Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270199016108/sx1081sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270199016108/sx1081Isup2.hkl |
CCDC reference: 145533
After isolation from the hexane extract of the plant, named following the Muell (Arg) classification system, Jatropha elliptica (Goulart et al.1993), the diastereomeric mixture of jatropholones (0.100 g) was submitted to flash chromatography on a silica-gel (230–400 mesh, Merck) column (internal diameter 2 cm; silica height 31 cm), using a mixture of hexane/ethylacetate (9:1 v/v) as eluent, collecting fractions of 10 ml. The column chromotography was followed by thin-layer chromotography (TLC), on silica-gel 60 F254 plates (layer thickness 0.2 mm, Riedel-deHaën), using the same eluent and two consecutive runs. TLC spots were visualized by UV irradiation and developed by using phosphomolybdic acid solution in ethanol (10%). The less-polar compound (JOH-A) was eluted first and left to crystallize in the same solvent system.
All the H atoms were located on Fourier difference maps. The H-atom positions were fixed and an overall isotropic displacement parameter was refined to U = 0.093 (4) Å2. The absolute stereochemistry could not be determined from refinement of the present data. No reflections related by Friedel symmetry were included in the final refinement, which otherwise included all of the independent intensities measured to θ = 25°.
Data collection: CAD-4 Software (Enraf–Nonius, 1989). Cell refinement: CAD-4 Software. Data reduction: CAD-4 Software. Program(s) used to solve structure: SHELXS86 (Sheldrick, 1990). Program(s) used to refine structure: SHELXL97 (Sheldrick, 1997). Molecular graphics: ZORTEP (Zsolnai, 1995).
Fig. 1. Projection of the title compound, showing the atom labelling with 50% probability displacement ellipsoids for non-H atoms. H atoms are of arbitrary sizes. |
C20H24O2 | Dx = 1.170 Mg m−3 |
Mr = 296.39 | Mo Kα radiation, λ = 0.71073 Å |
Tetragonal, P43212 | Cell parameters from 25 reflections |
a = 13.378 (2) Å | θ = 9.1–25.0° |
c = 18.803 (6) Å | µ = 0.07 mm−1 |
V = 3365.2 (13) Å3 | T = 293 K |
Z = 8 | Irregular, colourless |
F(000) = 1280 | 0.45 × 0.35 × 0.30 mm |
Nonius CAD-4 diffractometer | Rint = 0.030 |
Radiation source: fine-focus sealed tube | θmax = 25.0°, θmin = 1.9° |
Graphite monochromator | h = 0→15 |
ω/2θ scans | k = −15→15 |
6369 measured reflections | l = 0→22 |
2975 independent reflections | 3 standard reflections every 120 min |
2357 reflections with I > 2σ(I) | intensity decay: 0.4% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.057 | H-atom parameters constrained |
wR(F2) = 0.125 | w = 1/[σ2(Fo2) + (0.0773P)2 + 0.0458P] where P = (Fo2 + 2Fc2)/3 |
S = 1.16 | (Δ/σ)max < 0.001 |
2975 reflections | Δρmax = 0.16 e Å−3 |
204 parameters | Δρmin = −0.24 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.021 (2) |
C20H24O2 | Z = 8 |
Mr = 296.39 | Mo Kα radiation |
Tetragonal, P43212 | µ = 0.07 mm−1 |
a = 13.378 (2) Å | T = 293 K |
c = 18.803 (6) Å | 0.45 × 0.35 × 0.30 mm |
V = 3365.2 (13) Å3 |
Nonius CAD-4 diffractometer | Rint = 0.030 |
6369 measured reflections | 3 standard reflections every 120 min |
2975 independent reflections | intensity decay: 0.4% |
2357 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.057 | 0 restraints |
wR(F2) = 0.125 | H-atom parameters constrained |
S = 1.16 | Δρmax = 0.16 e Å−3 |
2975 reflections | Δρmin = −0.24 e Å−3 |
204 parameters |
Experimental. From hexane/ethylacetate (9:1) |
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 | ||
O2 | 0.82925 (14) | 0.91474 (15) | 0.08004 (12) | 0.0521 (5) | |
H2 | 0.8142 | 0.8564 | 0.0881 | 0.078* | |
C6A | 1.0958 (2) | 0.8696 (2) | 0.10962 (15) | 0.0420 (7) | |
C3 | 0.92836 (19) | 0.92812 (19) | 0.09233 (14) | 0.0385 (6) | |
C2 | 0.9625 (2) | 1.02591 (19) | 0.09787 (14) | 0.0409 (6) | |
O1 | 1.23230 (17) | 0.76079 (16) | 0.14012 (14) | 0.0703 (7) | |
C1B | 1.0645 (2) | 1.04524 (19) | 0.10970 (13) | 0.0418 (7) | |
C4 | 0.9749 (2) | 0.73985 (19) | 0.08873 (17) | 0.0475 (7) | |
H4A | 0.9405 | 0.7262 | 0.0444 | 0.057* | |
H4B | 0.9349 | 0.7148 | 0.1279 | 0.057* | |
C3A | 0.9953 (2) | 0.8498 (2) | 0.09700 (15) | 0.0415 (6) | |
C6 | 1.1485 (2) | 0.7734 (2) | 0.11625 (16) | 0.0481 (7) | |
C6B | 1.1330 (2) | 0.96686 (19) | 0.11459 (15) | 0.0445 (7) | |
C12 | 0.8870 (2) | 1.1084 (2) | 0.08889 (18) | 0.0520 (7) | |
H12A | 0.8549 | 1.1019 | 0.0435 | 0.078* | |
H12B | 0.9202 | 1.1720 | 0.0915 | 0.078* | |
H12C | 0.8379 | 1.1041 | 0.1260 | 0.078* | |
C13 | 1.0874 (3) | 0.5935 (2) | 0.1273 (2) | 0.0710 (11) | |
H13A | 1.1542 | 0.5681 | 0.1225 | 0.107* | |
H13B | 1.0411 | 0.5469 | 0.1068 | 0.107* | |
H13C | 1.0722 | 0.6025 | 0.1768 | 0.107* | |
C7 | 1.2421 (2) | 0.9881 (2) | 0.11894 (19) | 0.0544 (8) | |
C5 | 1.0793 (2) | 0.6931 (2) | 0.08902 (17) | 0.0491 (7) | |
H5 | 1.0974 | 0.6810 | 0.0393 | 0.059* | |
C1A | 1.1026 (2) | 1.1505 (2) | 0.11230 (16) | 0.0483 (7) | |
H1A | 1.1137 | 1.1803 | 0.0653 | 0.058* | |
C9A | 1.1788 (3) | 1.1806 (2) | 0.16691 (17) | 0.0608 (8) | |
H9A | 1.2311 | 1.2256 | 0.1492 | 0.073* | |
C10 | 1.0075 (3) | 1.2002 (3) | 0.22984 (19) | 0.0770 (11) | |
H10A | 1.0036 | 1.1289 | 0.2349 | 0.116* | |
H10B | 0.9421 | 1.2265 | 0.2202 | 0.116* | |
H10C | 1.0326 | 1.2289 | 0.2731 | 0.116* | |
C1 | 1.0764 (3) | 1.2257 (2) | 0.16948 (18) | 0.0601 (9) | |
C9 | 1.2135 (3) | 1.1061 (2) | 0.22084 (18) | 0.0691 (10) | |
H9B | 1.1558 | 1.0736 | 0.2419 | 0.083* | |
H9C | 1.2491 | 1.1407 | 0.2584 | 0.083* | |
C14 | 1.2995 (3) | 0.9752 (3) | 0.0630 (2) | 0.0728 (10) | |
H14A | 1.2721 | 0.9529 | 0.0204 | 0.087* | |
H14B | 1.3676 | 0.9886 | 0.0659 | 0.087* | |
C8 | 1.2817 (3) | 1.0270 (3) | 0.18853 (19) | 0.0735 (10) | |
H8A | 1.3476 | 1.0555 | 0.1810 | 0.088* | |
H8B | 1.2886 | 0.9718 | 0.2217 | 0.088* | |
C11 | 1.0670 (4) | 1.3336 (2) | 0.1444 (2) | 0.0843 (13) | |
H11A | 1.0783 | 1.3779 | 0.1838 | 0.126* | |
H11B | 1.0011 | 1.3445 | 0.1258 | 0.126* | |
H11C | 1.1156 | 1.3464 | 0.1080 | 0.126* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O2 | 0.0367 (10) | 0.0377 (10) | 0.0819 (13) | −0.0032 (8) | −0.0063 (10) | 0.0079 (11) |
C6A | 0.0387 (14) | 0.0350 (14) | 0.0523 (16) | −0.0001 (12) | 0.0006 (12) | 0.0040 (12) |
C3 | 0.0318 (14) | 0.0335 (14) | 0.0503 (14) | −0.0002 (10) | −0.0003 (12) | 0.0034 (12) |
C2 | 0.0399 (15) | 0.0349 (14) | 0.0480 (14) | 0.0000 (11) | −0.0005 (12) | 0.0019 (12) |
O1 | 0.0446 (12) | 0.0401 (12) | 0.1262 (19) | 0.0082 (9) | −0.0093 (13) | 0.0114 (13) |
C1B | 0.0475 (16) | 0.0311 (14) | 0.0469 (15) | −0.0031 (12) | −0.0058 (13) | 0.0030 (11) |
C4 | 0.0452 (16) | 0.0317 (14) | 0.0657 (17) | −0.0024 (12) | 0.0030 (14) | −0.0031 (13) |
C3A | 0.0405 (15) | 0.0333 (14) | 0.0506 (15) | −0.0046 (11) | 0.0037 (12) | 0.0013 (12) |
C6 | 0.0390 (16) | 0.0348 (15) | 0.0705 (18) | 0.0025 (12) | 0.0073 (14) | 0.0057 (14) |
C6B | 0.0427 (15) | 0.0342 (14) | 0.0564 (16) | −0.0047 (12) | −0.0058 (13) | 0.0029 (13) |
C12 | 0.0516 (18) | 0.0351 (15) | 0.0693 (19) | 0.0040 (13) | −0.0089 (15) | 0.0024 (13) |
C13 | 0.0525 (18) | 0.0347 (15) | 0.126 (3) | 0.0041 (15) | 0.005 (2) | 0.0088 (19) |
C7 | 0.0391 (16) | 0.0395 (15) | 0.084 (2) | −0.0047 (13) | −0.0106 (16) | 0.0114 (15) |
C5 | 0.0490 (17) | 0.0340 (15) | 0.0642 (17) | 0.0023 (12) | 0.0114 (15) | −0.0025 (13) |
C1A | 0.0516 (17) | 0.0317 (14) | 0.0618 (17) | −0.0080 (12) | −0.0101 (15) | 0.0089 (13) |
C9A | 0.065 (2) | 0.0412 (17) | 0.0763 (19) | −0.0158 (14) | −0.0166 (17) | 0.0069 (15) |
C10 | 0.093 (3) | 0.064 (2) | 0.074 (2) | −0.002 (2) | −0.005 (2) | −0.0128 (18) |
C1 | 0.076 (2) | 0.0317 (15) | 0.0729 (19) | −0.0051 (15) | −0.0181 (18) | −0.0023 (15) |
C9 | 0.082 (2) | 0.0524 (19) | 0.073 (2) | −0.0080 (18) | −0.0313 (19) | 0.0037 (16) |
C14 | 0.0405 (18) | 0.071 (2) | 0.107 (3) | −0.0043 (18) | −0.0009 (19) | 0.008 (2) |
C8 | 0.060 (2) | 0.063 (2) | 0.098 (3) | −0.0035 (18) | −0.028 (2) | 0.013 (2) |
C11 | 0.112 (3) | 0.0332 (17) | 0.108 (3) | −0.0012 (19) | −0.034 (3) | −0.0035 (19) |
O2—C3 | 1.358 (3) | C6—C5 | 1.507 (4) |
C6A—C3A | 1.390 (4) | C6B—C7 | 1.490 (4) |
C6A—C6B | 1.397 (4) | C13—C5 | 1.518 (4) |
C6A—C6 | 1.473 (4) | C7—C14 | 1.314 (5) |
C3—C3A | 1.381 (4) | C7—C8 | 1.505 (5) |
C3—C2 | 1.390 (4) | C1A—C9A | 1.502 (4) |
C2—C1B | 1.406 (4) | C1A—C1 | 1.513 (5) |
C2—C12 | 1.506 (4) | C9A—C9 | 1.496 (4) |
O1—C6 | 1.219 (4) | C9A—C1 | 1.497 (5) |
C1B—C6B | 1.396 (4) | C10—C1 | 1.502 (5) |
C1B—C1A | 1.498 (4) | C1—C11 | 1.524 (4) |
C4—C3A | 1.504 (4) | C9—C8 | 1.523 (5) |
C4—C5 | 1.530 (4) | ||
C3A—C6A—C6B | 122.2 (2) | C6A—C6B—C7 | 122.0 (2) |
C3A—C6A—C6 | 108.2 (2) | C14—C7—C6B | 120.3 (3) |
C6B—C6A—C6 | 129.6 (2) | C14—C7—C8 | 122.4 (3) |
O2—C3—C3A | 123.0 (2) | C6B—C7—C8 | 117.3 (3) |
O2—C3—C2 | 117.2 (2) | C6—C5—C13 | 114.8 (3) |
C3A—C3—C2 | 119.8 (2) | C6—C5—C4 | 105.7 (2) |
C3—C2—C1B | 120.3 (2) | C13—C5—C4 | 115.2 (2) |
C3—C2—C12 | 117.5 (2) | C1B—C1A—C9A | 120.4 (2) |
C1B—C2—C12 | 122.2 (3) | C1B—C1A—C1 | 124.7 (3) |
C6B—C1B—C2 | 120.6 (3) | C9A—C1A—C1 | 59.5 (2) |
C6B—C1B—C1A | 118.7 (2) | C9—C9A—C1 | 122.0 (3) |
C2—C1B—C1A | 120.6 (2) | C9—C9A—C1A | 119.6 (3) |
C3A—C4—C5 | 103.5 (2) | C1—C9A—C1A | 60.6 (2) |
C3—C3A—C6A | 119.6 (2) | C9A—C1—C10 | 119.7 (3) |
C3—C3A—C4 | 128.2 (3) | C9A—C1—C1A | 59.9 (2) |
C6A—C3A—C4 | 112.3 (2) | C10—C1—C1A | 121.9 (3) |
O1—C6—C6A | 126.3 (3) | C9A—C1—C11 | 116.6 (3) |
O1—C6—C5 | 126.2 (3) | C10—C1—C11 | 113.4 (3) |
C6A—C6—C5 | 107.4 (2) | C1A—C1—C11 | 115.4 (3) |
C1B—C6B—C6A | 117.5 (2) | C9A—C9—C8 | 112.3 (3) |
C1B—C6B—C7 | 120.3 (2) | C7—C8—C9 | 112.1 (3) |
Experimental details
Crystal data | |
Chemical formula | C20H24O2 |
Mr | 296.39 |
Crystal system, space group | Tetragonal, P43212 |
Temperature (K) | 293 |
a, c (Å) | 13.378 (2), 18.803 (6) |
V (Å3) | 3365.2 (13) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.07 |
Crystal size (mm) | 0.45 × 0.35 × 0.30 |
Data collection | |
Diffractometer | Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6369, 2975, 2357 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.596 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.057, 0.125, 1.16 |
No. of reflections | 2975 |
No. of parameters | 204 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.16, −0.24 |
O2—C3 | 1.358 (3) | C7—C8 | 1.505 (5) |
C6A—C3A | 1.390 (4) | C1A—C9A | 1.502 (4) |
C6A—C6 | 1.473 (4) | C1A—C1 | 1.513 (5) |
O1—C6 | 1.219 (4) | C9A—C9 | 1.496 (4) |
C1B—C1A | 1.498 (4) | C9A—C1 | 1.497 (5) |
C4—C3A | 1.504 (4) | C10—C1 | 1.502 (5) |
C4—C5 | 1.530 (4) | C1—C11 | 1.524 (4) |
C6—C5 | 1.507 (4) | C9—C8 | 1.523 (5) |
C6B—C7 | 1.490 (4) | ||
C6B—C1B—C1A | 118.7 (2) | C9A—C1A—C1 | 59.5 (2) |
C2—C1B—C1A | 120.6 (2) | C9—C9A—C1 | 122.0 (3) |
C3A—C4—C5 | 103.5 (2) | C9—C9A—C1A | 119.6 (3) |
C6A—C3A—C4 | 112.3 (2) | C1—C9A—C1A | 60.6 (2) |
O1—C6—C6A | 126.3 (3) | C9A—C1—C10 | 119.7 (3) |
C6A—C6—C5 | 107.4 (2) | C9A—C1—C1A | 59.9 (2) |
C1B—C6B—C7 | 120.3 (2) | C10—C1—C1A | 121.9 (3) |
C14—C7—C6B | 120.3 (3) | C9A—C1—C11 | 116.6 (3) |
C14—C7—C8 | 122.4 (3) | C10—C1—C11 | 113.4 (3) |
C6B—C7—C8 | 117.3 (3) | C1A—C1—C11 | 115.4 (3) |
C6—C5—C4 | 105.7 (2) | C9A—C9—C8 | 112.3 (3) |
C1B—C1A—C9A | 120.4 (2) | C7—C8—C9 | 112.1 (3) |
C1B—C1A—C1 | 124.7 (3) |
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Jatropholone (JOH), a natural phorbol-related mixture of diterpenes (JOH-A and JOH-B), was isolated from the hexane extract of Jatropha elliptica (Goulart et al., 1993). Its acetate was previously characterized by X-ray diffraction (Purushothaman et al., 1979). The tetracyclic array, consisting of fused five-, six-, seven- and three-membered rings with two potentially electroactive functionalities, suggests the possibility of interesting chemical transformations. However, apart from the total synthesis (Smith et al., 1986), little chemical information concerning the reactivity has been available. Recently, the diastereomeric mixture was investigated by electroanalysis (De Azevedo et al., 1998) and subjected to electrochemical and chemical reductions. Electrolysis (Hg cathode, DMF/TBAP) and catalytic hydrogenation (H2/PtO2) lead, in both processes, to high chemo- and stereoselectivities (De Azevedo et al., 1998). The phenolic proton and the positioning of the seven- and three-membered rings appear to play a very important role in the process. To understand the selectivities, structural information on the non-derivatized substrate is a fundamental requirement. Jatropholone A (JOH-A), (I), was therefore purified and its three-dimensionl structure determined by crystallographic analysis.
The five-membered ring has an envelope conformation, in which C5 is 0.259 (5) Å out of the plane formed by the remaining four atoms. The Cremer & Pople (1975) ring puckering parameters are q2 = 1.85 (4) Å and ϕ2 = 182 (1)° [Editorial note: PARST gives q2 = 0.167 (3) Å and ϕ2 = 85.0 (10)°]. The dihedral angle between the five-membered ring and six-membered aromatic ring is 5.6 (1)°. Atoms C1A and C7 are nearly coplanar with the aromatic ring, with distances of 0.068 (5) and 0.158 (5) Å, respectively, out of that plane. Atom C14 of the methylene group is located above the average plane of the aromatic ring, whereas atom C1 of the cyclopropane ring is below the plane. The distances of atoms C14 and C1 from this plane are, respectively, 1.308 (6) and -1.016 (6) Å.
The absolute stereochemistry could not be determined from the present data. The coordinates reflect only relative stereochemistry at the chiral centres. The stereochemistry of the H atoms of C1A and C9A, where the cyclopropane ring is fused to the cycloheptane ring, is cis. As measured by the C6A—C6B—C7—C14 torsion angle, the methylene moiety of the cycloheptane ring is twisted out of the plane of the aromatic ring system by 73.1 (1)°. The cyclopropane ring is twisted out of the plane of the aromatic system by 48.8 (2)°. The structure therefore demonstrates that, in the formation of the hydrogenated product JOHH-2, the reaction has occurred on the least sterically hindered side of the molecule.
The molecules are linked by hydrogen bonding: O2···O1i = 2.741 (3), HO2···O1i = 1.96, O2—HO2 = 0.82 Å, O2—HO2···O1i = 159°; symmetry code: (i) = -1/2 + x, 3/2 - y, 1/4 - z]. In addition, the shortest C···O contact may also represent a hydrogen bond: C13···O2ii = 3.335 (4), H13A···O2ii = 2.52 Å, C13A—H13A···O2ii = 143°; symmetry code: (ii) 1/2 + x, 3/2 - y, 1/4 - z.
A ZORTEP (Zsolnai, 1995) illustration of the formula unit is presented in Fig. 1.