(1R*,2R*,5R*,6S*)-6-Bromo-9-oxabi­cyclo­[3.3.1]nonan-2-ol

Simon, L.; Detert, H.; Schollmeyer, D.

doi:10.1107/S2414314625008545

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 10| Part 10| October 2025| x250854

https://doi.org/10.1107/S2414314625008545

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(1R,2R,5R,6S)-6-Bromo-9-oxabicyclo[3.3.1]nonan-2-ol

Lea Simon,^a Heiner Detert ^a ^* and Dieter Schollmeyer ^a

^aUniversity Mainz, Duesbergweg 10-14, 55099 Mainz, Germany
^*Correspondence e-mail: [email protected]

Edited by M. Bolte, Goethe-Universität Frankfurt, Germany (Received 24 September 2025; accepted 29 September 2025; online 9 October 2025)

Both six-membered rings in the title bicyclo[3.3.1] system, C₈H₁₃BrO₂, adopt a chair conformation. Hydrogen bonds from the hydroxy group to the ether bridge connect the molecules into zigzag chains: single-enantiomer chains propagating along the b-axis direction form the crystal.

Keywords: crystal structure; heterocycle; bromine; hydrogen bridge.

CCDC reference: 2492093

Structure description

The title compound, C₈H₁₃BrO₂ (Fig. 1), was prepared as part of a project on medium-sized rings (Detert et al., 1994 ; Detert & Meier 1997a ,b ) and transannular reactions (Detert et al., 1992 , Kraemer et al., 2009 ; Meier et al., 2009 ). The oxabicyclo[3.3.1] framework is close to being perfectly C_2v symmetrical with both six-membered rings in a chair conformation. The centrosymmetrical crystal is composed of two counter-directional chains generated by a twofold screw axis. Both of these zigzag chains run along the b-axis direction (Fig. 2). Each chain is composed of a single enantiomer, the molecules are connected via hydrogen-bond bridges (O10—H10⋯O9) with an O⋯O distance of 1.91 (6) Å and an O—H⋯O 164 (3)° angle. The chains are connected by C—H⋯O contacts (Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2B⋯O10ⁱ	0.95 (4)	2.45 (4)	3.378 (5)	164 (3)
O10—H10⋯O9ⁱⁱ	0.83 (6)	1.91 (6)	2.732 (4)	166 (5)
Symmetry codes: (i) $[x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (ii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Figure 1
View (Spek, 2009

) of the title compound. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
Part of the packing diagram. View along the c-axis direction (Spek, 2009

). Hydrogen atoms bonded to C atoms are omitted for clarity.

Synthesis and crystallization

The synthesis of the title compound was performed by dihydroxylation of 1,5-cyclooctadiene (Yates et al., 1972 ), acetalization, addition of bromine (Schollmeyer et al., 2020 ) and hydrolysis of the acetal concomitant with an intramolecular nucleophilic substitution of one bromine atom by a hydroxyl group according to Takahashi et al. (2000 ). (1R*,4S*,5S*,8R*)-4,5-Dibromo-10,10-dimethyl-9,11-dioxabicyclo[6.3.0]undecane was the main isomer (ca 10/1) of the bromination step. 2.50 g of the crude product were purified via silica column chromatography using a cyclohexane–ethyl acetate (1:10) and 2% triethylamine eluent. (1R*,4S*,5S*,8R*)-4,5-Dibromo-10,10-dimethyl-9,11-dioxabicyclo[6.3.0]undecane (4b) was obtained as a colorless oil (1.03 g, 3.01 mmol, 46% of theory). Then 0.90 g (2.63 mmol) of this mixture were dissolved in THF (4 ml), hydrochloric acid (1M, 4 ml) was added and the mixture was stirred at 323 K for 16 h while the reaction progress was monitored via TLC. After full conversion, the mixture was neutralized with saturated aqueous NaHCO₃ and extracted with ethyl acetate (4 × 25 ml). The combined organic layers were washed with brine (2 × 30 ml), dried over Na₂SO₄, and concentrated in vacuo. The residue was purified by column chromatography using cyclohexane-ethyl acetate as an eluent (1:1, R_f = 0.32). (1R*,2R*,5R*,6S*)-6-Bromo-9-oxabicyclo[3.3.1]nonan-2-ol was obtained as a crystalline, colorless solid (0.54 g, 2.44 mmol, 93% of theory) with m.p. = 341–344 K. Spectroscopic data: (assignment of signals follows IUPAC nomenclature): IR (ATR): ν (cm⁻¹) = 3390mb, 2940s,1733w, 1481m, 1443m, 1232m, 1084m, 1028s, 978m, 895s, 871s, 849s. ¹H-NMR (300 MHz, CDCl₃): δ = 4.37–4.28 (m, 1H, 1-H), 4.14–3.95 (m, 2H, 2-H, 6-H), 3.90 (t, J = 5.92 Hz, 1H, 5-H), 2.56 (s, 1H, OH), 2.50–2.15 (m, 2H, 7-H, 8-H), 2.19–1.92 (m, 3H, 3-H, 4-H, 8′-H), 1.92–1.64 (m, 3H, 3-H, 4-H, 7′-H). ¹³C-NMR (75 MHz, CDCl₃) δ = 71.92 (2-C), 70.05 (5-C), 68.07 (6-C), 53.08 (1-C), 29.07 (8-C), 27.48 (4-C), 27.38 (3-C), 17.99 (7-C). LC–MS: m/z 221.000 [M + H]⁺; (calculated for C₈H₁₄O₂Br [M + H]⁺: 221.018).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₈H₁₃BrO₂
M_r	221.09
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	120
a, b, c (Å)	9.5387 (7), 8.8911 (8), 10.2453 (7)
β (°)	97.088 (6)
V (Å³)	862.26 (12)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	4.72
Crystal size (mm)	0.60 × 0.35 × 0.14

Data collection
Diffractometer	Stoe IPDS 2T
Absorption correction	Integration (X-RED32; Stoe & Cie, 2020 )
T_min, T_max	0.196, 0.519
No. of measured, independent and observed [I > 2σ(I)] reflections	4579, 2057, 1808
R_int	0.023
(sin θ/λ)_max (Å⁻¹)	0.659

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.089, 1.27
No. of reflections	2057
No. of parameters	146
H-atom treatment	Only H-atom coordinates refined
Δρ_max, Δρ_min (e Å⁻³)	0.79, −0.54
Computer programs: X-AREA WinXpose, Recipe and Integrate (Stoe & Cie, 2020), SHELXT2014 (Sheldrick, 2015a ), SHELXL2019/2 (Sheldrick, 2015b ) and PLATON (Spek, 2009 ).

Structural data

CCDC reference: 2492093

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2414314625008545/bt4181sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314625008545/bt4181Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314625008545/bt4181Isup3.cml

checkCIF report

Computing details top

(1R*,2R*,5R*,6S*)-6-Bromo-9-oxabicyclo[3.3.1]nonan-2-ol top

Crystal data top

C₈H₁₃BrO₂	F(000) = 448
M_r = 221.09	D_x = 1.703 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 9.5387 (7) Å	Cell parameters from 8646 reflections
b = 8.8911 (8) Å	θ = 2.8–28.4°
c = 10.2453 (7) Å	µ = 4.72 mm⁻¹
β = 97.088 (6)°	T = 120 K
V = 862.26 (12) Å³	Block, colorless
Z = 4	0.60 × 0.35 × 0.14 mm

Data collection top

Stoe IPDS 2T diffractometer	2057 independent reflections
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	1808 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm^-1	R_int = 0.023
rotation method, ω scans	θ_max = 27.9°, θ_min = 3.0°
Absorption correction: integration (X-Red32; Stoe & Cie, 2020)	h = −11→12
T_min = 0.196, T_max = 0.519	k = −11→10
4579 measured reflections	l = −13→13

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F² > 2σ(F²)] = 0.042	Only H-atom coordinates refined
wR(F²) = 0.089	w = 1/[σ²(F_o²) + (0.0222P)² + 1.9676P] where P = (F_o² + 2F_c²)/3
S = 1.27	(Δ/σ)_max < 0.001
2057 reflections	Δρ_max = 0.79 e Å⁻³
146 parameters	Δρ_min = −0.54 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 freely refined, except H1 and H5 which were refined with U(H)=1.2U_eq(C). The H atoms of each CH₂ group were given a common displacement parameter.

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

	x	y	z	U_iso*/U_eq
Br1	0.19929 (4)	0.83866 (4)	0.25179 (4)	0.03210 (13)
C1	0.2223 (4)	0.5517 (4)	0.1306 (3)	0.0235 (7)
H1	0.220 (4)	0.620 (4)	0.059 (4)	0.028*
C2	0.1690 (4)	0.3953 (5)	0.0871 (4)	0.0306 (8)
H2A	0.065 (4)	0.393 (5)	0.065 (4)	0.029 (7)*
H2B	0.213 (4)	0.371 (5)	0.011 (4)	0.029 (7)*
C3	0.2108 (4)	0.2714 (4)	0.1884 (4)	0.0334 (8)
H3A	0.149 (5)	0.269 (5)	0.260 (4)	0.041 (9)*
H3B	0.196 (5)	0.176 (5)	0.148 (5)	0.041 (9)*
C4	0.3622 (4)	0.2883 (4)	0.2501 (4)	0.0316 (8)
H4	0.431 (4)	0.266 (5)	0.185 (4)	0.032 (11)*
C5	0.3972 (4)	0.4502 (4)	0.2913 (3)	0.0255 (7)
H5	0.492 (4)	0.458 (5)	0.314 (4)	0.031*
C6	0.3264 (4)	0.5148 (5)	0.4058 (3)	0.0277 (7)
H6A	0.343 (5)	0.436 (5)	0.472 (5)	0.045 (9)*
H6B	0.382 (5)	0.608 (6)	0.434 (4)	0.045 (9)*
C7	0.1695 (4)	0.5486 (4)	0.3687 (3)	0.0262 (7)
H7A	0.113 (4)	0.454 (5)	0.366 (4)	0.032 (8)*
H7B	0.138 (4)	0.616 (5)	0.439 (4)	0.032 (8)*
C8	0.1421 (4)	0.6236 (4)	0.2342 (3)	0.0247 (7)
H8	0.044 (4)	0.631 (4)	0.201 (4)	0.020 (9)*
O9	0.3704 (2)	0.5456 (3)	0.1771 (2)	0.0250 (5)
O10	0.3857 (4)	0.1913 (4)	0.3610 (3)	0.0464 (8)
H10	0.466 (6)	0.153 (6)	0.362 (5)	0.057 (16)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0394 (2)	0.02595 (18)	0.03210 (19)	0.00348 (17)	0.00881 (14)	0.00081 (15)
C1	0.0223 (16)	0.0300 (18)	0.0177 (15)	0.0044 (14)	0.0005 (12)	0.0003 (13)
C2	0.0251 (18)	0.038 (2)	0.0291 (18)	−0.0019 (16)	0.0043 (15)	−0.0090 (15)
C3	0.033 (2)	0.0276 (18)	0.041 (2)	−0.0023 (16)	0.0112 (17)	−0.0056 (16)
C4	0.031 (2)	0.0299 (18)	0.0356 (19)	0.0081 (15)	0.0133 (16)	0.0093 (15)
C5	0.0185 (16)	0.0355 (19)	0.0219 (16)	0.0024 (14)	0.0006 (13)	0.0047 (14)
C6	0.0258 (18)	0.037 (2)	0.0197 (15)	0.0042 (16)	0.0017 (14)	0.0017 (14)
C7	0.0272 (18)	0.0313 (18)	0.0210 (16)	−0.0015 (15)	0.0072 (14)	0.0000 (13)
C8	0.0210 (16)	0.0287 (18)	0.0241 (16)	0.0013 (14)	0.0016 (13)	−0.0004 (13)
O9	0.0230 (12)	0.0299 (13)	0.0228 (11)	−0.0029 (10)	0.0051 (9)	0.0041 (10)
O10	0.0464 (19)	0.0454 (18)	0.0523 (18)	0.0253 (15)	0.0260 (15)	0.0253 (14)

Geometric parameters (Å, º) top

Br1—C8	1.991 (4)	C4—H4	1.01 (4)
C1—O9	1.435 (4)	C5—O9	1.443 (4)
C1—C8	1.523 (5)	C5—C6	1.535 (5)
C1—C2	1.529 (5)	C5—H5	0.91 (4)
C1—H1	0.95 (4)	C6—C7	1.528 (5)
C2—C3	1.533 (6)	C6—H6A	0.97 (5)
C2—H2A	0.99 (4)	C6—H6B	1.01 (5)
C2—H2B	0.95 (4)	C7—C8	1.524 (5)
C3—C4	1.511 (6)	C7—H7A	1.00 (4)
C3—H3A	1.00 (5)	C7—H7B	1.01 (4)
C3—H3B	0.95 (5)	C8—H8	0.96 (4)
C4—O10	1.422 (4)	O10—H10	0.83 (6)
C4—C5	1.526 (6)

O9—C1—C8	110.1 (3)	O9—C5—C6	110.5 (3)
O9—C1—C2	109.9 (3)	C4—C5—C6	117.6 (3)
C8—C1—C2	114.1 (3)	O9—C5—H5	104 (3)
O9—C1—H1	102 (3)	C4—C5—H5	108 (3)
C8—C1—H1	108 (2)	C6—C5—H5	107 (3)
C2—C1—H1	112 (2)	C7—C6—C5	113.1 (3)
C1—C2—C3	114.0 (3)	C7—C6—H6A	113 (3)
C1—C2—H2A	112 (2)	C5—C6—H6A	102 (3)
C3—C2—H2A	108 (2)	C7—C6—H6B	112 (3)
C1—C2—H2B	106 (2)	C5—C6—H6B	105 (3)
C3—C2—H2B	106 (2)	H6A—C6—H6B	111 (4)
H2A—C2—H2B	110 (3)	C8—C7—C6	111.4 (3)
C4—C3—C2	111.6 (3)	C8—C7—H7A	108 (2)
C4—C3—H3A	109 (3)	C6—C7—H7A	111 (2)
C2—C3—H3A	112 (3)	C8—C7—H7B	111 (2)
C4—C3—H3B	111 (3)	C6—C7—H7B	108 (2)
C2—C3—H3B	110 (3)	H7A—C7—H7B	108 (3)
H3A—C3—H3B	104 (4)	C1—C8—C7	113.6 (3)
O10—C4—C3	108.8 (3)	C1—C8—Br1	108.1 (2)
O10—C4—C5	110.1 (3)	C7—C8—Br1	108.9 (2)
C3—C4—C5	112.0 (3)	C1—C8—H8	110 (2)
O10—C4—H4	111 (2)	C7—C8—H8	114 (2)
C3—C4—H4	112 (2)	Br1—C8—H8	102 (2)
C5—C4—H4	104 (2)	C1—O9—C5	111.1 (2)
O9—C5—C4	108.6 (3)	C4—O10—H10	108 (4)

O9—C1—C2—C3	49.8 (4)	C5—C6—C7—C8	−42.9 (4)
C8—C1—C2—C3	−74.3 (4)	O9—C1—C8—C7	−53.9 (4)
C1—C2—C3—C4	−42.3 (4)	C2—C1—C8—C7	70.1 (4)
C2—C3—C4—O10	168.0 (3)	O9—C1—C8—Br1	67.1 (3)
C2—C3—C4—C5	46.0 (4)	C2—C1—C8—Br1	−168.9 (2)
O10—C4—C5—O9	−179.2 (3)	C6—C7—C8—C1	43.8 (4)
C3—C4—C5—O9	−58.1 (4)	C6—C7—C8—Br1	−76.8 (3)
O10—C4—C5—C6	−52.9 (4)	C8—C1—O9—C5	63.7 (3)
C3—C4—C5—C6	68.3 (4)	C2—C1—O9—C5	−62.8 (3)
O9—C5—C6—C7	52.5 (4)	C4—C5—O9—C1	67.1 (3)
C4—C5—C6—C7	−72.9 (4)	C6—C5—O9—C1	−63.2 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2B···O10ⁱ	0.95 (4)	2.45 (4)	3.378 (5)	164 (3)
O10—H10···O9ⁱⁱ	0.83 (6)	1.91 (6)	2.732 (4)	166 (5)

Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) −x+1, y−1/2, −z+1/2.

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