.042 (2)0.040 (2)0.0082 (16)0.0092 (16)0.0146 (16)
C110.0384 (19)0.040 (2)0.038 (2)0.0170 (16)0.0032 (17)0.0099 (16)
C120.067 (3)0.050 (2)0.038 (2)0.029 (2)0.0031 (19)0.0043 (18)
C130.066 (3)0.041 (2)0.053 (3)0.0220 (19)0.000 (2)0.0044 (19)
C140.055 (2)0.043 (2)0.066 (3)0.0087 (18)0.009 (2)0.018 (2)
C150.061 (3)0.047 (2)0.049 (3)0.0110 (19)0.003 (2)0.0195 (19)
C160.043 (2)0.038 (2)0.038 (2)0.0111 (16)0.0035 (17)0.0119 (16)
C170.040 (2)0.064 (2)0.036 (2)0.0160 (18)0.0041 (18)0.0172 (19)
C180.079 (3)0.070 (3)0.055 (3)0.015 (2)0.005 (2)0.032 (2)
Geometric parameters (Å, º) top
O1—C11.362 (4)C6—H6A0.9300
O1—C21.385 (4)C7—C81.450 (4)
O2—C91.430 (4)C8—C91.494 (5)
O2—H2A0.97 (3)C9—C161.502 (4)
O3—C101.202 (4)C9—C101.556 (5)
O4—C171.224 (4)C11—C121.386 (4)
N1—C171.411 (5)C11—C161.391 (5)
N1—C101.420 (4)C12—C131.391 (5)
N1—C111.434 (4)C12—H12A0.9300
C1—C81.360 (5)C13—C141.359 (6)
C1—H1A0.9300C13—H13A0.9300
C2—C31.379 (5)C14—C151.381 (5)
C2—C71.385 (4)C14—H14A0.9300
C3—C41.371 (5)C15—C161.379 (5)
C3—H3A0.9300C15—H15A0.9300
C4—C51.398 (5)C17—C181.484 (5)
C4—H4A0.9300C18—H18A0.9600
C5—C61.381 (5)C18—H18B0.9600
C5—H5A0.9300C18—H18C0.9600
C6—C71.403 (5)
C1—O1—C2106.0 (3)C8—C9—C10107.9 (3)
C9—O2—H2A110 (2)C16—C9—C10102.0 (3)
C17—N1—C10125.8 (3)O3—C10—N1125.9 (3)
C17—N1—C11124.7 (3)O3—C10—C9126.3 (3)
C10—N1—C11109.3 (3)N1—C10—C9107.8 (3)
C8—C1—O1112.5 (3)C12—C11—C16120.7 (3)
C8—C1—H1A123.8C12—C11—N1129.6 (3)
O1—C1—H1A123.8C16—C11—N1109.7 (3)
C3—C2—C7123.9 (3)C11—C12—C13117.4 (4)
C3—C2—O1126.0 (3)C11—C12—H12A121.3
C7—C2—O1110.1 (3)C13—C12—H12A121.3
C4—C3—C2116.6 (3)C14—C13—C12122.1 (3)
C4—C3—H3A121.7C14—C13—H13A119.0
C2—C3—H3A121.7C12—C13—H13A119.0
C3—C4—C5121.3 (3)C13—C14—C15120.5 (4)
C3—C4—H4A119.4C13—C14—H14A119.8
C5—C4—H4A119.4C15—C14—H14A119.8
C6—C5—C4121.7 (4)C16—C15—C14118.9 (4)
C6—C5—H5A119.2C16—C15—H15A120.6
C4—C5—H5A119.2C14—C15—H15A120.6
C5—C6—C7117.6 (3)C15—C16—C11120.5 (3)
C5—C6—H6A121.2C15—C16—C9128.9 (3)
C7—C6—H6A121.2C11—C16—C9110.6 (3)
C2—C7—C6119.0 (3)O4—C17—N1118.8 (3)
C2—C7—C8106.0 (3)O4—C17—C18122.4 (3)
C6—C7—C8135.0 (3)N1—C17—C18118.8 (3)
C1—C8—C7105.4 (3)C17—C18—H18A109.5
C1—C8—C9126.8 (3)C17—C18—H18B109.5
C7—C8—C9127.7 (3)H18A—C18—H18B109.5
O2—C9—C8107.5 (3)C17—C18—H18C109.5
O2—C9—C16115.0 (3)H18A—C18—H18C109.5
C8—C9—C16113.9 (3)H18B—C18—H18C109.5
O2—C9—C10110.4 (3)
C2—O1—C1—C80.2 (4)C8—C9—C10—O368.1 (4)
C1—O1—C2—C3178.5 (4)C16—C9—C10—O3171.7 (3)
C1—O1—C2—C70.3 (4)O2—C9—C10—N1129.8 (3)
C7—C2—C3—C40.2 (6)C8—C9—C10—N1113.0 (3)
O1—C2—C3—C4178.8 (4)C16—C9—C10—N17.2 (3)
C2—C3—C4—C50.6 (6)C17—N1—C11—C120.0 (5)
C3—C4—C5—C60.9 (6)C10—N1—C11—C12175.9 (3)
C4—C5—C6—C70.3 (6)C17—N1—C11—C16179.6 (3)
C3—C2—C7—C60.7 (6)C10—N1—C11—C163.7 (4)
O1—C2—C7—C6179.5 (3)C16—C11—C12—C130.9 (5)
C3—C2—C7—C8178.2 (3)N1—C11—C12—C13178.7 (3)
O1—C2—C7—C80.6 (4)C11—C12—C13—C140.6 (6)
C5—C6—C7—C20.4 (6)C12—C13—C14—C150.9 (6)
C5—C6—C7—C8178.1 (4)C13—C14—C15—C162.1 (5)
O1—C1—C8—C70.6 (4)C14—C15—C16—C111.8 (5)
O1—C1—C8—C9176.5 (3)C14—C15—C16—C9179.6 (3)
C2—C7—C8—C10.7 (4)C12—C11—C16—C150.3 (5)
C6—C7—C8—C1179.4 (4)N1—C11—C16—C15180.0 (3)
C2—C7—C8—C9176.3 (3)C12—C11—C16—C9179.1 (3)
C6—C7—C8—C92.3 (7)N1—C11—C16—C91.2 (4)
C1—C8—C9—O2139.7 (4)O2—C9—C16—C1556.8 (5)
C7—C8—C9—O243.9 (4)C8—C9—C16—C1567.8 (5)
C1—C8—C9—C1611.1 (5)C10—C9—C16—C15176.3 (3)
C7—C8—C9—C16172.4 (3)O2—C9—C16—C11124.5 (3)
C1—C8—C9—C10101.3 (4)C8—C9—C16—C11110.9 (3)
C7—C8—C9—C1075.2 (4)C10—C9—C16—C115.1 (3)
C17—N1—C10—O33.9 (5)C10—N1—C17—O4168.1 (3)
C11—N1—C10—O3172.0 (3)C11—N1—C17—O47.1 (5)
C17—N1—C10—C9177.3 (3)C10—N1—C17—C1812.1 (5)
C11—N1—C10—C96.9 (3)C11—N1—C17—C18172.6 (3)
O2—C9—C10—O349.0 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C12—H12A···O40.932.302.841 (5)117
O2—H2A···O4i0.97 (4)1.98 (4)2.893 (4)155 (3)
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC18H13NO4
Mr307.29
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)7.5900 (6), 9.6858 (8), 10.4040 (9)
α, β, γ (°)74.141 (2), 83.650 (2), 78.772 (2)
V3)720.3 (1)
Z2
Radiation typeMo Kα
µ (mm1)0.10
Crystal size (mm)0.36 × 0.24 × 0.18
Data collection
DiffractometerSiemens SMART CCD area detector
diffractometer
Absorption correctionEmpirical (using intensity measurements)
SADABS (Sheldrick, 1996)
Tmin, Tmax0.965, 0.982
No. of measured, independent and
observed [I > 2σ(I)] reflections
3999, 2421, 1233
Rint0.091
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.072, 0.174, 0.86
No. of reflections2421
No. of parameters214
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.30, 0.31

Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SAINT, SHELXTL (Sheldrick, 1997), SHELXTL, PARST (Nardelli, 1995) and PLATON (Spek, 1990).

Selected geometric parameters (Å, º) top
O1—C11.362 (4)C1—C81.360 (5)
O1—C21.385 (4)C7—C81.450 (4)
O2—C91.430 (4)C8—C91.494 (5)
N1—C171.411 (5)C9—C161.502 (4)
N1—C101.420 (4)C9—C101.556 (5)
O2—C9—C8107.5 (3)C8—C9—C10107.9 (3)
C10—N1—C17—C1812.1 (5)C11—N1—C17—C18172.6 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C12—H12A···O40.932.302.841 (5)117
O2—H2A···O4i0.97 (4)1.98 (4)2.893 (4)155 (3)
Symmetry code: (i) x+1, y+1, z+1.
 

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