rac,endo-9-Hy­droxy-9-methyl­tri­cyclo­[5.2.2.02,6]undeca-4,10-dien-8-one

Detert, H.; El Kadi, B.; Schollmeyer, D.

doi:10.1107/S2414314626008825

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 11| Part 8| August 2026| x260882

https://doi.org/10.1107/S2414314626008825

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rac,endo-9-Hydroxy-9-methyltricyclo[5.2.2.0^2,6]undeca-4,10-dien-8-one

Heiner Detert,^a ^* Badr El Kadi ^a and Dieter Schollmeyer ^a

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

Edited by M. Bolte, Goethe-Universität Frankfurt, Germany (Received 24 August 2026; accepted 25 August 2026; online 28 August 2026)

The tricyclic molecule of the title compound, C₁₂H₁₄O₂, is composed of four nearly planar subunits. Hydrogen bonds connect the ketol units to chains along the a-axis direction. The structure is further consolidated by two C—H⋯O hydrogen bonds, one to the carbonyl and one to the hydroxy group.

Keywords: crystal structure; hydrogen bridges; ketol.

CCDC reference: 2583168

Structure description

The title compound, C₁₂H₁₄O₂ (Fig. 1), was prepared in a project on tricyclic frameworks (Detert & Schollmeyer, 2020 ; Schollmeyer & Detert, 2025 , 2026 ). The synthesis was performed in a Diels–Alder cycloaddition of o-quinolacetate and cyclopentadiene followed by hydrolysis. The tricyclic molecule is composed of a [2.2.2] propellane with an annulated cyclopentene. The nearly C₃-symmetrical carbon framework of the propellane is composed of three C₂ bridges, these are essentially coplanar with the bridgehead carbons C2, C5. Subunit C2–C1–C6–C5 is planar within 0.0284 (9) Å and subtends a dihedral angle of 58.54 (14)° with the unit C2–C10–C11–C5. The latter is planar within 0.006 (2) Å and the dihedral angle to the planar unit C2–C3–C4–C5 (max. deviation: 0.0032 Å) amounts to 58.09 (15)°. The third angle is slightly larger, 63.38 (14)°. The endo-configuration is proven by the dihedral angle between the planar cyclopentene [max. deviation 0.010 (2) Å] and the vinylene bridge C2–C10–C11–C5 of 63.14 (14)°. Four molecules fill the unit cell: they are symmetrically connected via a twofold screw axis parallel to the a-axis and physically via hydrogen bonds. The O1—H1O⋯O2 hydrogen bonds (Table 1, Fig. 2) connect the molecules into chains along the a-axis direction, and additional C—H⋯O interactions link the chains into ribbons.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O⋯O2ⁱ	0.85 (3)	1.99 (3)	2.809 (2)	162 (3)
C5—H5⋯O2ⁱⁱ	1.00	2.52	3.407 (3)	148
C9—H9⋯O1ⁱⁱⁱ	0.95	2.55	3.450 (3)	159
Symmetry codes: (i) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ ; (ii) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ ; (iii) .

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

Figure 2
Part of the packing diagram. Hydrogen bonds are shown as dashed lines. View along the c-axis direction. Hydrogen atoms not involved in hydrogen bonds are omitted for clarity. Symmetry-related molecules are shown in different colors.

Synthesis and crystallization

The synthesis was performed via Diels–Alder reaction of 1.10 g (6.62 mmol) 2-methyl-o-quinolacetate (Wessely & Sinwel, 1950 ) in 10 ml xylenes by dropwise addition of 0.46 g (1.05 eq) cyclopentadiene in 1.5 ml xylenes. The mixture was refluxed for 18 h while the color changed from yellow to orange and crystals separated. The solvent was distilled off, the residue was added to a mixture of 10 ml 1 M sodium hydroxide in water and 1 ml of methanol. After 16 h, the mixture was heated to 333 K until a brown compound separated. The mixture was acidulated, the precipitate was again dissolved in sodium hydroxide/methanol and reprecipitated by addition of hydrochloric acid. Single crystals were grown by slow evaporation of a solution of 60 mg of the precipitate in ether. After filtration through cotton, petroleum ether was added until the solution became turbid and again washed with ether. The now clear solution slowly evaporated and single crystals were collected mechanically from the partially coloured mixture. Yield 22 mg of colourless crystals with m.p. 399-402 K. Literature: 68% yield, m.p. 399-401 K. (Metlesics et al., 1958 ). IR (ATR): ñ (cm⁻¹): 3403 s, 3048w, 2983w, 2965w, 2935w, 2918w, 2895w, 2876m, 2845w, 1717vs, 1619w, 1441, 1386m, 1364m, 1355m, 1301s, 1264vw, 1234w, 1200w, 1151s, 1138s, 1112s, 1090m, 1050, 1014s, 975m, 948m, 925w, 892s, 853m, 790m, 778m, 750s, 731m, 708vs, 675s, 650w, 582vs, 499s; ¹H-NMR (400 MHz, CDCl₃): 6.37-6.24 (m, 1H, H8), 6.13-6.01 (m, 1H, H-11), 5.70 (dq, ³J = 5.7 Hz, ⁴J = 2.2 Hz, 1H, H-4), 5.44 (ddd, ³J = 5.8 Hz, ³J = 3.2 Hz, ⁴J = 1.5 Hz, 1H, H-5), 3.30-3.15 (m, 3H, H-2,-6,-7,), 3.00 (dt, ³J = 6.7 Hz, ⁴J = 2.2 Hz, 1H, H-1), 2.63-2.50 (m, 2H), 2.06-1.93 (m, 1H), 1.28 (s, 3H, CH₃). Annotation of NMR signals follows IUPAC nomenclature.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. The structure was refined as a racemic twin.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₂H₁₄O₂
M_r	190.23
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	120
a, b, c (Å)	7.3829 (3), 10.7318 (3), 12.2961 (4)
V (Å³)	974.24 (6)
Z	4
Radiation type	Cu Kα
μ (mm⁻¹)	0.70
Crystal size (mm)	0.56 × 0.25 × 0.24

Data collection
Diffractometer	Stoe Stadivari
No. of measured, independent and observed [I > 2σ(I)] reflections	5863, 1798, 1754
R_int	0.019
(sin θ/λ)_max (Å⁻¹)	0.607

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.033, 0.091, 1.12
No. of reflections	1798
No. of parameters	134
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.30, −0.14
Absolute structure	Refined as an inversion twin
Absolute structure parameter	0.5 (3)
Computer programs: X-AREA WinXpose, X-AREA Recipe and X-AREA Integrate (Stoe & Cie, 2020 ), SHELXT2014 (Sheldrick, 2015a ), SHELXL2019/2 (Sheldrick, 2015b ) and PLATON (Spek, 2009 ).

Structural data

CCDC reference: 2583168

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2414314626008825/bt4205sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314626008825/bt4205Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314626008825/bt4205Isup3.cml

checkCIF report

Computing details top

rac,endo-9-Hydroxy-9-methyltricyclo[5.2.2.0^2,6]undeca-4,10-dien-8-one top

Crystal data top

C₁₂H₁₄O₂	D_x = 1.297 Mg m⁻³
M_r = 190.23	Cu Kα radiation, λ = 1.54178 Å
Orthorhombic, P2₁2₁2₁	Cell parameters from 11043 reflections
a = 7.3829 (3) Å	θ = 3.6–69.9°
b = 10.7318 (3) Å	µ = 0.70 mm⁻¹
c = 12.2961 (4) Å	T = 120 K
V = 974.24 (6) Å³	Block, colorless
Z = 4	0.56 × 0.25 × 0.24 mm
F(000) = 408

Data collection top

Stoe Stadivari diffractometer	1754 reflections with I > 2σ(I)
Radiation source: microfocus tube	R_int = 0.019
Detector resolution: 13.33 pixels mm^-1	θ_max = 69.5°, θ_min = 5.5°
rotation method, ω scans	h = −8→8
5863 measured reflections	k = −13→11
1798 independent reflections	l = −14→14

Refinement top

Refinement on F²	H atoms treated by a mixture of independent and constrained refinement
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0498P)² + 0.2628P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.033	(Δ/σ)_max < 0.001
wR(F²) = 0.091	Δρ_max = 0.30 e Å⁻³
S = 1.12	Δρ_min = −0.14 e Å⁻³
1798 reflections	Extinction correction: SHELXL2019/2 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
134 parameters	Extinction coefficient: 0.027 (2)
0 restraints	Absolute structure: Refined as an inversion twin
Primary atom site location: dual	Absolute structure parameter: 0.5 (3)
Hydrogen site location: mixed

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. Refined as a 2-component inversion twin. The hydroxyl H atom was freely refined. Hydrogen atoms attached to carbons were placed at calculated positions and were refined in the riding-model approximation with C_tertiary–H = 1.00 Å, C_secondary–H = 0.99 Å, C_methyl–H = 0.98 Å, C_sp²–H = 0.95 Å, and with U_iso(H) = 1.5 U_eq(C_methyl) or with U_iso(H) = 1.2 U_eq(C) for the remaining H atoms. The methyl group was allowed to rotate but not to tip.

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

	x	y	z	U_iso*/U_eq
O1	0.2635 (2)	0.40578 (15)	0.39744 (12)	0.0250 (4)
H1O	0.210 (4)	0.346 (3)	0.429 (2)	0.044 (9)*
O2	0.5241 (2)	0.27907 (14)	0.52851 (13)	0.0278 (4)
C1	0.3673 (3)	0.46715 (19)	0.47879 (17)	0.0224 (5)
C2	0.4350 (3)	0.5909 (2)	0.43046 (17)	0.0240 (5)
H2	0.331230	0.647713	0.414050	0.029*
C3	0.5447 (3)	0.56246 (19)	0.32649 (17)	0.0232 (5)
H3	0.466378	0.516511	0.273651	0.028*
C4	0.7112 (3)	0.4804 (2)	0.35644 (16)	0.0230 (5)
H4	0.706449	0.399843	0.315708	0.028*
C5	0.7129 (3)	0.45495 (18)	0.48239 (16)	0.0227 (5)
H5	0.820256	0.404831	0.505697	0.027*
C6	0.5363 (3)	0.38798 (19)	0.50245 (15)	0.0217 (5)
C7	0.6217 (3)	0.6810 (2)	0.27121 (19)	0.0291 (5)
H7A	0.578751	0.687741	0.195158	0.035*
H7B	0.585296	0.756903	0.311409	0.035*
C8	0.8233 (3)	0.6633 (2)	0.27516 (18)	0.0294 (5)
H8	0.907499	0.722808	0.248544	0.035*
C9	0.8712 (3)	0.5560 (2)	0.31960 (18)	0.0280 (5)
H9	0.993364	0.529570	0.327363	0.034*
C10	0.5610 (3)	0.64894 (19)	0.51272 (18)	0.0252 (5)
H10	0.540961	0.729378	0.542666	0.030*
C11	0.7019 (3)	0.5787 (2)	0.53996 (17)	0.0248 (5)
H11	0.789473	0.604630	0.591891	0.030*
C12	0.2556 (3)	0.4843 (2)	0.58199 (18)	0.0295 (5)
H12A	0.144834	0.530609	0.564830	0.044*
H12B	0.326631	0.530835	0.635710	0.044*
H12C	0.223618	0.402526	0.611783	0.044*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0209 (8)	0.0261 (8)	0.0279 (8)	−0.0035 (6)	−0.0034 (6)	0.0023 (6)
O2	0.0274 (8)	0.0234 (8)	0.0325 (8)	0.0008 (6)	−0.0017 (7)	0.0033 (6)
C1	0.0192 (10)	0.0224 (10)	0.0255 (10)	0.0013 (8)	−0.0007 (8)	0.0000 (8)
C2	0.0202 (10)	0.0216 (10)	0.0302 (11)	0.0021 (8)	−0.0001 (8)	−0.0002 (9)
C3	0.0201 (10)	0.0262 (11)	0.0231 (10)	−0.0008 (8)	−0.0030 (8)	0.0018 (8)
C4	0.0217 (10)	0.0251 (10)	0.0223 (10)	0.0015 (9)	0.0004 (8)	−0.0020 (8)
C5	0.0183 (10)	0.0246 (10)	0.0252 (10)	0.0019 (8)	−0.0016 (8)	0.0013 (8)
C6	0.0224 (10)	0.0252 (11)	0.0174 (9)	0.0005 (9)	−0.0010 (8)	−0.0010 (8)
C7	0.0291 (12)	0.0288 (11)	0.0294 (11)	−0.0026 (9)	−0.0015 (9)	0.0048 (9)
C8	0.0268 (12)	0.0379 (13)	0.0236 (10)	−0.0081 (10)	0.0019 (9)	0.0009 (9)
C9	0.0213 (11)	0.0389 (13)	0.0237 (10)	0.0015 (9)	0.0037 (9)	−0.0026 (9)
C10	0.0250 (10)	0.0242 (10)	0.0265 (11)	−0.0030 (9)	0.0042 (8)	−0.0037 (8)
C11	0.0241 (10)	0.0279 (11)	0.0223 (10)	−0.0054 (8)	0.0000 (8)	−0.0014 (8)
C12	0.0260 (11)	0.0326 (12)	0.0301 (11)	−0.0018 (9)	0.0058 (9)	−0.0019 (9)

Geometric parameters (Å, º) top

O1—C1	1.422 (3)	C5—C11	1.508 (3)
O1—H1O	0.85 (3)	C5—C6	1.509 (3)
O2—C6	1.215 (3)	C5—H5	1.0000
C1—C12	1.524 (3)	C7—C8	1.501 (3)
C1—C6	1.538 (3)	C7—H7A	0.9900
C1—C2	1.538 (3)	C7—H7B	0.9900
C2—C10	1.509 (3)	C8—C9	1.323 (3)
C2—C3	1.544 (3)	C8—H8	0.9500
C2—H2	1.0000	C9—H9	0.9500
C3—C7	1.550 (3)	C10—C11	1.328 (3)
C3—C4	1.556 (3)	C10—H10	0.9500
C3—H3	1.0000	C11—H11	0.9500
C4—C9	1.503 (3)	C12—H12A	0.9800
C4—C5	1.573 (3)	C12—H12B	0.9800
C4—H4	1.0000	C12—H12C	0.9800

C1—O1—H1O	106 (2)	C6—C5—H5	112.5
O1—C1—C12	110.50 (17)	C4—C5—H5	112.5
O1—C1—C6	108.33 (16)	O2—C6—C5	124.45 (19)
C12—C1—C6	110.38 (17)	O2—C6—C1	121.39 (19)
O1—C1—C2	107.65 (16)	C5—C6—C1	114.02 (16)
C12—C1—C2	113.15 (17)	C8—C7—C3	104.18 (18)
C6—C1—C2	106.63 (16)	C8—C7—H7A	110.9
C10—C2—C1	107.33 (17)	C3—C7—H7A	110.9
C10—C2—C3	108.26 (18)	C8—C7—H7B	110.9
C1—C2—C3	108.67 (17)	C3—C7—H7B	110.9
C10—C2—H2	110.8	H7A—C7—H7B	108.9
C1—C2—H2	110.8	C9—C8—C7	112.9 (2)
C3—C2—H2	110.8	C9—C8—H8	123.5
C2—C3—C7	113.16 (18)	C7—C8—H8	123.5
C2—C3—C4	109.28 (17)	C8—C9—C4	112.6 (2)
C7—C3—C4	106.19 (18)	C8—C9—H9	123.7
C2—C3—H3	109.4	C4—C9—H9	123.7
C7—C3—H3	109.4	C11—C10—C2	114.70 (19)
C4—C3—H3	109.4	C11—C10—H10	122.7
C9—C4—C3	104.15 (17)	C2—C10—H10	122.7
C9—C4—C5	112.61 (18)	C10—C11—C5	115.05 (19)
C3—C4—C5	109.73 (17)	C10—C11—H11	122.5
C9—C4—H4	110.1	C5—C11—H11	122.5
C3—C4—H4	110.1	C1—C12—H12A	109.5
C5—C4—H4	110.1	C1—C12—H12B	109.5
C11—C5—C6	107.27 (16)	H12A—C12—H12B	109.5
C11—C5—C4	107.98 (16)	C1—C12—H12C	109.5
C6—C5—C4	103.71 (16)	H12A—C12—H12C	109.5
C11—C5—H5	112.5	H12B—C12—H12C	109.5

O1—C1—C2—C10	−174.12 (16)	C11—C5—C6—C1	49.8 (2)
C12—C1—C2—C10	63.5 (2)	C4—C5—C6—C1	−64.3 (2)
C6—C1—C2—C10	−58.0 (2)	O1—C1—C6—O2	−55.1 (2)
O1—C1—C2—C3	−57.2 (2)	C12—C1—C6—O2	66.0 (2)
C12—C1—C2—C3	−179.65 (18)	C2—C1—C6—O2	−170.69 (18)
C6—C1—C2—C3	58.8 (2)	O1—C1—C6—C5	120.74 (18)
C10—C2—C3—C7	−63.2 (2)	C12—C1—C6—C5	−118.15 (19)
C1—C2—C3—C7	−179.44 (17)	C2—C1—C6—C5	5.1 (2)
C10—C2—C3—C4	54.9 (2)	C2—C3—C7—C8	118.3 (2)
C1—C2—C3—C4	−61.4 (2)	C4—C3—C7—C8	−1.6 (2)
C2—C3—C4—C9	−121.26 (19)	C3—C7—C8—C9	1.6 (3)
C7—C3—C4—C9	1.1 (2)	C7—C8—C9—C4	−1.0 (3)
C2—C3—C4—C5	−0.5 (2)	C3—C4—C9—C8	−0.1 (2)
C7—C3—C4—C5	121.89 (18)	C5—C4—C9—C8	−119.0 (2)
C9—C4—C5—C11	62.1 (2)	C1—C2—C10—C11	58.2 (2)
C3—C4—C5—C11	−53.4 (2)	C3—C2—C10—C11	−58.9 (2)
C9—C4—C5—C6	175.74 (17)	C2—C10—C11—C5	1.1 (3)
C3—C4—C5—C6	60.2 (2)	C6—C5—C11—C10	−55.4 (2)
C11—C5—C6—O2	−134.5 (2)	C4—C5—C11—C10	55.8 (2)
C4—C5—C6—O2	111.4 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···O2ⁱ	0.85 (3)	1.99 (3)	2.809 (2)	162 (3)
C5—H5···O2ⁱⁱ	1.00	2.52	3.407 (3)	148
C9—H9···O1ⁱⁱⁱ	0.95	2.55	3.450 (3)	159

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

References

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