rac-(E,trans)-4-Bromo-10,10-dimethyl-9,11-dioxabi­cyclo­[6.3.0]undec-4-ene

Schollmeyer, D.; Heidrich, M.; Detert, H.

doi:10.1107/S2414314620013024

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 5| Part 9| September 2020| x201302

https://doi.org/10.1107/S2414314620013024

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rac-(E,trans)-4-Bromo-10,10-dimethyl-9,11-dioxabicyclo[6.3.0]undec-4-ene

Dieter Schollmeyer,^a Maximilian Heidrich ^a and Heiner Detert ^a ^*

^aJohannes Gutenberg University Mainz, Department of Chemistry, Duesbergweg 10-14, 55099 Mainz, Germany
^*Correspondence e-mail: detert@uni-mainz.de

Edited by M. Bolte, Goethe-Universität Frankfurt, Germany (Received 24 September 2020; accepted 25 September 2020; online 30 September 2020)

In the title compound, a cyclooctene ring in a twist-boat conformation and a dioxolane ring with a distorted envelope conformation are annulated in a 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.

Keywords: crystal structure; heterocycles; medium-sized ring; bromine.

CCDC reference: 2033919

Structure description

The title compound (Fig. 1) crystallizes as a racemic mixture 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 envelope conformation. 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.

Figure 1
Perspective view of the title compound. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
Partial packing diagram of the title compound, viewed along the a axis. H atoms not involved in C—H⋯O contacts are omitted.

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 chromatography 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 refinement details are summarized in Table 1.

Table 1
Experimental details

Crystal data
Chemical formula	C₁₁H₁₇BrO₂
M_r	261.15
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	120
a, b, c (Å)	7.5770 (6), 7.6838 (6), 10.2038 (8)
α, β, γ (°)	101.843 (6), 90.893 (6), 104.642 (6)
V (Å³)	561.11 (8)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	3.64
Crystal size (mm)	0.38 × 0.32 × 0.28

Data collection
Diffractometer	Stoe IPDS 2T
Absorption correction	Integration (X-RED32; Stoe & Cie, 2019 )
T_min, T_max	0.195, 0.460
No. of measured, independent and observed [I > 2σ(I)] reflections	4770, 2631, 2481
R_int	0.018
(sin θ/λ)_max (Å⁻¹)	0.658

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.087, 1.15
No. of reflections	2631
No. of parameters	129
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.73, −0.47
Computer programs: X-AREA WinXpose, Recipe and Integrate (Stoe & Cie, 2019), SIR2004 (Burla et al., 2005 ), SHELXL2018/3 (Sheldrick, 2015 ) and PLATON (Spek, 2020 ).

Structural data

CCDC reference: 2033919

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2414314620013024/bt4098sup1.cif

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

checkCIF report

Computing details top

Data collection: X-AREA WinXpose (Stoe & Cie, 2019); cell refinement: 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).

rac-(E,trans)-4-Bromo-10,10-dimethyl-9,11-dioxabicyclo[6.3.0]undec-4-ene top

Crystal data top

C₁₁H₁₇BrO₂	F(000) = 268
M_r = 261.15	D_x = 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

Data collection top

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	R_int = 0.018
rotation method, ω scans	θ_max = 27.9°, θ_min = 2.8°
Absorption correction: integration (X-RED32; Stoe & Cie, 2019)	h = −9→9
T_min = 0.195, T_max = 0.460	k = −9→10
4770 measured reflections	l = −13→13

Refinement top

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(F_o²) + (0.0141P)² + 2.0148P] where P = (F_o² + 2F_c²)/3
S = 1.15	(Δ/σ)_max < 0.001
2631 reflections	Δρ_max = 0.73 e Å⁻³
129 parameters	Δρ_min = −0.47 e Å⁻³
0 restraints

Special details top

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 U_iso(H) = 1.5 U_eq(C_methyl) or U_iso(H) = 1.2 U_eq(C) for the remaining H atoms.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
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*

Atomic displacement parameters (Å²) top

	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)

Geometric parameters (Å, º) top

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)

References

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