(±)-Asarinin

Asarinin, C₂₀H₁₈O₆, was isolated as a racemate from the shrub Zanthoxylum alatum. Both forms of the enantio­merically pure substance, (+)- and (−)-asarinin, have been the subject of a total of five previous structure determinations that are essentially identical except for the absolute stereochemistry. However, there seems to be some confusion in the literature concerning these structure determinations of asarinin and also those of its stereoisomer sesamin. The mol­ecular structure of racemic asarinin differs from that of the pure enantio­mers in the orientation of one ring system. In the packing of the racemate, mol­ecules are linked by C—H...O inter­actions to form ribbons parallel to [101].

S1. Comment

Zanthoxylum alatum (Rutaceae) is an evergreen shrub growing at up to 2000 m above sea level in the hot valleys of the Himalayan region. It has a variety of applications in traditional medicine, including anthelmintic and painkilling activities. Extracts of leaves are also used as disinfectants and against scabies and house flies. The chemical constituents of the plant's stem wood (Ishii, Hosoya, Ishikawa & Haginiwa, 1974), root wood (Ishii, Hosoya, Ishikawa, Hueda & Haginiwa 1974), and stem and root bark (Ishii et al., 1977), have been reported, and include coumarins, furoquinoline alkaloids, benzo[c]phenanthridines, lignans, steroids and terpenoids. However, studies of the bioactivity of these compounds from Z. alatum have not been reported to date.

A chloroform extract of the leaves of Z. alatum showed antifeedant activity against the larvae of Spodoptera litoralis, and also anti-proliferative activity against multi-resistant cell lines. Asarinin was identified as one of the major constituents of the chloroform extract. The asarinin sample obtained from the plant crystallized as a racemic compound, although a positive [α]_D²⁰ of 43° was observed. Pure (+)-asarinin has an [α]_D²⁰ of about 120° (Takahashi & Nakagawa, 1966).The (-)-enantiomer of asarinin seems to be the prevalent form in nature (as judged from citations in Chemical Abstracts [Reference?], but we have not counted these exactly). The observed [α]_D²⁰ implies that the two enantiomers occur in the plant in different proportions and that racemic asarinin crystallizes first. To the best of our knowledge, the structure of racemic asarinin, the title compound, (I), has never been reported, so we present it here.

The furofuran asarinin, (I), has four asymmetric centres (numbered C1, C2, C5 and C6 in this study, with relative configurations 1R, 2R, 5R and 6S). The naturally occurring stereoisomers epiasarinin (inverted at C6) and sesamin (inverted at C5) are also known; for a brief overview, see Aldous et al. (2006). A search of the Cambridge Structural Database (CSD, Version?; Allen, 2002; see also Table 2) reveals that several crystal structures have been reported, but in some cases confusion may have arisen. For epiasarinin, the structure of the synthetic racemate was determined by Aldous et al. (2006; we adopt an analogous atom-numering scheme for the racemate of asarinin), but no enantiomerically pure structure has yet been determined. Three closely similar structures of sesamin have been reported, by Baures et al. (1992), Hsieh et al. (2005) and Li et al. (2005). However, the sign of the optical rotation is given as (+) by Hsieh et al. (2005), as (-) by Li et al. (2005) and is not quoted by Baures et al. (1992). In no case could the absolute configuration be determined crystallographically because the anomalous dispersion effects were insignificant. For asarinin, there are no fewer than five reported structures in the CSD, but they are given three different families of refcodes. Again, the cells are closely similar. The references are: Li et al. (2005), optical rotation (-) [the space group is reported as P1 with two independent molecules, but the cell constants are close to those of the other determinations, and inspection of the structure suggests that the true space group is indeed P2₁]; Macías et al. [1992, (-)]; Parmar et al. [1998; optical rotation given as (-) in the database but (+) in the publication]; Il'in et al. [1994, (-)]; and Mata et al. (1998). For this last determination, the absolute configuration was determined crystallographically by exploiting the stronger anomalous dispersion effects of copper radiation, but the optical rotation was not given, so frustratingly no correlation has been established between the absolute configuration and the optical rotation for this compound despite five determinations of its crystal structure. The determination of the absolute configuration of (+)-asarinin by the `optical shift rule' (Freudenberg & Sidhu, 1961) has not been universally accepted [see e.g. Gunatilaka et al. (1982)].

The molecule of asarinin in the racemate is shown in Fig. 1. Molecular dimensions may be regarded as normal. A least-squares fit to the (inverted) molecule of VUKBUY gives an r.m.s. deviation of 0.08 Å for all atoms except C21–O28, since this ring is differently oriented with respect to the furofuran system [torsion angle O7—C6—C20—C21 = -3.0 (1)°, cf. -30.9° for the corresponding angle of VUKBUY].

In the packing pattern of (I), four short intramolecular H···O contacts might be interpreted as `weak' hydrogen bonds (Table 1). The two shortest of these link the molecules via inversion centres to form molecular ribbons parallel to [101] (Fig. 2).

Related literature

For related literature, see: Aldous et al. (2006); Allen (2002); Baures et al. (1992); Freudenberg & Sidhu (1961); Gunatilaka et al. (1982); Hsieh et al. (2005); Ishii et al. (1977); Ishii, Hosoya, Ishikawa & Haginiwa (1974); Ishii, Hosoya, Ishikawa, Hueda & Haginiwa (1974); Li et al. (2005); Mata et al. (1998); Takahashi & Nakagawa (1966).

S2. Experimental

The plant material was collected from Rudraprayag Uttarakhand, India (290 43' 19'' North, 780 31' 6'' East). The plant was identified by the Botanical Survey of India, Dehradun, and a voucher specimen has been deposited (BSD Accession No. 112749).

The shade-dried leaves of Z. alatum were exhaustively extracted with 90% ethanol at room temperature. The combined ethanolic extracts were concentrated under reduced pressure at 723 K to a dark viscous mass. Water was added (10% by weight) and the mixture was extracted with hexane (3 × 500 ml). The combined organic phases were washed with water and dried by evaporation of the solvent under reduced pressure to yield 35.4 g of solid residue. The water phase was again extracted, this time with chloroform (3 × 500 ml), and the combined chloroform phases were washed with water and dried with MgSO₄. Evaporation of the solvent under reduced pressure yielded another 6.5 g of solid residue. The extracts were tested against the polyphagous pest Spodoptera litoralis for antifeedant activity and against K526/Adr cells for cytotoxic activity.

The biologically active chloroform extract was subjected to column chromatography over silica gel (60–120 mesh) using chloroform–methanol of increasing polarity [Range of ratios?]. Eluates were collected in fractions of 50 ml and each was evaporated to dryness under reduced pressure. Fractions exhibiting similar thin-layer chromatography behaviour were combined. Three fractions collected upon elution with chloroform–methanol, Fr A (solvent ratios 39–46:100), Fr B (50–68:100) and Fr C (70–100:100), afforded solid material after evaporation of the solvents. Fraction B was again separated by chromatography with chloroform–methanol (9:1 v/v) to yield asarinine (12 mg).

To obtain single crystals of asarinin, the compound (1 mg) was dissolved in pentane (2 ml). The resulting solution was concentrated by evaporation in a slightly permeable screw-capped vial. Single crystals of (I) in the form of colourless laths [Tablet in CIF tables - please clarify] formed over a period of 96 h.

S3. Refinement

H atoms were placed in calculated positions and refined using a riding model, with C—H_arom = 0.95, C—H_methylene = 0.99 and C—H_methine = 1.00 Å, and with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

Fig. 1. The molecular structure of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. This enantiomer has the configurations S, S, S and R at C1, C2, C5 and C6, respectively.

Fig. 2. A packing diagram for (I), viewed perpendicular to (111). Dashed lines indicate hydrogen bonds. H atoms not involved in hydrogen bonds have been omitted for clarity.

(1RS,3aRS,4SS,6aRS)-1,4-bis(benzo[d][1,3]dioxol-5-yl)hexahydrofuro[3,4-c]furan

Crystal data

C20H18O6	Z = 2
Mr = 354.34	F(000) = 372
Triclinic, P1	Dx = 1.503 Mg m^−3
a = 6.5002 (4) Å	Cu Kα radiation, λ = 1.54184 Å
b = 10.8931 (7) Å	Cell parameters from 33759 reflections
c = 11.8005 (8) Å	θ = 4.0–75.7°
α = 103.793 (6)°	µ = 0.93 mm^−1
β = 102.111 (6)°	T = 100 K
γ = 95.836 (6)°	Tablet, colourless
V = 783.22 (9) Å^3	0.25 × 0.20 × 0.10 mm

Data collection

Oxford Xcalibur diffractometer with Nova source and Atlas detector	3254 independent reflections
Radiation source: Nova (Cu) X-ray Source	3200 reflections with I > 2σ(I)
Mirror monochromator	Rint = 0.027
Detector resolution: 10.3543 pixels mm^-1	θmax = 75.9°, θmin = 4.0°
ω scans	h = −8→8
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −13→13
Tmin = 0.770, Tmax = 1.000	l = −14→14
41535 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.086	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0399P)^2 + 0.3692P] where P = (Fo^2 + 2Fc^2)/3
3254 reflections	(Δ/σ)max = 0.002
235 parameters	Δρmax = 0.31 e Å^−3
0 restraints	Δρmin = −0.21 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.56365 (12)	0.57923 (7)	0.36599 (7)	0.01883 (18)
C1	0.35735 (17)	0.57985 (10)	0.17724 (9)	0.0162 (2)
H1	0.3451	0.6351	0.1203	0.019*
C2	0.44275 (17)	0.66030 (10)	0.30911 (9)	0.0163 (2)
H2	0.5429	0.7369	0.3103	0.020*
C4	0.68497 (18)	0.52866 (11)	0.28201 (10)	0.0188 (2)
H4A	0.7430	0.4530	0.3001	0.023*
H4B	0.8047	0.5941	0.2849	0.023*
C5	0.52740 (16)	0.49134 (10)	0.15893 (9)	0.0155 (2)
H5	0.5975	0.5055	0.0943	0.019*
C6	0.39849 (17)	0.35556 (10)	0.12489 (10)	0.0182 (2)
H6	0.4023	0.3288	0.2006	0.022*
O7	0.18453 (13)	0.36849 (8)	0.07580 (8)	0.0261 (2)
C8	0.15160 (18)	0.48480 (11)	0.15241 (10)	0.0211 (2)
H8A	0.1259	0.4704	0.2284	0.025*
H8B	0.0278	0.5174	0.1119	0.025*
C11	0.27919 (17)	0.70606 (10)	0.37603 (9)	0.0157 (2)
C12	0.22906 (17)	0.65162 (10)	0.46569 (9)	0.0156 (2)
H12	0.2957	0.5838	0.4868	0.019*
C13	0.07832 (17)	0.70191 (10)	0.52113 (9)	0.0157 (2)
C14	−0.02119 (17)	0.80026 (10)	0.49173 (9)	0.0164 (2)
C15	0.02389 (18)	0.85422 (10)	0.40406 (10)	0.0188 (2)
H15	−0.0454	0.9213	0.3834	0.023*
C16	0.17765 (18)	0.80495 (10)	0.34669 (10)	0.0185 (2)
H16	0.2139	0.8401	0.2858	0.022*
O17	0.00734 (13)	0.66835 (8)	0.61359 (7)	0.02143 (19)
C18	−0.15893 (18)	0.74211 (11)	0.63322 (10)	0.0210 (2)
H18A	−0.2983	0.6851	0.6088	0.025*
H18B	−0.1327	0.7873	0.7195	0.025*
O19	−0.16073 (13)	0.83282 (8)	0.56301 (7)	0.02070 (18)
C20	0.47343 (17)	0.25291 (10)	0.03896 (10)	0.0171 (2)
C21	0.33643 (18)	0.18013 (10)	−0.07008 (10)	0.0187 (2)
H21	0.1938	0.1942	−0.0942	0.022*
C22	0.41905 (18)	0.08719 (10)	−0.14047 (10)	0.0186 (2)
C23	0.62636 (18)	0.06578 (10)	−0.10748 (10)	0.0174 (2)
C24	0.76342 (18)	0.13606 (11)	−0.00203 (10)	0.0205 (2)
H24	0.9062	0.1216	0.0203	0.025*
C25	0.68222 (18)	0.23060 (11)	0.07133 (10)	0.0205 (2)
H25	0.7725	0.2811	0.1455	0.025*
O26	0.31790 (14)	0.00396 (9)	−0.25045 (8)	0.0294 (2)
C27	0.46989 (19)	−0.07388 (12)	−0.28494 (11)	0.0248 (3)
H27A	0.4911	−0.0672	−0.3640	0.030*
H27B	0.4177	−0.1646	−0.2919	0.030*
O28	0.66683 (13)	−0.03090 (8)	−0.19555 (7)	0.02196 (19)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0194 (4)	0.0244 (4)	0.0134 (4)	0.0100 (3)	0.0052 (3)	0.0025 (3)
C1	0.0169 (5)	0.0192 (5)	0.0137 (5)	0.0061 (4)	0.0058 (4)	0.0037 (4)
C2	0.0169 (5)	0.0167 (5)	0.0153 (5)	0.0041 (4)	0.0050 (4)	0.0025 (4)
C4	0.0171 (5)	0.0227 (5)	0.0155 (5)	0.0075 (4)	0.0052 (4)	−0.0002 (4)
C5	0.0151 (5)	0.0178 (5)	0.0140 (5)	0.0040 (4)	0.0056 (4)	0.0024 (4)
C6	0.0165 (5)	0.0189 (5)	0.0186 (5)	0.0029 (4)	0.0071 (4)	0.0016 (4)
O7	0.0147 (4)	0.0261 (4)	0.0287 (4)	0.0027 (3)	0.0060 (3)	−0.0098 (3)
C8	0.0163 (5)	0.0229 (6)	0.0206 (5)	0.0047 (4)	0.0059 (4)	−0.0031 (4)
C11	0.0157 (5)	0.0156 (5)	0.0132 (5)	0.0023 (4)	0.0036 (4)	−0.0007 (4)
C12	0.0160 (5)	0.0153 (5)	0.0143 (5)	0.0047 (4)	0.0026 (4)	0.0014 (4)
C13	0.0169 (5)	0.0170 (5)	0.0119 (5)	0.0024 (4)	0.0034 (4)	0.0019 (4)
C14	0.0156 (5)	0.0164 (5)	0.0157 (5)	0.0047 (4)	0.0049 (4)	−0.0005 (4)
C15	0.0214 (5)	0.0164 (5)	0.0191 (5)	0.0071 (4)	0.0049 (4)	0.0038 (4)
C16	0.0224 (5)	0.0176 (5)	0.0165 (5)	0.0040 (4)	0.0071 (4)	0.0042 (4)
O17	0.0248 (4)	0.0266 (4)	0.0208 (4)	0.0132 (3)	0.0136 (3)	0.0104 (3)
C18	0.0220 (6)	0.0259 (6)	0.0193 (5)	0.0107 (5)	0.0103 (4)	0.0064 (4)
O19	0.0227 (4)	0.0220 (4)	0.0221 (4)	0.0106 (3)	0.0121 (3)	0.0060 (3)
C20	0.0189 (5)	0.0155 (5)	0.0180 (5)	0.0025 (4)	0.0087 (4)	0.0029 (4)
C21	0.0185 (5)	0.0191 (5)	0.0190 (5)	0.0055 (4)	0.0058 (4)	0.0038 (4)
C22	0.0214 (5)	0.0180 (5)	0.0147 (5)	0.0033 (4)	0.0035 (4)	0.0021 (4)
C23	0.0213 (5)	0.0146 (5)	0.0183 (5)	0.0050 (4)	0.0099 (4)	0.0029 (4)
C24	0.0164 (5)	0.0216 (5)	0.0224 (6)	0.0044 (4)	0.0064 (4)	0.0020 (4)
C25	0.0181 (5)	0.0202 (5)	0.0192 (5)	0.0011 (4)	0.0046 (4)	−0.0013 (4)
O26	0.0282 (5)	0.0312 (5)	0.0198 (4)	0.0147 (4)	−0.0018 (3)	−0.0074 (3)
C27	0.0245 (6)	0.0247 (6)	0.0207 (6)	0.0078 (5)	0.0040 (5)	−0.0030 (5)
O28	0.0232 (4)	0.0214 (4)	0.0186 (4)	0.0082 (3)	0.0055 (3)	−0.0022 (3)

Geometric parameters (Å, º)

O1—C2	1.4319 (13)	C22—C23	1.3816 (16)
O1—C4	1.4365 (12)	C23—C24	1.3675 (16)
C1—C8	1.5349 (15)	C23—O28	1.3811 (12)
C1—C2	1.5447 (14)	C24—C25	1.4021 (15)
C1—C5	1.5543 (14)	O26—C27	1.4266 (14)
C2—C11	1.5082 (14)	C27—O28	1.4307 (14)
C4—C5	1.5276 (14)	C1—H1	1.0000
C5—C6	1.5410 (15)	C2—H2	1.0000
C6—O7	1.4250 (14)	C4—H4A	0.9900
C6—C20	1.5143 (14)	C4—H4B	0.9900
O7—C8	1.4346 (13)	C5—H5	1.0000
C11—C16	1.3938 (15)	C6—H6	1.0000
C11—C12	1.4078 (15)	C8—H8A	0.9900
C12—C13	1.3767 (14)	C8—H8B	0.9900
C13—O17	1.3798 (13)	C12—H12	0.9500
C13—C14	1.3823 (15)	C15—H15	0.9500
C14—C15	1.3725 (16)	C16—H16	0.9500
C14—O19	1.3782 (12)	C18—H18A	0.9900
C15—C16	1.4019 (15)	C18—H18B	0.9900
O17—C18	1.4353 (13)	C21—H21	0.9500
C18—O19	1.4322 (14)	C24—H24	0.9500
C20—C25	1.3931 (16)	C25—H25	0.9500
C20—C21	1.4023 (15)	C27—H27A	0.9900
C21—C22	1.3785 (15)	C27—H27B	0.9900
C22—O26	1.3777 (13)
C2—O1—C4	103.72 (8)	C23—O28—C27	105.44 (8)
C8—C1—C2	115.27 (9)	C8—C1—H1	111.5
C8—C1—C5	103.20 (8)	C2—C1—H1	111.5
C2—C1—C5	103.11 (8)	C5—C1—H1	111.5
O1—C2—C11	111.03 (8)	O1—C2—H2	108.2
O1—C2—C1	104.12 (8)	C11—C2—H2	108.2
C11—C2—C1	116.71 (9)	C1—C2—H2	108.2
O1—C4—C5	105.09 (8)	O1—C4—H4A	110.7
C4—C5—C6	114.11 (9)	C5—C4—H4A	110.7
C4—C5—C1	103.28 (8)	O1—C4—H4B	110.7
C6—C5—C1	103.46 (8)	C5—C4—H4B	110.7
O7—C6—C20	110.90 (9)	H4A—C4—H4B	108.8
O7—C6—C5	105.39 (9)	C4—C5—H5	111.8
C20—C6—C5	116.17 (9)	C6—C5—H5	111.8
C6—O7—C8	104.65 (8)	C1—C5—H5	111.8
O7—C8—C1	105.50 (8)	O7—C6—H6	108.0
C16—C11—C12	120.37 (10)	C20—C6—H6	108.0
C16—C11—C2	117.96 (9)	C5—C6—H6	108.0
C12—C11—C2	121.67 (9)	O7—C8—H8A	110.6
C13—C12—C11	116.42 (10)	C1—C8—H8A	110.6
C12—C13—O17	127.53 (10)	O7—C8—H8B	110.6
C12—C13—C14	122.84 (10)	C1—C8—H8B	110.6
O17—C13—C14	109.60 (9)	H8A—C8—H8B	108.8
C15—C14—O19	127.93 (10)	C13—C12—H12	121.8
C15—C14—C13	121.80 (10)	C11—C12—H12	121.8
O19—C14—C13	110.26 (9)	C14—C15—H15	121.8
C14—C15—C16	116.39 (10)	C16—C15—H15	121.8
C11—C16—C15	122.18 (10)	C11—C16—H16	118.9
C13—O17—C18	105.71 (8)	C15—C16—H16	118.9
O19—C18—O17	108.17 (8)	O19—C18—H18A	110.1
C14—O19—C18	105.51 (8)	O17—C18—H18A	110.1
C25—C20—C21	120.27 (10)	O19—C18—H18B	110.1
C25—C20—C6	118.44 (10)	O17—C18—H18B	110.1
C21—C20—C6	121.28 (10)	H18A—C18—H18B	108.4
C22—C21—C20	116.65 (10)	C22—C21—H21	121.7
O26—C22—C21	127.78 (10)	C20—C21—H21	121.7
O26—C22—C23	109.60 (9)	C23—C24—H24	121.7
C21—C22—C23	122.62 (10)	C25—C24—H24	121.7
C24—C23—O28	127.98 (10)	C20—C25—H25	118.9
C24—C23—C22	121.82 (10)	C24—C25—H25	118.9
O28—C23—C22	110.19 (10)	O26—C27—H27A	110.0
C23—C24—C25	116.50 (10)	O28—C27—H27A	110.0
C20—C25—C24	122.14 (10)	O26—C27—H27B	110.0
C22—O26—C27	106.08 (9)	O28—C27—H27B	110.0
O26—C27—O28	108.60 (9)	H27A—C27—H27B	108.3
C4—O1—C2—C11	171.12 (8)	O19—C14—C15—C16	178.33 (10)
C4—O1—C2—C1	44.73 (10)	C13—C14—C15—C16	−0.54 (16)
C8—C1—C2—O1	84.08 (10)	C12—C11—C16—C15	0.10 (17)
C5—C1—C2—O1	−27.58 (10)	C2—C11—C16—C15	−179.82 (10)
C8—C1—C2—C11	−38.66 (13)	C14—C15—C16—C11	0.35 (17)
C5—C1—C2—C11	−150.32 (9)	C12—C13—O17—C18	−176.22 (11)
C2—O1—C4—C5	−44.14 (10)	C14—C13—O17—C18	5.66 (12)
O1—C4—C5—C6	−86.43 (10)	C13—O17—C18—O19	−8.60 (11)
O1—C4—C5—C1	25.14 (11)	C15—C14—O19—C18	176.20 (11)
C8—C1—C5—C4	−118.87 (9)	C13—C14—O19—C18	−4.83 (12)
C2—C1—C5—C4	1.44 (10)	O17—C18—O19—C14	8.26 (11)
C8—C1—C5—C6	0.34 (10)	O7—C6—C20—C25	177.96 (10)
C2—C1—C5—C6	120.65 (9)	C5—C6—C20—C25	57.68 (14)
C4—C5—C6—O7	135.84 (9)	O7—C6—C20—C21	−2.96 (14)
C1—C5—C6—O7	24.37 (10)	C5—C6—C20—C21	−123.23 (11)
C4—C5—C6—C20	−100.96 (11)	C25—C20—C21—C22	0.50 (16)
C1—C5—C6—C20	147.57 (9)	C6—C20—C21—C22	−178.56 (10)
C20—C6—O7—C8	−167.79 (9)	C20—C21—C22—O26	−179.95 (11)
C5—C6—O7—C8	−41.30 (11)	C20—C21—C22—C23	−0.47 (16)
C6—O7—C8—C1	41.66 (11)	O26—C22—C23—C24	179.59 (10)
C2—C1—C8—O7	−136.40 (9)	C21—C22—C23—C24	0.03 (18)
C5—C1—C8—O7	−24.79 (11)	O26—C22—C23—O28	0.68 (13)
O1—C2—C11—C16	167.64 (9)	C21—C22—C23—O28	−178.88 (10)
C1—C2—C11—C16	−73.29 (13)	O28—C23—C24—C25	179.08 (10)
O1—C2—C11—C12	−12.29 (14)	C22—C23—C24—C25	0.37 (17)
C1—C2—C11—C12	106.79 (11)	C21—C20—C25—C24	−0.11 (17)
C16—C11—C12—C13	−0.37 (15)	C6—C20—C25—C24	178.98 (10)
C2—C11—C12—C13	179.56 (9)	C23—C24—C25—C20	−0.33 (17)
C11—C12—C13—O17	−177.70 (10)	C21—C22—O26—C27	−179.19 (11)
C11—C12—C13—C14	0.19 (16)	C23—C22—O26—C27	1.28 (13)
C12—C13—C14—C15	0.28 (17)	C22—O26—C27—O28	−2.71 (13)
O17—C13—C14—C15	178.50 (10)	C24—C23—O28—C27	178.86 (11)
C12—C13—C14—O19	−178.77 (9)	C22—C23—O28—C27	−2.32 (12)
O17—C13—C14—O19	−0.54 (12)	O26—C27—O28—C23	3.08 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4A···O17^i	0.99	2.41	3.3501 (14)	159
C15—H15···O26^ii	0.95	2.45	3.3093 (14)	151
C16—H16···O28^iii	0.95	2.67	3.5503 (14)	154
C18—H18B···O28^iv	0.99	2.60	3.2600 (13)	124

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