The natural diterpenoid kamebanin

Kamebanin, alternatively called rel-(−)-(1R,4R,8S,9R,10S,13S,16R)-2,8,16-tri­hydroxy-5,5,9-tri­methyl-14-methyl­enetetra­cyclo­[11.2.1.0^1,10.0^4,9]­hexadecan-15-one, C₂₀H₃₀O₄, is a natural diterpenoid which has cytotoxic and antibacterial activity. The mol­ecule is composed of three six-membered rings, which all adopt chair conformations, and one five-membered ring, which adopts an envelope conformation. The conjugated α-­methyl­ene­cyclo­pentanone ring is the active part in the mol­ecule due to the ring strain. All three hydroxy groups serve as hydrogen-bond donors and acceptors, forming a continuous two-dimensional network.

S1. Comment

The diterpenoid kamebanin, (I), has been previously isolated from the dry leaves of Rabdosia Kameba, from which mebadonin was also isolated earlier (Hirotsu et al., 1973), it possesses significant in vitro cytotoxicity (KB) and in vivo tumor inhibitory activity against Walker intramuscular carcinosarcoma in rats, and specific insecticidal activity against Lepidoptera larvae (Kubo et al., 1977). Its cytotoxic activity against KB tissue culture (LD₅₀) was 5.1 µg ml^-1 and the antibacterial activity against Bacillus subtilis was 10 µg ml^-1 (Yamaguchi et al., 1977). Its structure was established from spectroscopic evidence (Kubo et al., 1977). The structure of kamebanin has now been confirmed by X-ray diffraction.

The molecule (Fig. 1) contains three six-membered rings and one five-membered ring: ring A (C1–C5/C10) adopts a chair conformation, with puckering parameters (Cremer & Pople, 1975) Q = 0.571 (3) Å, θ = 179.5 (4)° and ϕ = 271 (17)°; ring B (C5–C10) also adopts a chair conformation, with Q = 0.598 (3) Å, θ = 168.7 (3)° and ϕ = 245.9 (15)°; ring C (C8/C9/C11–C14) adopts a chair conformation, with Q = 0.639 (3) Å, θ = 23.9 (3)° and ϕ = 289.4 (7)°; ring D (C8/C13–C16) adopts an envelope conformation, with the apex at C14, displaced by 0.657 (3) Å from the mean plane of the remaining four atoms.

Ring D is a conjugated α-methylenecyclopentanone and it has been found that the α-methylenecyclopentanone ring in Rabdosia diterpenes is highly reactive toward sulfhydryl (thiol) groups essential to enzyme function (Yamaguchi et al., 1977). It is believed that steric strain within the five-membered ring helps to increase the reactivity of the conjugated double bond (Chen et al., 1987). The extent of the deviation in the bond angles about C15 and C16 from ideal sp² angles (Table 1) shows that there must be significant strain within the five-membered ring. The deviation from ideal sp³ angles around C8 shows the steric strain within ring D also.

Xindongnin B (Fig. 2) has the same skeleton as kamebanin and its ring D adopts an envelope conformation with the apex at C14, displaced by 0.709 (7) Å from the mean plane of the remaining four atoms. The bond angle C16—C15—C8 is 109.3 (7)° and C15—C16—C13 is 105.0 (6)° (Wang et al., 1992), similar to the corresponding angles in kamebanin.

If an addition reaction takes place on the double bond of the α-methylenecyclopentanone ring, the ideal bond angles around C15 and C16 will approach 109.5°, which is close to the ideal angle for a five-membered ring. The steric strain within the α-methylenecyclopentanone apparently increases the reactivity of the conjugated double bond, which may act via a similar `Michael additional-type' reaction.

All three hydroxy groups in kamebanin serve as simultaneous hydrogen-bond donors and acceptors, resultiong in one intramolecular and two intermolecular O—H···O hydrogen bonds. An infinite two-dimensional network is formed parallel to (001) (Fig. 3). It is believed that the hydroxy groups help the molecule to bind to enzymes in the organism, and that these hydroxyl groups, in addition to an α-methylenecyclopentanone group, are required for inhibitory activity (Yamaguchi et al., 1977).

S2. Experimental

Kamebarin was isolated (Hirotsu et al., 1973) from the aerial part of Rabdosia leucophylla, which was collected from wild plants growing in the Kangding region, Sichuan Province, People's Republic of China. Crystals suitable for single-crystal X-ray diffraction analysis were obtained by slow evaporation at room temperature of a solution in chloroform/methanol (1:1 v/v).

S3. Refinement

The orientations of the hydroxy H atoms were proved initially from difference maps and were then refined by the SHELXL `nearest acceptor' method. The H atoms were placed in geometrically calculated positions and included in the final refinement as riding (C—H 0.93–0.98 Å) with U_iso values equal to 1.2U_eq of the corresponding carrier atom. Friedel reflections were merged before the final refinement and the relative stereochemistry is shown in the Scheme and figures. The absolute configuration is unknown.

Computing details

Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2002); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. View of the molecule of kamebanin, showing 50% probability displacement ellipsoids.
	Fig. 2. View of the molecule of xindongnin B, showing 50% probability displacement ellipsoids.
	Fig. 3. Part of the kamebanin crystal structure, showing the formation of a (001) sheet. For the sake of clarity, H atoms bonded to C atoms have been omitted. Atoms labelled with primes ('), asterisks (*), hashes (#) and dollar sign ($) are at the symmetry positions (3/2 + x,-1/2 - y, -z), (1/2 + x, -1/2 - y, -z), (3/2 + x, 1/2 - y, -z) and (1/2 + x, 1/2 - y, -z), respectively.

rel-(-)-(1R,4R,8S,9R,10S,13S,16R)-2,8,16-trihydroxy-5,5,9-trimethyl-14- methylenetetracyclo[11.2.1.0^1,10.0^4,9]hexadecan-15-one

Crystal data

C20H30O4	Dx = 1.224 Mg m^−3
Mr = 334.44	Melting point = 539–540 K
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 25 reflections
a = 6.568 (1) Å	θ = 3.1–12.9°
b = 13.282 (3) Å	µ = 0.08 mm^−1
c = 20.801 (5) Å	T = 289 K
V = 1814.6 (7) Å^3	Plate, colorless
Z = 4	0.66 × 0.54 × 0.08 mm
F(000) = 728

Data collection

Siemens P4 diffractometer	Rint = 0.016
Radiation source: normal-focus sealed tube	θmax = 26.5°, θmin = 1.8°
Graphite monochromator	h = 0→8
ω scans	k = 0→16
2363 measured reflections	l = −1→26
2176 independent reflections	3 standard reflections every 97 reflections
1446 reflections with I > 2σ(I)	intensity decay: 0.4%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.045	H-atom parameters constrained
wR(F^2) = 0.105	w = 1/[σ^2(Fo^2) + (0.0514P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.93	(Δ/σ)max < 0.001
2176 reflections	Δρmax = 0.16 e Å^−3
224 parameters	Δρmin = −0.16 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0071 (11)

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	0.3021 (4)	0.11106 (14)	0.33168 (11)	0.0448 (6)
H1O	0.2025	0.0824	0.3165	0.054*
O2	0.0783 (4)	0.56849 (15)	0.21511 (11)	0.0467 (6)
H2O	0.1697	0.5746	0.1886	0.056*
O3	0.3610 (3)	0.50675 (15)	0.13665 (11)	0.0437 (6)
H3O	0.4688	0.5358	0.1439	0.052*
O4	−0.1655 (4)	0.37908 (19)	0.15809 (11)	0.0547 (7)
C1	0.2431 (5)	0.2081 (2)	0.35526 (14)	0.0376 (7)
H1	0.0942	0.2094	0.3582	0.045*
C2	0.3286 (6)	0.2169 (2)	0.42323 (14)	0.0495 (9)
H2A	0.2853	0.1592	0.4484	0.059*
H2B	0.4761	0.2165	0.4215	0.059*
C3	0.2567 (7)	0.3126 (2)	0.45553 (15)	0.0607 (11)
H3A	0.3194	0.3172	0.4976	0.073*
H3B	0.1106	0.3085	0.4618	0.073*
C4	0.3050 (6)	0.4090 (3)	0.41797 (16)	0.0499 (9)
C5	0.2344 (5)	0.3933 (2)	0.34721 (13)	0.0353 (7)
H5	0.0874	0.3824	0.3512	0.042*
C6	0.2499 (6)	0.4876 (2)	0.30524 (15)	0.0417 (8)
H6A	0.2150	0.5468	0.3302	0.050*
H6B	0.3881	0.4954	0.2895	0.050*
C7	0.1042 (5)	0.4762 (2)	0.24928 (14)	0.0336 (7)
H7	−0.0288	0.4575	0.2670	0.040*
C8	0.1729 (5)	0.3908 (2)	0.20545 (13)	0.0293 (7)
C9	0.1884 (4)	0.2898 (2)	0.24561 (13)	0.0306 (7)
H9	0.0481	0.2750	0.2585	0.037*
C10	0.3109 (4)	0.2964 (2)	0.31095 (13)	0.0295 (7)
C11	0.2474 (5)	0.2022 (2)	0.19915 (14)	0.0392 (8)
H11A	0.3062	0.1484	0.2246	0.047*
H11B	0.1233	0.1763	0.1801	0.047*
C12	0.3958 (6)	0.2271 (2)	0.14481 (15)	0.0484 (9)
H12A	0.3896	0.1744	0.1125	0.058*
H12B	0.5333	0.2288	0.1618	0.058*
C13	0.3471 (5)	0.3285 (2)	0.11334 (15)	0.0388 (8)
H13	0.4375	0.3424	0.0769	0.047*
C14	0.3653 (5)	0.4085 (2)	0.16532 (15)	0.0327 (7)
H14	0.4886	0.3989	0.1911	0.039*
C15	0.0163 (5)	0.3707 (2)	0.15325 (15)	0.0362 (8)
C16	0.1270 (5)	0.3354 (2)	0.09450 (15)	0.0430 (9)
C17	0.0352 (7)	0.3149 (3)	0.03994 (17)	0.0679 (12)
H17A	−0.1052	0.3222	0.0365	0.081*
H17B	0.1107	0.2932	0.0047	0.081*
C18	0.1781 (8)	0.4934 (3)	0.44865 (17)	0.0789 (14)
H18A	0.2229	0.5574	0.4324	0.095*
H18B	0.1952	0.4918	0.4945	0.095*
H18C	0.0370	0.4839	0.4383	0.095*
C19	0.5298 (6)	0.4362 (3)	0.42530 (17)	0.0657 (12)
H19A	0.6115	0.3771	0.4192	0.079*
H19B	0.5532	0.4628	0.4676	0.079*
H19C	0.5660	0.4859	0.3938	0.079*
C20	0.5413 (4)	0.2926 (2)	0.30027 (15)	0.0397 (8)
H20A	0.5729	0.2411	0.2695	0.048*
H20B	0.6082	0.2779	0.3402	0.048*
H20C	0.5875	0.3565	0.2844	0.048*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0499 (15)	0.0299 (11)	0.0545 (14)	−0.0030 (11)	−0.0133 (13)	0.0028 (11)
O2	0.0508 (15)	0.0356 (11)	0.0538 (14)	0.0128 (12)	−0.0023 (12)	0.0065 (11)
O3	0.0401 (14)	0.0413 (12)	0.0498 (13)	−0.0078 (11)	−0.0037 (12)	0.0139 (11)
O4	0.0311 (14)	0.0787 (18)	0.0543 (15)	−0.0050 (13)	−0.0040 (12)	−0.0034 (14)
C1	0.0377 (17)	0.0335 (15)	0.0418 (18)	−0.0071 (16)	−0.0035 (16)	−0.0002 (15)
C2	0.070 (2)	0.0433 (18)	0.0352 (17)	−0.013 (2)	−0.0089 (18)	0.0131 (16)
C3	0.089 (3)	0.062 (2)	0.0304 (17)	−0.010 (2)	−0.005 (2)	−0.0019 (17)
C4	0.070 (3)	0.045 (2)	0.0352 (17)	−0.005 (2)	−0.0106 (19)	−0.0080 (16)
C5	0.0395 (18)	0.0325 (16)	0.0340 (16)	−0.0011 (15)	−0.0017 (15)	−0.0042 (14)
C6	0.048 (2)	0.0334 (16)	0.0436 (18)	0.0047 (17)	−0.0053 (18)	−0.0039 (15)
C7	0.0312 (16)	0.0301 (15)	0.0395 (17)	0.0032 (14)	−0.0007 (16)	0.0022 (13)
C8	0.0276 (16)	0.0265 (15)	0.0338 (15)	0.0010 (13)	−0.0014 (14)	−0.0007 (13)
C9	0.0318 (15)	0.0287 (14)	0.0315 (15)	−0.0037 (15)	−0.0003 (14)	0.0000 (13)
C10	0.0303 (16)	0.0282 (14)	0.0300 (15)	−0.0009 (14)	−0.0029 (13)	0.0017 (14)
C11	0.049 (2)	0.0283 (15)	0.0403 (17)	0.0016 (17)	−0.0009 (17)	−0.0021 (14)
C12	0.056 (2)	0.043 (2)	0.0460 (19)	0.0025 (18)	0.0112 (19)	−0.0065 (16)
C13	0.045 (2)	0.0412 (18)	0.0306 (15)	−0.0040 (16)	0.0118 (16)	−0.0015 (14)
C14	0.0272 (16)	0.0328 (16)	0.0381 (17)	0.0001 (13)	0.0021 (15)	0.0057 (14)
C15	0.0315 (18)	0.0375 (17)	0.0394 (18)	−0.0047 (14)	−0.0010 (15)	0.0092 (16)
C16	0.050 (2)	0.0439 (19)	0.0355 (17)	−0.0103 (17)	−0.0015 (17)	−0.0021 (15)
C17	0.064 (3)	0.088 (3)	0.051 (2)	−0.006 (3)	−0.004 (2)	−0.010 (2)
C18	0.119 (4)	0.073 (3)	0.045 (2)	0.006 (3)	−0.010 (3)	−0.025 (2)
C19	0.090 (3)	0.057 (2)	0.051 (2)	−0.014 (2)	−0.029 (2)	0.0020 (19)
C20	0.0363 (18)	0.0366 (16)	0.0461 (18)	−0.0017 (16)	−0.0077 (16)	0.0045 (16)

Geometric parameters (Å, º)

O1—C1	1.432 (3)	C8—C9	1.583 (4)
O1—H1O	0.8200	C9—C11	1.561 (4)
O2—C7	1.427 (3)	C9—C10	1.582 (4)
O2—H2O	0.8200	C9—H9	0.9800
O3—C14	1.435 (3)	C10—C20	1.531 (4)
O3—H3O	0.8200	C11—C12	1.528 (4)
O4—C15	1.204 (4)	C11—H11A	0.9700
C1—C2	1.526 (4)	C11—H11B	0.9700
C1—C10	1.557 (4)	C12—C13	1.531 (4)
C1—H1	0.9800	C12—H12A	0.9700
C2—C3	1.514 (4)	C12—H12B	0.9700
C2—H2A	0.9700	C13—C16	1.501 (5)
C2—H2B	0.9700	C13—C14	1.521 (4)
C3—C4	1.533 (4)	C13—H13	0.9800
C3—H3A	0.9700	C14—H14	0.9800
C3—H3B	0.9700	C15—C16	1.497 (4)
C4—C19	1.528 (5)	C16—C17	1.313 (5)
C4—C18	1.536 (5)	C17—H17A	0.9300
C4—C5	1.557 (4)	C17—H17B	0.9300
C5—C6	1.530 (4)	C18—H18A	0.9600
C5—C10	1.574 (4)	C18—H18B	0.9600
C5—H5	0.9800	C18—H18C	0.9600
C6—C7	1.515 (4)	C19—H19A	0.9600
C6—H6A	0.9700	C19—H19B	0.9600
C6—H6B	0.9700	C19—H19C	0.9600
C7—C8	1.524 (4)	C20—H20A	0.9600
C7—H7	0.9800	C20—H20B	0.9600
C8—C15	1.519 (4)	C20—H20C	0.9600
C8—C14	1.533 (4)
C1—O1—H1O	109.5	C20—C10—C1	110.1 (3)
C7—O2—H2O	109.5	C20—C10—C5	114.3 (3)
C14—O3—H3O	109.5	C1—C10—C5	104.0 (2)
O1—C1—C2	106.7 (2)	C20—C10—C9	112.1 (3)
O1—C1—C10	113.4 (2)	C1—C10—C9	108.8 (2)
C2—C1—C10	112.7 (2)	C5—C10—C9	107.1 (2)
O1—C1—H1	107.9	C12—C11—C9	117.1 (2)
C2—C1—H1	107.9	C12—C11—H11A	108.0
C10—C1—H1	107.9	C9—C11—H11A	108.0
C3—C2—C1	111.2 (3)	C12—C11—H11B	108.0
C3—C2—H2A	109.4	C9—C11—H11B	108.0
C1—C2—H2A	109.4	H11A—C11—H11B	107.3
C3—C2—H2B	109.4	C11—C12—C13	111.9 (3)
C1—C2—H2B	109.4	C11—C12—H12A	109.2
H2A—C2—H2B	108.0	C13—C12—H12A	109.2
C2—C3—C4	114.3 (3)	C11—C12—H12B	109.2
C2—C3—H3A	108.7	C13—C12—H12B	109.2
C4—C3—H3A	108.7	H12A—C12—H12B	107.9
C2—C3—H3B	108.7	C16—C13—C14	102.6 (3)
C4—C3—H3B	108.7	C16—C13—C12	111.5 (3)
H3A—C3—H3B	107.6	C14—C13—C12	107.1 (3)
C19—C4—C3	110.3 (3)	C16—C13—H13	111.7
C19—C4—C18	108.1 (3)	C14—C13—H13	111.7
C3—C4—C18	106.6 (3)	C12—C13—H13	111.7
C19—C4—C5	114.4 (3)	O3—C14—C13	109.8 (2)
C3—C4—C5	107.9 (3)	O3—C14—C8	110.5 (2)
C18—C4—C5	109.2 (3)	C13—C14—C8	102.4 (2)
C6—C5—C4	114.2 (2)	O3—C14—H14	111.3
C6—C5—C10	112.0 (2)	C13—C14—H14	111.3
C4—C5—C10	117.9 (3)	C8—C14—H14	111.3
C6—C5—H5	103.5	O4—C15—C16	125.4 (3)
C4—C5—H5	103.5	O4—C15—C8	126.6 (3)
C10—C5—H5	103.5	C16—C15—C8	108.0 (3)
C7—C6—C5	108.4 (3)	C17—C16—C15	123.2 (3)
C7—C6—H6A	110.0	C17—C16—C13	130.9 (3)
C5—C6—H6A	110.0	C15—C16—C13	105.9 (3)
C7—C6—H6B	110.0	C16—C17—H17A	120.0
C5—C6—H6B	110.0	C16—C17—H17B	120.0
H6A—C6—H6B	108.4	H17A—C17—H17B	120.0
O2—C7—C6	111.9 (2)	C4—C18—H18A	109.5
O2—C7—C8	112.1 (2)	C4—C18—H18B	109.5
C6—C7—C8	110.3 (2)	H18A—C18—H18B	109.5
O2—C7—H7	107.4	C4—C18—H18C	109.5
C6—C7—H7	107.4	H18A—C18—H18C	109.5
C8—C7—H7	107.4	H18B—C18—H18C	109.5
C15—C8—C7	111.0 (3)	C4—C19—H19A	109.5
C15—C8—C14	101.3 (2)	C4—C19—H19B	109.5
C7—C8—C14	117.1 (2)	H19A—C19—H19B	109.5
C15—C8—C9	105.8 (2)	C4—C19—H19C	109.5
C7—C8—C9	109.5 (2)	H19A—C19—H19C	109.5
C14—C8—C9	111.4 (2)	H19B—C19—H19C	109.5
C11—C9—C10	116.5 (2)	C10—C20—H20A	109.5
C11—C9—C8	108.7 (2)	C10—C20—H20B	109.5
C10—C9—C8	116.1 (2)	H20A—C20—H20B	109.5
C11—C9—H9	104.7	C10—C20—H20C	109.5
C10—C9—H9	104.7	H20A—C20—H20C	109.5
C8—C9—H9	104.7	H20B—C20—H20C	109.5
O1—C1—C2—C3	−174.1 (3)	C6—C5—C10—C9	−53.9 (3)
C10—C1—C2—C3	60.8 (4)	C4—C5—C10—C9	170.5 (3)
C1—C2—C3—C4	−55.6 (4)	C11—C9—C10—C20	50.5 (3)
C2—C3—C4—C19	−76.4 (4)	C8—C9—C10—C20	−79.6 (3)
C2—C3—C4—C18	166.5 (3)	C11—C9—C10—C1	−71.6 (3)
C2—C3—C4—C5	49.3 (4)	C8—C9—C10—C1	158.4 (2)
C19—C4—C5—C6	−63.5 (4)	C11—C9—C10—C5	176.6 (2)
C3—C4—C5—C6	173.3 (3)	C8—C9—C10—C5	46.6 (3)
C18—C4—C5—C6	57.8 (4)	C10—C9—C11—C12	−96.9 (3)
C19—C4—C5—C10	71.1 (4)	C8—C9—C11—C12	36.5 (4)
C3—C4—C5—C10	−52.1 (4)	C9—C11—C12—C13	−42.2 (4)
C18—C4—C5—C10	−167.6 (3)	C11—C12—C13—C16	−50.9 (3)
C4—C5—C6—C7	−157.3 (3)	C11—C12—C13—C14	60.7 (3)
C10—C5—C6—C7	65.4 (3)	C16—C13—C14—O3	−73.7 (3)
C5—C6—C7—O2	168.1 (3)	C12—C13—C14—O3	168.7 (3)
C5—C6—C7—C8	−66.3 (3)	C16—C13—C14—C8	43.6 (3)
O2—C7—C8—C15	−60.9 (3)	C12—C13—C14—C8	−73.9 (3)
C6—C7—C8—C15	173.7 (2)	C15—C8—C14—O3	76.2 (3)
O2—C7—C8—C14	54.7 (3)	C7—C8—C14—O3	−44.6 (3)
C6—C7—C8—C14	−70.7 (3)	C9—C8—C14—O3	−171.7 (2)
O2—C7—C8—C9	−177.3 (2)	C15—C8—C14—C13	−40.7 (3)
C6—C7—C8—C9	57.3 (3)	C7—C8—C14—C13	−161.5 (2)
C15—C8—C9—C11	57.3 (3)	C9—C8—C14—C13	71.4 (3)
C7—C8—C9—C11	176.9 (2)	C7—C8—C15—O4	−33.4 (4)
C14—C8—C9—C11	−51.9 (3)	C14—C8—C15—O4	−158.4 (3)
C15—C8—C9—C10	−169.0 (2)	C9—C8—C15—O4	85.3 (4)
C7—C8—C9—C10	−49.4 (3)	C7—C8—C15—C16	148.2 (2)
C14—C8—C9—C10	81.8 (3)	C14—C8—C15—C16	23.1 (3)
O1—C1—C10—C20	−55.9 (3)	C9—C8—C15—C16	−93.1 (3)
C2—C1—C10—C20	65.5 (3)	O4—C15—C16—C17	4.0 (5)
O1—C1—C10—C5	−178.7 (3)	C8—C15—C16—C17	−177.5 (3)
C2—C1—C10—C5	−57.4 (3)	O4—C15—C16—C13	−175.0 (3)
O1—C1—C10—C9	67.4 (3)	C8—C15—C16—C13	3.5 (3)
C2—C1—C10—C9	−171.3 (3)	C14—C13—C16—C17	152.1 (4)
C6—C5—C10—C20	70.9 (3)	C12—C13—C16—C17	−93.5 (4)
C4—C5—C10—C20	−64.6 (4)	C14—C13—C16—C15	−29.0 (3)
C6—C5—C10—C1	−169.0 (3)	C12—C13—C16—C15	85.4 (3)
C4—C5—C10—C1	55.5 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2O···O3	0.82	1.89	2.605 (3)	146
O1—H1O···O2^i	0.82	1.97	2.741 (3)	157
O3—H3O···O1^ii	0.82	1.88	2.692 (3)	173

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