Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801015847/ob6077sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801015847/ob6077Isup2.hkl |
CCDC reference: 175996
Key indicators
- Single-crystal X-ray study
- T = 295 K
- Mean (C-C) = 0.006 Å
- R factor = 0.053
- wR factor = 0.128
- Data-to-parameter ratio = 10.0
checkCIF results
No syntax errors found ADDSYM reports no extra symmetry General Notes
REFLT_03 From the CIF: _diffrn_reflns_theta_max 28.25 From the CIF: _reflns_number_total 2291 Count of symmetry unique reflns 2291 Completeness (_total/calc) 100.00% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 0 Fraction of Friedel pairs measured 0.000 Are heavy atom types Z>Si present no Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF.
The plant was collected in the mountain near the Shangqiu City, Shanxi province, People's Republic of China. The identity of the plant was confirmed by Dr Li Bao-Lin of Shanxi Normal University. 2 kg of dried powder of the whole herb of Rabdosia var lophanthoides were soaked three times with 95% EtOH at room temperature. The ethanolic extracts were evaporated under reduced pressure, the residue was successively fractioned with petroleum ether, EtOAc and n-BuOH. The residue of EtOAc fraction was subjected to column chromatography over silica gel. The column was eluted with petroleum ether–EtOAc mixture, the crude compound was purified by column chromatography on silica gel with acetone–chloroform mixture to obtain pure title compound, (I), (m.p. 569–571 K). Crystals of (I) were obtained by slow evaporation from an aqueous solution containing chloroform and methanol in a 1:1 ratio at room temperature.
H atoms were placed in the geometrically calculated positions and included in the final refinement in the riding-model approximation with Uiso values equal to 1.2Ueq of the corresponding carrier atom. Since the Flack (1983) parameter was 2(2), the Friedel reflections were merged before the final refinement; the relative stereochemistry is shown in the Scheme and Figures.
Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL/PC (Siemens, 1991); software used to prepare material for publication: SHELXTL97.
Fig. 1. The molecular structure of (I) showing 50% probability displacement ellipsoids. | |
Fig. 2. The crystal-packing diagram of (I) viewed down the b axis. H atoms have been omitted for clarity. |
C20H26O5 | Dx = 1.315 Mg m−3 |
Mr = 346.41 | Melting point: 569-571K K |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.569 (2) Å | Cell parameters from 29 reflections |
b = 9.397 (2) Å | θ = 3.3–12.2° |
c = 12.310 (3) Å | µ = 0.09 mm−1 |
β = 92.62 (2)° | T = 295 K |
V = 874.6 (4) Å3 | Prism, colorless |
Z = 2 | 0.42 × 0.34 × 0.14 mm |
F(000) = 372 |
Siemens P4 diffractometer | Rint = 0.023 |
Radiation source: normal-focus sealed tube | θmax = 28.3°, θmin = 1.7° |
Graphite monochromator | h = 0→10 |
ω scans | k = 0→12 |
2561 measured reflections | l = −16→16 |
2291 independent reflections | 3 standard reflections every 97 reflections |
1206 reflections with I > 2σ(I) | intensity decay: 2.9% |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.053 | w = 1/[σ2(Fo2) + (0.0602P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.128 | (Δ/σ)max < 0.001 |
S = 0.87 | Δρmax = 0.24 e Å−3 |
2291 reflections | Δρmin = −0.18 e Å−3 |
228 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
1 restraint | Extinction coefficient: 0.017 (4) |
Primary atom site location: structure-invariant direct methods | Absolute structure: see text |
Secondary atom site location: difference Fourier map |
C20H26O5 | V = 874.6 (4) Å3 |
Mr = 346.41 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 7.569 (2) Å | µ = 0.09 mm−1 |
b = 9.397 (2) Å | T = 295 K |
c = 12.310 (3) Å | 0.42 × 0.34 × 0.14 mm |
β = 92.62 (2)° |
Siemens P4 diffractometer | Rint = 0.023 |
2561 measured reflections | 3 standard reflections every 97 reflections |
2291 independent reflections | intensity decay: 2.9% |
1206 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.053 | 1 restraint |
wR(F2) = 0.128 | H-atom parameters constrained |
S = 0.87 | Δρmax = 0.24 e Å−3 |
2291 reflections | Δρmin = −0.18 e Å−3 |
228 parameters | Absolute structure: see text |
Experimental. IR(KBr) νmax: 1747, 1721 cm-1. no UV absorption. 13C NMR (125 MHz, pyridine): δ (p.p.m.) 215.2(C), 176.2(C), 171.1(C), 76.3(CH2), 69.1(CH2), 57.3(C), 51.0(CH), 48.9(CH), 42.9(CH), 39.2(C), 38.9(C), 35.7(CH), 31.9(CH2), 30.4(CH2), 29.6(2*CH2), 25.1(CH3), 18.0(CH2), 17.5(CH2), 16.5(CH3). |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.6597 (4) | 0.8513 (3) | 1.0259 (2) | 0.0551 (9) | |
O2 | 0.3713 (4) | 0.8213 (4) | 0.6934 (3) | 0.0560 (9) | |
O3 | 0.5983 (4) | 0.6198 (4) | 1.0273 (3) | 0.0670 (11) | |
O4 | 0.2426 (4) | 0.7159 (5) | 0.5532 (2) | 0.0691 (10) | |
O5 | 0.1478 (3) | 0.5268 (4) | 0.7755 (2) | 0.0538 (9) | |
C1 | 0.7476 (5) | 0.7709 (4) | 0.6820 (3) | 0.0413 (11) | |
H1A | 0.8468 | 0.7075 | 0.6723 | 0.050* | |
H1B | 0.6727 | 0.7682 | 0.6160 | 0.050* | |
C2 | 0.8163 (6) | 0.9219 (5) | 0.6999 (4) | 0.0525 (12) | |
H2A | 0.8723 | 0.9548 | 0.6352 | 0.063* | |
H2B | 0.7185 | 0.9851 | 0.7136 | 0.063* | |
C3 | 0.9479 (5) | 0.9245 (5) | 0.7955 (3) | 0.0482 (11) | |
H3A | 0.9778 | 1.0229 | 0.8117 | 0.058* | |
H3B | 1.0552 | 0.8774 | 0.7745 | 0.058* | |
C4 | 0.8858 (5) | 0.8539 (4) | 0.8997 (3) | 0.0353 (9) | |
C5 | 0.7698 (4) | 0.7204 (4) | 0.8812 (3) | 0.0304 (8) | |
H5 | 0.8465 | 0.6364 | 0.8806 | 0.036* | |
C6 | 0.6681 (6) | 0.7189 (6) | 0.9843 (3) | 0.0475 (11) | |
C7 | 0.3358 (5) | 0.7048 (6) | 0.6345 (4) | 0.0484 (11) | |
C8 | 0.4117 (5) | 0.5627 (5) | 0.6710 (3) | 0.0389 (11) | |
C9 | 0.5709 (5) | 0.5640 (4) | 0.7592 (3) | 0.0356 (10) | |
H9 | 0.5213 | 0.5345 | 0.8278 | 0.043* | |
C10 | 0.6417 (4) | 0.7174 (5) | 0.7778 (3) | 0.0304 (8) | |
C11 | 0.7056 (5) | 0.4510 (5) | 0.7318 (4) | 0.0537 (13) | |
H11A | 0.7910 | 0.4413 | 0.7926 | 0.064* | |
H11B | 0.7688 | 0.4821 | 0.6693 | 0.064* | |
C12 | 0.6222 (6) | 0.3059 (5) | 0.7070 (4) | 0.0572 (13) | |
H12A | 0.7076 | 0.2457 | 0.6727 | 0.069* | |
H12B | 0.5920 | 0.2608 | 0.7746 | 0.069* | |
C13 | 0.4565 (5) | 0.3184 (5) | 0.6326 (4) | 0.0491 (12) | |
H13 | 0.4526 | 0.2415 | 0.5787 | 0.059* | |
C14 | 0.4519 (5) | 0.4614 (6) | 0.5765 (3) | 0.0527 (13) | |
H14A | 0.3596 | 0.4651 | 0.5193 | 0.063* | |
H14B | 0.5647 | 0.4836 | 0.5462 | 0.063* | |
C15 | 0.2615 (5) | 0.4759 (6) | 0.7234 (3) | 0.0463 (12) | |
C16 | 0.2857 (6) | 0.3197 (6) | 0.6958 (5) | 0.0654 (15) | |
H16 | 0.3098 | 0.2684 | 0.7642 | 0.078* | |
C17 | 0.1287 (7) | 0.2563 (7) | 0.6424 (6) | 0.108 (3) | |
H17A | 0.0916 | 0.3130 | 0.5806 | 0.129* | |
H17B | 0.0354 | 0.2524 | 0.6926 | 0.129* | |
H17C | 0.1558 | 0.1617 | 0.6188 | 0.129* | |
C18 | 1.0503 (5) | 0.8124 (5) | 0.9721 (3) | 0.0520 (12) | |
H18A | 1.0129 | 0.7690 | 1.0379 | 0.078* | |
H18B | 1.1185 | 0.8961 | 0.9897 | 0.078* | |
H18C | 1.1213 | 0.7463 | 0.9338 | 0.078* | |
C19 | 0.7665 (6) | 0.9488 (5) | 0.9650 (4) | 0.0498 (12) | |
H19A | 0.8363 | 1.0100 | 1.0138 | 0.060* | |
H19B | 0.6922 | 1.0078 | 0.9170 | 0.060* | |
C20 | 0.4783 (5) | 0.8075 (5) | 0.7926 (3) | 0.0458 (11) | |
H20A | 0.4082 | 0.7647 | 0.8479 | 0.055* | |
H20B | 0.5143 | 0.9014 | 0.8178 | 0.055* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0577 (19) | 0.058 (2) | 0.0513 (19) | −0.0063 (17) | 0.0189 (15) | −0.0134 (17) |
O2 | 0.0417 (16) | 0.056 (2) | 0.069 (2) | 0.0167 (17) | −0.0127 (15) | −0.0020 (19) |
O3 | 0.077 (2) | 0.074 (3) | 0.051 (2) | −0.031 (2) | 0.0151 (18) | 0.0030 (19) |
O4 | 0.0596 (19) | 0.089 (3) | 0.0572 (19) | 0.006 (2) | −0.0179 (16) | 0.019 (2) |
O5 | 0.0317 (14) | 0.074 (2) | 0.0566 (19) | 0.0000 (17) | 0.0091 (14) | −0.0068 (18) |
C1 | 0.038 (2) | 0.046 (3) | 0.041 (2) | −0.006 (2) | 0.0038 (19) | −0.001 (2) |
C2 | 0.055 (3) | 0.051 (3) | 0.052 (3) | −0.009 (2) | 0.008 (2) | 0.001 (2) |
C3 | 0.047 (2) | 0.045 (3) | 0.053 (3) | −0.017 (2) | 0.009 (2) | −0.003 (2) |
C4 | 0.0347 (19) | 0.036 (2) | 0.035 (2) | −0.0030 (18) | 0.0040 (16) | −0.0047 (18) |
C5 | 0.0312 (18) | 0.029 (2) | 0.0307 (19) | −0.0026 (19) | 0.0019 (15) | 0.000 (2) |
C6 | 0.048 (2) | 0.051 (3) | 0.043 (2) | −0.006 (3) | 0.0012 (19) | 0.002 (3) |
C7 | 0.0263 (19) | 0.069 (3) | 0.049 (3) | 0.003 (3) | −0.0009 (19) | 0.008 (3) |
C8 | 0.0248 (19) | 0.055 (3) | 0.037 (2) | −0.0037 (19) | −0.0008 (17) | 0.000 (2) |
C9 | 0.0294 (19) | 0.042 (3) | 0.035 (2) | −0.0048 (18) | −0.0008 (16) | 0.002 (2) |
C10 | 0.0251 (17) | 0.034 (2) | 0.0320 (19) | 0.0055 (19) | 0.0028 (14) | −0.002 (2) |
C11 | 0.046 (2) | 0.040 (3) | 0.073 (3) | 0.004 (2) | −0.018 (2) | −0.014 (2) |
C12 | 0.059 (3) | 0.046 (3) | 0.065 (3) | −0.012 (3) | −0.006 (2) | −0.009 (3) |
C13 | 0.040 (2) | 0.055 (3) | 0.053 (3) | −0.006 (2) | 0.005 (2) | −0.018 (3) |
C14 | 0.039 (2) | 0.079 (4) | 0.040 (2) | 0.003 (3) | −0.0001 (19) | −0.014 (3) |
C15 | 0.027 (2) | 0.068 (3) | 0.044 (2) | −0.006 (2) | 0.0003 (18) | −0.009 (2) |
C16 | 0.054 (3) | 0.066 (4) | 0.077 (3) | −0.021 (3) | 0.018 (3) | −0.017 (3) |
C17 | 0.064 (3) | 0.097 (6) | 0.165 (7) | −0.034 (4) | 0.029 (4) | −0.033 (5) |
C18 | 0.047 (2) | 0.051 (3) | 0.057 (3) | −0.008 (2) | −0.010 (2) | −0.003 (3) |
C19 | 0.054 (3) | 0.041 (3) | 0.056 (3) | −0.002 (2) | 0.016 (2) | −0.007 (2) |
C20 | 0.036 (2) | 0.046 (3) | 0.055 (3) | 0.008 (2) | −0.002 (2) | −0.006 (2) |
O1—C6 | 1.348 (6) | C9—C10 | 1.551 (6) |
O1—C19 | 1.453 (5) | C9—H9 | 0.9800 |
O2—C7 | 1.334 (6) | C10—C20 | 1.516 (5) |
O2—C20 | 1.439 (5) | C11—C12 | 1.527 (6) |
O3—C6 | 1.205 (6) | C11—H11A | 0.9700 |
O4—C7 | 1.203 (5) | C11—H11B | 0.9700 |
O5—C15 | 1.196 (5) | C12—C13 | 1.524 (6) |
C1—C2 | 1.524 (6) | C12—H12A | 0.9700 |
C1—C10 | 1.540 (5) | C12—H12B | 0.9700 |
C1—H1A | 0.9700 | C13—C14 | 1.510 (7) |
C1—H1B | 0.9700 | C13—C16 | 1.539 (6) |
C2—C3 | 1.507 (6) | C13—H13 | 0.9800 |
C2—H2A | 0.9700 | C14—H14A | 0.9700 |
C2—H2B | 0.9700 | C14—H14B | 0.9700 |
C3—C4 | 1.537 (5) | C15—C16 | 1.520 (7) |
C3—H3A | 0.9700 | C16—C17 | 1.459 (7) |
C3—H3B | 0.9700 | C16—H16 | 0.9800 |
C4—C19 | 1.524 (6) | C17—H17A | 0.9600 |
C4—C5 | 1.542 (5) | C17—H17B | 0.9600 |
C4—C18 | 1.548 (5) | C17—H17C | 0.9600 |
C5—C6 | 1.514 (5) | C18—H18A | 0.9600 |
C5—C10 | 1.566 (5) | C18—H18B | 0.9600 |
C5—H5 | 0.9800 | C18—H18C | 0.9600 |
C7—C8 | 1.514 (7) | C19—H19A | 0.9700 |
C8—C14 | 1.544 (6) | C19—H19B | 0.9700 |
C8—C15 | 1.562 (6) | C20—H20A | 0.9700 |
C8—C9 | 1.584 (5) | C20—H20B | 0.9700 |
C9—C11 | 1.521 (6) | ||
C6—O1—C19 | 110.4 (3) | C9—C11—H11A | 109.0 |
C7—O2—C20 | 118.6 (4) | C12—C11—H11A | 109.0 |
C2—C1—C10 | 112.3 (3) | C9—C11—H11B | 109.0 |
C2—C1—H1A | 109.1 | C12—C11—H11B | 109.0 |
C10—C1—H1A | 109.1 | H11A—C11—H11B | 107.8 |
C2—C1—H1B | 109.1 | C13—C12—C11 | 111.9 (4) |
C10—C1—H1B | 109.1 | C13—C12—H12A | 109.2 |
H1A—C1—H1B | 107.9 | C11—C12—H12A | 109.2 |
C3—C2—C1 | 109.7 (4) | C13—C12—H12B | 109.2 |
C3—C2—H2A | 109.7 | C11—C12—H12B | 109.2 |
C1—C2—H2A | 109.7 | H12A—C12—H12B | 107.9 |
C3—C2—H2B | 109.7 | C14—C13—C12 | 110.2 (4) |
C1—C2—H2B | 109.7 | C14—C13—C16 | 102.8 (4) |
H2A—C2—H2B | 108.2 | C12—C13—C16 | 112.6 (4) |
C2—C3—C4 | 115.3 (3) | C14—C13—H13 | 110.4 |
C2—C3—H3A | 108.4 | C12—C13—H13 | 110.4 |
C4—C3—H3A | 108.4 | C16—C13—H13 | 110.4 |
C2—C3—H3B | 108.4 | C13—C14—C8 | 101.9 (3) |
C4—C3—H3B | 108.4 | C13—C14—H14A | 111.4 |
H3A—C3—H3B | 107.5 | C8—C14—H14A | 111.4 |
C19—C4—C3 | 113.5 (4) | C13—C14—H14B | 111.4 |
C19—C4—C5 | 101.9 (3) | C8—C14—H14B | 111.4 |
C3—C4—C5 | 115.0 (3) | H14A—C14—H14B | 109.3 |
C19—C4—C18 | 108.9 (3) | O5—C15—C16 | 127.1 (4) |
C3—C4—C18 | 108.7 (3) | O5—C15—C8 | 124.6 (5) |
C5—C4—C18 | 108.5 (3) | C16—C15—C8 | 108.3 (4) |
C6—C5—C4 | 101.1 (3) | C17—C16—C15 | 113.0 (5) |
C6—C5—C10 | 111.2 (3) | C17—C16—C13 | 117.0 (4) |
C4—C5—C10 | 117.5 (3) | C15—C16—C13 | 103.5 (4) |
C6—C5—H5 | 108.9 | C17—C16—H16 | 107.6 |
C4—C5—H5 | 108.9 | C15—C16—H16 | 107.6 |
C10—C5—H5 | 108.9 | C13—C16—H16 | 107.6 |
O3—C6—O1 | 121.1 (4) | C16—C17—H17A | 109.5 |
O3—C6—C5 | 128.8 (5) | C16—C17—H17B | 109.5 |
O1—C6—C5 | 110.1 (4) | H17A—C17—H17B | 109.5 |
O4—C7—O2 | 118.5 (5) | C16—C17—H17C | 109.5 |
O4—C7—C8 | 121.6 (5) | H17A—C17—H17C | 109.5 |
O2—C7—C8 | 119.9 (3) | H17B—C17—H17C | 109.5 |
C7—C8—C14 | 113.9 (4) | C4—C18—H18A | 109.5 |
C7—C8—C15 | 108.0 (3) | C4—C18—H18B | 109.5 |
C14—C8—C15 | 99.3 (4) | H18A—C18—H18B | 109.5 |
C7—C8—C9 | 117.6 (4) | C4—C18—H18C | 109.5 |
C14—C8—C9 | 110.5 (3) | H18A—C18—H18C | 109.5 |
C15—C8—C9 | 105.4 (3) | H18B—C18—H18C | 109.5 |
C11—C9—C10 | 116.8 (3) | O1—C19—C4 | 105.1 (3) |
C11—C9—C8 | 109.9 (3) | O1—C19—H19A | 110.7 |
C10—C9—C8 | 110.8 (3) | C4—C19—H19A | 110.7 |
C11—C9—H9 | 106.2 | O1—C19—H19B | 110.7 |
C10—C9—H9 | 106.2 | C4—C19—H19B | 110.7 |
C8—C9—H9 | 106.2 | H19A—C19—H19B | 108.8 |
C20—C10—C1 | 111.5 (3) | O2—C20—C10 | 112.3 (3) |
C20—C10—C9 | 105.0 (3) | O2—C20—H20A | 109.1 |
C1—C10—C9 | 112.2 (3) | C10—C20—H20A | 109.1 |
C20—C10—C5 | 111.8 (3) | O2—C20—H20B | 109.1 |
C1—C10—C5 | 107.0 (3) | C10—C20—H20B | 109.1 |
C9—C10—C5 | 109.5 (3) | H20A—C20—H20B | 107.9 |
C9—C11—C12 | 113.1 (3) | ||
C10—C1—C2—C3 | 64.8 (4) | C8—C9—C10—C5 | 168.1 (3) |
C1—C2—C3—C4 | −50.5 (5) | C6—C5—C10—C20 | 38.5 (5) |
C2—C3—C4—C19 | −80.6 (5) | C4—C5—C10—C20 | −77.3 (4) |
C2—C3—C4—C5 | 36.2 (5) | C6—C5—C10—C1 | 160.7 (4) |
C2—C3—C4—C18 | 158.1 (4) | C4—C5—C10—C1 | 45.0 (4) |
C19—C4—C5—C6 | −32.2 (4) | C6—C5—C10—C9 | −77.4 (4) |
C3—C4—C5—C6 | −155.4 (4) | C4—C5—C10—C9 | 166.8 (3) |
C18—C4—C5—C6 | 82.6 (4) | C10—C9—C11—C12 | −175.9 (4) |
C19—C4—C5—C10 | 89.0 (4) | C8—C9—C11—C12 | −48.6 (5) |
C3—C4—C5—C10 | −34.3 (4) | C9—C11—C12—C13 | 44.5 (6) |
C18—C4—C5—C10 | −156.2 (3) | C11—C12—C13—C14 | 17.5 (5) |
C19—O1—C6—O3 | 175.1 (4) | C11—C12—C13—C16 | −96.6 (5) |
C19—O1—C6—C5 | −6.0 (5) | C12—C13—C14—C8 | −71.5 (4) |
C4—C5—C6—O3 | −156.4 (4) | C16—C13—C14—C8 | 48.7 (4) |
C10—C5—C6—O3 | 78.0 (6) | C7—C8—C14—C13 | −159.4 (3) |
C4—C5—C6—O1 | 24.8 (4) | C15—C8—C14—C13 | −44.9 (4) |
C10—C5—C6—O1 | −100.8 (4) | C9—C8—C14—C13 | 65.6 (4) |
C20—O2—C7—O4 | 178.1 (4) | C7—C8—C15—O5 | −34.9 (5) |
C20—O2—C7—C8 | −1.6 (6) | C14—C8—C15—O5 | −153.9 (4) |
O4—C7—C8—C14 | 32.3 (6) | C9—C8—C15—O5 | 91.6 (5) |
O2—C7—C8—C14 | −147.9 (4) | C7—C8—C15—C16 | 144.6 (4) |
O4—C7—C8—C15 | −76.9 (5) | C14—C8—C15—C16 | 25.6 (5) |
O2—C7—C8—C15 | 102.8 (4) | C9—C8—C15—C16 | −88.8 (4) |
O4—C7—C8—C9 | 164.0 (4) | O5—C15—C16—C17 | 54.9 (7) |
O2—C7—C8—C9 | −16.3 (6) | C8—C15—C16—C17 | −124.7 (5) |
C7—C8—C9—C11 | −140.4 (4) | O5—C15—C16—C13 | −177.6 (4) |
C14—C8—C9—C11 | −7.2 (5) | C8—C15—C16—C13 | 2.9 (5) |
C15—C8—C9—C11 | 99.1 (4) | C14—C13—C16—C17 | 93.7 (6) |
C7—C8—C9—C10 | −9.8 (5) | C12—C13—C16—C17 | −147.8 (6) |
C14—C8—C9—C10 | 123.3 (4) | C14—C13—C16—C15 | −31.4 (5) |
C15—C8—C9—C10 | −130.3 (4) | C12—C13—C16—C15 | 87.1 (5) |
C2—C1—C10—C20 | 62.2 (4) | C6—O1—C19—C4 | −15.9 (4) |
C2—C1—C10—C9 | 179.7 (3) | C3—C4—C19—O1 | 154.3 (3) |
C2—C1—C10—C5 | −60.2 (4) | C5—C4—C19—O1 | 30.1 (4) |
C11—C9—C10—C20 | 174.8 (3) | C18—C4—C19—O1 | −84.4 (4) |
C8—C9—C10—C20 | 48.0 (4) | C7—O2—C20—C10 | 46.5 (5) |
C11—C9—C10—C1 | 53.6 (4) | C1—C10—C20—O2 | 52.5 (5) |
C8—C9—C10—C1 | −73.2 (4) | C9—C10—C20—O2 | −69.3 (4) |
C11—C9—C10—C5 | −65.0 (4) | C5—C10—C20—O2 | 172.1 (3) |
Experimental details
Crystal data | |
Chemical formula | C20H26O5 |
Mr | 346.41 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 295 |
a, b, c (Å) | 7.569 (2), 9.397 (2), 12.310 (3) |
β (°) | 92.62 (2) |
V (Å3) | 874.6 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.42 × 0.34 × 0.14 |
Data collection | |
Diffractometer | Siemens P4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2561, 2291, 1206 |
Rint | 0.023 |
(sin θ/λ)max (Å−1) | 0.666 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.053, 0.128, 0.87 |
No. of reflections | 2291 |
No. of parameters | 228 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.24, −0.18 |
Absolute structure | See text |
Computer programs: XSCANS (Siemens, 1994), XSCANS, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), XP in SHELXTL/PC (Siemens, 1991), SHELXTL97.
C2—C3—C4—C5 | 36.2 (5) | C18—C4—C5—C10 | −156.2 (3) |
C2—C3—C4—C18 | 158.1 (4) | C4—C5—C10—C1 | 45.0 (4) |
C3—C4—C5—C10 | −34.3 (4) |
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Rabdosia lophanthoides is widely distributed in South and Southeast Asia and has long been used as folk medicine in China. Its concoctions are used for the treatment of acute icteric hepatitis, acute cholecystitis, enteritis, laryngopharyngitis, gynopathy and lepromatous leprosy (Wu & Li, 1977). As the natural diterpenoids isolated from plants which belong to rabdosia category usually have the bioactivity of antibiotic and antitumor (Zhu, 1982), in order to isolate bioactive constituents from this plant, we investigated the whole herb of Rabdosia var lophanthoides, which led to the isolation of the title compound, ()I, the natural diterpenoid ludongnin B. The ludongnin B had been previously isolated from Rabdosia rubescens Hara (Sun et al., 1988; Zheng et al., 1986), its structure was established from the IR, 1H NMR and 13C NMR spectral evidence. This is the first time that ludongnin B has been isolated from Rabdosia lophanthoides, and its structure was confirmed by the X-ray.
The title compound, (I), is composed of three six-membered rings and two five-membered rings (Fig. 1). The cyclohexane ring B (C1—C5/C10) exists in a twist chair conformation owing to the cis fusion with ring A. This is also indicated by the smaller torsion angles C2—C3—C4—C5 of 36.2 (5)°, C3—C4—C5—C10 of -34.3 (4)° and C4—C5—C10—C1 of 45.0 (4)°. Ring C (C7—C10/C20/O2) adopts a sofa conformation with the apex at C10, displaced by 0.745 (5) Å from the mean plane of the remaining five atoms, and ring D (C8—C9/C11—C14) adopts a boat conformation. The two five-membered rings, A (C4—C6/O1/C19) and E (C8/C13—C16), adopt envelope conformations, with C4 and C14 displaced by 0.521 (6) and 0.715 (6) Å, respectively, from the mean plane of the remaining four atoms. The C18 methyl group is equatorial to ring B and the associated torsion angles are 158.1 (4) (C2—C3—C4—C18) and -156.2 (3)° (C18—C4—C5—C10). The isobenzofuran ring system couples almost orthogonally to the methanocyclohepta[c] pyran moiety through a spiro-C atom.