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The structure of trilobolide-6-O-isobutyrate, C23H32O9, isolated from the flower of Wedelia trilobata, shows an eudesmanolide sesquiterpene skeleton constructed from the fusion of two cyclohexane rings and a lactone ring.
Supporting information
CCDC reference: 214815
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (C-C) = 0.009 Å
- R factor = 0.051
- wR factor = 0.153
- Data-to-parameter ratio = 7.6
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Alert Level A:
TYPE_089 Alert A _refine_ls_abs_structure_Flack is not of type numb.
REFI_021 Alert A _refine_ls_abs_structure_details is missing
Absolute structure method and Friedel-pair number.
This should be present as the _refine_ls_abs_structure_Flack or Roger
field has been filled out.
Alert Level C:
REFNR_01 Alert C Ratio of reflections to parameters is < 8 for a
non-centrosymmetric structure, where ZMAX < 18
sine(theta)/lambda 0.5946
Proportion of unique data used 0.5079
Ratio reflections to parameters 7.5679
PLAT_737 Alert C D...A Calc 2.985(7), Rep 2.986(3) .... 2.33 su-Ratio
O5 -O9 1.555 1.545
General Notes
REFLT_03
From the CIF: _diffrn_reflns_theta_max 25.00
From the CIF: _reflns_number_total 4172
Count of symmetry unique reflns 2123
Completeness (_total/calc) 196.51%
TEST3: Check Friedels for noncentro structure
Estimate of Friedel pairs measured 2049
Fraction of Friedel pairs measured 0.965
Are heavy atom types Z>Si present no
ALERT: MoKa measured Friedel data cannot be used to
determine absolute structure in a light-atom
study EXCEPT under VERY special conditions.
It is preferred that Friedel data is merged in such cases.
2 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
2 Alert Level C = Please check
The flowers of Wedelia trilobata growing in Hong Kong were collected in April, 2002. The pulverized dried flowers (500 g) were extracted with MeOH three times under reflux temperature. The extract was concentrated in vacuo to give a residue (98.8 g). A large portion of the residue (90 g) was suspended in distilled water and partitioned with petroleum ether, CHCl3, EtOAc and n-BuOH successively. The CHCl3 fraction (4.58 g) was subjected to column chromatography over silica gel (Merck, 60 g) and eluted with a gradient hexane–EtOAc system (from 0:100 to 100:0) to afford 26 fractions. rilobolide-6-O-isobutyrate (80 mg) was obtained from fraction 23 and further recrystallized from an acetone solution of the compound.
H atoms were included in the riding model approximation and assigned 1.2Ueq (CH and CH2) and 1.5Ueq (CH3) of the atom to which they were bonded. The hydroxy H atom was located from a difference map and its O—H distance was restrained to 0.82 Å. Terminal atoms C22 and C23 exhibit significant thermal motion and were refined isotropically.
Data collection: SMART (Bruker, 1998); cell refinement: SMART and SAINT (Bruker, 1998); data reduction: SHELXS97 (Sheldrick, 1990); program(s) used to solve structure: SHELXTL/PC (Sheldrick, 1997); program(s) used to refine structure: SHELXTL/PC; molecular graphics: XP (Bruker, 1998); software used to prepare material for publication: SHELXTL/PC.
Crystal data top
C23H32O9 | Dx = 1.267 Mg m−3 |
Mr = 452.49 | Mo Kα radiation, λ = 0.71073 Å |
Hexagonal, P65 | Cell parameters from 4824 reflections |
a = 9.8368 (8) Å | θ = 2.4–20.8° |
c = 42.455 (5) Å | µ = 0.10 mm−1 |
V = 3557.6 (6) Å3 | T = 293 K |
Z = 6 | Block, colorless |
F(000) = 1452 | 0.62 × 0.34 × 0.29 mm |
Data collection top
Siemens SMART/CCD diffractometer | 3029 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.063 |
Graphite monochromator | θmax = 25.0°, θmin = 2.4° |
ω scans | h = −11→7 |
19275 measured reflections | k = −11→11 |
4172 independent reflections | l = −50→50 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.051 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.153 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.105P)2 + 0.2647P] where P = (Fo2 + 2Fc2)/3 |
2119 reflections | (Δ/σ)max < 0.001 |
280 parameters | Δρmax = 0.30 e Å−3 |
1 restraint | Δρmin = −0.31 e Å−3 |
Crystal data top
C23H32O9 | Z = 6 |
Mr = 452.49 | Mo Kα radiation |
Hexagonal, P65 | µ = 0.10 mm−1 |
a = 9.8368 (8) Å | T = 293 K |
c = 42.455 (5) Å | 0.62 × 0.34 × 0.29 mm |
V = 3557.6 (6) Å3 | |
Data collection top
Siemens SMART/CCD diffractometer | 3029 reflections with I > 2σ(I) |
19275 measured reflections | Rint = 0.063 |
4172 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.051 | 1 restraint |
wR(F2) = 0.153 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.30 e Å−3 |
2119 reflections | Δρmin = −0.31 e Å−3 |
280 parameters | |
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. |
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 (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 1.0229 (4) | 0.4731 (4) | 0.15271 (7) | 0.0534 (8) | |
O2 | 0.7978 (6) | 0.3943 (7) | 0.17972 (11) | 0.0958 (16) | |
O3 | 0.8361 (4) | 0.5346 (4) | 0.08709 (7) | 0.0448 (7) | |
O4 | 0.8481 (7) | 0.6893 (8) | 0.12673 (14) | 0.122 (2) | |
O5 | 0.8084 (5) | 0.0559 (4) | 0.05076 (10) | 0.0687 (11) | |
H5A | 0.8146 | −0.0236 | 0.0484 | 0.08 (2)* | |
O6 | 1.1286 (4) | 0.3798 (4) | 0.02784 (7) | 0.0486 (8) | |
O7 | 1.0525 (5) | 0.3461 (6) | −0.02266 (8) | 0.0718 (11) | |
O8 | 1.0362 (5) | 0.7789 (4) | 0.05164 (8) | 0.0556 (9) | |
O9 | 0.8391 (7) | 0.7867 (5) | 0.02710 (11) | 0.0889 (15) | |
C1 | 0.9351 (6) | 0.3630 (6) | 0.12733 (11) | 0.0501 (11) | |
H1A | 0.8296 | 0.3499 | 0.1265 | 0.060* | |
C2 | 0.9204 (7) | 0.2058 (6) | 0.13451 (12) | 0.0619 (14) | |
H2A | 0.8634 | 0.1644 | 0.1541 | 0.074* | |
H2B | 1.0238 | 0.2174 | 0.1368 | 0.074* | |
C3 | 0.8322 (7) | 0.0934 (6) | 0.10729 (13) | 0.0634 (14) | |
H3A | 0.8211 | −0.0083 | 0.1119 | 0.076* | |
H3B | 0.7277 | 0.0797 | 0.1059 | 0.076* | |
C4 | 0.9140 (6) | 0.1505 (5) | 0.07540 (11) | 0.0519 (12) | |
C5 | 0.9342 (5) | 0.3163 (5) | 0.06973 (10) | 0.0412 (10) | |
H5B | 0.8265 | 0.2969 | 0.0710 | 0.049* | |
C6 | 0.9848 (5) | 0.3804 (5) | 0.03632 (10) | 0.0409 (9) | |
H6A | 0.9019 | 0.3098 | 0.0218 | 0.049* | |
C7 | 1.0154 (6) | 0.5468 (5) | 0.03049 (11) | 0.0449 (10) | |
H7A | 1.0960 | 0.5926 | 0.0141 | 0.054* | |
C8 | 1.0765 (6) | 0.6583 (5) | 0.05857 (11) | 0.0449 (10) | |
H8A | 1.1908 | 0.7060 | 0.0600 | 0.054* | |
C9 | 1.0026 (5) | 0.5819 (5) | 0.08962 (10) | 0.0412 (10) | |
H9A | 1.0509 | 0.6586 | 0.1067 | 0.049* | |
C10 | 1.0203 (5) | 0.4385 (5) | 0.09645 (10) | 0.0408 (10) | |
C11 | 0.8805 (6) | 0.5655 (6) | 0.01966 (11) | 0.0540 (12) | |
C12 | 0.9120 (7) | 0.7198 (6) | 0.03235 (12) | 0.0562 (13) | |
C13 | 0.7620 (9) | 0.4789 (9) | 0.00149 (15) | 0.085 (2) | |
H13A | 0.6921 | 0.5125 | −0.0041 | 0.102* | |
H13B | 0.7469 | 0.3833 | −0.0059 | 0.102* | |
C14 | 1.0630 (7) | 0.1371 (7) | 0.07467 (14) | 0.0659 (15) | |
H14A | 1.0356 | 0.0302 | 0.0785 | 0.099* | |
H14B | 1.1345 | 0.2035 | 0.0906 | 0.099* | |
H14C | 1.1120 | 0.1692 | 0.0544 | 0.099* | |
C15 | 1.1982 (6) | 0.4990 (6) | 0.09873 (11) | 0.0510 (11) | |
H15A | 1.2420 | 0.5723 | 0.1158 | 0.076* | |
H15B | 1.2482 | 0.5501 | 0.0794 | 0.076* | |
H15C | 1.2150 | 0.4122 | 0.1024 | 0.076* | |
C16 | 0.9365 (8) | 0.4699 (8) | 0.17795 (13) | 0.0657 (14) | |
C17 | 1.0411 (10) | 0.5783 (9) | 0.20335 (16) | 0.087 (2) | |
H17A | 0.9782 | 0.5753 | 0.2209 | 0.131* | |
H17B | 1.0986 | 0.6834 | 0.1953 | 0.131* | |
H17C | 1.1133 | 0.5452 | 0.2101 | 0.131* | |
C18 | 0.7774 (7) | 0.6038 (7) | 0.10565 (13) | 0.0645 (15) | |
C19 | 0.6121 (8) | 0.5561 (10) | 0.09579 (19) | 0.089 (2) | |
H19A | 0.5719 | 0.6066 | 0.1092 | 0.133* | |
H19B | 0.5468 | 0.4442 | 0.0976 | 0.133* | |
H19C | 0.6123 | 0.5870 | 0.0743 | 0.133* | |
C20 | 1.1473 (6) | 0.3604 (7) | −0.00316 (12) | 0.0548 (12) | |
C21 | 1.2954 (8) | 0.3593 (9) | −0.00938 (14) | 0.0805 (19) | |
H21A | 1.3739 | 0.4137 | 0.0071 | 0.097* | |
C22 | 1.2545 (19) | 0.194 (2) | −0.0127 (5) | 0.221 (8)* | |
H22A | 1.2169 | 0.1408 | 0.0071 | 0.331* | |
H22B | 1.3459 | 0.1892 | −0.0190 | 0.331* | |
H22C | 1.1741 | 0.1437 | −0.0284 | 0.331* | |
C23 | 1.3581 (19) | 0.4185 (17) | −0.0409 (4) | 0.182 (6)* | |
H23A | 1.3908 | 0.5281 | −0.0422 | 0.273* | |
H23B | 1.2781 | 0.3617 | −0.0564 | 0.273* | |
H23C | 1.4463 | 0.4043 | −0.0449 | 0.273* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.069 (2) | 0.063 (2) | 0.0340 (16) | 0.0379 (18) | −0.0070 (15) | −0.0044 (14) |
O2 | 0.082 (3) | 0.132 (4) | 0.076 (3) | 0.055 (3) | 0.012 (2) | −0.018 (3) |
O3 | 0.0487 (17) | 0.0510 (18) | 0.0449 (16) | 0.0325 (15) | −0.0010 (13) | −0.0038 (13) |
O4 | 0.121 (4) | 0.164 (6) | 0.123 (5) | 0.102 (4) | −0.031 (4) | −0.086 (4) |
O5 | 0.090 (3) | 0.0450 (19) | 0.078 (3) | 0.039 (2) | −0.025 (2) | −0.0193 (18) |
O6 | 0.0532 (18) | 0.0615 (19) | 0.0426 (17) | 0.0373 (16) | −0.0063 (14) | −0.0113 (14) |
O7 | 0.073 (3) | 0.110 (3) | 0.0447 (19) | 0.055 (3) | −0.0066 (18) | −0.014 (2) |
O8 | 0.078 (2) | 0.0415 (18) | 0.0532 (19) | 0.0340 (17) | −0.0072 (17) | 0.0003 (14) |
O9 | 0.141 (4) | 0.091 (3) | 0.078 (3) | 0.091 (3) | −0.034 (3) | −0.016 (2) |
C1 | 0.065 (3) | 0.047 (3) | 0.039 (2) | 0.028 (2) | −0.005 (2) | −0.0015 (19) |
C2 | 0.088 (4) | 0.054 (3) | 0.052 (3) | 0.041 (3) | 0.001 (3) | 0.011 (2) |
C3 | 0.076 (4) | 0.044 (3) | 0.067 (3) | 0.027 (3) | −0.003 (3) | 0.008 (2) |
C4 | 0.065 (3) | 0.040 (2) | 0.055 (3) | 0.029 (2) | −0.011 (2) | −0.007 (2) |
C5 | 0.046 (2) | 0.039 (2) | 0.046 (2) | 0.027 (2) | −0.0029 (18) | −0.0043 (18) |
C6 | 0.042 (2) | 0.044 (2) | 0.041 (2) | 0.025 (2) | −0.0068 (18) | −0.0043 (17) |
C7 | 0.057 (3) | 0.044 (2) | 0.041 (2) | 0.031 (2) | 0.004 (2) | 0.0014 (19) |
C8 | 0.048 (2) | 0.039 (2) | 0.050 (2) | 0.023 (2) | −0.0058 (19) | −0.0022 (19) |
C9 | 0.047 (2) | 0.037 (2) | 0.041 (2) | 0.022 (2) | −0.0097 (18) | −0.0086 (17) |
C10 | 0.050 (3) | 0.040 (2) | 0.036 (2) | 0.025 (2) | −0.0054 (18) | −0.0039 (17) |
C11 | 0.075 (3) | 0.062 (3) | 0.043 (2) | 0.048 (3) | −0.012 (2) | −0.008 (2) |
C12 | 0.084 (4) | 0.060 (3) | 0.047 (3) | 0.052 (3) | −0.007 (2) | 0.003 (2) |
C13 | 0.119 (6) | 0.102 (5) | 0.072 (4) | 0.083 (5) | −0.052 (4) | −0.036 (4) |
C14 | 0.095 (4) | 0.060 (3) | 0.067 (3) | 0.057 (3) | −0.014 (3) | −0.010 (3) |
C15 | 0.059 (3) | 0.056 (3) | 0.047 (2) | 0.036 (3) | −0.012 (2) | −0.009 (2) |
C16 | 0.082 (4) | 0.086 (4) | 0.047 (3) | 0.056 (4) | 0.003 (3) | −0.005 (3) |
C17 | 0.114 (5) | 0.107 (5) | 0.059 (4) | 0.070 (5) | −0.017 (3) | −0.029 (4) |
C18 | 0.077 (4) | 0.077 (4) | 0.059 (3) | 0.053 (3) | −0.002 (3) | −0.007 (3) |
C19 | 0.077 (4) | 0.118 (6) | 0.095 (5) | 0.067 (4) | 0.014 (4) | 0.004 (4) |
C20 | 0.059 (3) | 0.066 (3) | 0.047 (3) | 0.037 (3) | −0.002 (2) | −0.011 (2) |
C21 | 0.080 (4) | 0.122 (6) | 0.061 (3) | 0.067 (4) | 0.001 (3) | −0.015 (3) |
Geometric parameters (Å, º) top
O1—C16 | 1.359 (7) | C8—C9 | 1.512 (7) |
O1—C1 | 1.464 (6) | C8—H8A | 0.9800 |
O2—C16 | 1.185 (8) | C9—C10 | 1.534 (6) |
O3—C18 | 1.346 (6) | C9—H9A | 0.9800 |
O3—C9 | 1.465 (6) | C10—C15 | 1.544 (7) |
O4—C18 | 1.186 (7) | C11—C13 | 1.299 (8) |
O5—C4 | 1.439 (6) | C11—C12 | 1.490 (7) |
O5—H5A | 0.8200 | C13—H13A | 0.9300 |
O6—C20 | 1.355 (6) | C13—H13B | 0.9300 |
O6—C6 | 1.463 (5) | C14—H14A | 0.9600 |
O7—C20 | 1.201 (6) | C14—H14B | 0.9600 |
O8—C12 | 1.338 (6) | C14—H14C | 0.9600 |
O8—C8 | 1.456 (5) | C15—H15A | 0.9600 |
O9—C12 | 1.211 (6) | C15—H15B | 0.9600 |
C1—C2 | 1.510 (7) | C15—H15C | 0.9600 |
C1—C10 | 1.533 (7) | C16—C17 | 1.504 (9) |
C1—H1A | 0.9800 | C17—H17A | 0.9600 |
C2—C3 | 1.534 (8) | C17—H17B | 0.9600 |
C2—H2A | 0.9700 | C17—H17C | 0.9600 |
C2—H2B | 0.9700 | C18—C19 | 1.509 (9) |
C3—C4 | 1.531 (8) | C19—H19A | 0.9600 |
C3—H3A | 0.9700 | C19—H19B | 0.9600 |
C3—H3B | 0.9700 | C19—H19C | 0.9600 |
C4—C14 | 1.536 (8) | C20—C21 | 1.487 (8) |
C4—C5 | 1.560 (6) | C21—C23 | 1.468 (18) |
C5—C6 | 1.531 (6) | C21—C22 | 1.48 (2) |
C5—C10 | 1.559 (6) | C21—H21A | 0.9800 |
C5—H5B | 0.9800 | C22—H22A | 0.9600 |
C6—C7 | 1.529 (6) | C22—H22B | 0.9600 |
C6—H6A | 0.9800 | C22—H22C | 0.9600 |
C7—C11 | 1.500 (7) | C23—H23A | 0.9600 |
C7—C8 | 1.525 (6) | C23—H23B | 0.9600 |
C7—H7A | 0.9800 | C23—H23C | 0.9600 |
| | | |
C16—O1—C1 | 115.6 (4) | C9—C10—C5 | 107.7 (3) |
C18—O3—C9 | 119.4 (4) | C15—C10—C5 | 114.6 (4) |
C4—O5—H5A | 109.5 | C13—C11—C12 | 123.0 (5) |
C20—O6—C6 | 116.0 (3) | C13—C11—C7 | 131.4 (5) |
C12—O8—C8 | 109.3 (3) | C12—C11—C7 | 105.5 (4) |
O1—C1—C2 | 109.1 (4) | O9—C12—O8 | 122.4 (5) |
O1—C1—C10 | 107.1 (4) | O9—C12—C11 | 127.5 (5) |
C2—C1—C10 | 114.7 (4) | O8—C12—C11 | 110.1 (4) |
O1—C1—H1A | 108.6 | C11—C13—H13A | 120.0 |
C2—C1—H1A | 108.6 | C11—C13—H13B | 120.0 |
C10—C1—H1A | 108.6 | H13A—C13—H13B | 120.0 |
C1—C2—C3 | 108.5 (4) | C4—C14—H14A | 109.5 |
C1—C2—H2A | 110.0 | C4—C14—H14B | 109.5 |
C3—C2—H2A | 110.0 | H14A—C14—H14B | 109.5 |
C1—C2—H2B | 110.0 | C4—C14—H14C | 109.5 |
C3—C2—H2B | 110.0 | H14A—C14—H14C | 109.5 |
H2A—C2—H2B | 108.4 | H14B—C14—H14C | 109.5 |
C4—C3—C2 | 113.4 (4) | C10—C15—H15A | 109.5 |
C4—C3—H3A | 108.9 | C10—C15—H15B | 109.5 |
C2—C3—H3A | 108.9 | H15A—C15—H15B | 109.5 |
C4—C3—H3B | 108.9 | C10—C15—H15C | 109.5 |
C2—C3—H3B | 108.9 | H15A—C15—H15C | 109.5 |
H3A—C3—H3B | 107.7 | H15B—C15—H15C | 109.5 |
O5—C4—C3 | 109.2 (4) | O2—C16—O1 | 125.1 (6) |
O5—C4—C14 | 109.9 (4) | O2—C16—C17 | 124.4 (6) |
C3—C4—C14 | 109.6 (4) | O1—C16—C17 | 110.5 (6) |
O5—C4—C5 | 103.7 (4) | C16—C17—H17A | 109.5 |
C3—C4—C5 | 106.8 (4) | C16—C17—H17B | 109.5 |
C14—C4—C5 | 117.3 (4) | H17A—C17—H17B | 109.5 |
C6—C5—C10 | 114.6 (3) | C16—C17—H17C | 109.5 |
C6—C5—C4 | 114.8 (4) | H17A—C17—H17C | 109.5 |
C10—C5—C4 | 115.5 (3) | H17B—C17—H17C | 109.5 |
C6—C5—H5B | 103.2 | O4—C18—O3 | 123.5 (6) |
C10—C5—H5B | 103.2 | O4—C18—C19 | 126.0 (6) |
C4—C5—H5B | 103.2 | O3—C18—C19 | 110.4 (5) |
O6—C6—C7 | 106.9 (4) | C18—C19—H19A | 109.5 |
O6—C6—C5 | 110.0 (3) | C18—C19—H19B | 109.5 |
C7—C6—C5 | 116.2 (4) | H19A—C19—H19B | 109.5 |
O6—C6—H6A | 107.8 | C18—C19—H19C | 109.5 |
C7—C6—H6A | 107.8 | H19A—C19—H19C | 109.5 |
C5—C6—H6A | 107.8 | H19B—C19—H19C | 109.5 |
C11—C7—C8 | 101.9 (3) | O7—C20—O6 | 122.3 (5) |
C11—C7—C6 | 117.9 (4) | O7—C20—C21 | 125.7 (5) |
C8—C7—C6 | 116.1 (4) | O6—C20—C21 | 112.0 (4) |
C11—C7—H7A | 106.7 | C23—C21—C22 | 100.3 (11) |
C8—C7—H7A | 106.7 | C23—C21—C20 | 112.2 (8) |
C6—C7—H7A | 106.7 | C22—C21—C20 | 107.3 (9) |
O8—C8—C9 | 108.8 (4) | C23—C21—H21A | 112.1 |
O8—C8—C7 | 104.9 (3) | C22—C21—H21A | 112.1 |
C9—C8—C7 | 113.9 (4) | C20—C21—H21A | 112.1 |
O8—C8—H8A | 109.7 | C21—C22—H22A | 109.5 |
C9—C8—H8A | 109.7 | C21—C22—H22B | 109.5 |
C7—C8—H8A | 109.7 | H22A—C22—H22B | 109.5 |
O3—C9—C8 | 106.1 (3) | C21—C22—H22C | 109.5 |
O3—C9—C10 | 110.2 (4) | H22A—C22—H22C | 109.5 |
C8—C9—C10 | 112.0 (4) | H22B—C22—H22C | 109.5 |
O3—C9—H9A | 109.5 | C21—C23—H23A | 109.5 |
C8—C9—H9A | 109.5 | C21—C23—H23B | 109.5 |
C10—C9—H9A | 109.5 | H23A—C23—H23B | 109.5 |
C1—C10—C9 | 108.7 (4) | C21—C23—H23C | 109.5 |
C1—C10—C15 | 111.9 (4) | H23A—C23—H23C | 109.5 |
C9—C10—C15 | 106.6 (4) | H23B—C23—H23C | 109.5 |
C1—C10—C5 | 107.1 (4) | | |
| | | |
C16—O1—C1—C2 | −85.8 (5) | C2—C1—C10—C9 | 170.8 (4) |
C16—O1—C1—C10 | 149.6 (4) | O1—C1—C10—C15 | 49.4 (5) |
O1—C1—C2—C3 | −178.4 (4) | C2—C1—C10—C15 | −71.8 (5) |
C10—C1—C2—C3 | −58.4 (6) | O1—C1—C10—C5 | 175.9 (3) |
C1—C2—C3—C4 | 59.3 (6) | C2—C1—C10—C5 | 54.7 (5) |
C2—C3—C4—O5 | −168.2 (4) | O3—C9—C10—C1 | −59.2 (4) |
C2—C3—C4—C14 | 71.4 (6) | C8—C9—C10—C1 | −177.0 (4) |
C2—C3—C4—C5 | −56.6 (6) | O3—C9—C10—C15 | −180.0 (3) |
O5—C4—C5—C6 | −53.4 (5) | C8—C9—C10—C15 | 62.2 (4) |
C3—C4—C5—C6 | −168.7 (4) | O3—C9—C10—C5 | 56.6 (4) |
C14—C4—C5—C6 | 68.0 (5) | C8—C9—C10—C5 | −61.3 (5) |
O5—C4—C5—C10 | 169.8 (4) | C6—C5—C10—C1 | 170.0 (4) |
C3—C4—C5—C10 | 54.5 (5) | C4—C5—C10—C1 | −53.2 (5) |
C14—C4—C5—C10 | −68.8 (5) | C6—C5—C10—C9 | 53.2 (5) |
C20—O6—C6—C7 | −83.2 (5) | C4—C5—C10—C9 | −169.9 (4) |
C20—O6—C6—C5 | 149.9 (4) | C6—C5—C10—C15 | −65.2 (5) |
C10—C5—C6—O6 | 82.3 (4) | C4—C5—C10—C15 | 71.7 (5) |
C4—C5—C6—O6 | −54.8 (5) | C8—C7—C11—C13 | −162.7 (7) |
C10—C5—C6—C7 | −39.3 (5) | C6—C7—C11—C13 | −34.5 (9) |
C4—C5—C6—C7 | −176.4 (4) | C8—C7—C11—C12 | 21.5 (5) |
O6—C6—C7—C11 | 146.6 (4) | C6—C7—C11—C12 | 149.8 (4) |
C5—C6—C7—C11 | −90.2 (5) | C8—O8—C12—O9 | 167.6 (5) |
O6—C6—C7—C8 | −92.2 (4) | C8—O8—C12—C11 | −11.7 (6) |
C5—C6—C7—C8 | 31.0 (6) | C13—C11—C12—O9 | −2.6 (10) |
C12—O8—C8—C9 | −96.6 (4) | C7—C11—C12—O9 | 173.6 (6) |
C12—O8—C8—C7 | 25.6 (5) | C13—C11—C12—O8 | 176.7 (6) |
C11—C7—C8—O8 | −28.3 (5) | C7—C11—C12—O8 | −7.2 (6) |
C6—C7—C8—O8 | −157.7 (4) | C1—O1—C16—O2 | −5.4 (8) |
C11—C7—C8—C9 | 90.6 (5) | C1—O1—C16—C17 | 175.5 (5) |
C6—C7—C8—C9 | −38.8 (6) | C9—O3—C18—O4 | −8.9 (9) |
C18—O3—C9—C8 | −114.3 (4) | C9—O3—C18—C19 | 171.4 (5) |
C18—O3—C9—C10 | 124.3 (4) | C6—O6—C20—O7 | 0.7 (7) |
O8—C8—C9—O3 | 51.9 (4) | C6—O6—C20—C21 | −179.2 (5) |
C7—C8—C9—O3 | −64.8 (4) | O7—C20—C21—C23 | 29.4 (11) |
O8—C8—C9—C10 | 172.1 (3) | O6—C20—C21—C23 | −150.7 (8) |
C7—C8—C9—C10 | 55.5 (5) | O7—C20—C21—C22 | −79.8 (12) |
O1—C1—C10—C9 | −68.0 (4) | O6—C20—C21—C22 | 100.1 (11) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O5—H5A···O9i | 0.82 | 2.19 | 2.986 (3) | 163 |
Symmetry code: (i) x, y−1, z. |
Experimental details
Crystal data |
Chemical formula | C23H32O9 |
Mr | 452.49 |
Crystal system, space group | Hexagonal, P65 |
Temperature (K) | 293 |
a, c (Å) | 9.8368 (8), 42.455 (5) |
V (Å3) | 3557.6 (6) |
Z | 6 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.62 × 0.34 × 0.29 |
|
Data collection |
Diffractometer | Siemens SMART/CCD diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 19275, 4172, 3029 |
Rint | 0.063 |
(sin θ/λ)max (Å−1) | 0.595 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.051, 0.153, 1.04 |
No. of reflections | 2119 |
No. of parameters | 280 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.30, −0.31 |
Absolute structure parameter | unk |
Selected geometric parameters (Å, º) topO1—C16 | 1.359 (7) | O6—C20 | 1.355 (6) |
O1—C1 | 1.464 (6) | O6—C6 | 1.463 (5) |
O2—C16 | 1.185 (8) | O7—C20 | 1.201 (6) |
O3—C18 | 1.346 (6) | O8—C12 | 1.338 (6) |
O3—C9 | 1.465 (6) | O8—C8 | 1.456 (5) |
O4—C18 | 1.186 (7) | O9—C12 | 1.211 (6) |
O5—C4 | 1.439 (6) | C11—C13 | 1.299 (8) |
| | | |
C13—C11—C12 | 123.0 (5) | C12—C11—C7 | 105.5 (4) |
C13—C11—C7 | 131.4 (5) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O5—H5A···O9i | 0.82 | 2.19 | 2.986 (3) | 163 |
Symmetry code: (i) x, y−1, z. |
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Wedelia is a large genus of the Compositae family from which many eudesmanolide sesquiterpenes have been isolated in recent years (Bohlmann et al., 1981; Farag et al., 1996; Ferreira et al., 1994; Ragasa et al., 1993). Wedelia trilobata, a vigorous creeping herb native to tropical areas, was introduced into Hong Kong and utilized as a substitute of W. chinensis, a Traditional Chinese medicine used for the treatment of the common cold, hepatitis, indigestion and infections (Jiangsu New Medical College, 1977). As part of our effort to search for antitumor agents from natural sources, the investigation of the chemical components of W. trilobata flowers has been undertaken. In this connection, the title compound, trilobolide-6-O-isobutyrate, (I), has been isolated and studied by X-ray crystallography. Compound (I) was previously isolated from W. trilobata (Bohlmann et al., 1981) and W. prostrata (Farag et al., 1996) and its chemical structure elucidated based on spectroscopic methods.
Compound (I) (Fig. 1 and Table 1) is characterized by the fusion of two cyclohexane rings (ring A and B) with a lactone ring (ring C). Rings A and B are trans-fused and rings B and C are cis-fused. Ring A exists in a chair conformation, with a mean torsion angle of 56° (ideal angle = 56°). Ring B exists in a twist-chair conformation, as indicated by the mean torsion angle of 47°. Finally, the five-membered lactone ring C adopts an envelope conformation with atom C8 displaced by 0.42 Å from the least-squares plane of the remaining four atoms. The acetoxyl group at C1 and the hydroxy group at C4 adopt equatorial positions. The methyl groups at C4 and C10, the isobutyrate group at C6 and the acetoxyl group at C9 occupy axial positions.
An intermolecular hydrogen bond, involving O5—H and O9i, with an O5···O9 distance of 2.986 (3) Å, is noted [symmetry code: (i) x, y − 1, z].