Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807037233/bt2437sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807037233/bt2437Isup2.hkl |
CCDC reference: 660199
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.
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).
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).
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).
Fig. 1. The molecular structure of the title compound, with atom labels and 30% probability displacement ellipsoids for non-H atoms. |
C8H9BrO3 | Dx = 1.877 Mg m−3 |
Mr = 233.06 | Mo Kα radiation, λ = 0.71073 Å |
Tetragonal, P41212 | Cell parameters from 8780 reflections |
Hall symbol: P 4abw 2nw | θ = 2.6–25.0° |
a = 7.9963 (8) Å | µ = 4.95 mm−1 |
c = 25.793 (4) Å | T = 293 K |
V = 1649.2 (3) Å3 | Block, colourless |
Z = 8 | 0.78 × 0.65 × 0.46 mm |
F(000) = 928 |
Stoe IPDS 2 diffractometer | 1426 independent reflections |
Radiation source: fine-focus sealed tube | 1117 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.143 |
Detector resolution: 6.67 pixels mm-1 | θmax = 24.9°, θmin = 2.7° |
ω scans | h = −9→9 |
Absorption correction: integration (X-RED; Stoe & Cie, 2002) | k = −9→8 |
Tmin = 0.059, Tmax = 0.157 | l = −19→30 |
5824 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)] = 0.045 | H-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 reflections | Δρmax = 0.42 e Å−3 |
110 parameters | Δρmin = −0.29 e Å−3 |
0 restraints | Absolute structure: Flack (1983), with 522 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.34 (3) |
C8H9BrO3 | Z = 8 |
Mr = 233.06 | Mo Kα radiation |
Tetragonal, P41212 | µ = 4.95 mm−1 |
a = 7.9963 (8) Å | T = 293 K |
c = 25.793 (4) Å | 0.78 × 0.65 × 0.46 mm |
V = 1649.2 (3) Å3 |
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 = 0.157 | Rint = 0.143 |
5824 measured reflections |
R[F2 > 2σ(F2)] = 0.045 | H-atom parameters constrained |
wR(F2) = 0.110 | Δρmax = 0.42 e Å−3 |
S = 1.02 | Δρmin = −0.29 e Å−3 |
1426 reflections | Absolute structure: Flack (1983), with 522 Friedel pairs |
110 parameters | Absolute structure parameter: 0.34 (3) |
0 restraints |
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 | 0.6184 (11) | −0.2846 (8) | 0.3165 (3) | 0.070 (2) | |
H1A | 0.7033 | −0.3242 | 0.3403 | 0.084* | |
H1B | 0.5265 | −0.3638 | 0.3162 | 0.084* | |
C2 | 0.5583 (8) | −0.1138 (7) | 0.3317 (2) | 0.0528 (15) | |
C3 | 0.5627 (7) | −0.0588 (8) | 0.3896 (2) | 0.0568 (16) | |
H3A | 0.4592 | −0.0055 | 0.4001 | 0.068* | |
H3B | 0.5866 | −0.1519 | 0.4125 | 0.068* | |
C4 | 0.7069 (8) | 0.0648 (9) | 0.3875 (3) | 0.0639 (19) | |
H4 | 0.7611 | 0.0845 | 0.4210 | 0.077* | |
C5 | 0.6421 (9) | 0.2222 (9) | 0.3614 (3) | 0.0602 (16) | |
H5 | 0.5544 | 0.2908 | 0.3773 | 0.072* | |
C6 | 0.6362 (8) | 0.1761 (8) | 0.3068 (2) | 0.0570 (16) | |
H6 | 0.5440 | 0.2119 | 0.2844 | 0.068* | |
C7 | 0.6960 (7) | −0.0041 (8) | 0.3073 (2) | 0.0516 (15) | |
C8 | 0.7576 (10) | −0.1007 (9) | 0.2614 (3) | 0.071 (2) | |
H8A | 0.7220 | −0.0478 | 0.2294 | 0.085* | |
H8B | 0.8787 | −0.1071 | 0.2616 | 0.085* | |
O1 | 0.6858 (7) | −0.2648 (6) | 0.26597 (18) | 0.0793 (15) | |
O2 | 0.7611 (6) | 0.2926 (6) | 0.3246 (2) | 0.0738 (14) | |
O3 | 0.8157 (5) | −0.0030 (6) | 0.34874 (18) | 0.0660 (13) | |
Br1 | 0.34058 (9) | −0.07413 (11) | 0.29948 (3) | 0.0739 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.092 (6) | 0.059 (4) | 0.058 (4) | 0.005 (4) | −0.003 (4) | 0.007 (3) |
C2 | 0.055 (3) | 0.057 (3) | 0.047 (3) | 0.006 (4) | −0.005 (3) | 0.007 (3) |
C3 | 0.057 (4) | 0.074 (4) | 0.039 (3) | 0.014 (4) | 0.003 (3) | 0.005 (3) |
C4 | 0.062 (4) | 0.086 (5) | 0.044 (4) | 0.001 (4) | −0.003 (3) | −0.016 (4) |
C5 | 0.060 (4) | 0.065 (4) | 0.055 (4) | −0.003 (4) | 0.001 (3) | −0.014 (3) |
C6 | 0.054 (4) | 0.058 (4) | 0.060 (4) | −0.010 (3) | −0.001 (3) | 0.005 (3) |
C7 | 0.053 (3) | 0.060 (4) | 0.042 (3) | 0.000 (3) | 0.003 (3) | −0.009 (3) |
C8 | 0.086 (5) | 0.069 (4) | 0.058 (4) | −0.004 (5) | 0.015 (4) | −0.016 (4) |
O1 | 0.106 (4) | 0.067 (3) | 0.065 (3) | −0.003 (3) | 0.022 (3) | −0.014 (3) |
O2 | 0.075 (3) | 0.070 (3) | 0.076 (3) | −0.022 (3) | 0.011 (3) | −0.017 (3) |
O3 | 0.052 (2) | 0.089 (3) | 0.057 (3) | 0.010 (3) | −0.002 (2) | −0.013 (2) |
Br1 | 0.0620 (4) | 0.0834 (6) | 0.0764 (5) | −0.0113 (4) | −0.0173 (4) | 0.0136 (4) |
C1—O1 | 1.418 (8) | C4—H4 | 0.9800 |
C1—C2 | 1.501 (9) | C5—C6 | 1.458 (9) |
C1—H1A | 0.9700 | C5—O2 | 1.459 (9) |
C1—H1B | 0.9700 | C5—H5 | 0.9800 |
C2—C7 | 1.542 (9) | C6—O2 | 1.441 (8) |
C2—C3 | 1.556 (8) | C6—C7 | 1.518 (9) |
C2—Br1 | 1.956 (6) | C6—H6 | 0.9800 |
C3—C4 | 1.519 (8) | C7—O3 | 1.435 (7) |
C3—H3A | 0.9700 | C7—C8 | 1.498 (9) |
C3—H3B | 0.9700 | C8—O1 | 1.437 (9) |
C4—O3 | 1.431 (7) | C8—H8A | 0.9700 |
C4—C5 | 1.518 (10) | C8—H8B | 0.9700 |
O1—C1—C2 | 105.1 (5) | O2—C5—C4 | 112.7 (6) |
O1—C1—H1A | 110.7 | C6—C5—H5 | 121.6 |
C2—C1—H1A | 110.7 | O2—C5—H5 | 121.6 |
O1—C1—H1B | 110.7 | C4—C5—H5 | 121.6 |
C2—C1—H1B | 110.7 | O2—C6—C5 | 60.4 (4) |
H1A—C1—H1B | 108.8 | O2—C6—C7 | 113.1 (5) |
C1—C2—C7 | 100.5 (5) | C5—C6—C7 | 102.8 (5) |
C1—C2—C3 | 120.1 (5) | O2—C6—H6 | 121.4 |
C7—C2—C3 | 102.4 (5) | C5—C6—H6 | 121.4 |
C1—C2—Br1 | 108.7 (5) | C7—C6—H6 | 121.4 |
C7—C2—Br1 | 111.7 (4) | O3—C7—C8 | 111.9 (6) |
C3—C2—Br1 | 112.5 (4) | O3—C7—C6 | 102.2 (5) |
C4—C3—C2 | 99.6 (5) | C8—C7—C6 | 125.9 (6) |
C4—C3—H3A | 111.9 | O3—C7—C2 | 100.1 (5) |
C2—C3—H3A | 111.9 | C8—C7—C2 | 105.3 (5) |
C4—C3—H3B | 111.9 | C6—C7—C2 | 108.6 (5) |
C2—C3—H3B | 111.9 | O1—C8—C7 | 105.9 (6) |
H3A—C3—H3B | 109.6 | O1—C8—H8A | 110.5 |
O3—C4—C5 | 102.3 (6) | C7—C8—H8A | 110.5 |
O3—C4—C3 | 103.9 (5) | O1—C8—H8B | 110.5 |
C5—C4—C3 | 107.2 (5) | C7—C8—H8B | 110.5 |
O3—C4—H4 | 114.1 | H8A—C8—H8B | 108.7 |
C5—C4—H4 | 114.1 | C1—O1—C8 | 109.2 (5) |
C3—C4—H4 | 114.1 | C6—O2—C5 | 60.4 (4) |
C6—C5—O2 | 59.2 (4) | C4—O3—C7 | 96.7 (4) |
C6—C5—C4 | 103.3 (6) | ||
O1—C1—C2—C7 | −37.0 (7) | C1—C2—C7—O3 | −87.4 (5) |
O1—C1—C2—C3 | −148.2 (6) | C3—C2—C7—O3 | 36.9 (6) |
O1—C1—C2—Br1 | 80.3 (6) | Br1—C2—C7—O3 | 157.5 (4) |
C1—C2—C3—C4 | 107.5 (7) | C1—C2—C7—C8 | 28.8 (7) |
C7—C2—C3—C4 | −2.6 (6) | C3—C2—C7—C8 | 153.1 (6) |
Br1—C2—C3—C4 | −122.6 (5) | Br1—C2—C7—C8 | −86.3 (6) |
C2—C3—C4—O3 | −33.0 (6) | C1—C2—C7—C6 | 166.0 (5) |
C2—C3—C4—C5 | 74.8 (6) | C3—C2—C7—C6 | −69.7 (6) |
O3—C4—C5—C6 | 32.7 (6) | Br1—C2—C7—C6 | 50.9 (6) |
C3—C4—C5—C6 | −76.2 (6) | O3—C7—C8—O1 | 97.0 (7) |
O3—C4—C5—O2 | −29.1 (7) | C6—C7—C8—O1 | −138.2 (6) |
C3—C4—C5—O2 | −138.1 (5) | C2—C7—C8—O1 | −10.8 (8) |
C4—C5—C6—O2 | −108.7 (6) | C2—C1—O1—C8 | 32.6 (8) |
O2—C5—C6—C7 | 109.5 (5) | C7—C8—O1—C1 | −13.2 (8) |
C4—C5—C6—C7 | 0.8 (6) | C7—C6—O2—C5 | −91.9 (6) |
O2—C6—C7—O3 | 29.0 (6) | C4—C5—O2—C6 | 92.3 (6) |
C5—C6—C7—O3 | −34.1 (6) | C5—C4—O3—C7 | −53.5 (6) |
O2—C6—C7—C8 | −99.9 (7) | C3—C4—O3—C7 | 58.0 (6) |
C5—C6—C7—C8 | −162.9 (6) | C8—C7—O3—C4 | −168.7 (6) |
O2—C6—C7—C2 | 134.1 (5) | C6—C7—O3—C4 | 54.1 (5) |
C5—C6—C7—C2 | 71.1 (6) | C2—C7—O3—C4 | −57.6 (5) |
Experimental details
Crystal data | |
Chemical formula | C8H9BrO3 |
Mr | 233.06 |
Crystal system, space group | Tetragonal, P41212 |
Temperature (K) | 293 |
a, c (Å) | 7.9963 (8), 25.793 (4) |
V (Å3) | 1649.2 (3) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 4.95 |
Crystal size (mm) | 0.78 × 0.65 × 0.46 |
Data collection | |
Diffractometer | Stoe IPDS 2 |
Absorption correction | Integration (X-RED; Stoe & Cie, 2002) |
Tmin, Tmax | 0.059, 0.157 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5824, 1426, 1117 |
Rint | 0.143 |
(sin θ/λ)max (Å−1) | 0.593 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.110, 1.02 |
No. of reflections | 1426 |
No. of parameters | 110 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.42, −0.29 |
Absolute structure | Flack (1983), with 522 Friedel pairs |
Absolute structure parameter | 0.34 (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).
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).