(1R,4R,5aS,7S,9aS)-7,9a-Dimethyl-6-methyl­ene-3-oxo-1,3,4,5,5a,6,7,8,9,9a-deca­hydro­naphtho­[1,2-c]furan-1,4-diyl diacetate

Mudyiwa, M.; Rajab, M.S.; Fronczek, F.R.; Watkins, S.F.

doi:10.1107/S1600536812033636

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 68| Part 9| September 2012| Pages o2612-o2613

doi:10.1107/S1600536812033636

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(1R,4R,5aS,7S,9aS)-7,9a-Dimethyl-6-methylene-3-oxo-1,3,4,5,5a,6,7,8,9,9a-decahydronaphtho[1,2-c]furan-1,4-diyl diacetate

Mercy Mudyiwa,^a Mohamed S. Rajab,^a Frank R. Fronczek ^a ^* and Steven F. Watkins ^a

^aDepartment of Chemistry, Louisiana State University, Baton Rouge, LA 70803-1804, USA
^*Correspondence e-mail: ffroncz@lsu.edu

(Received 16 July 2012; accepted 25 July 2012; online 1 August 2012)

The title compound, C₁₉H₂₄O₆, is a sesquiterpene lactone isolated from the Kenyan plant Warburgia ugandensis. Ring A adopts a chair conformation, ring B is in a C₂ twist conformation and the lactone ring is nearly planar with maximum deviation 0.007 (1) Å. The reported absolute configuration is based on that of the similar compound bromo-parasiticolide A and is supported by analysis of Bijvoet differences from light atoms in Mo Kα radiation.

Related literature

For related structures, see: Fukuyama et al. (1975 ) (Bromo-parasiticolide A; PARASB); Ikhiri et al. (1995 ) (ZOXLIH); Aranda et al. (2001 ) (ABUKIR); King et al. (1973 ) (PRPRDE); Rossmann & Lipscomb (1958 ) (IRSBBZ); Rahbaek et al. (1997 ) (NEYKOR), Zhang et al. (2006 ) (UCOLAA, UCOKUT); Harinantenaina et al. (2007 ) (NIDJUG); McCorkindale et al. (1981 ) (PEBRLD); Hayashi et al. (2010 ) (VUTCIX). For the absolute configuration of sesquiterpene lactones, see: Fischer et al. (1979 ). For a description of the Cambridge Structural Database, see: Allen (2002 ). For the absolute configuration from Bijvoet pairs, see: Hooft et al. (2008 ). For compounds from Warburgia ugandensis, see: Wube et al. (2005 ) and for related compounds, see: Garland (1969 ); Kokwaro (1976 ).

Experimental

Crystal data

C₁₉H₂₄O₆
M_r = 348.38
Tetragonal, P 4₃ 2₁ 2
a = 13.014 (2) Å
c = 21.167 (3) Å
V = 3584.9 (9) Å³
Z = 8
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.37 × 0.25 × 0.25 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997 ) T_min = 0.966, T_max = 0.977
11378 measured reflections
6507 independent reflections
5934 reflections with I > 2σ(I)
R_int = 0.021

Refinement

R[F² > 2σ(F²)] = 0.036
wR(F²) = 0.092
S = 1.02
6507 reflections
231 parameters
H-atom parameters constrained
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.21 e Å⁻³
Absolute structure: Flack (1983 ). 2776 Bijvoet pairs
Flack parameter: 0.4 (6)

Data collection: COLLECT (Nonius, 2000 ); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SIR2002 (Burla et al., 2003 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536812033636/bt5979sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812033636/bt5979Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812033636/bt5979Isup3.cml

checkCIF report

Comment top

Coloratanolide and drimanolide sesquiterpene lactones, such as title compound I, have been isolated from the stem bark of Warburgia ugandensis Sprague (Canellaceae) as described by Wube et al. (2005). Plants of the genus Warburgia are of interest because of their use by herbalists in Kenya for the treatment of a number of parasitic diseases (Kokwaro, 1976). Compound I is the first sesquiterpene lactone to be crystallographically characterized which has the coloratanolide skeleton, (CAS 60306–54-9). The absolute configuration reported herein is based on the configuration of bromo-parasiticolide A (Fukuyama et al., 1975), CCDC refcode PARASB (Allen, 2002), and supported by analysis of 2776 Bijvoet pairs.

Related literature top

For related structures, see: Fukuyama et al. (1975) (Bromo-parasiticolide A; PARASB); Ikhiri et al. (1995) (ZOXLIH); Aranda et al. (2001) (ABUKIR); King et al. (1973) (PRPRDE); Rossmann & Lipscomb (1958) (IRSBBZ); Rahbaek et al. (1997) (NEYKOR), Zhang et al. (2006) (UCOLAA, UCOKUT); Harinantenaina et al. (2007) (NIDJUG); McCorkindale et al. (1981) (PEBRLD); Hayashi et al. (2010) (VUTCIX). For the absolute configuration of sesquiterpene lactones, see: Fischer et al. (1979). For a description of the Cambridge Structural Database, see: Allen (2002). For the absolute configuration from Bijvoet pairs, see: Hooft et al. (2008). For compounds from Warburgia ugandensis, see: Wube et al. (2005) and for elated compounds, see: Garland (1969); Kokwaro (1976).

Experimental top

Compound I was isolated from the stem bark of Warburgia ugandensis Sprague (Canellaceae) collected in Eldoret, Uasin Gishu District, Kenya. Crystals suitable for diffraction were grown from acetone/hexane/ethyl ether.

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

Fig. 1. View of (I) (50% probability displacement ellipsoids)

(1R,4R,5aS,7S,9aS)-7,9a-Dimethyl- 6-methylene-3-oxo-1,3,4,5,5a,6,7,8,9,9a- decahydronaphtho[1,2-c]furan-1,4-diyl diacetate top

Crystal data top

C₁₉H₂₄O₆	D_x = 1.291 Mg m⁻³
M_r = 348.38	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4₃2₁2	Cell parameters from 6310 reflections
Hall symbol: P 4nw 2abw	θ = 2.5–32.6°
a = 13.014 (2) Å	µ = 0.10 mm⁻¹
c = 21.167 (3) Å	T = 100 K
V = 3584.9 (9) Å³	Prism, colorless
Z = 8	0.37 × 0.25 × 0.25 mm
F(000) = 1488

Data collection top

Nonius KappaCCD diffractometer	6507 independent reflections
Radiation source: sealed tube	5934 reflections with I > 2σ(I)
Horizonally mounted graphite crystal monochromator	R_int = 0.021
Detector resolution: 9 pixels mm^-1	θ_max = 32.6°, θ_min = 3.1°
ϕ and ω scans	h = −19→19
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997)	k = −13→13
T_min = 0.966, T_max = 0.977	l = −30→31
11378 measured reflections

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)] = 0.036	H-atom parameters constrained
wR(F²) = 0.092	w = 1/[σ²(F_o²) + (0.0489P)² + 0.548P] where P = (F_o² + 2F_c²)/3
S = 1.02	(Δ/σ)_max = 0.001
6507 reflections	Δρ_max = 0.28 e Å⁻³
231 parameters	Δρ_min = −0.21 e Å⁻³
0 restraints	Absolute structure: Flack (1983). 2776 Bijvoet pairs
0 constraints	Absolute structure parameter: 0.4 (6)
Primary atom site location: structure-invariant direct methods

Crystal data top

C₁₉H₂₄O₆	Z = 8
M_r = 348.38	Mo Kα radiation
Tetragonal, P4₃2₁2	µ = 0.10 mm⁻¹
a = 13.014 (2) Å	T = 100 K
c = 21.167 (3) Å	0.37 × 0.25 × 0.25 mm
V = 3584.9 (9) Å³

Data collection top

Nonius KappaCCD diffractometer	6507 independent reflections
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997)	5934 reflections with I > 2σ(I)
T_min = 0.966, T_max = 0.977	R_int = 0.021
11378 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.036	H-atom parameters constrained
wR(F²) = 0.092	Δρ_max = 0.28 e Å⁻³
S = 1.02	Δρ_min = −0.21 e Å⁻³
6507 reflections	Absolute structure: Flack (1983). 2776 Bijvoet pairs
231 parameters	Absolute structure parameter: 0.4 (6)
0 restraints

Special details top

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.

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

	x	y	z	U_iso*/U_eq
C1	0.99387 (7)	0.15194 (7)	0.38460 (4)	0.01487 (16)
C2	1.10097 (8)	0.17487 (8)	0.41219 (5)	0.01852 (17)
H2A	1.1216	0.2454	0.4001	0.022*
H2B	1.0972	0.172	0.4589	0.022*
C3	1.18311 (8)	0.09896 (9)	0.38923 (5)	0.02218 (19)
H3A	1.2483	0.1131	0.4117	0.027*
H3B	1.1952	0.11	0.3436	0.027*
C4	1.15268 (8)	−0.01396 (8)	0.40011 (5)	0.02003 (18)
H4	1.1451	−0.0238	0.4467	0.024*
C5	1.04822 (8)	−0.03292 (8)	0.37083 (4)	0.01737 (17)
C6	0.96687 (7)	0.03709 (7)	0.39832 (4)	0.01477 (15)
H6	0.9717	0.0288	0.4452	0.018*
C7	0.85545 (7)	0.01232 (8)	0.38106 (4)	0.01717 (17)
H7A	0.8433	−0.0624	0.3855	0.021*
H7B	0.8425	0.0315	0.3365	0.021*
C8	0.78177 (8)	0.07130 (7)	0.42426 (4)	0.01629 (17)
H8	0.711	0.0714	0.4058	0.02*
C9	0.81884 (7)	0.17881 (7)	0.43274 (4)	0.01617 (16)
C10	0.75719 (8)	0.26445 (8)	0.45837 (5)	0.01949 (18)
C11	0.91383 (8)	0.32891 (8)	0.42864 (5)	0.01760 (17)
H11	0.9261	0.3685	0.3889	0.021*
C12	0.91114 (7)	0.21474 (7)	0.41591 (4)	0.01502 (16)
C13	0.99210 (8)	0.17746 (8)	0.31324 (4)	0.02007 (18)
H13A	0.9224	0.1675	0.2967	0.03*
H13B	1.0398	0.1319	0.2908	0.03*
H13C	1.013	0.2491	0.3069	0.03*
C14	1.23690 (9)	−0.08734 (10)	0.37789 (6)	0.0301 (2)
H14A	1.216	−0.1583	0.3865	0.045*
H14B	1.3008	−0.0722	0.4005	0.045*
H14C	1.2478	−0.0785	0.3324	0.045*
C15	1.02974 (9)	−0.10108 (9)	0.32528 (5)	0.0227 (2)
H15A	0.9625	−0.1076	0.3083	0.027*
H15B	1.0838	−0.1431	0.3098	0.027*
C16	1.02993 (9)	0.44956 (8)	0.47234 (5)	0.02094 (19)
C17	1.10061 (10)	0.46776 (9)	0.52658 (5)	0.0266 (2)
H17A	1.139	0.5315	0.5196	0.04*
H17B	1.1487	0.4101	0.5302	0.04*
H17C	1.0605	0.4736	0.5656	0.04*
C18	0.71756 (8)	−0.05724 (8)	0.49413 (5)	0.02047 (18)
C19	0.72455 (9)	−0.10197 (10)	0.55937 (5)	0.0262 (2)
H19A	0.6552	−0.1138	0.5759	0.039*
H19B	0.7611	−0.054	0.5871	0.039*
H19C	0.7619	−0.1673	0.5577	0.039*
O1	1.00912 (8)	0.50921 (7)	0.43108 (4)	0.0327 (2)
O2	0.98905 (6)	0.35231 (6)	0.47497 (3)	0.01904 (14)
O3	0.81477 (6)	0.35250 (6)	0.45508 (4)	0.02120 (15)
O4	0.67051 (6)	0.26478 (7)	0.47800 (4)	0.02641 (17)
O5	0.78024 (6)	0.02495 (6)	0.48730 (3)	0.01794 (14)
O6	0.66441 (8)	−0.09022 (8)	0.45248 (4)	0.0323 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0147 (4)	0.0157 (4)	0.0142 (4)	−0.0010 (3)	−0.0002 (3)	0.0010 (3)
C2	0.0154 (4)	0.0190 (4)	0.0212 (4)	−0.0020 (3)	−0.0014 (3)	−0.0006 (4)
C3	0.0148 (4)	0.0253 (5)	0.0265 (5)	0.0002 (4)	0.0006 (4)	−0.0006 (4)
C4	0.0184 (4)	0.0222 (5)	0.0195 (4)	0.0046 (3)	0.0007 (3)	−0.0013 (3)
C5	0.0191 (4)	0.0171 (4)	0.0159 (4)	0.0011 (3)	0.0017 (3)	0.0018 (3)
C6	0.0154 (4)	0.0153 (4)	0.0137 (4)	−0.0006 (3)	0.0001 (3)	0.0005 (3)
C7	0.0178 (4)	0.0176 (4)	0.0161 (4)	−0.0031 (3)	−0.0002 (3)	−0.0014 (3)
C8	0.0149 (4)	0.0186 (4)	0.0154 (4)	−0.0019 (3)	−0.0008 (3)	0.0012 (3)
C9	0.0158 (4)	0.0168 (4)	0.0160 (4)	0.0010 (3)	−0.0007 (3)	−0.0002 (3)
C10	0.0187 (4)	0.0206 (4)	0.0192 (4)	0.0020 (3)	−0.0018 (3)	−0.0011 (3)
C11	0.0185 (4)	0.0165 (4)	0.0178 (4)	0.0004 (3)	−0.0019 (3)	0.0008 (3)
C12	0.0162 (4)	0.0152 (4)	0.0137 (4)	0.0005 (3)	−0.0020 (3)	0.0008 (3)
C13	0.0241 (5)	0.0214 (4)	0.0147 (4)	−0.0002 (4)	0.0017 (3)	0.0038 (3)
C14	0.0222 (5)	0.0337 (6)	0.0342 (6)	0.0087 (4)	0.0005 (4)	−0.0060 (5)
C15	0.0255 (5)	0.0218 (5)	0.0208 (4)	0.0002 (4)	0.0027 (4)	−0.0028 (4)
C16	0.0249 (5)	0.0159 (4)	0.0220 (4)	−0.0026 (4)	0.0036 (4)	−0.0028 (3)
C17	0.0311 (6)	0.0235 (5)	0.0253 (5)	−0.0089 (4)	−0.0024 (4)	−0.0033 (4)
C18	0.0191 (4)	0.0222 (4)	0.0202 (4)	−0.0040 (4)	0.0008 (4)	0.0028 (4)
C19	0.0248 (5)	0.0304 (6)	0.0233 (5)	−0.0026 (4)	−0.0003 (4)	0.0089 (4)
O1	0.0492 (6)	0.0191 (4)	0.0299 (4)	−0.0068 (4)	−0.0052 (4)	0.0050 (3)
O2	0.0226 (4)	0.0154 (3)	0.0191 (3)	−0.0040 (3)	−0.0034 (3)	0.0015 (2)
O3	0.0197 (3)	0.0178 (3)	0.0261 (3)	0.0027 (3)	0.0010 (3)	−0.0020 (3)
O4	0.0181 (3)	0.0295 (4)	0.0316 (4)	0.0029 (3)	0.0022 (3)	−0.0046 (3)
O5	0.0172 (3)	0.0207 (3)	0.0159 (3)	−0.0035 (3)	−0.0009 (2)	0.0027 (3)
O6	0.0364 (5)	0.0361 (5)	0.0243 (4)	−0.0189 (4)	−0.0047 (4)	0.0026 (3)

Geometric parameters (Å, º) top

C1—C12	1.5054 (14)	C10—O3	1.3709 (13)
C1—C2	1.5403 (14)	C11—O2	1.4187 (12)
C1—C13	1.5468 (13)	C11—O3	1.4386 (13)
C1—C6	1.5627 (13)	C11—C12	1.5104 (14)
C2—C3	1.5346 (15)	C11—H11	1
C2—H2A	0.99	C13—H13A	0.98
C2—H2B	0.99	C13—H13B	0.98
C3—C4	1.5393 (16)	C13—H13C	0.98
C3—H3A	0.99	C14—H14A	0.98
C3—H3B	0.99	C14—H14B	0.98
C4—C5	1.5143 (14)	C14—H14C	0.98
C4—C14	1.5279 (15)	C15—H15A	0.95
C4—H4	1	C15—H15B	0.95
C5—C15	1.3321 (14)	C16—O1	1.1994 (14)
C5—C6	1.5131 (13)	C16—O2	1.3740 (12)
C6—C7	1.5297 (14)	C16—C17	1.4902 (15)
C6—H6	1	C17—H17A	0.98
C7—C8	1.5313 (14)	C17—H17B	0.98
C7—H7A	0.99	C17—H17C	0.98
C7—H7B	0.99	C18—O6	1.2000 (13)
C8—O5	1.4646 (12)	C18—O5	1.3529 (12)
C8—C9	1.4908 (14)	C18—C19	1.5013 (15)
C8—H8	1	C19—H19A	0.98
C9—C12	1.3373 (14)	C19—H19B	0.98
C9—C10	1.4766 (14)	C19—H19C	0.98
C10—O4	1.2021 (13)

C12—C1—C2	112.03 (8)	O4—C10—O3	121.84 (10)
C12—C1—C13	107.62 (8)	O4—C10—C9	129.76 (10)
C2—C1—C13	110.01 (8)	O3—C10—C9	108.37 (8)
C12—C1—C6	106.06 (7)	O2—C11—O3	107.67 (8)
C2—C1—C6	108.56 (8)	O2—C11—C12	110.52 (8)
C13—C1—C6	112.55 (8)	O3—C11—C12	104.98 (8)
C3—C2—C1	112.68 (8)	O2—C11—H11	111.1
C3—C2—H2A	109.1	O3—C11—H11	111.1
C1—C2—H2A	109.1	C12—C11—H11	111.1
C3—C2—H2B	109.1	C9—C12—C1	124.74 (9)
C1—C2—H2B	109.1	C9—C12—C11	108.49 (9)
H2A—C2—H2B	107.8	C1—C12—C11	126.58 (9)
C2—C3—C4	112.83 (8)	C1—C13—H13A	109.5
C2—C3—H3A	109	C1—C13—H13B	109.5
C4—C3—H3A	109	H13A—C13—H13B	109.5
C2—C3—H3B	109	C1—C13—H13C	109.5
C4—C3—H3B	109	H13A—C13—H13C	109.5
H3A—C3—H3B	107.8	H13B—C13—H13C	109.5
C5—C4—C14	114.59 (9)	C4—C14—H14A	109.5
C5—C4—C3	108.98 (8)	C4—C14—H14B	109.5
C14—C4—C3	111.47 (9)	H14A—C14—H14B	109.5
C5—C4—H4	107.1	C4—C14—H14C	109.5
C14—C4—H4	107.1	H14A—C14—H14C	109.5
C3—C4—H4	107.1	H14B—C14—H14C	109.5
C15—C5—C6	123.58 (9)	C5—C15—H15A	120
C15—C5—C4	124.53 (9)	C5—C15—H15B	120
C6—C5—C4	111.88 (8)	H15A—C15—H15B	120
C5—C6—C7	116.39 (8)	O1—C16—O2	122.57 (10)
C5—C6—C1	110.31 (8)	O1—C16—C17	126.69 (10)
C7—C6—C1	111.73 (8)	O2—C16—C17	110.74 (9)
C5—C6—H6	105.9	C16—C17—H17A	109.5
C7—C6—H6	105.9	C16—C17—H17B	109.5
C1—C6—H6	105.9	H17A—C17—H17B	109.5
C6—C7—C8	110.20 (8)	C16—C17—H17C	109.5
C6—C7—H7A	109.6	H17A—C17—H17C	109.5
C8—C7—H7A	109.6	H17B—C17—H17C	109.5
C6—C7—H7B	109.6	O6—C18—O5	123.49 (10)
C8—C7—H7B	109.6	O6—C18—C19	124.89 (10)
H7A—C7—H7B	108.1	O5—C18—C19	111.61 (9)
O5—C8—C9	106.34 (7)	C18—C19—H19A	109.5
O5—C8—C7	110.25 (8)	C18—C19—H19B	109.5
C9—C8—C7	109.86 (8)	H19A—C19—H19B	109.5
O5—C8—H8	110.1	C18—C19—H19C	109.5
C9—C8—H8	110.1	H19A—C19—H19C	109.5
C7—C8—H8	110.1	H19B—C19—H19C	109.5
C12—C9—C10	108.79 (9)	C16—O2—C11	115.91 (8)
C12—C9—C8	125.92 (9)	C10—O3—C11	109.35 (8)
C10—C9—C8	125.23 (9)	C18—O5—C8	115.54 (8)

C12—C1—C2—C3	170.06 (8)	C8—C9—C10—O4	1.98 (17)
C13—C1—C2—C3	−70.28 (11)	C12—C9—C10—O3	1.20 (11)
C6—C1—C2—C3	53.28 (10)	C8—C9—C10—O3	−176.04 (9)
C1—C2—C3—C4	−53.11 (12)	C10—C9—C12—C1	−176.62 (8)
C2—C3—C4—C5	53.61 (11)	C8—C9—C12—C1	0.59 (15)
C2—C3—C4—C14	−178.93 (9)	C10—C9—C12—C11	−1.26 (10)
C14—C4—C5—C15	−5.67 (16)	C8—C9—C12—C11	175.95 (9)
C3—C4—C5—C15	120.00 (11)	C2—C1—C12—C9	−137.96 (10)
C14—C4—C5—C6	175.82 (9)	C13—C1—C12—C9	100.99 (11)
C3—C4—C5—C6	−58.51 (10)	C6—C1—C12—C9	−19.68 (12)
C15—C5—C6—C7	11.94 (14)	C2—C1—C12—C11	47.52 (12)
C4—C5—C6—C7	−169.54 (8)	C13—C1—C12—C11	−73.53 (11)
C15—C5—C6—C1	−116.70 (11)	C6—C1—C12—C11	165.80 (8)
C4—C5—C6—C1	61.83 (10)	O2—C11—C12—C9	116.73 (9)
C12—C1—C6—C5	−177.79 (7)	O3—C11—C12—C9	0.90 (10)
C2—C1—C6—C5	−57.24 (9)	O2—C11—C12—C1	−68.02 (12)
C13—C1—C6—C5	64.78 (10)	O3—C11—C12—C1	176.15 (8)
C12—C1—C6—C7	51.08 (9)	O1—C16—O2—C11	−4.93 (15)
C2—C1—C6—C7	171.64 (8)	C17—C16—O2—C11	174.94 (9)
C13—C1—C6—C7	−66.34 (10)	O3—C11—O2—C16	−92.25 (10)
C5—C6—C7—C8	166.12 (8)	C12—C11—O2—C16	153.62 (8)
C1—C6—C7—C8	−65.93 (10)	O4—C10—O3—C11	−178.80 (10)
C6—C7—C8—O5	−74.35 (10)	C9—C10—O3—C11	−0.60 (11)
C6—C7—C8—C9	42.52 (10)	O2—C11—O3—C10	−117.91 (9)
O5—C8—C9—C12	107.52 (10)	C12—C11—O3—C10	−0.14 (10)
C7—C8—C9—C12	−11.78 (13)	O6—C18—O5—C8	−1.47 (15)
O5—C8—C9—C10	−75.71 (11)	C19—C18—O5—C8	177.62 (9)
C7—C8—C9—C10	164.99 (9)	C9—C8—O5—C18	158.03 (8)
C12—C9—C10—O4	179.22 (11)	C7—C8—O5—C18	−82.93 (10)

Experimental details

Crystal data
Chemical formula	C₁₉H₂₄O₆
M_r	348.38
Crystal system, space group	Tetragonal, P4₃2₁2
Temperature (K)	100
a, c (Å)	13.014 (2), 21.167 (3)
V (Å³)	3584.9 (9)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.37 × 0.25 × 0.25

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	Multi-scan (SCALEPACK; Otwinowski & Minor, 1997)
T_min, T_max	0.966, 0.977
No. of measured, independent and observed [I > 2σ(I)] reflections	11378, 6507, 5934
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.757

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.092, 1.02
No. of reflections	6507
No. of parameters	231
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.28, −0.21
Absolute structure	Flack (1983). 2776 Bijvoet pairs
Absolute structure parameter	0.4 (6)

Computer programs: COLLECT (Nonius, 2000), DENZO and SCALEPACK (Otwinowski & Minor, 1997), SIR2002 (Burla et al., 2003), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Acknowledgements

Purchase of the diffractometer was made possible by grant No. LEQSF(1999–2000)-ESH-TR-13, administered by the Louisiana Board of Regents.

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