Methyl 3,5,5,6,8,8-hexa­methyl-5,6,7,8-tetra­hydro­naphthalene-2-carboxyl­ate (AHTN–COOMe)

Kuhlich, P.; Emmerling, F.; Piechotta, C.; Nehls, I.

doi:10.1107/S1600536811002601

Methyl 3,5,5,6,8,8-hexamethyl-5,6,7,8-tetrahydronaphthalene-2-carboxylate (AHTN–COOMe)

P. Kuhlich, F. Emmerling, C. Piechotta and I. Nehls

Crystals of the title compound, C₁₈H₂₆O₂, were grown from ethyl acetate. Due to the racemic precursor, the title compound is also obtained as a racemate. Disorder was observed during structure refinement, originating from two possible half-chair conformations of the non-aromatic ring. The disorder was refined by introducing split positions in the cyclo-hexane ring regarding the two possible R and S-enantiomers at the chiral CH group [ratio 0.744 (3):0.256 (3)]. The crystal structure features pairs of inversion-related molecules connected by pairs of non-classical C—H

O hydrogen bonds.

Read article Similar articles

Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536811002601/zl2346sup1.cif Contains datablocks I, global
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536811002601/zl2346Isup2.hkl Contains datablock I

CCDC reference: 811409

checkCIF report

Key indicators

Single-crystal X-ray study
T = 193 K
Mean (C-C) = 0.002 Å
Disorder in main residue
R factor = 0.054
wR factor = 0.152
Data-to-parameter ratio = 14.2

checkCIF/PLATON results

No syntax errors found



Alert level G
PLAT301_ALERT_3_G Note: Main Residue  Disorder ...................      26.00 Perc.
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......         10
PLAT811_ALERT_5_G No ADDSYM Analysis: Too Many Excluded Atoms ....          !

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   3 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

Comment top

The title compound is the product of an esterification of 3,5,5,6,8,8-hexamethyl-5,6,7,8- tetrahydronaphthalene-2-carboxylic acid (AHTN-COOH) with methanol. AHTN-COOH itself is the product of a haloform reaction from 1-(3,5,5,6,8,8-hexamethyl-5,6,7,8- tetrahydronaphthalen-2-yl)ethan-1-one (AHTN) and sodium hypochlorite solution. Two slightly different syntheses of AHTN-COOH are described by Kuhlich et al. (2010) and by Valdersnes et al. (2006). The crystal structure of AHTN-COOH was described previously by Kuhlich et al. (2010). The crystal structure of AHTN was determined by De Ridder et al. (1990).

The title compound can either be obtained in a two-step synthesis, described by Valdersnes et al. (2006) or, as described here, in a one-step procedure (see Experimental).

AHTN itself is a widely used fragrance in cosmetics and cleaning products. It is introduced into the environment mainly via sewage treatment plants and can be found in surface water at low µg/L concentration (Heberer, 2003). It is in focus of interest due to its low estrogenic potential (Bitsch et al., 2002). Due to their structural similarities to AHTN, the title compound and AHTN-COOH might also have estrogenic or even toxic properties themselves.

The title compound was found in human breast milk and piscine fatty tissue by Valdersnes et al. (2006) proofing its ubiquitary occurrence.

The molecule crystallizes in the monoclinic space group P2₁/n. The molecular structure of the compound and the atom-labeling scheme are shown in Fig 1. The structure is disordered in the non aromatic ring. This disorder can be described as pseudo mirror-symmetric with respect to the aromatic ring's plane, resulting in two moieties (ratio 0.744 (3):0.256 (3)).

A general puckering analysis according to Cremer and Pople (Cremer & Pople, 1975) led to a half-chair conformation for both enantiomers. The S-enantiomer (C4-C5-C9-C10B-C11B-C12) has a puckering amplitude (Q) of 0.526 (6) Å and 0.502 (2) Å for the R-enantiomer (C4-C5-C9-C10-C11-C12), respectively. The maximum deviation from planarity for C11/C11B is -0.3587 (39) of the R-enantiomer and 0.3335 (14) of the S-enantiomer, respectively, proofing the nearly mirror-symmetric setup.

Each molecule is surrounded by three next neighbors, whereas the centroids of the molecules are arranged in sheets parallel to the (202) plane.

A detailed description of the disorder treatment can be found in the refinement section. The molecules form pairs via non classical hydrogen bonds (C18—H26···O2) (see dashed green bonds in Fig. 2).

Related literature top

For the occurrence of the title compound in human breast milk and the fatty tissue of fish, see: Valdersnes et al. (2006). The title compound is the product of an esterification of 3,5,5,6,8,8-hexamethyl-5,6,7,8- tetrahydronaphthalene-2-carboxylic acid (AHTN—COOH) with methanol. For the synthesis of the acid, see: Kuhlich et al. (2010); Valdersnes et al. (2006). For the crystal structures of AHTN and AHTN–COOH, see: De Ridder et al. (1990) and Kuhlich et al. (2010), respectively. For the environmental occurrence and estrogenic activity of AHTN, see: Heberer (2003); Bitsch et al. (2002). For puckering parameters, see: Cremer & Pople (1975).

Experimental top

The methyl ester of 1-(3,5,5,6,8,8-hexamethyl-5,6,7,8- tetrahydronaphthalen-2-yl)ethan-1-one (AHTN) was synthesized by stirring a solution of 1 mg AHTN dissolved in 100 mL methanol and 50 mL 10% sodium hypochlorite solution at room temperature. After 24 h of stirring precipitated sodium chloride was dissolved with water and the organic compound was extracted three times with 50 mL ethyl acetate each. The organic solvents were combined, washed with water and dried with sodium sulfate. For single-crystal X-ray crystallography white and clear crystals of the title compound were grown by solvent evaporation (ethyl acetate) at ambient temperature over a period of three days [m.p. 348 K]. IR (ν, cm^-1): 1720(s), 1687(s), 1609(s), 1550(s), 1495(s), 1435(s), 1390(s), 1360(s), 1298(s), 1255(s), 1245(s), 1191(s), 1141(s), 1103(s), 1021(s), 980(s), 944(s), 916(s); ¹H-NMR (500 MHz, CD₃OD, TMS): δ = 7.83 (1H, s), 7.23 (1H, s), 3.83 (3H, s), 2.48 (3H, s), 1.85 (1H, ddq, J_H,H'=2.7 Hz, J_H,H''=13.2 Hz, J_H,Me=6.9 Hz), 1.61 (1H, dd, ²J=13.6 Hz, ³J=13.2 Hz), 1.38 (1H, dd, ²J=13.6 Hz, ³J=2.7 Hz), 1.30 (3H, s), 1.26 (3H, s), 1.22 (3H, s), 1.04 (3H, s), 0.98 (3H, d, J=6.9 Hz); ¹³C-NMR (125 MHz, CD₃OD, TMS): δ = 169.7, 151.8, 143.5, 137.8, 131.8, 130.2, 127.8, 52.1, 44.6, 38.9, 35.7, 34.9, 32.6, 32.4, 28.9, 25.1, 21.7, 17.1; (+)-ESI/MS: 275.6 (60) [M+H⁺], 297.5 (100) [M+Na⁺].

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: CORINC (Dräger & Gattow, 1971); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top

	Fig. 1. : Left: ORTEP representation of the title compound with atomic labeling shown with 30% probability displacement ellipsoids. Right: Atoms belonging to the minor disordered moiety and their bonds are presented in light gray and as thin black lines respectively. Hydrogen atoms are omitted for the sake of clarity.
	Fig. 2. : View of the unit cell of the title compound along [010]. Hydrogen bonds are drawn as dashed green lines. The minor disordered moiety is omitted for clarity.

Methyl 3,5,5,6,8,8-hexamethyl-5,6,7,8-tetrahydronaphthalene-2-carboxylate top

Crystal data top

C₁₈H₂₆O₂	F(000) = 600
M_r = 274.39	D_x = 1.122 Mg m⁻³
Monoclinic, P2₁/n	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: -P 2yn	Cell parameters from 25 reflections
a = 11.5049 (11) Å	θ = 65–69°
b = 11.9482 (5) Å	µ = 0.55 mm⁻¹
c = 12.1078 (13) Å	T = 193 K
β = 102.612 (5)°	Block, colourless
V = 1624.2 (2) Å³	0.45 × 0.40 × 0.30 mm
Z = 4

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.047
Radiation source: rotating anode	θ_max = 69.8°, θ_min = 4.8°
Graphite monochromator	h = 0→14
ω/2θ scans	k = −14→14
5083 measured reflections	l = −14→14
3062 independent reflections	3 standard reflections every 60 min
2856 reflections with I > 2σ(I)	intensity decay: 3%

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.054	H-atom parameters constrained
wR(F²) = 0.152	w = 1/[σ²(F_o²) + (0.0889P)² + 0.4305P] where P = (F_o² + 2F_c²)/3
S = 1.03	(Δ/σ)_max = 0.001
3062 reflections	Δρ_max = 0.29 e Å⁻³
216 parameters	Δρ_min = −0.26 e Å⁻³
10 restraints	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0070 (8)

Crystal data top

C₁₈H₂₆O₂	V = 1624.2 (2) Å³
M_r = 274.39	Z = 4
Monoclinic, P2₁/n	Cu Kα radiation
a = 11.5049 (11) Å	µ = 0.55 mm⁻¹
b = 11.9482 (5) Å	T = 193 K
c = 12.1078 (13) Å	0.45 × 0.40 × 0.30 mm
β = 102.612 (5)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.047
5083 measured reflections	3 standard reflections every 60 min
3062 independent reflections	intensity decay: 3%
2856 reflections with I > 2σ(I)

Refinement top

R[F² > 2σ(F²)] = 0.054	10 restraints
wR(F²) = 0.152	H-atom parameters constrained
S = 1.03	Δρ_max = 0.29 e Å⁻³
3062 reflections	Δρ_min = −0.26 e Å⁻³
216 parameters

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. 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 > 2sigma(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.

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
O1	0.34558 (10)	1.32637 (9)	−0.02324 (9)	0.0454 (3)
O2	0.44327 (15)	1.40647 (10)	0.13483 (11)	0.0711 (5)
C1	0.40482 (12)	1.32335 (11)	0.08442 (12)	0.0353 (3)
C2	0.41364 (11)	1.20805 (11)	0.13210 (10)	0.0283 (3)
C3	0.34903 (11)	1.12216 (11)	0.06975 (10)	0.0284 (3)
H23	0.2999	1.1396	−0.0020	0.034*
C4	0.35277 (10)	1.01170 (11)	0.10740 (10)	0.0267 (3)
C5	0.42442 (11)	0.98674 (11)	0.21369 (10)	0.0280 (3)
C6	0.48890 (11)	1.07419 (11)	0.27540 (10)	0.0310 (3)
H4	0.5373	1.0571	0.3476	0.037*
C7	0.48699 (11)	1.18407 (11)	0.23842 (10)	0.0297 (3)
C8	0.56520 (13)	1.26927 (13)	0.31130 (12)	0.0412 (4)
H1	0.6091	1.2331	0.3806	0.062*
H2	0.5156	1.3295	0.3310	0.062*
H3	0.6217	1.3005	0.2696	0.062*
C9	0.43809 (13)	0.86813 (12)	0.26390 (11)	0.0358 (4)
C10	0.33564 (19)	0.79143 (16)	0.19751 (16)	0.0364 (5)	0.744 (3)
H16	0.2599	0.8165	0.2176	0.044*	0.744 (3)
C11	0.32069 (18)	0.80706 (15)	0.07020 (16)	0.0352 (4)	0.744 (3)
H11	0.3979	0.7929	0.0493	0.042*	0.744 (3)
H12	0.2627	0.7515	0.0302	0.042*	0.744 (3)
C15	0.3518 (4)	0.6672 (3)	0.2281 (5)	0.0516 (9)	0.744 (3)
H13	0.2785	0.6265	0.1949	0.077*	0.744 (3)
H14	0.3692	0.6587	0.3106	0.077*	0.744 (3)
H15	0.4180	0.6368	0.1984	0.077*	0.744 (3)
C10B	0.3875 (6)	0.7792 (5)	0.1773 (5)	0.0364 (5)	0.256 (3)
H16B	0.4408	0.7776	0.1222	0.044*	0.256 (3)
C11B	0.2689 (5)	0.8159 (4)	0.1118 (5)	0.0352 (4)	0.256 (3)
H11B	0.2177	0.8350	0.1651	0.042*	0.256 (3)
H12B	0.2307	0.7532	0.0638	0.042*	0.256 (3)
C15B	0.3853 (14)	0.6606 (11)	0.2212 (16)	0.0516 (9)	0.256 (3)
H13B	0.4661	0.6383	0.2595	0.077*	0.256 (3)
H14B	0.3559	0.6098	0.1577	0.077*	0.256 (3)
H15B	0.3327	0.6569	0.2747	0.077*	0.256 (3)
C12	0.27785 (11)	0.92416 (11)	0.03173 (11)	0.0318 (3)
C13	0.1469 (4)	0.9422 (4)	0.0305 (4)	0.0414 (9)	0.744 (3)
H5	0.0990	0.8866	−0.0190	0.062*	0.744 (3)
H6	0.1232	1.0176	0.0023	0.062*	0.744 (3)
H7	0.1339	0.9342	0.1075	0.062*	0.744 (3)
C14	0.2948 (2)	0.93749 (19)	−0.09371 (18)	0.0374 (5)	0.744 (3)
H8	0.3800	0.9388	−0.0936	0.056*	0.744 (3)
H9	0.2580	1.0076	−0.1258	0.056*	0.744 (3)
H10	0.2570	0.8744	−0.1395	0.056*	0.744 (3)
C16	0.4257 (4)	0.8693 (6)	0.3874 (3)	0.0576 (11)	0.744 (3)
H17	0.4953	0.9059	0.4345	0.086*	0.744 (3)
H18	0.4202	0.7922	0.4135	0.086*	0.744 (3)
H19	0.3535	0.9104	0.3930	0.086*	0.744 (3)
C17	0.5617 (2)	0.8238 (2)	0.2576 (2)	0.0464 (6)	0.744 (3)
H20	0.5676	0.8189	0.1782	0.070*	0.744 (3)
H21	0.5734	0.7494	0.2923	0.070*	0.744 (3)
H22	0.6230	0.8749	0.2982	0.070*	0.744 (3)
C13B	0.1450 (11)	0.9619 (14)	0.0068 (14)	0.0414 (9)	0.256 (3)
H5B	0.0939	0.8991	−0.0254	0.062*	0.256 (3)
H6B	0.1334	1.0242	−0.0473	0.062*	0.256 (3)
H7B	0.1241	0.9862	0.0773	0.062*	0.256 (3)
C14B	0.3189 (7)	0.8985 (6)	−0.0673 (6)	0.0374 (5)	0.256 (3)
H8B	0.3208	0.9670	−0.1115	0.056*	0.256 (3)
H9B	0.2652	0.8441	−0.1128	0.056*	0.256 (3)
H10B	0.3993	0.8668	−0.0462	0.056*	0.256 (3)
C16B	0.3894 (15)	0.876 (2)	0.3749 (13)	0.0576 (11)	0.256 (3)
H17B	0.4310	0.9355	0.4231	0.086*	0.256 (3)
H18B	0.4029	0.8042	0.4155	0.086*	0.256 (3)
H19B	0.3038	0.8918	0.3554	0.086*	0.256 (3)
C17B	0.5738 (8)	0.8426 (8)	0.3014 (7)	0.0464 (6)	0.256 (3)
H20B	0.6116	0.8534	0.2371	0.070*	0.256 (3)
H21B	0.5851	0.7651	0.3279	0.070*	0.256 (3)
H22B	0.6101	0.8934	0.3629	0.070*	0.256 (3)
C18	0.33250 (17)	1.43507 (14)	−0.07628 (16)	0.0561 (5)
H24	0.2983	1.4873	−0.0297	0.084*
H25	0.2796	1.4293	−0.1514	0.084*
H26	0.4107	1.4624	−0.0838	0.084*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0551 (7)	0.0345 (6)	0.0423 (6)	−0.0050 (5)	0.0009 (5)	0.0096 (4)
O2	0.1106 (12)	0.0323 (6)	0.0585 (8)	−0.0166 (7)	−0.0076 (7)	0.0010 (5)
C1	0.0362 (7)	0.0302 (7)	0.0399 (7)	−0.0030 (5)	0.0091 (6)	0.0000 (5)
C2	0.0269 (6)	0.0288 (7)	0.0313 (6)	0.0003 (5)	0.0108 (5)	−0.0009 (5)
C3	0.0272 (6)	0.0312 (7)	0.0270 (6)	0.0007 (5)	0.0066 (5)	−0.0006 (5)
C4	0.0252 (6)	0.0293 (7)	0.0275 (6)	0.0000 (5)	0.0101 (5)	−0.0018 (5)
C5	0.0292 (6)	0.0312 (7)	0.0268 (6)	0.0023 (5)	0.0130 (5)	0.0012 (5)
C6	0.0320 (7)	0.0372 (7)	0.0243 (6)	0.0022 (5)	0.0072 (5)	−0.0009 (5)
C7	0.0277 (6)	0.0342 (7)	0.0289 (6)	−0.0004 (5)	0.0101 (5)	−0.0066 (5)
C8	0.0415 (8)	0.0406 (8)	0.0388 (7)	−0.0035 (6)	0.0031 (6)	−0.0098 (6)
C9	0.0452 (8)	0.0337 (7)	0.0306 (7)	0.0020 (6)	0.0132 (5)	0.0062 (5)
C10	0.0429 (12)	0.0309 (9)	0.0411 (10)	−0.0002 (9)	0.0216 (8)	0.0049 (7)
C11	0.0417 (10)	0.0276 (9)	0.0390 (10)	−0.0032 (7)	0.0149 (7)	−0.0046 (7)
C15	0.066 (3)	0.0331 (10)	0.0607 (13)	−0.0013 (14)	0.0255 (19)	0.0079 (8)
C10B	0.0429 (12)	0.0309 (9)	0.0411 (10)	−0.0002 (9)	0.0216 (8)	0.0049 (7)
C11B	0.0417 (10)	0.0276 (9)	0.0390 (10)	−0.0032 (7)	0.0149 (7)	−0.0046 (7)
C15B	0.066 (3)	0.0331 (10)	0.0607 (13)	−0.0013 (14)	0.0255 (19)	0.0079 (8)
C12	0.0322 (7)	0.0292 (7)	0.0340 (7)	−0.0025 (5)	0.0073 (5)	−0.0034 (5)
C13	0.0314 (8)	0.043 (2)	0.052 (2)	−0.0091 (10)	0.0133 (11)	−0.0071 (14)
C14	0.0466 (13)	0.0345 (13)	0.0325 (11)	−0.0042 (9)	0.0117 (9)	−0.0053 (8)
C16	0.091 (3)	0.0511 (14)	0.0374 (14)	0.006 (3)	0.029 (2)	0.0144 (12)
C17	0.0529 (12)	0.0383 (13)	0.0484 (16)	0.0109 (9)	0.0119 (13)	0.0057 (12)
C13B	0.0314 (8)	0.043 (2)	0.052 (2)	−0.0091 (10)	0.0133 (11)	−0.0071 (14)
C14B	0.0466 (13)	0.0345 (13)	0.0325 (11)	−0.0042 (9)	0.0117 (9)	−0.0053 (8)
C16B	0.091 (3)	0.0511 (14)	0.0374 (14)	0.006 (3)	0.029 (2)	0.0144 (12)
C17B	0.0529 (12)	0.0383 (13)	0.0484 (16)	0.0109 (9)	0.0119 (13)	0.0057 (12)
C18	0.0646 (11)	0.0412 (9)	0.0583 (10)	−0.0050 (8)	0.0038 (8)	0.0200 (7)

Geometric parameters (Å, º) top

O1—C1	1.3330 (17)	C11B—H11B	0.9900
O1—C18	1.4422 (18)	C11B—H12B	0.9900
O2—C1	1.1986 (18)	C15B—H13B	0.9800
C1—C2	1.4886 (18)	C15B—H14B	0.9800
C2—C3	1.3895 (18)	C15B—H15B	0.9800
C2—C7	1.4060 (18)	C12—C14B	1.415 (7)
C3—C4	1.3939 (18)	C12—C13	1.519 (4)
C3—H23	0.9500	C12—C13B	1.559 (12)
C4—C5	1.4005 (18)	C12—C14	1.581 (2)
C4—C12	1.5270 (17)	C13—H5	0.9800
C5—C6	1.3994 (18)	C13—H6	0.9800
C5—C9	1.5365 (18)	C13—H7	0.9800
C6—C7	1.3858 (19)	C14—H8	0.9800
C6—H4	0.9500	C14—H9	0.9800
C7—C8	1.5092 (18)	C14—H10	0.9800
C8—H1	0.9800	C16—H17	0.9800
C8—H2	0.9800	C16—H18	0.9800
C8—H3	0.9800	C16—H19	0.9800
C9—C10B	1.517 (6)	C17—H20	0.9800
C9—C16	1.532 (4)	C17—H21	0.9800
C9—C17	1.535 (3)	C17—H22	0.9800
C9—C17B	1.558 (9)	C13B—H5B	0.9800
C9—C16B	1.567 (12)	C13B—H6B	0.9800
C9—C10	1.569 (2)	C13B—H7B	0.9800
C10—C11	1.525 (3)	C14B—H8B	0.9800
C10—C15	1.531 (4)	C14B—H9B	0.9800
C10—H16	1.0000	C14B—H10B	0.9800
C11—C12	1.522 (2)	C16B—H17B	0.9800
C11—H11	0.9900	C16B—H18B	0.9800
C11—H12	0.9900	C16B—H19B	0.9800
C15—H13	0.9800	C17B—H20B	0.9800
C15—H14	0.9800	C17B—H21B	0.9800
C15—H15	0.9800	C17B—H22B	0.9800
C10B—C11B	1.487 (8)	C18—H24	0.9800
C10B—C15B	1.515 (13)	C18—H25	0.9800
C10B—H16B	1.0000	C18—H26	0.9800
C11B—C12	1.633 (5)

C1—O1—C18	116.18 (12)	C12—C11B—H12B	109.1
O2—C1—O1	121.91 (13)	H11B—C11B—H12B	107.9
O2—C1—C2	125.66 (13)	C10B—C15B—H13B	109.5
O1—C1—C2	112.42 (11)	C10B—C15B—H14B	109.5
C3—C2—C7	119.33 (12)	H13B—C15B—H14B	109.5
C3—C2—C1	119.32 (11)	C10B—C15B—H15B	109.5
C7—C2—C1	121.35 (12)	H13B—C15B—H15B	109.5
C2—C3—C4	123.16 (11)	H14B—C15B—H15B	109.5
C2—C3—H23	118.4	C14B—C12—C13	122.5 (4)
C4—C3—H23	118.4	C14B—C12—C11	85.1 (3)
C3—C4—C5	118.17 (11)	C13—C12—C11	112.82 (19)
C3—C4—C12	118.64 (11)	C14B—C12—C4	114.0 (3)
C5—C4—C12	123.19 (12)	C13—C12—C4	109.7 (2)
C6—C5—C4	117.95 (12)	C11—C12—C4	110.08 (12)
C6—C5—C9	118.74 (11)	C14B—C12—C13B	113.2 (7)
C4—C5—C9	123.29 (12)	C4—C12—C13B	108.6 (7)
C7—C6—C5	124.45 (11)	C13—C12—C14	107.86 (18)
C7—C6—H4	117.8	C11—C12—C14	106.67 (13)
C5—C6—H4	117.8	C4—C12—C14	109.60 (12)
C6—C7—C2	116.93 (11)	C13B—C12—C14	96.1 (6)
C6—C7—C8	119.00 (12)	C14B—C12—C11B	114.1 (4)
C2—C7—C8	124.04 (12)	C13—C12—C11B	85.8 (2)
C7—C8—H1	109.5	C4—C12—C11B	106.7 (2)
C7—C8—H2	109.5	C13B—C12—C11B	99.1 (6)
H1—C8—H2	109.5	C14—C12—C11B	133.4 (2)
C7—C8—H3	109.5	C12—C13—H5	109.5
H1—C8—H3	109.5	C12—C13—H6	109.5
H2—C8—H3	109.5	C12—C13—H7	109.5
C10B—C9—C16	125.2 (4)	C12—C14—H8	109.5
C10B—C9—C17	86.8 (3)	C12—C14—H9	109.5
C16—C9—C17	109.67 (19)	C12—C14—H10	109.5
C10B—C9—C5	112.5 (2)	C9—C16—H17	109.5
C16—C9—C5	110.8 (3)	C9—C16—H18	109.5
C17—C9—C5	108.32 (14)	C9—C16—H19	109.5
C10B—C9—C17B	105.9 (4)	C9—C17—H20	109.5
C16—C9—C17B	91.1 (4)	C9—C17—H21	109.5
C5—C9—C17B	107.8 (4)	C9—C17—H22	109.5
C10B—C9—C16B	118.5 (10)	C12—C13B—H5B	109.5
C17—C9—C16B	124.8 (6)	C12—C13B—H6B	109.5
C5—C9—C16B	105.2 (9)	H5B—C13B—H6B	109.5
C17B—C9—C16B	106.5 (7)	C12—C13B—H7B	109.5
C17—C9—C10	111.94 (15)	H5B—C13B—H7B	109.5
C5—C9—C10	109.60 (12)	H6B—C13B—H7B	109.5
C17B—C9—C10	128.9 (4)	C12—C14B—H8B	109.5
C16B—C9—C10	95.9 (9)	C12—C14B—H9B	109.5
C11—C10—C15	110.1 (2)	H8B—C14B—H9B	109.5
C11—C10—C9	110.65 (14)	C12—C14B—H10B	109.5
C15—C10—C9	113.8 (2)	H8B—C14B—H10B	109.5
C11—C10—H16	107.3	H9B—C14B—H10B	109.5
C15—C10—H16	107.3	C9—C16B—H17B	109.5
C9—C10—H16	107.3	C9—C16B—H18B	109.5
C12—C11—C10	112.30 (14)	H17B—C16B—H18B	109.5
C12—C11—H11	109.1	C9—C16B—H19B	109.5
C10—C11—H11	109.1	H17B—C16B—H19B	109.5
C12—C11—H12	109.1	H18B—C16B—H19B	109.5
C10—C11—H12	109.1	C9—C17B—H20B	109.5
H11—C11—H12	107.9	C9—C17B—H21B	109.5
C11B—C10B—C15B	112.3 (8)	H20B—C17B—H21B	109.5
C11B—C10B—C9	109.3 (4)	C9—C17B—H22B	109.5
C15B—C10B—C9	116.5 (9)	H20B—C17B—H22B	109.5
C11B—C10B—H16B	106.0	H21B—C17B—H22B	109.5
C15B—C10B—H16B	106.0	O1—C18—H24	109.5
C9—C10B—H16B	106.0	O1—C18—H25	109.5
C10B—C11B—C12	112.4 (4)	H24—C18—H25	109.5
C10B—C11B—H11B	109.1	O1—C18—H26	109.5
C12—C11B—H11B	109.1	H24—C18—H26	109.5
C10B—C11B—H12B	109.1	H25—C18—H26	109.5

C18—O1—C1—O2	1.2 (2)	C17B—C9—C10—C15	36.1 (5)
C18—O1—C1—C2	179.86 (13)	C16B—C9—C10—C15	−80.7 (8)
O2—C1—C2—C3	169.86 (15)	C15—C10—C11—C12	167.6 (2)
O1—C1—C2—C3	−8.72 (18)	C9—C10—C11—C12	−65.6 (2)
O2—C1—C2—C7	−10.8 (2)	C16—C9—C10B—C11B	94.2 (5)
O1—C1—C2—C7	170.60 (11)	C17—C9—C10B—C11B	−153.9 (4)
C7—C2—C3—C4	0.10 (18)	C5—C9—C10B—C11B	−45.4 (5)
C1—C2—C3—C4	179.43 (11)	C17B—C9—C10B—C11B	−162.8 (5)
C2—C3—C4—C5	0.59 (18)	C16B—C9—C10B—C11B	77.8 (9)
C2—C3—C4—C12	179.94 (11)	C10—C9—C10B—C11B	43.7 (4)
C3—C4—C5—C6	−0.56 (17)	C16—C9—C10B—C15B	−34.4 (8)
C12—C4—C5—C6	−179.88 (11)	C17—C9—C10B—C15B	77.5 (7)
C3—C4—C5—C9	−178.83 (11)	C5—C9—C10B—C15B	−174.0 (6)
C12—C4—C5—C9	1.85 (18)	C17B—C9—C10B—C15B	68.5 (8)
C4—C5—C6—C7	−0.15 (19)	C16B—C9—C10B—C15B	−50.9 (10)
C9—C5—C6—C7	178.20 (11)	C10—C9—C10B—C15B	−85.0 (8)
C5—C6—C7—C2	0.83 (19)	C15B—C10B—C11B—C12	−161.7 (8)
C5—C6—C7—C8	−177.28 (12)	C9—C10B—C11B—C12	67.4 (5)
C3—C2—C7—C6	−0.78 (17)	C10—C11—C12—C14B	162.2 (4)
C1—C2—C7—C6	179.90 (11)	C10—C11—C12—C13	−74.5 (3)
C3—C2—C7—C8	177.23 (12)	C10—C11—C12—C4	48.37 (18)
C1—C2—C7—C8	−2.10 (19)	C10—C11—C12—C13B	−83.0 (8)
C6—C5—C9—C10B	−166.3 (3)	C10—C11—C12—C14	167.20 (16)
C4—C5—C9—C10B	12.0 (3)	C10—C11—C12—C11B	−41.0 (4)
C6—C5—C9—C16	48.2 (2)	C3—C4—C12—C14B	69.9 (3)
C4—C5—C9—C16	−133.5 (2)	C5—C4—C12—C14B	−110.8 (3)
C6—C5—C9—C17	−72.09 (16)	C3—C4—C12—C13	−71.72 (18)
C4—C5—C9—C17	106.17 (16)	C5—C4—C12—C13	107.60 (17)
C6—C5—C9—C17B	−50.0 (3)	C3—C4—C12—C11	163.56 (12)
C4—C5—C9—C17B	128.3 (3)	C5—C4—C12—C11	−17.12 (17)
C6—C5—C9—C16B	63.4 (8)	C3—C4—C12—C13B	−57.3 (6)
C4—C5—C9—C16B	−118.4 (8)	C5—C4—C12—C13B	122.0 (6)
C6—C5—C9—C10	165.52 (12)	C3—C4—C12—C14	46.53 (17)
C4—C5—C9—C10	−16.23 (17)	C5—C4—C12—C14	−134.15 (14)
C16—C9—C10—C11	166.1 (2)	C3—C4—C12—C11B	−163.2 (2)
C17—C9—C10—C11	−74.04 (19)	C5—C4—C12—C11B	16.1 (3)
C5—C9—C10—C11	46.17 (18)	C10B—C11B—C12—C14B	75.9 (6)
C17B—C9—C10—C11	−88.6 (5)	C10B—C11B—C12—C13	−160.2 (5)
C16B—C9—C10—C11	154.6 (7)	C10B—C11B—C12—C11	50.5 (4)
C16—C9—C10—C15	−69.3 (3)	C10B—C11B—C12—C4	−50.9 (5)
C17—C9—C10—C15	50.6 (2)	C10B—C11B—C12—C13B	−163.5 (8)
C5—C9—C10—C15	170.84 (18)	C10B—C11B—C12—C14	89.0 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H23···O1	0.95	2.32	2.6839 (17)	103
C18—H26···O2ⁱ	0.98	2.47	3.397 (2)	157

Symmetry code: (i) −x+1, −y+3, −z.

Experimental details

Crystal data
Chemical formula	C₁₈H₂₆O₂
M_r	274.39
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	193
a, b, c (Å)	11.5049 (11), 11.9482 (5), 12.1078 (13)
β (°)	102.612 (5)
V (Å³)	1624.2 (2)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	0.55
Crystal size (mm)	0.45 × 0.40 × 0.30

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	5083, 3062, 2856
R_int	0.047
(sin θ/λ)_max (Å⁻¹)	0.609

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.054, 0.152, 1.03
No. of reflections	3062
No. of parameters	216
No. of restraints	10
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.29, −0.26

Computer programs: CAD-4 Software (Enraf–Nonius, 1989), CORINC (Dräger & Gattow, 1971), SIR97 (Altomare et al., 1999), SHELXTL (Sheldrick, 2008), PLATON (Spek, 2009).