Two conformers of 10,11-dihydro-5H-dibenzo[a,d]cyclo­heptene spiro-linked with homobenzoquinone epoxide

The crystal structures of the two thermally equilibrated conformational isomers of the epoxide 1',5'-dimethyl­spiro[10,11-dihydro-5H-dibenzo[a,d]cyclo­heptene-5,8'-4'-oxatricyclo[5.1.0.0^3,5]octane]-2',6'-dione, C₂₃H₂₀O₃, have been determined by X-ray diffraction. In the tricyclic dione skeleton, the oxirane and cyclo­propane rings adopt an anti structure with respect to the conjunct quinone frame. The spiro-linked 10,11-dihydro-5H-dibenzo[a,d]cyclo­heptene ring of the major isomer has a fairly twisted boat form, folding opposite to the adjoining cyclo­propane methyl substituent, whereas the seven-membered ring of the minor isomer has an almost ideal twist-boat form, inversely folding to the side of the relevant methyl group. The conformational structures of these isomers have been compared with those of the corresponding isomers of the unepoxidized homobenzoquinone.

S1. Comment

Conformationally, 10,11-dihydro-5H-dibenzo[a,d]cycloheptene and its derivatives have received considerable pharmacological attention in view of their potential as a suitable subunit for drug-receptor concave–convex interaction (Burger, 1983). In our previous paper, we reported that the reaction of 5-diazo-10,11-dihydro-5H-dibenzo[a,d]cycloheptene and 2,5-dimethyl-1, 4-benzoquinone gave the corresponding spirohomobenzoquinone (Ia) via the conformationally locked nitrogen release of the primary adduct pyrazoline (Oshima & Nagai, 1994). Compound (Ia) was found to tranform to the more stable conformer (Ib) at 373 K by way of a complete one-way conformational inversion of the spiro-linked 10,11-dihydro-5H-dibenzo[a,d]cycloheptene moiety (Oshima et al. 1999). We also found that the epoxidation of these conformers (Ia) and (Ib) proceeded without any conformational inversion to give the corresponding epoxides (IIa) and (IIb), respectively, but that thermal equilibration was attained at 373 K in CDCl₃ in preference of (IIb) (96%, by ¹H NMR) (Asahara, Koizumi & Oshima, unpublished results).

In this paper, we describe the conformational details of these two isomers, (IIa) and (IIb), as determined by X-ray crystallography and compare them with the parent unepoxidized conformers (Ia) and (Ib).

As shown in Fig. 1(a), the dibenzo-fused cycloheptene ring in (IIa) adopts a fairly twisted boat conformation, folding opposite to the cyclopropane CH₃ substituent in analogy with (Ia), but the dihedral angle [θ = 33.1 (4)°] of the –CH₂—CH₂– bridge and the intramolecular bond angle [ω =108.9 (2)°] centered at the spiro-C atom are larger than the corresponding values for (Ia) [27.3 (3) and 107.8 (2)°, respectively]. On the other hand, as shown in Fig. 1(b), the conformationally inverted (IIb) adopts a more highly twisted boat conformation, with θ = 63.6 (3)° and ω = 113 (2)°; the corresponding angles for (Ib) are 55.5 (9) and 111.3 (7)°. It was also found that ω is well correlated with θ, probably because of the constrained dibenzo fusion, i.e. ω = 0.133θ + 104 (n = 4 and R = 0.99, where n and R are the number of data points and the correlation coefficient, respectively).

We also compared these angles θ and ω with the corresponding crystalline values [57.9 (2) and 114.6 (2)°] for the least strained pristine 10,11-dihydro-5H-dibenzo[a,d]cycloheptene, (III) (Reboul & Cristau, 1981). The less stable conformers (Ia) and (IIa) possess the considerably smaller θ values than the ideal gauche angle, while the stable isomers (Ib) and (IIb) as well as (III) adopt substantially the gauche conformations for the –CH₂—CH₂– bridge.

A perusal of the X-ray structure of (IIa) indicates that several atoms of the dibenzo-fused seven-membered ring occupy crowded positions almost touching the underlying quinone component, as represented by the very short spatial distances between C8 and H20 (2.72 Å), O1 and H16 (2.75 Å), and O1 and H14 (2.87 Å). These unfavorable non-bonding interactions may be taken as a driving force for the conformational isomerization. However, such a van der Waals contact was also observed for the stable (IIb), in particular, between the ethano-bridge H14 atom and the facing carbonyl O2 atom (2.44 Å), appreciably raising the strain energy of (IIb).

With respect to the structure of the quinone frame, (IIb) is especially characterized by being almost planar, as shown by the dihedral angles of 177.8 (2) and −176.1 (2)° for the bond linkages O2—C4—C3—C2 and O1—C7—C2—C3, respectively, whereas the other conformers (Ia), (Ib) and (IIa) adopt slightly folded (12–22°) boat conformations, as indicated by the corresponding angles of 157.7 (3) and −163.5 (3)° for (Ia), 164.0 (14) and −168.2 (13)° for (Ib), and 163.8 (3) and −164.4 (3)° for (IIa), respectively. Of further interest is the fact that the C atoms of the oxirane rings of (IIa) and (IIb) are almost planar, as indicated by the angles of 355° or more when we add the three angles made by the substituents of the oxirane ring and another carbon center. Such a geometrical planarity of oxirane C atoms is commonly known for most of the oxirane derivatives compiled in the Cambridge Structural Database (Version 5.22 of January 2002; Allen, 2002) (Oki et al., 2003).

S2. Experimental

Samples of (IIa) and (IIb) were synthesized by epoxidation of the parent compounds (Ia) and (Ib), respectively, and were recrystallized from a mixture of pentane and tert-butyl methyl ether (10:1). Compound (IIa): m.p. 456.3–457.9 K; ¹H (CDCl₃): δ 0.77 (3H, s), 1.60 (3H, s), 2.44 (1H, s), 2.73–2.97 (2H, m), 3.00 (1H, s), 3.30–3.40 (1H, m), 4.08–4.17(1H, m), 6.95–6.99 (2H, m), 7.00–7.26 (6H, m); ¹³C (CDCl₃): δ 13.4, 18.5, 29.8, 31.6, 38.0, 44.9, 48.1, 59.7, 60.6, 125.8, 126.3, 126.5, 126.9, 128.1, 128.1, 130.2, 132.2, 134.9, 138.6, 139.2, 140.4, 197.4, 201.0. Compound (IIb): m.p. 425.4–426.3 K; ¹H (CDCl₃): δ 1.21 (3H, s), 1.34 (3H, s), 2.71–2.95 (2H, m), 2.73 (1H, s), 2.97 (1H, s), 3.41–3.67 (2H, m), 7.0–7.37 (8H, m); ¹³C (CDCl₃): δ 14.6, 16.3, 30.3, 32.2, 37.9, 39.5, 48.8, 60.1, 61.0, 126.1, 126.2, 126.8, 127.2, 128.2, 128.7, 130.2, 131.7, 135.5, 136.9, 138.4, 141.0, 199.0, 199.4.

S3. Refinement

H atoms bonded to C atoms were placed in geometrically idealized positions, with C—H distances of 0.95–0.98 Å, and refined as riding atoms, with U_iso(H) values of 1.2U_eq(C).

Computing details

For both compounds, data collection: PROCESS-AUTO (Rigaku Corporation, 1998); cell refinement: PROCESS-AUTO. Data reduction: TEXSAN (Molecular Structure Corporation & Rigaku Corporation, 2000) for (IIa); TEXSAN (Molecular Structure Corporation & Rigaku Corporation, 2000 for (IIb). For both compounds, program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: TEXSAN; software used to prepare material for publication: TEXSAN.

Figures

	Fig. 1. The molecular structure of isomer (IIa), with the atomic numbering scheme. Displacement ellipsoids are plotted at the 35% probability level. H atoms are drawn as spheres of arbitrary radii.
	Fig. 2. The molecular structure of isomer (IIb), with the atomic numbering scheme. Displacement ellipsoids are plotted at the 35% probability level. H atoms are drawn as spheres of arbitrary radii.

(IIa) 1',5'-dimethylspiro[10,11-dihydro-5H-dibenzo[a,d]cycloheptene-5,8'- 4'-oxatricyclo[5.1.0.0^3,5]octane]-2',6'-dione

Crystal data

C23H20O3	Dx = 1.311 Mg m^−3
Mr = 344.41	Melting point = 183.1–184.7 K
Monoclinic, P21/a	Mo Kα radiation, λ = 0.7107 Å
a = 12.517 (1) Å	Cell parameters from 15836 reflections
b = 10.206 (1) Å	θ = 2.7–27.5°
c = 14.704 (2) Å	µ = 0.09 mm^−1
β = 111.747 (7)°	T = 223 K
V = 1744.7 (4) Å^3	Platelet, colorless
Z = 4	0.30 × 0.20 × 0.10 mm

Data collection

Rigaku R-AXIS RAPID imaging-plate diffractometer	2584 reflections with F^2 > 2σ(F^2)
Detector resolution: 8.00 pixels mm^-1	Rint = 0.081
ω scans	θmax = 27.5°
Absorption correction: multi-scan (Higashi, 1995)	h = −16→16
Tmin = 0.974, Tmax = 0.991	k = −13→13
13852 measured reflections	l = −19→19
3922 independent reflections

Refinement

Refinement on F^2	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.086	w = 1/(σ^2(Fo^2) + {0.05[Max(Fo^2,0) + 2Fc^2]/3}^2)
wR(F^2) = 0.188	(Δ/σ)max = 0.007
S = 1.96	Δρmax = 0.60 e Å^−3
3922 reflections	Δρmin = −0.46 e Å^−3
235 parameters

Special details

Refinement. Refinement using reflections with F² > −10.0 σ(F²). The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2.0 σ(F²) is used only for calculating R-factor (gt).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	−0.2400 (2)	−0.4268 (2)	−0.5602 (2)	0.0620 (8)
O2	−0.3936 (2)	−0.5743 (2)	−0.9365 (2)	0.0448 (7)
O3	−0.2593 (2)	−0.6545 (2)	−0.7128 (2)	0.0459 (7)
C1	−0.3681 (3)	−0.6727 (3)	−0.6012 (2)	0.049 (1)
C2	−0.3369 (2)	−0.5921 (3)	−0.6732 (2)	0.0338 (8)
C3	−0.3773 (2)	−0.6275 (3)	−0.7771 (2)	0.0335 (8)
C4	−0.3842 (2)	−0.5312 (3)	−0.8560 (2)	0.0322 (8)
C5	−0.3721 (2)	−0.3884 (3)	−0.8334 (2)	0.0295 (7)
C6	−0.3228 (2)	−0.3541 (3)	−0.7235 (2)	0.0317 (7)
C7	−0.2963 (2)	−0.4533 (3)	−0.6453 (2)	0.0387 (8)
C8	−0.3285 (2)	−0.3082 (3)	−0.8990 (2)	0.0409 (9)
C9	−0.4498 (2)	−0.3263 (3)	−0.7858 (2)	0.0267 (7)
C10	−0.5424 (2)	−0.4046 (2)	−0.7675 (2)	0.0264 (7)
C11	−0.6123 (2)	−0.4896 (3)	−0.8400 (2)	0.0317 (7)
C12	−0.7003 (2)	−0.5597 (3)	−0.8267 (3)	0.0408 (9)
C13	−0.7214 (3)	−0.5423 (3)	−0.7423 (3)	0.047 (1)
C14	−0.6556 (3)	−0.4545 (3)	−0.6719 (3)	0.0416 (9)
C15	−0.5666 (2)	−0.3825 (3)	−0.6826 (2)	0.0325 (8)
C16	−0.5057 (3)	−0.2854 (3)	−0.6012 (2)	0.0434 (9)
C17	−0.4396 (3)	−0.1678 (3)	−0.6215 (2)	0.0443 (9)
C18	−0.4885 (2)	−0.1111 (3)	−0.7233 (2)	0.0357 (8)
C19	−0.5367 (2)	0.0144 (3)	−0.7406 (3)	0.0466 (10)
C20	−0.5802 (3)	0.0676 (3)	−0.8330 (3)	0.051 (1)
C21	−0.5789 (2)	−0.0046 (3)	−0.9135 (3)	0.0465 (10)
C22	−0.5340 (2)	−0.1318 (3)	−0.8979 (2)	0.0371 (8)
C23	−0.4880 (2)	−0.1846 (3)	−0.8041 (2)	0.0294 (7)
H1	−0.4199	−0.6239	−0.5794	0.0597*
H2	−0.3012	−0.6931	−0.5463	0.0597*
H3	−0.4054	−0.7512	−0.6313	0.0597*
H4	−0.4276	−0.7015	−0.7965	0.0398*
H5	−0.2743	−0.2780	−0.7076	0.0381*
H6	−0.3797	−0.3163	−0.9660	0.0512*
H7	−0.3231	−0.2178	−0.8815	0.0512*
H8	−0.2541	−0.3382	−0.8941	0.0512*
H9	−0.5985	−0.4993	−0.9005	0.0386*
H10	−0.7481	−0.6196	−0.8771	0.0492*
H11	−0.7834	−0.5911	−0.7337	0.0552*
H12	−0.6713	−0.4437	−0.6127	0.0524*
H13	−0.5611	−0.2492	−0.5782	0.0524*
H14	−0.4506	−0.3342	−0.5482	0.0524*
H15	−0.4354	−0.0998	−0.5751	0.0514*
H16	−0.3618	−0.1960	−0.6091	0.0514*
H17	−0.5381	0.0648	−0.6852	0.0566*
H18	−0.6122	0.1545	−0.8428	0.0601*
H19	−0.6104	0.0315	−0.9803	0.0567*
H20	−0.5353	−0.1848	−0.9532	0.0455*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.075 (2)	0.049 (1)	0.036 (1)	0.001 (1)	−0.010 (1)	−0.005 (1)
O2	0.058 (1)	0.043 (1)	0.038 (1)	0.004 (1)	0.023 (1)	−0.005 (1)
O3	0.043 (1)	0.039 (1)	0.054 (2)	0.0074 (9)	0.016 (1)	0.002 (1)
C1	0.065 (2)	0.044 (2)	0.037 (2)	0.001 (2)	0.017 (2)	0.011 (2)
C2	0.035 (1)	0.030 (2)	0.032 (2)	0.005 (1)	0.008 (1)	0.002 (1)
C3	0.032 (1)	0.026 (1)	0.042 (2)	−0.002 (1)	0.013 (1)	0.000 (1)
C4	0.031 (1)	0.033 (2)	0.034 (2)	0.001 (1)	0.012 (1)	−0.002 (1)
C5	0.027 (1)	0.030 (1)	0.033 (2)	0.000 (1)	0.012 (1)	0.003 (1)
C6	0.024 (1)	0.023 (1)	0.045 (2)	−0.003 (1)	0.010 (1)	−0.003 (1)
C7	0.034 (1)	0.037 (2)	0.037 (2)	0.003 (1)	0.004 (1)	−0.005 (1)
C8	0.038 (2)	0.039 (2)	0.055 (2)	0.002 (1)	0.029 (1)	0.004 (2)
C9	0.025 (1)	0.024 (1)	0.030 (2)	−0.0010 (10)	0.009 (1)	0.001 (1)
C10	0.028 (1)	0.021 (1)	0.030 (2)	0.0045 (10)	0.010 (1)	0.006 (1)
C11	0.030 (1)	0.031 (2)	0.032 (2)	0.000 (1)	0.010 (1)	0.000 (1)
C12	0.036 (2)	0.029 (2)	0.059 (2)	−0.004 (1)	0.019 (1)	−0.003 (2)
C13	0.044 (2)	0.032 (2)	0.077 (3)	−0.003 (1)	0.036 (2)	0.005 (2)
C14	0.054 (2)	0.034 (2)	0.052 (2)	0.006 (1)	0.037 (2)	0.010 (2)
C15	0.036 (1)	0.029 (1)	0.032 (2)	0.007 (1)	0.013 (1)	0.003 (1)
C16	0.052 (2)	0.048 (2)	0.032 (2)	0.007 (2)	0.017 (1)	−0.001 (2)
C17	0.048 (2)	0.043 (2)	0.041 (2)	−0.003 (1)	0.015 (1)	−0.020 (2)
C18	0.030 (1)	0.027 (2)	0.050 (2)	−0.004 (1)	0.015 (1)	−0.006 (1)
C19	0.043 (2)	0.028 (2)	0.073 (3)	−0.004 (1)	0.026 (2)	−0.010 (2)
C20	0.041 (2)	0.027 (2)	0.091 (3)	0.004 (1)	0.032 (2)	0.008 (2)
C21	0.035 (2)	0.040 (2)	0.067 (3)	0.006 (1)	0.021 (2)	0.024 (2)
C22	0.030 (1)	0.035 (2)	0.048 (2)	0.000 (1)	0.017 (1)	0.008 (2)
C23	0.023 (1)	0.025 (1)	0.041 (2)	−0.002 (1)	0.014 (1)	0.002 (1)

Geometric parameters (Å, º)

O1—C7	1.218 (4)	C11—C12	1.388 (4)
O2—C4	1.227 (4)	C11—H9	0.971
O3—C2	1.451 (4)	C12—C13	1.372 (6)
O3—C3	1.454 (3)	C12—H10	0.976
C1—C2	1.503 (5)	C13—C14	1.386 (4)
C1—H1	0.962	C13—H11	0.969
C1—H2	0.945	C14—C15	1.391 (5)
C1—H3	0.950	C14—H12	0.966
C2—C3	1.465 (4)	C15—C16	1.524 (4)
C2—C7	1.510 (4)	C16—C17	1.548 (5)
C3—C4	1.497 (4)	C16—H13	0.951
C3—H4	0.957	C16—H14	0.965
C4—C5	1.490 (4)	C17—C18	1.507 (4)
C5—C6	1.541 (4)	C17—H15	0.961
C5—C8	1.513 (5)	C17—H16	0.966
C5—C9	1.531 (4)	C18—C19	1.399 (4)
C6—C7	1.475 (4)	C18—C23	1.408 (5)
C6—C9	1.539 (3)	C19—C20	1.375 (6)
C6—H5	0.960	C19—H17	0.970
C8—H6	0.960	C20—C21	1.399 (6)
C8—H7	0.953	C20—H18	0.961
C8—H8	0.957	C21—C22	1.400 (4)
C9—C10	1.512 (4)	C21—H19	0.984
C9—C23	1.516 (4)	C22—C23	1.391 (4)
C10—C11	1.401 (4)	C22—H20	0.971
C10—C15	1.408 (5)
O1···C1^i	3.436 (4)	O3···C13^iii	3.184 (4)
O2···O2^ii	3.032 (4)	O3···C19^iv	3.290 (4)
O2···C11^ii	3.377 (4)	O3···C20^iv	3.446 (5)
O2···C4^ii	3.452 (3)	O3···C12^iii	3.574 (4)
O2···C5^ii	3.583 (3)
C2—O3—C3	60.6 (2)	C9—C10—C11	119.7 (3)
C2—C1—H1	109.6	C9—C10—C15	120.3 (2)
C2—C1—H2	110.0	C11—C10—C15	119.7 (3)
C2—C1—H3	110.1	C10—C11—C12	121.1 (3)
H1—C1—H2	108.9	C10—C11—H9	119.2
H1—C1—H3	108.4	C12—C11—H9	119.7
H2—C1—H3	109.8	C11—C12—C13	119.3 (3)
O3—C2—C1	115.4 (2)	C11—C12—H10	120.8
O3—C2—C3	59.8 (2)	C13—C12—H10	119.9
O3—C2—C7	108.3 (2)	C12—C13—C14	119.9 (3)
C1—C2—C3	121.4 (2)	C12—C13—H11	118.9
C1—C2—C7	118.1 (3)	C14—C13—H11	121.2
C3—C2—C7	117.8 (3)	C13—C14—C15	122.4 (4)
O3—C3—C2	59.6 (2)	C13—C14—H12	118.9
O3—C3—C4	112.5 (2)	C15—C14—H12	118.7
O3—C3—H4	116.2	C10—C15—C14	117.4 (3)
C2—C3—C4	123.0 (2)	C10—C15—C16	126.2 (3)
C2—C3—H4	116.0	C14—C15—C16	116.4 (3)
C4—C3—H4	116.4	C15—C16—C17	120.1 (3)
O2—C4—C3	118.0 (3)	C15—C16—H13	108.2
O2—C4—C5	122.1 (3)	C15—C16—H14	107.4
C3—C4—C5	119.8 (3)	C17—C16—H13	106.3
C4—C5—C6	115.1 (2)	C17—C16—H14	106.4
C4—C5—C8	114.7 (3)	H13—C16—H14	108.1
C4—C5—C9	118.5 (3)	C16—C17—C18	116.1 (2)
C6—C5—C8	116.5 (2)	C16—C17—H15	108.4
C6—C5—C9	60.1 (2)	C16—C17—H16	107.8
C8—C5—C9	120.5 (2)	C18—C17—H15	108.8
C5—C6—C7	123.3 (2)	C18—C17—H16	108.2
C5—C6—C9	59.6 (2)	H15—C17—H16	107.2
C5—C6—H5	114.3	C17—C18—C19	121.5 (3)
C7—C6—C9	118.4 (2)	C17—C18—C23	120.5 (3)
C7—C6—H5	115.2	C19—C18—C23	118.0 (3)
C9—C6—H5	114.6	C18—C19—C20	121.9 (4)
O1—C7—C2	119.7 (3)	C18—C19—H17	118.3
O1—C7—C6	121.8 (3)	C20—C19—H17	119.8
C2—C7—C6	118.4 (2)	C19—C20—C21	120.2 (3)
C5—C8—H6	110.3	C19—C20—H18	120.2
C5—C8—H7	111.0	C21—C20—H18	119.6
C5—C8—H8	110.4	C20—C21—C22	118.7 (3)
H6—C8—H7	108.4	C20—C21—H19	121.4
H6—C8—H8	108.1	C22—C21—H19	119.9
H7—C8—H8	108.6	C21—C22—C23	121.0 (3)
C5—C9—C6	60.3 (2)	C21—C22—H20	119.9
C5—C9—C10	121.4 (2)	C23—C22—H20	119.1
C5—C9—C23	121.8 (3)	C9—C23—C18	117.3 (3)
C6—C9—C10	119.2 (2)	C9—C23—C22	122.2 (3)
C6—C9—C23	118.0 (2)	C18—C23—C22	120.1 (3)
C10—C9—C23	108.9 (2)
O1—C7—C2—O3	−99.5 (4)	C6—C9—C10—C11	−114.4 (3)
O1—C7—C2—C1	34.0 (4)	C6—C9—C10—C15	72.2 (3)
O1—C7—C2—C3	−164.4 (3)	C6—C9—C23—C18	−68.1 (4)
O1—C7—C6—C5	167.4 (3)	C6—C9—C23—C22	119.5 (3)
O1—C7—C6—C9	−122.1 (3)	C7—C6—C5—C8	−142.6 (3)
O2—C4—C3—O3	96.4 (3)	C7—C6—C5—C9	105.9 (3)
O2—C4—C3—C2	163.8 (3)	C7—C6—C9—C10	−2.3 (4)
O2—C4—C5—C6	−161.0 (3)	C7—C6—C9—C23	133.5 (3)
O2—C4—C5—C8	−21.7 (3)	C8—C5—C6—C9	111.6 (3)
O2—C4—C5—C9	130.7 (3)	C8—C5—C9—C10	147.0 (2)
O3—C2—C3—C4	−98.5 (3)	C8—C5—C9—C23	1.4 (3)
O3—C2—C7—C6	78.2 (3)	C9—C10—C11—C12	−177.9 (2)
O3—C3—C2—C1	−103.1 (3)	C9—C10—C15—C14	177.8 (2)
O3—C3—C2—C7	95.9 (3)	C9—C10—C15—C16	−1.3 (4)
O3—C3—C4—C5	−79.6 (3)	C9—C23—C18—C17	7.0 (4)
C1—C2—O3—C3	113.0 (3)	C9—C23—C18—C19	−172.2 (3)
C1—C2—C3—C4	158.4 (3)	C9—C23—C22—C21	173.7 (3)
C1—C2—C7—C6	−148.2 (3)	C10—C9—C23—C18	71.9 (3)
C2—O3—C3—C4	116.1 (3)	C10—C9—C23—C22	−100.5 (3)
C2—C3—C4—C5	−12.3 (4)	C10—C11—C12—C13	1.9 (4)
C2—C7—C6—C5	−10.3 (4)	C10—C15—C14—C13	−1.9 (4)
C2—C7—C6—C9	60.2 (4)	C10—C15—C16—C17	21.6 (4)
C3—O3—C2—C7	−112.1 (3)	C11—C10—C9—C23	106.2 (3)
C3—C2—C7—C6	13.4 (4)	C11—C10—C15—C14	4.4 (4)
C3—C4—C5—C6	14.9 (4)	C11—C10—C15—C16	−174.7 (3)
C3—C4—C5—C8	154.2 (2)	C11—C12—C13—C14	0.6 (4)
C3—C4—C5—C9	−53.3 (3)	C12—C11—C10—C15	−4.5 (4)
C4—C3—C2—C7	−2.5 (4)	C12—C13—C14—C15	−0.6 (4)
C4—C5—C6—C7	−4.0 (4)	C13—C14—C15—C16	177.3 (3)
C4—C5—C6—C9	−109.8 (3)	C14—C15—C16—C17	−157.5 (3)
C4—C5—C9—C6	104.2 (3)	C15—C10—C9—C23	−67.2 (3)
C4—C5—C9—C10	−3.8 (3)	C15—C16—C17—C18	33.1 (4)
C4—C5—C9—C23	−149.4 (2)	C16—C17—C18—C19	112.2 (3)
C5—C6—C9—C10	111.7 (3)	C16—C17—C18—C23	−67.0 (4)
C5—C6—C9—C23	−112.5 (3)	C17—C18—C19—C20	179.1 (3)
C5—C9—C6—C7	−114.0 (3)	C17—C18—C23—C22	179.6 (3)
C5—C9—C10—C11	−43.3 (3)	C18—C19—C20—C21	1.0 (5)
C5—C9—C10—C15	143.3 (2)	C18—C23—C22—C21	1.6 (4)
C5—C9—C23—C18	−138.8 (3)	C19—C18—C23—C22	0.3 (4)
C5—C9—C23—C22	48.9 (3)	C19—C20—C21—C22	0.8 (5)
C6—C5—C9—C10	−108.0 (3)	C20—C19—C18—C23	−1.6 (5)
C6—C5—C9—C23	106.4 (2)	C20—C21—C22—C23	−2.1 (4)
C6—C9—C5—C8	−105.0 (2)	C20—C21—C22—C23	−2.1 (4)

Symmetry codes: (i) −x−1/2, y+1/2, −z−1; (ii) −x−1, −y−1, −z−2; (iii) x+1/2, −y−3/2, z; (iv) x+1/2, −y−1/2, z.

(IIb)

Crystal data

C23H20O3	Melting point = 152.2–153.1 K
Mr = 344.41	Mo Kα radiation, λ = 0.7107 Å
Orthorhombic, Pbca	Cell parameters from 38732 reflections
a = 9.4653 (3) Å	θ = 1.6–27.5°
b = 14.6974 (4) Å	µ = 0.09 mm^−1
c = 25.3890 (9) Å	T = 213 K
V = 3532.0 (2) Å^3	Platelet, colorless
Z = 8	0.30 × 0.30 × 0.10 mm
Dx = 1.295 Mg m^−3

Data collection

Rigaku R-AXIS RAPID imaging-plate diffractometer	2670 reflections with F^2 > 2.0σ(F^2)
Detector resolution: 8.00 pixels mm^-1	Rint = 0.085
ω scans	θmax = 27.4°
Absorption correction: multi-scan (Higashi, 1995)	h = −12→12
Tmin = 0.974, Tmax = 0.992	k = −19→16
26252 measured reflections	l = −32→32
3955 independent reflections

Refinement

Refinement on F^2	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.077	w = 1/[σ^2(Fo^2) + (0.05000(Max(Fo^2,0) + 2Fc^2)/3)^2]
wR(F^2) = 0.176	(Δ/σ)max = 0.008
S = 1.90	Δρmax = 0.54 e Å^−3
3955 reflections	Δρmin = −0.45 e Å^−3
235 parameters

Special details

Refinement. Refinement using reflections with F² > −10.0 σ(F²). The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2.0 σ(F²) is used only for calculating R-factor (gt).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.6459 (2)	0.0325 (1)	0.04870 (8)	0.0353 (6)
O2	0.3140 (2)	−0.0376 (1)	0.21843 (8)	0.0312 (5)
O3	0.6056 (2)	−0.0913 (1)	0.15553 (8)	0.0319 (5)
C1	0.7844 (3)	0.0335 (2)	0.1481 (1)	0.0372 (9)
C2	0.6357 (3)	0.0025 (2)	0.1403 (1)	0.0246 (7)
C3	0.5413 (3)	−0.0170 (2)	0.1847 (1)	0.0246 (7)
C4	0.3845 (3)	−0.0178 (2)	0.1799 (1)	0.0224 (7)
C5	0.3176 (3)	−0.0019 (1)	0.1273 (1)	0.0200 (6)
C6	0.4138 (3)	0.0210 (2)	0.0821 (1)	0.0198 (6)
C7	0.5697 (3)	0.0209 (2)	0.0868 (1)	0.0243 (7)
C8	0.1849 (3)	−0.0564 (2)	0.1168 (1)	0.0302 (8)
C9	0.3270 (2)	0.0978 (2)	0.1068 (1)	0.0176 (6)
C10	0.4003 (3)	0.1686 (1)	0.1406 (1)	0.0178 (6)
C11	0.5259 (3)	0.2098 (2)	0.1254 (1)	0.0226 (7)
C12	0.5885 (3)	0.2760 (2)	0.1563 (1)	0.0277 (7)
C13	0.5242 (3)	0.3032 (2)	0.2025 (1)	0.0311 (8)
C14	0.3967 (3)	0.2648 (2)	0.2172 (1)	0.0268 (7)
C15	0.3327 (3)	0.1977 (2)	0.1867 (1)	0.0216 (6)
C16	0.1862 (3)	0.1642 (2)	0.1985 (1)	0.0253 (7)
C17	0.0798 (3)	0.2058 (2)	0.1608 (1)	0.0262 (7)
C18	0.0918 (3)	0.1841 (2)	0.1023 (1)	0.0237 (7)
C19	−0.0192 (3)	0.2169 (2)	0.0709 (1)	0.0365 (9)
C20	−0.0256 (3)	0.2029 (2)	0.0175 (1)	0.0426 (9)
C21	0.0826 (4)	0.1559 (2)	−0.0072 (1)	0.0377 (9)
C22	0.1952 (3)	0.1237 (2)	0.0223 (1)	0.0264 (7)
C23	0.2013 (3)	0.1354 (2)	0.0770 (1)	0.0204 (6)
H1	0.7937	0.0955	0.1372	0.0469*
H2	0.8098	0.0290	0.1843	0.0469*
H3	0.8477	−0.0028	0.1278	0.0469*
H4	0.5789	−0.0051	0.2194	0.0297*
H5	0.3796	0.0011	0.0484	0.0231*
H6	0.1151	−0.0415	0.1426	0.0374*
H7	0.1493	−0.0428	0.0829	0.0374*
H8	0.2050	−0.1198	0.1191	0.0374*
H9	0.5695	0.1914	0.0925	0.0275*
H10	0.6768	0.3032	0.1456	0.0337*
H11	0.5672	0.3484	0.2244	0.0380*
H12	0.3506	0.2849	0.2495	0.0344*
H13	0.1619	0.1807	0.2340	0.0305*
H14	0.1831	0.0996	0.1956	0.0305*
H15	0.0863	0.2703	0.1643	0.0304*
H16	−0.0123	0.1870	0.1719	0.0304*
H17	−0.0948	0.2493	0.0881	0.0438*
H18	−0.1042	0.2259	−0.0029	0.0500*
H19	0.0787	0.1452	−0.0441	0.0435*
H20	0.2708	0.0922	0.0045	0.0321*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.027 (1)	0.045 (1)	0.033 (1)	−0.0003 (9)	0.009 (1)	−0.0073 (10)
O2	0.033 (1)	0.0295 (10)	0.031 (1)	0.0044 (8)	0.004 (1)	0.0102 (9)
O3	0.0249 (10)	0.0199 (8)	0.051 (1)	0.0030 (7)	−0.001 (1)	0.0028 (9)
C1	0.024 (1)	0.038 (2)	0.050 (2)	−0.003 (1)	−0.009 (2)	0.006 (1)
C2	0.020 (1)	0.016 (1)	0.038 (2)	0.0022 (10)	−0.005 (1)	−0.001 (1)
C3	0.026 (1)	0.022 (1)	0.025 (2)	0.001 (1)	−0.004 (1)	0.004 (1)
C4	0.027 (1)	0.015 (1)	0.025 (2)	0.0009 (10)	0.000 (1)	0.002 (1)
C5	0.019 (1)	0.016 (1)	0.026 (2)	−0.0012 (9)	−0.001 (1)	0.000 (1)
C6	0.021 (1)	0.020 (1)	0.018 (1)	0.0009 (10)	−0.002 (1)	−0.002 (1)
C7	0.024 (1)	0.022 (1)	0.027 (2)	0.004 (1)	0.003 (1)	−0.004 (1)
C8	0.026 (1)	0.022 (1)	0.043 (2)	−0.005 (1)	−0.006 (1)	0.002 (1)
C9	0.016 (1)	0.019 (1)	0.017 (1)	−0.0006 (9)	0.002 (1)	−0.001 (1)
C10	0.018 (1)	0.016 (1)	0.020 (1)	0.0022 (9)	−0.003 (1)	0.0019 (10)
C11	0.022 (1)	0.020 (1)	0.026 (2)	0.0032 (10)	0.000 (1)	0.003 (1)
C12	0.024 (1)	0.019 (1)	0.041 (2)	−0.003 (1)	−0.008 (1)	0.002 (1)
C13	0.037 (2)	0.019 (1)	0.037 (2)	0.003 (1)	−0.020 (2)	−0.006 (1)
C14	0.035 (2)	0.022 (1)	0.023 (1)	0.010 (1)	−0.006 (1)	−0.003 (1)
C15	0.023 (1)	0.020 (1)	0.021 (1)	0.0075 (10)	−0.003 (1)	0.000 (1)
C16	0.028 (1)	0.022 (1)	0.025 (2)	0.006 (1)	0.006 (1)	−0.004 (1)
C17	0.019 (1)	0.026 (1)	0.034 (2)	0.002 (1)	0.003 (1)	−0.005 (1)
C18	0.020 (1)	0.020 (1)	0.032 (2)	0.0015 (10)	−0.001 (1)	0.002 (1)
C19	0.027 (1)	0.034 (1)	0.048 (2)	0.010 (1)	0.000 (2)	0.003 (1)
C20	0.036 (2)	0.045 (2)	0.047 (2)	0.012 (1)	−0.013 (2)	0.010 (2)
C21	0.045 (2)	0.040 (2)	0.028 (2)	0.006 (1)	−0.011 (2)	0.005 (1)
C22	0.025 (1)	0.027 (1)	0.027 (2)	0.004 (1)	−0.002 (1)	0.001 (1)
C23	0.021 (1)	0.016 (1)	0.025 (2)	−0.0012 (9)	−0.003 (1)	0.001 (1)

Geometric parameters (Å, º)

O1—C7	1.218 (4)	C11—C12	1.384 (4)
O2—C4	1.220 (3)	C11—H9	0.970
O3—C2	1.460 (3)	C12—C13	1.379 (4)
O3—C3	1.452 (3)	C12—H10	0.966
C1—C2	1.492 (4)	C13—C14	1.384 (4)
C1—H1	0.957	C13—H11	0.958
C1—H2	0.952	C14—C15	1.393 (4)
C1—H3	0.954	C14—H12	0.975
C2—C3	1.466 (4)	C15—C16	1.502 (4)
C2—C7	1.521 (4)	C16—C17	1.518 (4)
C3—C4	1.490 (4)	C16—H13	0.961
C3—H4	0.967	C16—H14	0.952
C4—C5	1.495 (4)	C17—C18	1.524 (4)
C5—C6	1.503 (4)	C17—H15	0.954
C5—C8	1.514 (4)	C17—H16	0.957
C5—C9	1.557 (3)	C18—C19	1.404 (4)
C6—C7	1.480 (4)	C18—C23	1.413 (4)
C6—C9	1.530 (3)	C19—C20	1.374 (5)
C6—H5	0.961	C19—H17	0.963
C8—H6	0.956	C20—C21	1.385 (5)
C8—H7	0.946	C20—H18	0.966
C8—H8	0.954	C21—C22	1.385 (4)
C9—C10	1.517 (3)	C21—H19	0.950
C9—C23	1.515 (4)	C22—C23	1.401 (4)
C10—C11	1.390 (4)	C22—H20	0.965
C10—C15	1.400 (4)
O3···C17^i	3.462 (3)	O2···C14^i	3.523 (3)
O3···C12^ii	3.491 (3)	O2···C1^v	3.557 (4)
O1···C22^iii	3.284 (3)	O2···C3^v	3.578 (3)
O1···C6^iii	3.460 (3)	C8···C13^i	3.593 (4)
O2···C13^iv	3.444 (3)	C13···C16^vi	3.585 (4)
C2—O3—C3	60.4 (2)	C9—C10—C11	122.1 (2)
C2—C1—H1	109.8	C9—C10—C15	118.3 (2)
C2—C1—H2	110.2	C11—C10—C15	119.4 (2)
C2—C1—H3	110.5	C10—C11—C12	120.9 (2)
H1—C1—H2	108.7	C10—C11—H9	118.9
H1—C1—H3	108.5	C12—C11—H9	120.1
H2—C1—H3	109.0	C11—C12—C13	119.8 (2)
O3—C2—C1	115.9 (2)	C11—C12—H10	120.1
O3—C2—C3	59.5 (2)	C13—C12—H10	120.1
O3—C2—C7	108.9 (2)	C12—C13—C14	119.8 (3)
C1—C2—C3	122.2 (3)	C12—C13—H11	120.6
C1—C2—C7	116.9 (2)	C14—C13—H11	119.7
C3—C2—C7	118.1 (2)	C13—C14—C15	121.2 (3)
O3—C3—C2	60.1 (2)	C13—C14—H12	119.6
O3—C3—C4	111.7 (2)	C15—C14—H12	119.2
O3—C3—H4	116.5	C10—C15—C14	118.8 (2)
C2—C3—C4	123.1 (2)	C10—C15—C16	119.2 (2)
C2—C3—H4	116.1	C14—C15—C16	121.6 (2)
C4—C3—H4	116.3	C15—C16—C17	110.8 (2)
O2—C4—C3	118.8 (2)	C15—C16—H13	108.9
O2—C4—C5	121.5 (2)	C15—C16—H14	109.9
C3—C4—C5	119.6 (2)	C17—C16—H13	109.3
C4—C5—C6	117.4 (2)	C17—C16—H14	109.5
C4—C5—C8	115.2 (2)	H13—C16—H14	108.4
C4—C5—C9	114.9 (2)	C16—C17—C18	118.7 (2)
C6—C5—C8	119.1 (2)	C16—C17—H15	107.4
C6—C5—C9	60.0 (2)	C16—C17—H16	107.6
C8—C5—C9	119.1 (2)	C18—C17—H15	107.2
C5—C6—C7	122.9 (2)	C18—C17—H16	107.1
C5—C6—C9	61.8 (2)	H15—C17—H16	108.5
C5—C6—H5	114.1	C17—C18—C19	115.2 (2)
C7—C6—C9	120.2 (2)	C17—C18—C23	127.1 (2)
C7—C6—H5	114.0	C19—C18—C23	117.7 (3)
C9—C6—H5	114.1	C18—C19—C20	122.8 (3)
O1—C7—C2	119.4 (2)	C18—C19—H17	118.0
O1—C7—C6	121.8 (3)	C20—C19—H17	119.2
C2—C7—C6	118.8 (2)	C19—C20—C21	119.2 (3)
C5—C8—H6	109.4	C19—C20—H18	120.7
C5—C8—H7	110.1	C21—C20—H18	120.1
C5—C8—H8	109.9	C20—C21—C22	119.7 (3)
H6—C8—H7	109.3	C20—C21—H19	120.0
H6—C8—H8	108.6	C22—C21—H19	120.3
H7—C8—H8	109.5	C21—C22—C23	121.7 (3)
C5—C9—C6	58.2 (2)	C21—C22—H20	118.8
C5—C9—C10	118.8 (2)	C23—C22—H20	119.6
C5—C9—C23	117.7 (2)	C9—C23—C18	122.3 (2)
C6—C9—C10	119.5 (2)	C9—C23—C22	118.8 (2)
C6—C9—C23	119.1 (2)	C18—C23—C22	118.8 (2)
C10—C9—C23	113.0 (2)
O3—C2—C3—C4	−97.7 (3)	C6—C9—C10—C11	45.7 (3)
O3—C2—C7—O1	−111.3 (3)	C6—C9—C10—C15	−139.1 (2)
O3—C2—C7—C6	66.7 (3)	C6—C9—C23—C18	159.8 (2)
O3—C3—C2—C1	−103.2 (3)	C6—C9—C23—C22	−21.9 (3)
O3—C3—C2—C7	96.4 (2)	C7—C6—C5—C8	−141.8 (2)
O3—C3—C4—O2	110.2 (3)	C7—C6—C5—C9	109.5 (2)
O3—C3—C4—C5	−65.0 (3)	C7—C6—C9—C10	−6.0 (3)
O1—C7—C2—C1	22.4 (3)	C7—C6—C9—C23	140.1 (2)
O1—C7—C2—C3	−176.1 (2)	C8—C5—C6—C9	108.7 (2)
O1—C7—C6—C5	174.1 (2)	C8—C5—C9—C10	142.5 (2)
O1—C7—C6—C9	−111.9 (3)	C8—C5—C9—C23	−0.1 (4)
O2—C4—C3—C2	177.8 (2)	C9—C10—C11—C12	178.2 (2)
O2—C4—C5—C6	−179.3 (2)	C9—C10—C15—C14	−178.0 (2)
O2—C4—C5—C8	−31.1 (3)	C9—C10—C15—C16	−5.2 (3)
O2—C4—C5—C9	113.1 (3)	C9—C23—C18—C17	−0.5 (4)
C1—C2—O3—C3	113.7 (3)	C9—C23—C18—C19	179.3 (2)
C1—C2—C3—C4	159.1 (2)	C9—C23—C22—C21	179.5 (2)
C1—C2—C7—C6	−159.6 (2)	C10—C9—C23—C18	−52.1 (3)
C2—O3—C3—C4	116.7 (3)	C10—C9—C23—C22	126.2 (2)
C2—C3—C4—C5	2.6 (3)	C10—C11—C12—C13	−1.3 (4)
C2—C7—C6—C5	−3.9 (3)	C10—C15—C14—C13	0.6 (4)
C2—C7—C6—C9	70.1 (3)	C10—C15—C16—C17	−70.4 (3)
C3—O3—C2—C7	−112.1 (2)	C11—C10—C9—C23	−102.3 (3)
C3—C2—C7—C6	1.9 (3)	C11—C10—C15—C14	−2.7 (4)
C3—C4—C5—C6	−4.3 (3)	C11—C10—C15—C16	170.1 (2)
C3—C4—C5—C8	143.9 (2)	C11—C12—C13—C14	−0.8 (4)
C3—C4—C5—C9	−71.9 (3)	C12—C11—C10—C15	3.1 (4)
C4—C3—C2—C7	−1.3 (3)	C12—C13—C14—C15	1.1 (4)
C4—C5—C6—C7	5.1 (3)	C13—C14—C15—C16	−172.0 (2)
C4—C5—C6—C9	−104.4 (2)	C14—C15—C16—C17	102.2 (3)
C4—C5—C9—C6	108.5 (2)	C15—C10—C9—C23	72.9 (3)
C4—C5—C9—C10	−0.2 (3)	C15—C16—C17—C18	63.6 (3)
C4—C5—C9—C23	−142.8 (2)	C16—C17—C18—C19	173.3 (2)
C5—C6—C9—C10	107.6 (2)	C16—C17—C18—C23	−6.9 (4)
C5—C6—C9—C23	−106.4 (2)	C17—C18—C19—C20	−179.6 (3)
C5—C9—C6—C7	−113.6 (3)	C17—C18—C23—C22	−178.8 (2)
C5—C9—C10—C11	113.4 (3)	C18—C19—C20—C21	−1.2 (5)
C5—C9—C10—C15	−71.4 (3)	C18—C23—C22—C21	−2.2 (4)
C5—C9—C23—C18	92.6 (3)	C19—C18—C23—C22	1.0 (3)
C5—C9—C23—C22	−89.1 (3)	C19—C20—C21—C22	0.1 (4)
C6—C5—C9—C10	−108.7 (2)	C20—C19—C18—C23	0.6 (4)
C6—C5—C9—C23	108.7 (2)	C20—C21—C22—C23	1.6 (4)
C6—C9—C5—C8	−108.8 (3)	C20—C21—C22—C23	1.6 (4)

Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) −x+3/2, y−1/2, z; (iii) −x+1, −y, −z; (iv) −x+1, y−1/2, −z+1/2; (v) x−1/2, y, −z+1/2; (vi) x+1/2, y, −z+1/2.