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Interest in the title structure, C20H24O2, lies in the novel cis ring junction between the three- and seven-membered rings. This stereochemical arrangement causes the methylene moiety and the cycloheptane ring to be twisted out of the plane of the aromatic ring. The cyclopropane ring is also twisted out of the plane of the aromatic system. The molecules are linked by an O-H...O hydrogen bond [O...O 2.741 (3) Å].

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270199016108/sx1081sup1.cif
Contains datablocks (I), default

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270199016108/sx1081Isup2.hkl
Contains datablock I

CCDC reference: 145533

Comment top

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.

Experimental top

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.

Refinement top

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).

Computing details top

Figures top
[Figure 1] 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.
(I) top
Crystal data top
C20H24O2Dx = 1.170 Mg m3
Mr = 296.39Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P43212Cell parameters from 25 reflections
a = 13.378 (2) Åθ = 9.1–25.0°
c = 18.803 (6) ŵ = 0.07 mm1
V = 3365.2 (13) Å3T = 293 K
Z = 8Irregular, colourless
F(000) = 12800.45 × 0.35 × 0.30 mm
Data collection top
Nonius CAD-4
diffractometer
Rint = 0.030
Radiation source: fine-focus sealed tubeθmax = 25.0°, θmin = 1.9°
Graphite monochromatorh = 015
ω/2θ scansk = 1515
6369 measured reflectionsl = 022
2975 independent reflections3 standard reflections every 120 min
2357 reflections with I > 2σ(I) intensity decay: 0.4%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.057H-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 reflectionsΔρmax = 0.16 e Å3
204 parametersΔρmin = 0.24 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.021 (2)
Crystal data top
C20H24O2Z = 8
Mr = 296.39Mo Kα radiation
Tetragonal, P43212µ = 0.07 mm1
a = 13.378 (2) ÅT = 293 K
c = 18.803 (6) Å0.45 × 0.35 × 0.30 mm
V = 3365.2 (13) Å3
Data collection top
Nonius CAD-4
diffractometer
Rint = 0.030
6369 measured reflections3 standard reflections every 120 min
2975 independent reflections intensity decay: 0.4%
2357 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0570 restraints
wR(F2) = 0.125H-atom parameters constrained
S = 1.16Δρmax = 0.16 e Å3
2975 reflectionsΔρmin = 0.24 e Å3
204 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O20.82925 (14)0.91474 (15)0.08004 (12)0.0521 (5)
H20.81420.85640.08810.078*
C6A1.0958 (2)0.8696 (2)0.10962 (15)0.0420 (7)
C30.92836 (19)0.92812 (19)0.09233 (14)0.0385 (6)
C20.9625 (2)1.02591 (19)0.09787 (14)0.0409 (6)
O11.23230 (17)0.76079 (16)0.14012 (14)0.0703 (7)
C1B1.0645 (2)1.04524 (19)0.10970 (13)0.0418 (7)
C40.9749 (2)0.73985 (19)0.08873 (17)0.0475 (7)
H4A0.94050.72620.04440.057*
H4B0.93490.71480.12790.057*
C3A0.9953 (2)0.8498 (2)0.09700 (15)0.0415 (6)
C61.1485 (2)0.7734 (2)0.11625 (16)0.0481 (7)
C6B1.1330 (2)0.96686 (19)0.11459 (15)0.0445 (7)
C120.8870 (2)1.1084 (2)0.08889 (18)0.0520 (7)
H12A0.85491.10190.04350.078*
H12B0.92021.17200.09150.078*
H12C0.83791.10410.12600.078*
C131.0874 (3)0.5935 (2)0.1273 (2)0.0710 (11)
H13A1.15420.56810.12250.107*
H13B1.04110.54690.10680.107*
H13C1.07220.60250.17680.107*
C71.2421 (2)0.9881 (2)0.11894 (19)0.0544 (8)
C51.0793 (2)0.6931 (2)0.08902 (17)0.0491 (7)
H51.09740.68100.03930.059*
C1A1.1026 (2)1.1505 (2)0.11230 (16)0.0483 (7)
H1A1.11371.18030.06530.058*
C9A1.1788 (3)1.1806 (2)0.16691 (17)0.0608 (8)
H9A1.23111.22560.14920.073*
C101.0075 (3)1.2002 (3)0.22984 (19)0.0770 (11)
H10A1.00361.12890.23490.116*
H10B0.94211.22650.22020.116*
H10C1.03261.22890.27310.116*
C11.0764 (3)1.2257 (2)0.16948 (18)0.0601 (9)
C91.2135 (3)1.1061 (2)0.22084 (18)0.0691 (10)
H9B1.15581.07360.24190.083*
H9C1.24911.14070.25840.083*
C141.2995 (3)0.9752 (3)0.0630 (2)0.0728 (10)
H14A1.27210.95290.02040.087*
H14B1.36760.98860.06590.087*
C81.2817 (3)1.0270 (3)0.18853 (19)0.0735 (10)
H8A1.34761.05550.18100.088*
H8B1.28860.97180.22170.088*
C111.0670 (4)1.3336 (2)0.1444 (2)0.0843 (13)
H11A1.07831.37790.18380.126*
H11B1.00111.34450.12580.126*
H11C1.11561.34640.10800.126*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O20.0367 (10)0.0377 (10)0.0819 (13)0.0032 (8)0.0063 (10)0.0079 (11)
C6A0.0387 (14)0.0350 (14)0.0523 (16)0.0001 (12)0.0006 (12)0.0040 (12)
C30.0318 (14)0.0335 (14)0.0503 (14)0.0002 (10)0.0003 (12)0.0034 (12)
C20.0399 (15)0.0349 (14)0.0480 (14)0.0000 (11)0.0005 (12)0.0019 (12)
O10.0446 (12)0.0401 (12)0.1262 (19)0.0082 (9)0.0093 (13)0.0114 (13)
C1B0.0475 (16)0.0311 (14)0.0469 (15)0.0031 (12)0.0058 (13)0.0030 (11)
C40.0452 (16)0.0317 (14)0.0657 (17)0.0024 (12)0.0030 (14)0.0031 (13)
C3A0.0405 (15)0.0333 (14)0.0506 (15)0.0046 (11)0.0037 (12)0.0013 (12)
C60.0390 (16)0.0348 (15)0.0705 (18)0.0025 (12)0.0073 (14)0.0057 (14)
C6B0.0427 (15)0.0342 (14)0.0564 (16)0.0047 (12)0.0058 (13)0.0029 (13)
C120.0516 (18)0.0351 (15)0.0693 (19)0.0040 (13)0.0089 (15)0.0024 (13)
C130.0525 (18)0.0347 (15)0.126 (3)0.0041 (15)0.005 (2)0.0088 (19)
C70.0391 (16)0.0395 (15)0.084 (2)0.0047 (13)0.0106 (16)0.0114 (15)
C50.0490 (17)0.0340 (15)0.0642 (17)0.0023 (12)0.0114 (15)0.0025 (13)
C1A0.0516 (17)0.0317 (14)0.0618 (17)0.0080 (12)0.0101 (15)0.0089 (13)
C9A0.065 (2)0.0412 (17)0.0763 (19)0.0158 (14)0.0166 (17)0.0069 (15)
C100.093 (3)0.064 (2)0.074 (2)0.002 (2)0.005 (2)0.0128 (18)
C10.076 (2)0.0317 (15)0.0729 (19)0.0051 (15)0.0181 (18)0.0023 (15)
C90.082 (2)0.0524 (19)0.073 (2)0.0080 (18)0.0313 (19)0.0037 (16)
C140.0405 (18)0.071 (2)0.107 (3)0.0043 (18)0.0009 (19)0.008 (2)
C80.060 (2)0.063 (2)0.098 (3)0.0035 (18)0.028 (2)0.013 (2)
C110.112 (3)0.0332 (17)0.108 (3)0.0012 (19)0.034 (3)0.0035 (19)
Geometric parameters (Å, º) top
O2—C31.358 (3)C6—C51.507 (4)
C6A—C3A1.390 (4)C6B—C71.490 (4)
C6A—C6B1.397 (4)C13—C51.518 (4)
C6A—C61.473 (4)C7—C141.314 (5)
C3—C3A1.381 (4)C7—C81.505 (5)
C3—C21.390 (4)C1A—C9A1.502 (4)
C2—C1B1.406 (4)C1A—C11.513 (5)
C2—C121.506 (4)C9A—C91.496 (4)
O1—C61.219 (4)C9A—C11.497 (5)
C1B—C6B1.396 (4)C10—C11.502 (5)
C1B—C1A1.498 (4)C1—C111.524 (4)
C4—C3A1.504 (4)C9—C81.523 (5)
C4—C51.530 (4)
C3A—C6A—C6B122.2 (2)C6A—C6B—C7122.0 (2)
C3A—C6A—C6108.2 (2)C14—C7—C6B120.3 (3)
C6B—C6A—C6129.6 (2)C14—C7—C8122.4 (3)
O2—C3—C3A123.0 (2)C6B—C7—C8117.3 (3)
O2—C3—C2117.2 (2)C6—C5—C13114.8 (3)
C3A—C3—C2119.8 (2)C6—C5—C4105.7 (2)
C3—C2—C1B120.3 (2)C13—C5—C4115.2 (2)
C3—C2—C12117.5 (2)C1B—C1A—C9A120.4 (2)
C1B—C2—C12122.2 (3)C1B—C1A—C1124.7 (3)
C6B—C1B—C2120.6 (3)C9A—C1A—C159.5 (2)
C6B—C1B—C1A118.7 (2)C9—C9A—C1122.0 (3)
C2—C1B—C1A120.6 (2)C9—C9A—C1A119.6 (3)
C3A—C4—C5103.5 (2)C1—C9A—C1A60.6 (2)
C3—C3A—C6A119.6 (2)C9A—C1—C10119.7 (3)
C3—C3A—C4128.2 (3)C9A—C1—C1A59.9 (2)
C6A—C3A—C4112.3 (2)C10—C1—C1A121.9 (3)
O1—C6—C6A126.3 (3)C9A—C1—C11116.6 (3)
O1—C6—C5126.2 (3)C10—C1—C11113.4 (3)
C6A—C6—C5107.4 (2)C1A—C1—C11115.4 (3)
C1B—C6B—C6A117.5 (2)C9A—C9—C8112.3 (3)
C1B—C6B—C7120.3 (2)C7—C8—C9112.1 (3)

Experimental details

Crystal data
Chemical formulaC20H24O2
Mr296.39
Crystal system, space groupTetragonal, P43212
Temperature (K)293
a, c (Å)13.378 (2), 18.803 (6)
V3)3365.2 (13)
Z8
Radiation typeMo Kα
µ (mm1)0.07
Crystal size (mm)0.45 × 0.35 × 0.30
Data collection
DiffractometerNonius CAD-4
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
6369, 2975, 2357
Rint0.030
(sin θ/λ)max1)0.596
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.057, 0.125, 1.16
No. of reflections2975
No. of parameters204
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.16, 0.24

Selected geometric parameters (Å, º) top
O2—C31.358 (3)C7—C81.505 (5)
C6A—C3A1.390 (4)C1A—C9A1.502 (4)
C6A—C61.473 (4)C1A—C11.513 (5)
O1—C61.219 (4)C9A—C91.496 (4)
C1B—C1A1.498 (4)C9A—C11.497 (5)
C4—C3A1.504 (4)C10—C11.502 (5)
C4—C51.530 (4)C1—C111.524 (4)
C6—C51.507 (4)C9—C81.523 (5)
C6B—C71.490 (4)
C6B—C1B—C1A118.7 (2)C9A—C1A—C159.5 (2)
C2—C1B—C1A120.6 (2)C9—C9A—C1122.0 (3)
C3A—C4—C5103.5 (2)C9—C9A—C1A119.6 (3)
C6A—C3A—C4112.3 (2)C1—C9A—C1A60.6 (2)
O1—C6—C6A126.3 (3)C9A—C1—C10119.7 (3)
C6A—C6—C5107.4 (2)C9A—C1—C1A59.9 (2)
C1B—C6B—C7120.3 (2)C10—C1—C1A121.9 (3)
C14—C7—C6B120.3 (3)C9A—C1—C11116.6 (3)
C14—C7—C8122.4 (3)C10—C1—C11113.4 (3)
C6B—C7—C8117.3 (3)C1A—C1—C11115.4 (3)
C6—C5—C4105.7 (2)C9A—C9—C8112.3 (3)
C1B—C1A—C9A120.4 (2)C7—C8—C9112.1 (3)
C1B—C1A—C1124.7 (3)
 

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