Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801005505/tk6010sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801005505/tk6010Isup2.hkl |
CCDC reference: 165652
To a refluxing suspension of sodium hydride (15.2 mmol) in THF under nitrogen was added dropwise a solution of α,α'-dibromo-o-xylene (3.79 mmol) and 1,5-bis(2-hydroxyphenoxy)-3-oxapentane (3.79 mmol) in THF over a period of 3 h. The mixture was then refluxed for an additional 24 h. After cooling to room temperature, 10% aqueous hydrochloric acid was added. The solvent was removed under reduced pressure and the residual mixture was extracted with dichloromethane. The organic layer was washed with water, dried over anhydrous magnesium sulfate, and evaporated in vacuo. The crude product was chromatographed on a silica-gel column using a mixed solvent of ethyl acetate and n-hexane (1:1) as eluent, and recrystallization from dichloromethane/n-hexane (1:20, v/v) gave (II) as a crystalline solid in 72% yield (m.p. 398–400 K). IR (KBr pellet) 3065, 2880, 1596, 1498, 1258, 1119, 949 and 741 cm-1. 1H NMR (CDCl3): δ 7.65–7.39 (m, 4H, Ar—H), 7.10–6.88 (m, 8H, Ar—H), 5.31 (s, 4H, OCH2Ar), 4.20 (t, 4H, OCH2CH2O) and 3.92 (t, 4H, OCH2CH2O).
C4 was disordered over two positions and their sites were refined anisotropically using the PART command in SHELXL97 (Sheldrick, 1997). All H atoms were located in their idealized positions with Uiso constrained to be 1.2 times the equivalent isotropic displacement of the parent atoms. The number of Friedel pairs measured is 180 and the fraction of Friedel pairs measured is 0.113. As there are no heavy-atom, i.e. Z > Si, types present, the absolute structure was not determined.
Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
C24H24O5 | Dx = 1.278 Mg m−3 |
Mr = 392.43 | Mo Kα radiation, λ = 0.71069 Å |
Orthorhombic, Cmc21 | Cell parameters from 20 reflections |
a = 21.585 (4) Å | θ = 11.4–14.1° |
b = 11.675 (3) Å | µ = 0.09 mm−1 |
c = 8.092 (2) Å | T = 293 K |
V = 2039.3 (8) Å3 | Block, colorless |
Z = 4 | 0.37 × 0.25 × 0.20 mm |
F(000) = 832 |
Enraf-Nonius CAD-4 diffractometer | Rint = 0.011 |
Radiation source: fine-focus sealed tube | θmax = 30.0°, θmin = 3.2° |
Graphite monochromator | h = 0→30 |
non–profiled ω/2θ scans | k = 0→16 |
1650 measured reflections | l = −11→5 |
1597 independent reflections | 3 standard reflections every 300 min |
708 reflections with I > 2σ(I) | intensity decay: 1% |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.045 | w = 1/[σ2(Fo2) + (0.036P)2 + 0.0439P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.107 | (Δ/σ)max < 0.001 |
S = 0.98 | Δρmax = 0.11 e Å−3 |
1597 reflections | Δρmin = −0.14 e Å−3 |
144 parameters | Extinction correction: SHELXL97, Fc*kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
1 restraint | Extinction coefficient: 0.0098 (9) |
Primary atom site location: structure-invariant direct methods | Absolute structure: Flack (1983) |
Secondary atom site location: difference Fourier map | Absolute structure parameter: 0 (3) |
C24H24O5 | V = 2039.3 (8) Å3 |
Mr = 392.43 | Z = 4 |
Orthorhombic, Cmc21 | Mo Kα radiation |
a = 21.585 (4) Å | µ = 0.09 mm−1 |
b = 11.675 (3) Å | T = 293 K |
c = 8.092 (2) Å | 0.37 × 0.25 × 0.20 mm |
Enraf-Nonius CAD-4 diffractometer | Rint = 0.011 |
1650 measured reflections | 3 standard reflections every 300 min |
1597 independent reflections | intensity decay: 1% |
708 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.045 | H-atom parameters constrained |
wR(F2) = 0.107 | Δρmax = 0.11 e Å−3 |
S = 0.98 | Δρmin = −0.14 e Å−3 |
1597 reflections | Absolute structure: Flack (1983) |
144 parameters | Absolute structure parameter: 0 (3) |
1 restraint |
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 | Occ. (<1) | |
C1 | 0.9687 (2) | 0.8209 (4) | −0.6581 (7) | 0.0934 (19) | |
H1 | 0.9468 | 0.8125 | −0.7563 | 0.112* | |
C2 | 0.9388 (2) | 0.8332 (4) | −0.5134 (9) | 0.0940 (18) | |
H2 | 0.8957 | 0.8322 | −0.5133 | 0.113* | |
C3 | 0.96910 (19) | 0.8471 (4) | −0.3669 (5) | 0.0692 (15) | |
C4 | 0.9173 (5) | 0.8819 (7) | −0.2460 (12) | 0.090 (3) | 0.58 |
H4A | 0.9328 | 0.9384 | −0.1683 | 0.108* | 0.58 |
H4B | 0.8830 | 0.9154 | −0.3062 | 0.108* | 0.58 |
C4' | 0.9518 (5) | 0.8372 (12) | −0.1759 (15) | 0.061 (3) | 0.42 |
H4A' | 0.9832 | 0.7931 | −0.1182 | 0.073* | 0.42 |
H4B' | 0.9499 | 0.9129 | −0.1267 | 0.073* | 0.42 |
C5 | 0.8552 (2) | 0.8064 (5) | −0.0406 (6) | 0.0649 (12) | |
C6 | 0.8196 (2) | 0.9030 (4) | −0.0356 (7) | 0.0818 (15) | |
H6 | 0.8257 | 0.9608 | −0.1130 | 0.098* | |
C7 | 0.7743 (2) | 0.9148 (5) | 0.0850 (9) | 0.111 (2) | |
H7 | 0.7501 | 0.9806 | 0.0883 | 0.134* | |
C8 | 0.7653 (3) | 0.8303 (7) | 0.1983 (9) | 0.123 (2) | |
H8 | 0.7348 | 0.8381 | 0.2786 | 0.148* | |
C9 | 0.8015 (3) | 0.7334 (6) | 0.1934 (7) | 0.0992 (17) | |
H9 | 0.7952 | 0.6760 | 0.2714 | 0.119* | |
C10 | 0.8471 (2) | 0.7196 (5) | 0.0747 (6) | 0.0697 (13) | |
C11 | 0.8905 (2) | 0.5526 (4) | 0.2021 (7) | 0.0989 (16) | |
H11A | 0.8534 | 0.5065 | 0.2138 | 0.119* | |
H11B | 0.8960 | 0.5976 | 0.3018 | 0.119* | |
C12 | 0.9458 (2) | 0.4774 (4) | 0.1736 (7) | 0.0974 (17) | |
H12A | 0.9462 | 0.4155 | 0.2535 | 0.117* | |
H12B | 0.9440 | 0.4444 | 0.0637 | 0.117* | |
O1 | 0.89803 (19) | 0.7865 (3) | −0.1631 (4) | 0.0840 (10) | |
O2 | 0.88555 (14) | 0.6266 (3) | 0.0595 (4) | 0.0818 (10) | |
O3 | 1.0000 | 0.5450 (3) | 0.1905 (6) | 0.0758 (12) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.144 (6) | 0.070 (3) | 0.066 (3) | 0.013 (3) | −0.047 (4) | −0.005 (3) |
C2 | 0.057 (3) | 0.089 (4) | 0.136 (6) | 0.000 (3) | −0.002 (4) | −0.041 (4) |
C3 | 0.087 (4) | 0.052 (3) | 0.069 (3) | −0.017 (2) | 0.021 (3) | −0.017 (2) |
C4 | 0.115 (9) | 0.062 (6) | 0.094 (8) | 0.027 (6) | 0.045 (7) | 0.005 (5) |
C4' | 0.052 (8) | 0.076 (8) | 0.056 (8) | 0.033 (7) | −0.002 (7) | −0.007 (7) |
C5 | 0.063 (3) | 0.077 (4) | 0.054 (3) | −0.009 (3) | 0.006 (3) | −0.011 (3) |
C6 | 0.080 (4) | 0.087 (4) | 0.078 (4) | 0.006 (3) | 0.001 (3) | −0.012 (3) |
C7 | 0.074 (4) | 0.144 (6) | 0.117 (5) | 0.010 (4) | 0.018 (4) | −0.042 (5) |
C8 | 0.078 (5) | 0.187 (7) | 0.105 (5) | −0.008 (5) | 0.027 (5) | −0.033 (6) |
C9 | 0.074 (4) | 0.147 (5) | 0.077 (4) | −0.031 (4) | 0.021 (4) | 0.005 (4) |
C10 | 0.067 (3) | 0.088 (4) | 0.054 (3) | −0.011 (3) | 0.000 (3) | −0.003 (3) |
C11 | 0.120 (4) | 0.101 (4) | 0.076 (4) | −0.040 (3) | −0.016 (4) | 0.039 (4) |
C12 | 0.164 (5) | 0.053 (3) | 0.076 (4) | −0.033 (4) | −0.027 (4) | 0.018 (3) |
O1 | 0.104 (3) | 0.067 (2) | 0.081 (2) | −0.0027 (19) | 0.043 (2) | 0.007 (2) |
O2 | 0.099 (2) | 0.091 (2) | 0.0552 (19) | −0.009 (2) | 0.006 (2) | 0.015 (2) |
O3 | 0.101 (3) | 0.048 (2) | 0.079 (3) | 0.000 | 0.000 | 0.000 (3) |
C1—C2 | 1.345 (6) | C5—C10 | 1.389 (5) |
C1—C1i | 1.349 (9) | C6—C7 | 1.388 (7) |
C2—C3 | 1.363 (6) | C7—C8 | 1.361 (7) |
C3—C3i | 1.334 (8) | C8—C9 | 1.375 (6) |
C3—C4 | 1.540 (8) | C9—C10 | 1.385 (6) |
C3—C4' | 1.594 (13) | C10—O2 | 1.372 (5) |
C4—O1 | 1.366 (9) | C11—O2 | 1.445 (5) |
C4'—O1 | 1.307 (11) | C11—C12 | 1.498 (6) |
C5—C6 | 1.365 (6) | C12—O3 | 1.418 (4) |
C5—O1 | 1.375 (5) | O3—C12i | 1.418 (4) |
C2—C1—C1i | 118.7 (3) | C8—C7—C6 | 120.1 (6) |
C1—C2—C3 | 122.6 (5) | C7—C8—C9 | 119.7 (6) |
C3i—C3—C2 | 118.6 (3) | C8—C9—C10 | 121.3 (6) |
C3i—C3—C4 | 136.5 (5) | O2—C10—C9 | 125.7 (6) |
C2—C3—C4 | 103.7 (6) | O2—C10—C5 | 116.2 (5) |
C3i—C3—C4' | 103.5 (4) | C9—C10—C5 | 118.1 (5) |
C2—C3—C4' | 136.2 (6) | O2—C11—C12 | 106.7 (5) |
C4—C3—C4' | 39.9 (4) | O3—C12—C11 | 108.5 (3) |
O1—C4—C3 | 108.6 (5) | C4'—O1—C4 | 47.2 (5) |
O1—C4'—C3 | 108.5 (8) | C4'—O1—C5 | 125.3 (6) |
C6—C5—O1 | 122.7 (5) | C4—O1—C5 | 114.9 (5) |
C6—C5—C10 | 120.8 (5) | C10—O2—C11 | 116.5 (4) |
O1—C5—C10 | 116.5 (5) | C12i—O3—C12 | 111.3 (5) |
C5—C6—C7 | 120.0 (5) | ||
C1i—C1—C2—C3 | 0.8 (7) | C6—C5—C10—O2 | −179.6 (4) |
C1—C2—C3—C3i | −0.8 (7) | O1—C5—C10—O2 | 4.0 (5) |
C1—C2—C3—C4 | 168.8 (6) | C6—C5—C10—C9 | 0.6 (6) |
C1—C2—C3—C4' | −163.7 (8) | O1—C5—C10—C9 | −175.8 (4) |
C3i—C3—C4—O1 | −96.6 (8) | O2—C11—C12—O3 | 71.7 (5) |
C2—C3—C4—O1 | 96.8 (8) | C3—C4'—O1—C4 | −55.8 (7) |
C4'—C3—C4—O1 | −53.4 (8) | C3—C4'—O1—C5 | −148.6 (5) |
C3i—C3—C4'—O1 | −152.0 (7) | C3—C4—O1—C4' | 58.9 (8) |
C2—C3—C4'—O1 | 12.6 (14) | C3—C4—O1—C5 | 174.9 (5) |
C4—C3—C4'—O1 | 57.0 (7) | C6—C5—O1—C4' | 74.6 (10) |
O1—C5—C6—C7 | 175.7 (4) | C10—C5—O1—C4' | −109.0 (9) |
C10—C5—C6—C7 | −0.5 (6) | C6—C5—O1—C4 | 20.7 (8) |
C5—C6—C7—C8 | −0.1 (8) | C10—C5—O1—C4 | −163.0 (7) |
C6—C7—C8—C9 | 0.4 (10) | C9—C10—O2—C11 | −17.6 (6) |
C7—C8—C9—C10 | −0.2 (9) | C5—C10—O2—C11 | 162.6 (3) |
C8—C9—C10—O2 | 179.9 (5) | C12—C11—O2—C10 | −165.7 (3) |
C8—C9—C10—C5 | −0.3 (7) | C11—C12—O3—C12i | 176.9 (3) |
Symmetry code: (i) −x+2, y, z. |
Experimental details
Crystal data | |
Chemical formula | C24H24O5 |
Mr | 392.43 |
Crystal system, space group | Orthorhombic, Cmc21 |
Temperature (K) | 293 |
a, b, c (Å) | 21.585 (4), 11.675 (3), 8.092 (2) |
V (Å3) | 2039.3 (8) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.37 × 0.25 × 0.20 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1650, 1597, 708 |
Rint | 0.011 |
(sin θ/λ)max (Å−1) | 0.702 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.107, 0.98 |
No. of reflections | 1597 |
No. of parameters | 144 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.11, −0.14 |
Absolute structure | Flack (1983) |
Absolute structure parameter | 0 (3) |
Computer programs: CAD-4 EXPRESS (Enraf-Nonius, 1994), CAD-4 EXPRESS, XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), WinGX (Farrugia, 1999).
Since the first report on crown ethers (Pedersen, 1967), a great number of crown compounds containing one or more aromatic subunits have been investigated (Gokel & Korzeniowski, 1982; Izatt & Christensen, 1978, 1979, 1981; Vögtle & Weber, 1985; Lindoy, 1989; Weber et al., 1989). A number of crown compounds bearing two macrocyclic polyether rings within the molecule, which are referred to as biscrowns, have also been synthesized (Timko et al., 1974; Frensch & Vögtle, 1979; Rebek et al., 1980; Lee et al., 1992). In our previous paper, we reported the preparation of a new crown ether, (I), and its solid-state structure, which could be a precursor of the common-nuclear biscrown ether, bearing a benzene ring (Sim et al., 2001).
We now report a new preparation of crown ether (II) and its solid-state structure, which is the parent crown ether unit of (I). The preparation of (II) has been reported by Weber and Vögtle (1976), but the yield was rather low when KOH with dimethylformamide (DMF) was used. Therefore, alternative reaction conditions were examined so as to optimize the cyclization yield. In the reaction of α,α'-dibromo-o-xylene with 1,5-bis(2-hydroxyphenoxy)-3-oxapentane, the use of n-BuLi with tetrahydrofuran (THF) gave a 65% yield. Sodium hydride and THF provided a 72% yield but potassium tert-butoxide with THF gave only a moderate 50% yield. Herein, we report the optimized reaction conditions (sodium hydride and THF) for (II), as well as its solid-state structure.
Compound (II), with the atomic labelling scheme, is shown in Fig. 1. There is crystallographic mirror symmetry in (II) so that half a molecule comprises the asymmetric unit. In the diethylene glycol chain-bridging benzo groups B and B', the C10—O2—C11 [116.5 (4)°] and C12—O3—-C12i [111.3 (5)°] angles are slightly greater than tetrahedral, while the O2—C11—C12 [106.7 (5)°] and O3—C12—C11 [108.5 (3)°] angles are very close to tetrahedral [symmetry operation: (i) 2 - x, y, z]. The dihedral angle between rings B and B' is 83.4 (1)°. In the A-to-B ring connectivity, the C3—C4—O1—C5 torsion angle is 174.9 (5)° [for the minor component of the disorder associated with C4, C3—C4'—O1—C5 is -148.6 (5)°] which indicates that ring A is situated trans to ring B, with a dihedral angle of 69.2 (1)° between them. In the diethylene glycol group, the O—C—C—O and two C—O—O—C torsion angles are gauche and trans, respectively, as there is one extra atom in the diethylene glycol backbone. All these conformations are very similar to those found in (I) (Sim et al., 2001). The interatomic distances O1···O3 of 4.580 (5) Å, O1···O2i of 5.344 (5) Å and O2···O2i of 4.941 (6) Å suggest sufficient room for the introduction of a guest atom/molecule inside the cavity. The closest intermolecular distance of 2.41 Å occurs between H11b and H12bii which suggests that the molecular packing is governed by van der Waals forces [symmetry operation: (ii) x, 1 - y, 0.5 + z].