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In the title compound, C8H9BrO3, the boat form of the six-membered ring is almost symmetrical with respect to the ep­oxy bridge. The two five-membered rings generated by the ep­oxy bridge of the six-membered ring adopt envelope conformations, whereas the third five-membered ring adopts a half-chair conformation. The refinement results suggest partial inversion twinning.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807037233/bt2437sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807037233/bt2437Isup2.hkl
Contains datablock I

CCDC reference: 660199

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.009 Å
  • R factor = 0.045
  • wR factor = 0.110
  • Data-to-parameter ratio = 13.0

checkCIF/PLATON results

No syntax errors found



Alert level A PLAT027_ALERT_3_A _diffrn_reflns_theta_full (too) Low ............ 24.94 Deg.
Author Response: The data were collected on an a STOE IPDS II diffractometer with an image plate detector. Because of the long c parameter (25.793(4)) of the unit cell, the reflection spots were rather close to each other and to prevent the overlopping of these reflections we had to increase the crystal to detector distance to 150 mm resulting decreasing in the theta-full.

Alert level C RINTA01_ALERT_3_C The value of Rint is greater than 0.10 Rint given 0.143 STRVA01_ALERT_4_C Flack test results are ambiguous. From the CIF: _refine_ls_abs_structure_Flack 0.340 From the CIF: _refine_ls_abs_structure_Flack_su 0.030 PLAT020_ALERT_3_C The value of Rint is greater than 0.10 ......... 0.14 PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low ....... 0.98 PLAT033_ALERT_2_C Flack Parameter Value Deviates 2 * su from zero. 0.34 PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size ....... 0.78 mm PLAT320_ALERT_2_C Check Hybridisation of C7 in Main Residue . ? PLAT341_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ... 9
Alert level G REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF. From the CIF: _diffrn_reflns_theta_max 24.94 From the CIF: _reflns_number_total 1426 Count of symmetry unique reflns 925 Completeness (_total/calc) 154.16% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 501 Fraction of Friedel pairs measured 0.542 Are heavy atom types Z>Si present yes PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature 293 K PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature . 293 K PLAT791_ALERT_1_G Confirm the Absolute Configuration of C2 = . S PLAT791_ALERT_1_G Confirm the Absolute Configuration of C4 = . R PLAT791_ALERT_1_G Confirm the Absolute Configuration of C5 = . S PLAT791_ALERT_1_G Confirm the Absolute Configuration of C6 = . R PLAT791_ALERT_1_G Confirm the Absolute Configuration of C7 = . R
1 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 8 ALERT level C = Check and explain 8 ALERT level G = General alerts; check 7 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 2 ALERT type 2 Indicator that the structure model may be wrong or deficient 6 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

Over the years, the intramolecular Diels–Alder reaction (IMDA) has proved to be a simple but effective step in many natural product syntheses, and the range and variety of triene systems employed is multifarious (Woo et al., 1994; Rogers et al., 1991). Unfortunately, examples employing furan as the dienic component (IMDAF) are less numerous due to the reluctance of the aromatic ring to undergo [4 + 2] cycloaddition. However in recent years the IMDAF has been studied extensively by several research groups (Rogatchov et al., 2002; Fokas et al., 2003; Paulvannan et al., 1999) and consequently numerous persuasive methodologies have emerged in order to coerce the participation of the furan ring.

We have been examining systematically IMDAF cycloadditon, (Demircan et al., 2006; Karaarslan et al., 2007) fragmentation of furan ring following by thermal IMDAF reaction either using Lewis Acids or bases are current project. Therefore the precursor was chosen in an epoxidized form, 2 which was derived from a double bond of 1 [Scheme 1]. Here we report that this precursor, 2 shows a single-crystal specialty. Epoxidation of 1 was performed under standard condition in dichloromethane at 273 K. The solid product was purified by flash column chromatography using hexane: ethyl acetate as an eluent solvent system.

Figure 1 shows the molecular structure of the title compound. While the (O1/C1/C2/C7/C8) ring adopts a half chair conformation, tetrahydrofuran (O3/C4—C7) and bromo-attached tetrahydrofuran (O3/C7/C2/C3/C4) rings adopt envelope conformations, and the total puckering parameter QT values are 0.352 (7), 0.528 (7) and 0.560 (7) A°, respectively (Cremer & Pople, 1975).

For closely related compounds, see Koşar et al. (2006), Büyükgüngör et al. (2005).

Related literature top

For related literature, see: Büyükgüngör et al. (2005); Cremer & Pople (1975); Demircan et al. (2006); Fokas et al. (2003); Karaarslan et al. (2007); Koşar et al. (2006); Paulvannan & Jacobs (1999); Rogatchov et al. (2002); Rogers & Keay (1991); Woo & Keay (1994).

Experimental top

To a solution of meta-chloroperbenzoic acid (m-CPBA) (0.54 mg, 3.15 mmol), which had previously been purified and re-crystallized from dry diethyl ether, in dichloromethane (10 ml), cooled to 273 K, was added dropwise a solution of 7a-bromo-1,6,7,7a-tetrahydro-3a,6-epoxy-2-benzofuran (3.15 mmol) in dichloromethane (10 ml) over a period of 3 min. The reaction mixture was stirred at room temperature for 4 h and then diluted with cold 4% sodium bicarbonate solution (4 ml). The organic layer was separated, washed with water (20 ml) and concentrated in vacuo. The residue was subjected to flash column chromatography. As white crystal (0.48 g, 65%). m.p: 345–346 K, t.l.c., (Hexane: Ethyl acetate (8:2)): Rf: 0.35.

Refinement top

All H atoms were positioned geometrically and refined using a riding model with C—H = 0.96 and 0.97 Å, and Uiso = 1.5 Ueq(C). The crystal turned out to be a racemic twin with a ratio of twin components of 0.52 (4)/0.48 (4).

Structure description top

Over the years, the intramolecular Diels–Alder reaction (IMDA) has proved to be a simple but effective step in many natural product syntheses, and the range and variety of triene systems employed is multifarious (Woo et al., 1994; Rogers et al., 1991). Unfortunately, examples employing furan as the dienic component (IMDAF) are less numerous due to the reluctance of the aromatic ring to undergo [4 + 2] cycloaddition. However in recent years the IMDAF has been studied extensively by several research groups (Rogatchov et al., 2002; Fokas et al., 2003; Paulvannan et al., 1999) and consequently numerous persuasive methodologies have emerged in order to coerce the participation of the furan ring.

We have been examining systematically IMDAF cycloadditon, (Demircan et al., 2006; Karaarslan et al., 2007) fragmentation of furan ring following by thermal IMDAF reaction either using Lewis Acids or bases are current project. Therefore the precursor was chosen in an epoxidized form, 2 which was derived from a double bond of 1 [Scheme 1]. Here we report that this precursor, 2 shows a single-crystal specialty. Epoxidation of 1 was performed under standard condition in dichloromethane at 273 K. The solid product was purified by flash column chromatography using hexane: ethyl acetate as an eluent solvent system.

Figure 1 shows the molecular structure of the title compound. While the (O1/C1/C2/C7/C8) ring adopts a half chair conformation, tetrahydrofuran (O3/C4—C7) and bromo-attached tetrahydrofuran (O3/C7/C2/C3/C4) rings adopt envelope conformations, and the total puckering parameter QT values are 0.352 (7), 0.528 (7) and 0.560 (7) A°, respectively (Cremer & Pople, 1975).

For closely related compounds, see Koşar et al. (2006), Büyükgüngör et al. (2005).

For related literature, see: Büyükgüngör et al. (2005); Cremer & Pople (1975); Demircan et al. (2006); Fokas et al. (2003); Karaarslan et al. (2007); Koşar et al. (2006); Paulvannan & Jacobs (1999); Rogatchov et al. (2002); Rogers & Keay (1991); Woo & Keay (1994).

Computing details top

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, with atom labels and 30% probability displacement ellipsoids for non-H atoms.
3a-Bromoperhydro-2,6a-epoxyoxireno[e][2]benzofuran top
Crystal data top
C8H9BrO3Dx = 1.877 Mg m3
Mr = 233.06Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P41212Cell parameters from 8780 reflections
Hall symbol: P 4abw 2nwθ = 2.6–25.0°
a = 7.9963 (8) ŵ = 4.95 mm1
c = 25.793 (4) ÅT = 293 K
V = 1649.2 (3) Å3Block, colourless
Z = 80.78 × 0.65 × 0.46 mm
F(000) = 928
Data collection top
Stoe IPDS 2
diffractometer
1426 independent reflections
Radiation source: fine-focus sealed tube1117 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.143
Detector resolution: 6.67 pixels mm-1θmax = 24.9°, θmin = 2.7°
ω scansh = 99
Absorption correction: integration
(X-RED; Stoe & Cie, 2002)
k = 98
Tmin = 0.059, Tmax = 0.157l = 1930
5824 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)] = 0.045H-atom parameters constrained
wR(F2) = 0.110 w = 1/[σ2(Fo2) + (0.0436P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max < 0.001
1426 reflectionsΔρmax = 0.42 e Å3
110 parametersΔρmin = 0.29 e Å3
0 restraintsAbsolute structure: Flack (1983), with 522 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.34 (3)
Crystal data top
C8H9BrO3Z = 8
Mr = 233.06Mo Kα radiation
Tetragonal, P41212µ = 4.95 mm1
a = 7.9963 (8) ÅT = 293 K
c = 25.793 (4) Å0.78 × 0.65 × 0.46 mm
V = 1649.2 (3) Å3
Data collection top
Stoe IPDS 2
diffractometer
1426 independent reflections
Absorption correction: integration
(X-RED; Stoe & Cie, 2002)
1117 reflections with I > 2σ(I)
Tmin = 0.059, Tmax = 0.157Rint = 0.143
5824 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.045H-atom parameters constrained
wR(F2) = 0.110Δρmax = 0.42 e Å3
S = 1.02Δρmin = 0.29 e Å3
1426 reflectionsAbsolute structure: Flack (1983), with 522 Friedel pairs
110 parametersAbsolute structure parameter: 0.34 (3)
0 restraints
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
C10.6184 (11)0.2846 (8)0.3165 (3)0.070 (2)
H1A0.70330.32420.34030.084*
H1B0.52650.36380.31620.084*
C20.5583 (8)0.1138 (7)0.3317 (2)0.0528 (15)
C30.5627 (7)0.0588 (8)0.3896 (2)0.0568 (16)
H3A0.45920.00550.40010.068*
H3B0.58660.15190.41250.068*
C40.7069 (8)0.0648 (9)0.3875 (3)0.0639 (19)
H40.76110.08450.42100.077*
C50.6421 (9)0.2222 (9)0.3614 (3)0.0602 (16)
H50.55440.29080.37730.072*
C60.6362 (8)0.1761 (8)0.3068 (2)0.0570 (16)
H60.54400.21190.28440.068*
C70.6960 (7)0.0041 (8)0.3073 (2)0.0516 (15)
C80.7576 (10)0.1007 (9)0.2614 (3)0.071 (2)
H8A0.72200.04780.22940.085*
H8B0.87870.10710.26160.085*
O10.6858 (7)0.2648 (6)0.26597 (18)0.0793 (15)
O20.7611 (6)0.2926 (6)0.3246 (2)0.0738 (14)
O30.8157 (5)0.0030 (6)0.34874 (18)0.0660 (13)
Br10.34058 (9)0.07413 (11)0.29948 (3)0.0739 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.092 (6)0.059 (4)0.058 (4)0.005 (4)0.003 (4)0.007 (3)
C20.055 (3)0.057 (3)0.047 (3)0.006 (4)0.005 (3)0.007 (3)
C30.057 (4)0.074 (4)0.039 (3)0.014 (4)0.003 (3)0.005 (3)
C40.062 (4)0.086 (5)0.044 (4)0.001 (4)0.003 (3)0.016 (4)
C50.060 (4)0.065 (4)0.055 (4)0.003 (4)0.001 (3)0.014 (3)
C60.054 (4)0.058 (4)0.060 (4)0.010 (3)0.001 (3)0.005 (3)
C70.053 (3)0.060 (4)0.042 (3)0.000 (3)0.003 (3)0.009 (3)
C80.086 (5)0.069 (4)0.058 (4)0.004 (5)0.015 (4)0.016 (4)
O10.106 (4)0.067 (3)0.065 (3)0.003 (3)0.022 (3)0.014 (3)
O20.075 (3)0.070 (3)0.076 (3)0.022 (3)0.011 (3)0.017 (3)
O30.052 (2)0.089 (3)0.057 (3)0.010 (3)0.002 (2)0.013 (2)
Br10.0620 (4)0.0834 (6)0.0764 (5)0.0113 (4)0.0173 (4)0.0136 (4)
Geometric parameters (Å, º) top
C1—O11.418 (8)C4—H40.9800
C1—C21.501 (9)C5—C61.458 (9)
C1—H1A0.9700C5—O21.459 (9)
C1—H1B0.9700C5—H50.9800
C2—C71.542 (9)C6—O21.441 (8)
C2—C31.556 (8)C6—C71.518 (9)
C2—Br11.956 (6)C6—H60.9800
C3—C41.519 (8)C7—O31.435 (7)
C3—H3A0.9700C7—C81.498 (9)
C3—H3B0.9700C8—O11.437 (9)
C4—O31.431 (7)C8—H8A0.9700
C4—C51.518 (10)C8—H8B0.9700
O1—C1—C2105.1 (5)O2—C5—C4112.7 (6)
O1—C1—H1A110.7C6—C5—H5121.6
C2—C1—H1A110.7O2—C5—H5121.6
O1—C1—H1B110.7C4—C5—H5121.6
C2—C1—H1B110.7O2—C6—C560.4 (4)
H1A—C1—H1B108.8O2—C6—C7113.1 (5)
C1—C2—C7100.5 (5)C5—C6—C7102.8 (5)
C1—C2—C3120.1 (5)O2—C6—H6121.4
C7—C2—C3102.4 (5)C5—C6—H6121.4
C1—C2—Br1108.7 (5)C7—C6—H6121.4
C7—C2—Br1111.7 (4)O3—C7—C8111.9 (6)
C3—C2—Br1112.5 (4)O3—C7—C6102.2 (5)
C4—C3—C299.6 (5)C8—C7—C6125.9 (6)
C4—C3—H3A111.9O3—C7—C2100.1 (5)
C2—C3—H3A111.9C8—C7—C2105.3 (5)
C4—C3—H3B111.9C6—C7—C2108.6 (5)
C2—C3—H3B111.9O1—C8—C7105.9 (6)
H3A—C3—H3B109.6O1—C8—H8A110.5
O3—C4—C5102.3 (6)C7—C8—H8A110.5
O3—C4—C3103.9 (5)O1—C8—H8B110.5
C5—C4—C3107.2 (5)C7—C8—H8B110.5
O3—C4—H4114.1H8A—C8—H8B108.7
C5—C4—H4114.1C1—O1—C8109.2 (5)
C3—C4—H4114.1C6—O2—C560.4 (4)
C6—C5—O259.2 (4)C4—O3—C796.7 (4)
C6—C5—C4103.3 (6)
O1—C1—C2—C737.0 (7)C1—C2—C7—O387.4 (5)
O1—C1—C2—C3148.2 (6)C3—C2—C7—O336.9 (6)
O1—C1—C2—Br180.3 (6)Br1—C2—C7—O3157.5 (4)
C1—C2—C3—C4107.5 (7)C1—C2—C7—C828.8 (7)
C7—C2—C3—C42.6 (6)C3—C2—C7—C8153.1 (6)
Br1—C2—C3—C4122.6 (5)Br1—C2—C7—C886.3 (6)
C2—C3—C4—O333.0 (6)C1—C2—C7—C6166.0 (5)
C2—C3—C4—C574.8 (6)C3—C2—C7—C669.7 (6)
O3—C4—C5—C632.7 (6)Br1—C2—C7—C650.9 (6)
C3—C4—C5—C676.2 (6)O3—C7—C8—O197.0 (7)
O3—C4—C5—O229.1 (7)C6—C7—C8—O1138.2 (6)
C3—C4—C5—O2138.1 (5)C2—C7—C8—O110.8 (8)
C4—C5—C6—O2108.7 (6)C2—C1—O1—C832.6 (8)
O2—C5—C6—C7109.5 (5)C7—C8—O1—C113.2 (8)
C4—C5—C6—C70.8 (6)C7—C6—O2—C591.9 (6)
O2—C6—C7—O329.0 (6)C4—C5—O2—C692.3 (6)
C5—C6—C7—O334.1 (6)C5—C4—O3—C753.5 (6)
O2—C6—C7—C899.9 (7)C3—C4—O3—C758.0 (6)
C5—C6—C7—C8162.9 (6)C8—C7—O3—C4168.7 (6)
O2—C6—C7—C2134.1 (5)C6—C7—O3—C454.1 (5)
C5—C6—C7—C271.1 (6)C2—C7—O3—C457.6 (5)

Experimental details

Crystal data
Chemical formulaC8H9BrO3
Mr233.06
Crystal system, space groupTetragonal, P41212
Temperature (K)293
a, c (Å)7.9963 (8), 25.793 (4)
V3)1649.2 (3)
Z8
Radiation typeMo Kα
µ (mm1)4.95
Crystal size (mm)0.78 × 0.65 × 0.46
Data collection
DiffractometerStoe IPDS 2
Absorption correctionIntegration
(X-RED; Stoe & Cie, 2002)
Tmin, Tmax0.059, 0.157
No. of measured, independent and
observed [I > 2σ(I)] reflections
5824, 1426, 1117
Rint0.143
(sin θ/λ)max1)0.593
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.045, 0.110, 1.02
No. of reflections1426
No. of parameters110
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.42, 0.29
Absolute structureFlack (1983), with 522 Friedel pairs
Absolute structure parameter0.34 (3)

Computer programs: X-AREA (Stoe & Cie, 2002), X-AREA, X-RED (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

 

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