organic compounds
rac-(E,trans)-4-Bromo-10,10-dimethyl-9,11-dioxabicyclo[6.3.0]undec-4-ene
aJohannes Gutenberg University Mainz, Department of Chemistry, Duesbergweg 10-14, 55099 Mainz, Germany
*Correspondence e-mail: detert@uni-mainz.de
In the title compound, a cyclooctene ring in a twist-boat conformation and a dioxolane ring with a distorted trans configuration. Alternating strands of single enantiomers build up the crystal. Within the strands, the molecules are connected by weak C—H⋯O hydrogen bonds.
are annulated in aKeywords: crystal structure; heterocycles; medium-sized ring; bromine.
CCDC reference: 2033919
Structure description
The title compound (Fig. 1) crystallizes as a of R,R- and S,S-enantiomers forming strands of identical enantiomers along the b-axis direction (Fig. 2). The molecules in the strands are connected via weak C—H⋯O contacts (H7B⋯O9 2.586 Å). A center of inversion relates these molecules with their enantiomeric counterparts in the parallel strands. The eight-membered ring features a twist-boat conformation. It is annulated to a dioxolane ring in a distorted Within this envelope, atoms C4, C5, O11, and C10 are essentially coplanar (r.m.s. deviation 0.017 Å) but O9 lies 0.477 (2) Å below the mean plane. The cyclooctene part has two planar moieties: one is the olefinic part (C2—C1—C8—C7), the other one [planar within 0.034 (2) Å] is composed of the four methylene groups (C3—C2—C7—C6); these planes subtend a dihedral angle of 69.3 (2)°. A trans-ethylene bridge (C4,C5) connects the rings; atom C4 lies 0.357 (5) Å above the central plane of the cyclooctene moiety while C5 is positioned 0.541 (5) Å below this plane.
Synthesis and crystallization
The title compound was prepared in two steps from 4-bromo-9-oxabicyclo[6.1.0]non-4-ene (Mayer & Meier, 1989) via hydrolysis of the epoxide to the trans-diol in alkaline (pH 10) water/dioxane (1/4) [1H NMR: 6.02 (t, 1H), 3.58 (m, 2 H), 3.17 (s, 2 H, OH), 2.81 (ddd, 1 H), 2.58 (ddd, 1 H), 2.0–2.33 (m, 4 H), 1.58 (m, 12 H); IR: (KBr): 3320, 2918, 1635, 1450, 1430, 1040, 980) and cetalization with 2,2-dimethoxypropane. Alternatively, it may be prepared, more conveniently, from 10,10-dimethyl-9,11-dioxabicyclo[6.3.0]undec-4-ene (Golding et al., 1980) via bromination (Takahashi et al., 2000) and dehydrobromination with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Procedure: DBU (6 ml) was added to 4,5-dibromo-10,10-dimethyl-9,11-dioxabicyclo[6.3.0]undec-4-ene (8.92 g, 0.026 mol) in toluene (20 ml) and the mixture was stirred for 72 h. After filtration, the organic layer was washed with water (3 × 20 ml), brine, and dried over MgSO4. The solvent was evaporated in vacuo and the residue purified by on silica (cyclohexane/ethyl acetate 40/1) to give the title compound as a yellowish oil in 88% yield (5.98 g). Crystallization from ethanol solution yielded colorless crystals, m.p. 313 K.
Spectroscopic data: 1H NMR (CDCl3): 6.03 (t, J = 8.2 Hz, 1 H), 3.88 (m, 2 H), 2.76 (ddd, J = 15.1 Hz, J′ = 10.4 Hz, J′′ = 10.2 Hz), 1 H), 2.54 (ddd, J = 14.7 Hz, J = 6.6 Hz, J′′ = 3.9 Hz, 1 H), 2.30 (m, 1 H), 2.16 (m, 3H), 1.55 (m, 2H), 1.38 (s, 3H), 1.37 (s, 3H). 13C NMR: 130.6 (CH), 124.0 (C—Br), 107.7 (O—C—O), 80.7(C—O), 79.9 (C—O), 32.2, 32.0, 29.4, 26.8 (CH3), 24.7.
Refinement
Crystal data, data collection and structure .
details are summarized in Table 1Structural data
CCDC reference: 2033919
https://doi.org/10.1107/S2414314620013024/bt4098sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314620013024/bt4098Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314620013024/bt4098Isup3.cml
Data collection: X-AREA WinXpose (Stoe & Cie, 2019); cell
X-AREA Recipe (Stoe & Cie, 2019); data reduction: X-AREA Integrate (Stoe & Cie, 2019); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015); molecular graphics: PLATON (Spek, 2020).C11H17BrO2 | F(000) = 268 |
Mr = 261.15 | Dx = 1.546 Mg m−3 |
Triclinic, P1 | Melting point: 313 K |
a = 7.5770 (6) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 7.6838 (6) Å | Cell parameters from 10380 reflections |
c = 10.2038 (8) Å | θ = 2.8–28.4° |
α = 101.843 (6)° | µ = 3.64 mm−1 |
β = 90.893 (6)° | T = 120 K |
γ = 104.642 (6)° | Block, colourless |
V = 561.11 (8) Å3 | 0.38 × 0.32 × 0.28 mm |
Z = 2 |
Stoe IPDS 2T diffractometer | 2631 independent reflections |
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus | 2481 reflections with I > 2σ(I) |
Detector resolution: 6.67 pixels mm-1 | Rint = 0.018 |
rotation method, ω scans | θmax = 27.9°, θmin = 2.8° |
Absorption correction: integration (X-RED32; Stoe & Cie, 2019) | h = −9→9 |
Tmin = 0.195, Tmax = 0.460 | k = −9→10 |
4770 measured reflections | l = −13→13 |
Refinement on F2 | Primary atom site location: dual |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.034 | H-atom parameters constrained |
wR(F2) = 0.087 | w = 1/[σ2(Fo2) + (0.0141P)2 + 2.0148P] where P = (Fo2 + 2Fc2)/3 |
S = 1.15 | (Δ/σ)max < 0.001 |
2631 reflections | Δρmax = 0.73 e Å−3 |
129 parameters | Δρmin = −0.47 e Å−3 |
0 restraints |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. Hydrogen atoms were placed at calculated positions and were refined in the riding-model approximation with C–H ranging from 0.95 Å to 1.00 Å, and with Uiso(H) = 1.5 Ueq(Cmethyl) or Uiso(H) = 1.2 Ueq(C) for the remaining H atoms. |
x | y | z | Uiso*/Ueq | ||
Br1 | 0.69071 (4) | 0.73859 (5) | 0.45594 (3) | 0.02384 (10) | |
C1 | 0.5268 (4) | 0.7199 (4) | 0.3056 (3) | 0.0190 (6) | |
C2 | 0.5275 (4) | 0.5685 (4) | 0.1873 (3) | 0.0213 (6) | |
H2A | 0.653108 | 0.553370 | 0.179600 | 0.026* | |
H2B | 0.491553 | 0.603426 | 0.104621 | 0.026* | |
C3 | 0.3971 (4) | 0.3848 (4) | 0.1982 (3) | 0.0202 (6) | |
H3A | 0.383050 | 0.297930 | 0.110069 | 0.024* | |
H3B | 0.453460 | 0.332706 | 0.263967 | 0.024* | |
C4 | 0.2085 (4) | 0.3970 (4) | 0.2404 (3) | 0.0186 (6) | |
H4 | 0.217565 | 0.462069 | 0.336747 | 0.022* | |
C5 | 0.0995 (4) | 0.4826 (4) | 0.1559 (3) | 0.0191 (6) | |
H5 | 0.143866 | 0.470280 | 0.063509 | 0.023* | |
C6 | 0.0962 (4) | 0.6811 (4) | 0.2095 (3) | 0.0216 (6) | |
H6A | 0.059598 | 0.693629 | 0.302984 | 0.026* | |
H6B | 0.001262 | 0.708981 | 0.155601 | 0.026* | |
C7 | 0.2785 (4) | 0.8259 (4) | 0.2082 (3) | 0.0243 (7) | |
H7A | 0.329199 | 0.797994 | 0.119793 | 0.029* | |
H7B | 0.254789 | 0.948843 | 0.219350 | 0.029* | |
C8 | 0.4184 (4) | 0.8321 (4) | 0.3168 (3) | 0.0219 (6) | |
H8 | 0.429359 | 0.921776 | 0.398046 | 0.026* | |
O9 | 0.0976 (3) | 0.2121 (3) | 0.2245 (2) | 0.0214 (5) | |
C10 | −0.0876 (4) | 0.2202 (4) | 0.2147 (3) | 0.0208 (6) | |
O11 | −0.0850 (3) | 0.3686 (3) | 0.1490 (3) | 0.0252 (5) | |
C12 | −0.1986 (4) | 0.0422 (5) | 0.1258 (4) | 0.0260 (7) | |
H12A | −0.149514 | 0.026435 | 0.037059 | 0.039* | |
H12B | −0.326342 | 0.046279 | 0.116452 | 0.039* | |
H12C | −0.191901 | −0.061399 | 0.166112 | 0.039* | |
C13 | −0.1592 (5) | 0.2577 (5) | 0.3534 (4) | 0.0265 (7) | |
H13A | −0.081067 | 0.372480 | 0.407651 | 0.040* | |
H13B | −0.158069 | 0.155628 | 0.397053 | 0.040* | |
H13C | −0.284551 | 0.269087 | 0.344726 | 0.040* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.02067 (16) | 0.02777 (17) | 0.02333 (17) | 0.00805 (12) | −0.00350 (11) | 0.00432 (12) |
C1 | 0.0179 (14) | 0.0207 (14) | 0.0172 (14) | 0.0025 (11) | −0.0001 (11) | 0.0049 (11) |
C2 | 0.0169 (14) | 0.0223 (15) | 0.0221 (15) | 0.0023 (11) | 0.0036 (11) | 0.0026 (12) |
C3 | 0.0181 (14) | 0.0179 (14) | 0.0245 (15) | 0.0050 (11) | 0.0011 (11) | 0.0042 (12) |
C4 | 0.0162 (14) | 0.0169 (14) | 0.0228 (15) | 0.0034 (11) | −0.0005 (11) | 0.0056 (11) |
C5 | 0.0146 (13) | 0.0196 (14) | 0.0234 (15) | 0.0029 (11) | −0.0011 (11) | 0.0073 (12) |
C6 | 0.0194 (14) | 0.0219 (15) | 0.0249 (16) | 0.0077 (12) | −0.0029 (12) | 0.0055 (12) |
C7 | 0.0242 (16) | 0.0199 (15) | 0.0290 (17) | 0.0057 (12) | −0.0057 (13) | 0.0065 (13) |
C8 | 0.0198 (15) | 0.0172 (14) | 0.0253 (16) | 0.0014 (11) | −0.0019 (12) | 0.0019 (12) |
O9 | 0.0145 (10) | 0.0178 (10) | 0.0331 (13) | 0.0040 (8) | 0.0007 (9) | 0.0088 (9) |
C10 | 0.0142 (13) | 0.0214 (15) | 0.0281 (16) | 0.0042 (11) | −0.0002 (11) | 0.0088 (12) |
O11 | 0.0159 (11) | 0.0232 (11) | 0.0375 (14) | 0.0019 (9) | −0.0047 (9) | 0.0136 (10) |
C12 | 0.0197 (15) | 0.0251 (16) | 0.0309 (18) | 0.0017 (12) | 0.0003 (13) | 0.0064 (13) |
C13 | 0.0199 (15) | 0.0303 (17) | 0.0288 (17) | 0.0058 (13) | 0.0034 (13) | 0.0065 (14) |
Br1—C1 | 1.917 (3) | C6—H6A | 0.9900 |
C1—C8 | 1.324 (4) | C6—H6B | 0.9900 |
C1—C2 | 1.496 (4) | C7—C8 | 1.507 (4) |
C2—C3 | 1.532 (4) | C7—H7A | 0.9900 |
C2—H2A | 0.9900 | C7—H7B | 0.9900 |
C2—H2B | 0.9900 | C8—H8 | 0.9500 |
C3—C4 | 1.519 (4) | O9—C10 | 1.423 (4) |
C3—H3A | 0.9900 | C10—O11 | 1.433 (4) |
C3—H3B | 0.9900 | C10—C12 | 1.512 (5) |
C4—O9 | 1.432 (4) | C10—C13 | 1.521 (5) |
C4—C5 | 1.531 (4) | C12—H12A | 0.9800 |
C4—H4 | 1.0000 | C12—H12B | 0.9800 |
C5—O11 | 1.441 (4) | C12—H12C | 0.9800 |
C5—C6 | 1.518 (4) | C13—H13A | 0.9800 |
C5—H5 | 1.0000 | C13—H13B | 0.9800 |
C6—C7 | 1.541 (4) | C13—H13C | 0.9800 |
C8—C1—C2 | 125.9 (3) | C7—C6—H6B | 108.5 |
C8—C1—Br1 | 118.7 (2) | H6A—C6—H6B | 107.5 |
C2—C1—Br1 | 115.3 (2) | C8—C7—C6 | 113.1 (3) |
C1—C2—C3 | 112.4 (3) | C8—C7—H7A | 109.0 |
C1—C2—H2A | 109.1 | C6—C7—H7A | 109.0 |
C3—C2—H2A | 109.1 | C8—C7—H7B | 109.0 |
C1—C2—H2B | 109.1 | C6—C7—H7B | 109.0 |
C3—C2—H2B | 109.1 | H7A—C7—H7B | 107.8 |
H2A—C2—H2B | 107.9 | C1—C8—C7 | 123.8 (3) |
C4—C3—C2 | 114.7 (3) | C1—C8—H8 | 118.1 |
C4—C3—H3A | 108.6 | C7—C8—H8 | 118.1 |
C2—C3—H3A | 108.6 | C10—O9—C4 | 106.7 (2) |
C4—C3—H3B | 108.6 | O9—C10—O11 | 105.1 (2) |
C2—C3—H3B | 108.6 | O9—C10—C12 | 108.3 (3) |
H3A—C3—H3B | 107.6 | O11—C10—C12 | 108.9 (3) |
O9—C4—C3 | 107.0 (2) | O9—C10—C13 | 110.8 (3) |
O9—C4—C5 | 103.2 (2) | O11—C10—C13 | 110.8 (3) |
C3—C4—C5 | 117.5 (3) | C12—C10—C13 | 112.7 (3) |
O9—C4—H4 | 109.6 | C10—O11—C5 | 109.5 (2) |
C3—C4—H4 | 109.6 | C10—C12—H12A | 109.5 |
C5—C4—H4 | 109.6 | C10—C12—H12B | 109.5 |
O11—C5—C6 | 107.9 (2) | H12A—C12—H12B | 109.5 |
O11—C5—C4 | 103.7 (2) | C10—C12—H12C | 109.5 |
C6—C5—C4 | 117.6 (3) | H12A—C12—H12C | 109.5 |
O11—C5—H5 | 109.1 | H12B—C12—H12C | 109.5 |
C6—C5—H5 | 109.1 | C10—C13—H13A | 109.5 |
C4—C5—H5 | 109.1 | C10—C13—H13B | 109.5 |
C5—C6—C7 | 115.2 (3) | H13A—C13—H13B | 109.5 |
C5—C6—H6A | 108.5 | C10—C13—H13C | 109.5 |
C7—C6—H6A | 108.5 | H13A—C13—H13C | 109.5 |
C5—C6—H6B | 108.5 | H13B—C13—H13C | 109.5 |
C8—C1—C2—C3 | −90.1 (4) | Br1—C1—C8—C7 | −177.4 (2) |
Br1—C1—C2—C3 | 86.3 (3) | C6—C7—C8—C1 | 83.7 (4) |
C1—C2—C3—C4 | 46.3 (4) | C3—C4—O9—C10 | −158.8 (2) |
C2—C3—C4—O9 | 170.9 (3) | C5—C4—O9—C10 | −34.3 (3) |
C2—C3—C4—C5 | 55.6 (4) | C4—O9—C10—O11 | 32.6 (3) |
O9—C4—C5—O11 | 22.7 (3) | C4—O9—C10—C12 | 148.9 (3) |
C3—C4—C5—O11 | 140.1 (3) | C4—O9—C10—C13 | −87.1 (3) |
O9—C4—C5—C6 | 141.8 (3) | O9—C10—O11—C5 | −17.2 (3) |
C3—C4—C5—C6 | −100.8 (3) | C12—C10—O11—C5 | −133.1 (3) |
O11—C5—C6—C7 | −173.1 (3) | C13—C10—O11—C5 | 102.5 (3) |
C4—C5—C6—C7 | 70.1 (4) | C6—C5—O11—C10 | −129.1 (3) |
C5—C6—C7—C8 | −74.8 (4) | C4—C5—O11—C10 | −3.6 (3) |
C2—C1—C8—C7 | −1.2 (5) |
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