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Acta Cryst. (2010). E66, o2139-o2140    [ doi:10.1107/S160053681002903X ]

3-Oxo-18[alpha]-olean-28,13[beta]-olide

R. C. Santos, R. M. A. Pinto, A. Matos Beja, J. A. R. Salvador and J. A. Paixão

Abstract top

The title terpene, C30H46O3, is a 28,13[beta]-lactone of oleanolic acid prepared with bismuth trifluoromethanesulfonate (OTf), Bi(OTf)3·xH2O. All rings are trans-fused. The X-ray study shows the inversion of the orientation of 18-H in the lactonization reaction. A quantum chemical ab-initio Roothaan Hartree-Fock calculation of the equilibrium geometry of the isolated molecule gives values for bond lengths and valency angles in close agreement with experimental values. The calculation also reproduces the observed molecular conformation, with puckering parameters that agree well with those determined from the crystallographic study.

Comment top

The natural products have been the source of the main anticancer drugs for centuries and represent 50% of drugs used in the clinic in developed countries (Koehn & Carter, 2005). As the largest class of natural products, pentacyclic triterpenoids biosynthesized in plants by squalene cyclization represent a varied class of bioactive natural products (Gershenzon & Dudareva, 2007; Salvador, 2010; Dzubak et al., 2006). Among them oleanolic acid was reported to display several biological effects including anti-inflammatory (Ringbom et al., 1998), anti-viral (Ma et al., 2000), anti-bacterial (Horiuchi et al., 2007) and in particular anti-cancer activities. It has been shown to act at various stages of tumor development, including inhibition of tumourigenesis, inhibition of tumor promotion (Tokuda et al., 1986), induction of tumor cell differentiation and apoptosis (Lee et al., 1994) and inhibition of angiogenesis, invasion tumor cells and metastasis (Sohn et al., 1995). The lactonization reaction of oleanane type triterpenoids, with a C12═C13 double bond, under acid conditions has been reported. This classical transformation involves a 28,13β-lactonization with 18-H inversion of orientation with the formation of an oleanane type γ-lactone (Cheriti et al., 1994). As part of our current interest on the application of bismuth(III) salts to the chemistry of triterpenoids (Salvador et al., 2009), we have recently reported the 28,13β-lactonization of oleanolic acid in CH2Cl2, using bismuth trifluoromethanesulfonate, Bi(OTf)3.xH2O (Salvador et al., 2009). Mindful of the biological and synthetic importance of such molecules, we report in this communication the molecular structure of the 3-oxo-18α-olean-28,13β-olide determined by single-crystal X-ray diffraction, and compare it with that of the free molecule as given by quantum mechanical ab-initio calculation.

The structure of this compound with the corresponding atomic numbering scheme is shown in Fig. 1. This triterpenoid compound is an oleanane type with a 28,13β-lactone. The typical C12═C13 double bond is absent. The inversion of orientation of 18-H in the lactonization reaction was unequivocally demonstrated by this X-ray crystallographic study. Bond lengths and angles are within the range of expected average values. All six-membered rings are fused trans- and have slightly distorted chair conformations, the D-ring being more heavily distorted towards a half-chair conformation due to the strain induced by the lactonization, as shown by the Cremer & Pople, (1975) parameters: [ring A: Q = 0.517 (4)Å, θ = 6.8 (4)° and φ = 341 (4)°; B: Q = 0.570 (3)Å, θ = 11.7 (3)° and φ = 3.9 (17)°; C: Q = 0.573 (3)Å, θ = 12.0 (3)° and φ = 23.8 (14)°; D: Q = 0.646 (3)Å, θ = 20.5 (3)° and φ = 65.3 (9)°; E: Q = 0.522 (4)Å, θ = 12.8 (4)° and φ = 181.5 (17)°].

The lactone ring has an envelope conformation [q2 = 0.457 (3)Å and φ2 = 71.6 (4)° and asymmetry parameters (Duax & Norton, 1975) ΔCs(C18) = ΔCs(C28, O13) = 0.8 (3)°].

Ab-initio Roothaan Hartree–Fock calculations reproduce well the observed bond length and valency angles of the molecule. Also, the calculated conformation of the rings are very close to the experimental values.

There are no strong hydrogen bonds in the crystal structure, due to the lack of strong H-donors. One weak C—H···O intramolecular interaction can be spotted in the molecule, involving atoms C26 and O13.

Related literature top

For general background to the use of natural products as sources of anticancer drugs, see: Koehn & Carter (2005). For the biological activity of oleanolic acid, see: Ringbom et al. (1998); Ma et al. (2000); Tokuda et al. (1986); Horiuchi et al. (2007); Lee et al. (1994); Sohn et al. (1995). For the biosynthesis of pentacyclic triterpenoids, see: Gershenzon & Dudareva (2007); Salvador (2010); Dzubak et al. (2006). For the lactonization reaction of oleanane-type triterpenoids, see: Cheriti et al. (1994). For the synthesis of the title compound, see: Salvador et al. (2009). For related structures, see: Eggleston (1987); Chang et al. (1982); Sutthivaiyakit et al. (2001); Wang et al. (2006). For puckering and asymmetry parameters, see: Cremer & Pople (1975); Duax & Norton (1975). The quantum chemical calculations were performed with the computer program GAMESS (Schmidt et al., 1993).

Experimental top

To a solution of oleanonic acid (91.4 mg, 0.20 mmol) in CH2Cl2 (10 ml), Bi(OTf)3.xH2O (29.1 mg, 0.04 mmol) was added. After 24 h under magnetic stirring at reflux temperature, the reaction was completed as verified by TLC control. The reaction mixture was concentrated under reduced pressure and the resulting residue dissolved in diethyl ether (100 ml). The organic phase was washed with NaHCO3 (10% aq), water, dried with anhydrous Na2SO4, and concentrated under reduced pressure to give the title compound as a white solid (86.8 mg, 95% yield). M.p. with thermal decomposition observed at about 583 K (from acetonitrile/acetone); IR (film) 2958, 1757, 1703, 1447, 1393, 1260 cm-1; 1H NMR (400 MHz; CDCl3; Me4Si) 0.84 (3 H, s), 0.89 (3 H, s), 1.00 (3 H, s), 1.04 (3 H, s), 1.09 (3 H, s), 1.15 (3 H, d, J 1/2), 1.22 (3 H, s), 2.41 (1 H, td, J 15.8, 7.3 and 4.2, 2-Ha), 2.54 (1 H, td, J 15.8, 10.3 and 7.5, 2-Hb); 13C NMR (100 MHz; CDCl3; Me4Si) 16.0, 17.8, 18.7, 19.1, 19.4, 21.1, 23.1, 26.0, 26.5, 26.6, 27.8, 29.9, 31.5, 33.0, 34.1, 34.2, 35.2, 36.2, 36.7, 39.8, 41.3, 43.9, 45.0, 47.3, 47.4, 49.4, 54.9, 89.5, 179.1, 217.6; EI–MS m/z (%): 455 (18) [M+ 1]+, 437 (5), 409 (4), 235 (15), 218 (38), 203 (64), 189 (100), 119 (93).

In order to gain some insight on how the crystal packing of title compound might affect the molecular geometry we have performed a quantum chemical calculation on the equilibrium geometry of the free molecule. These calculations were performed with the computer program GAMESS (Schmidt et al., 1993). A molecular orbital Roothan Hartree–Fock method was used with an extended 6-31 G(d,p) basis set. Tight conditions for convergence of both the self-consistent field cycles and maximum density and energy gradient variations were imposed (10-6 atomic units). The program was run on the Milipeia cluster of UC–LCA (using 16 Opteron cores, 2.2 GHz runing Linux).

Refinement top

All hydrogen atoms were refined as riding on their parent atoms using SHELXL97 defaults: C—H = 0.97Å with Uiso(H) = 1.2Ueq(C) for methylene H; C—H = 0.96Å with Uiso(H) = 1.5Ueq(C) for methyl H; C—H = 0.98Å with Uiso(H) = 1.2Ueq(C) for methine H. The absolute configuration was not determined from the X-ray data, as the molecule lacks any strong anomalous scatterer atom at the Mo Kα wavelength, but was known from the synthetic route. Friedel pairs of reflections (2247 pairs) were merged before refinement.

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. The H atoms are presented as a small spheres of arbitrary radius.
3-Oxo-18α-olean-28,13β-olide top
Crystal data top
C30H46O3Dx = 1.188 Mg m−3
Mr = 454.67Melting point: 583 K
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
a = 6.7789 (3) ÅCell parameters from 4019 reflections
b = 12.3122 (6) Åθ = 3.1–21.5°
c = 15.4524 (7) ŵ = 0.07 mm−1
β = 99.644 (2)°T = 295 K
V = 1271.48 (10) Å3Plate, colourless
Z = 20.45 × 0.17 × 0.04 mm
F(000) = 500
Data collection top
Bruker APEXII CCD area-detector
diffractometer		2536 independent reflections
Radiation source: fine-focus sealed tube1805 reflections with I > 2σ(I)
graphiteRint = 0.057
φ– and ω–scansθmax = 25.8°, θmin = 3.3°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2000)		h = −8→8
Tmin = 0.746, Tmax = 1.0k = −14→15
16467 measured reflectionsl = −18→18
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.042Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.100H-atom parameters constrained
S = 1.08 w = 1/[σ2(Fo2) + (0.0386P)2 + 0.2321P]
where P = (Fo2 + 2Fc2)/3
2536 reflections(Δ/σ)max < 0.001
305 parametersΔρmax = 0.14 e Å−3
1 restraintΔρmin = −0.17 e Å−3
Crystal data top
C30H46O3V = 1271.48 (10) Å3
Mr = 454.67Z = 2
Monoclinic, P21Mo Kα radiation
a = 6.7789 (3) ŵ = 0.07 mm−1
b = 12.3122 (6) ÅT = 295 K
c = 15.4524 (7) Å0.45 × 0.17 × 0.04 mm
β = 99.644 (2)°
Data collection top
Bruker APEXII CCD area-detector
diffractometer		2536 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2000)		1805 reflections with I > 2σ(I)
Tmin = 0.746, Tmax = 1.0Rint = 0.057
16467 measured reflectionsθmax = 25.8°
Refinement top
R[F2 > 2σ(F2)] = 0.042H-atom parameters constrained
wR(F2) = 0.100Δρmax = 0.14 e Å−3
S = 1.08Δρmin = −0.17 e Å−3
2536 reflectionsAbsolute structure: ?
305 parametersFlack parameter: ?
1 restraintRogers parameter: ?
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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
O130.4607 (3)−0.02601 (19)0.48624 (13)0.0397 (6)
O280.7505 (3)0.0179 (3)0.56915 (16)0.0794 (10)
O3−0.5087 (4)−0.0157 (4)0.0038 (2)0.0996 (12)
C1−0.1906 (5)−0.1242 (3)0.1826 (2)0.0491 (9)
H1A−0.2856−0.09180.21540.059*
H1B−0.1540−0.19480.20810.059*
C2−0.2931 (6)−0.1399 (4)0.0868 (2)0.0646 (11)
H2A−0.2056−0.18120.05540.077*
H2B−0.4155−0.18120.08560.077*
C3−0.3412 (5)−0.0339 (4)0.0419 (2)0.0575 (10)
C4−0.1742 (5)0.0484 (3)0.0468 (2)0.0520 (10)
C23−0.0394 (6)0.0166 (5)−0.0194 (2)0.0835 (16)
H23A−0.11230.0244−0.07800.125*
H23B0.0026−0.0575−0.00980.125*
H23C0.07600.0631−0.01200.125*
C24−0.2693 (7)0.1595 (4)0.0201 (3)0.0878 (16)
H24A−0.34450.1550−0.03820.132*
H24B−0.16600.21310.02170.132*
H24C−0.35680.17960.06030.132*
C5−0.0633 (4)0.0555 (3)0.1440 (2)0.0407 (8)
H5−0.16230.08750.17600.049*
C60.1103 (5)0.1352 (3)0.1581 (2)0.0583 (11)
H6A0.07420.20010.12340.070*
H6B0.22570.10270.13870.070*
C70.1632 (5)0.1656 (3)0.2547 (2)0.0542 (10)
H7A0.05140.20470.27170.065*
H7B0.27700.21440.26210.065*
C80.2137 (4)0.0679 (3)0.3170 (2)0.0356 (8)
C260.4243 (4)0.0295 (4)0.3042 (2)0.0578 (11)
H26A0.42970.02500.24260.087*
H26B0.4510−0.04070.33060.087*
H26C0.52290.08040.33150.087*
C90.0551 (4)−0.0227 (2)0.29225 (17)0.0292 (7)
H9−0.06790.00650.30880.035*
C10−0.0033 (4)−0.0528 (3)0.19274 (19)0.0376 (8)
C110.1095 (5)−0.1204 (3)0.3527 (2)0.0406 (8)
H11A0.0099−0.17690.33730.049*
H11B0.2376−0.14910.34350.049*
C120.1212 (4)−0.0914 (2)0.44899 (19)0.0335 (7)
H12A−0.0135−0.07850.46010.040*
H12B0.1738−0.15360.48400.040*
C130.2476 (4)0.0060 (2)0.48011 (18)0.0266 (7)
C140.2075 (4)0.1043 (2)0.4157 (2)0.0317 (7)
C27−0.0006 (4)0.1511 (3)0.4245 (2)0.0460 (9)
H27A−0.09240.09240.42780.069*
H27B−0.04910.19540.37430.069*
H27C0.01080.19430.47680.069*
C150.3649 (5)0.1931 (3)0.4452 (2)0.0546 (10)
H15A0.48790.17410.42460.066*
H15B0.31770.26120.41770.066*
C160.4105 (6)0.2097 (3)0.5445 (2)0.0559 (11)
H16A0.30180.25020.56280.067*
H16B0.53130.25280.55900.067*
C170.4383 (4)0.1023 (3)0.5959 (2)0.0376 (8)
C220.5210 (5)0.1223 (3)0.6926 (2)0.0504 (10)
H22A0.65950.14510.69820.061*
H22B0.44640.18090.71390.061*
C210.5095 (5)0.0229 (3)0.7492 (2)0.0498 (9)
H21A0.54750.04300.81040.060*
H21B0.6049−0.03070.73580.060*
C200.3009 (5)−0.0285 (3)0.7359 (2)0.0436 (8)
C190.2422 (4)−0.0582 (3)0.63857 (18)0.0361 (8)
H19A0.3342−0.11290.62400.043*
H19B0.1093−0.08990.62930.043*
C180.2434 (4)0.0383 (2)0.57641 (18)0.0288 (7)
H180.12920.08600.57970.035*
C290.3103 (7)−0.1316 (4)0.7907 (2)0.0714 (13)
H29A0.1787−0.16220.78600.107*
H29B0.3608−0.11470.85100.107*
H29C0.3975−0.18310.76960.107*
C300.1485 (5)0.0488 (4)0.7642 (2)0.0659 (12)
H30A0.02150.01290.75960.099*
H30B0.13500.11170.72690.099*
H30C0.19290.07070.82390.099*
C280.5721 (4)0.0295 (3)0.5524 (2)0.0458 (9)
C250.1610 (5)−0.1171 (4)0.1569 (2)0.0607 (11)
H25A0.2562−0.06740.13940.091*
H25B0.1014−0.15940.10710.091*
H25C0.2277−0.16450.20180.091*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O130.0281 (10)0.0565 (15)0.0345 (12)0.0119 (10)0.0056 (9)0.0031 (12)
O280.0242 (12)0.156 (3)0.0571 (16)0.0006 (16)0.0051 (10)0.0102 (19)
O30.0579 (16)0.149 (3)0.082 (2)−0.002 (2)−0.0183 (14)0.010 (2)
C10.061 (2)0.047 (2)0.037 (2)−0.0057 (18)0.0020 (16)−0.0074 (18)
C20.067 (2)0.071 (3)0.051 (3)−0.010 (2)−0.0014 (19)−0.013 (2)
C30.052 (2)0.084 (3)0.033 (2)0.006 (2)−0.0018 (16)−0.009 (2)
C40.051 (2)0.070 (3)0.0314 (19)0.007 (2)−0.0031 (15)0.0083 (19)
C230.070 (3)0.152 (5)0.030 (2)0.003 (3)0.0140 (18)0.006 (3)
C240.106 (3)0.093 (4)0.051 (3)0.016 (3)−0.025 (2)0.017 (3)
C50.0375 (16)0.052 (2)0.0326 (18)0.0052 (16)0.0044 (13)0.0061 (16)
C60.064 (2)0.069 (3)0.039 (2)−0.013 (2)0.0010 (17)0.021 (2)
C70.064 (2)0.052 (2)0.043 (2)−0.0184 (19)−0.0026 (17)0.0150 (19)
C80.0326 (15)0.043 (2)0.0314 (18)−0.0024 (14)0.0055 (13)0.0088 (15)
C260.0335 (16)0.100 (3)0.043 (2)0.002 (2)0.0128 (14)0.005 (2)
C90.0298 (14)0.0299 (18)0.0292 (16)0.0054 (13)0.0086 (11)0.0008 (15)
C100.0355 (16)0.046 (2)0.0319 (18)0.0097 (15)0.0074 (12)−0.0008 (16)
C110.0567 (19)0.0298 (18)0.0341 (19)0.0041 (16)0.0036 (14)−0.0011 (15)
C120.0444 (17)0.0251 (17)0.0308 (18)−0.0017 (14)0.0057 (13)0.0006 (14)
C130.0239 (13)0.0277 (17)0.0291 (16)0.0007 (12)0.0072 (11)0.0002 (13)
C140.0334 (15)0.0265 (17)0.0339 (18)−0.0027 (13)0.0021 (12)0.0023 (15)
C270.0503 (19)0.038 (2)0.047 (2)0.0142 (16)−0.0005 (15)−0.0047 (17)
C150.068 (2)0.044 (2)0.047 (2)−0.0272 (19)−0.0070 (17)0.0108 (18)
C160.071 (2)0.041 (2)0.050 (2)−0.0314 (19)−0.0097 (18)0.0028 (19)
C170.0334 (15)0.043 (2)0.0347 (18)−0.0147 (14)0.0018 (13)0.0031 (16)
C220.0487 (19)0.055 (3)0.045 (2)−0.0213 (18)−0.0012 (15)−0.0043 (19)
C210.0466 (18)0.063 (2)0.037 (2)−0.0108 (18)−0.0020 (14)0.000 (2)
C200.0480 (17)0.052 (2)0.0299 (17)−0.0110 (17)0.0046 (13)−0.0015 (18)
C190.0387 (16)0.039 (2)0.0314 (18)−0.0067 (14)0.0076 (12)−0.0006 (15)
C180.0245 (13)0.0292 (18)0.0326 (17)−0.0015 (12)0.0044 (11)−0.0013 (15)
C290.098 (3)0.077 (3)0.035 (2)−0.030 (3)−0.001 (2)0.008 (2)
C300.059 (2)0.094 (3)0.048 (2)−0.010 (2)0.0200 (17)−0.025 (2)
C280.0321 (17)0.070 (3)0.0352 (19)−0.0053 (17)0.0054 (13)0.013 (2)
C250.062 (2)0.081 (3)0.038 (2)0.033 (2)0.0065 (17)−0.006 (2)
Geometric parameters (Å, °) top
O13—C281.351 (4)C11—H11B0.9700
O13—C131.485 (3)C12—C131.505 (4)
O28—C281.202 (3)C12—H12A0.9700
O3—C31.209 (4)C12—H12B0.9700
C1—C101.530 (4)C13—C181.545 (4)
C1—C21.539 (5)C13—C141.562 (4)
C1—H1A0.9700C14—C151.542 (4)
C1—H1B0.9700C14—C271.551 (4)
C2—C31.488 (6)C27—H27A0.9600
C2—H2A0.9700C27—H27B0.9600
C2—H2B0.9700C27—H27C0.9600
C3—C41.512 (5)C15—C161.528 (5)
C4—C231.533 (5)C15—H15A0.9700
C4—C241.538 (6)C15—H15B0.9700
C4—C51.566 (4)C16—C171.537 (5)
C23—H23A0.9600C16—H16A0.9700
C23—H23B0.9600C16—H16B0.9700
C23—H23C0.9600C17—C281.510 (5)
C24—H24A0.9600C17—C181.525 (4)
C24—H24B0.9600C17—C221.526 (4)
C24—H24C0.9600C22—C211.514 (5)
C5—C61.520 (5)C22—H22A0.9700
C5—C101.551 (4)C22—H22B0.9700
C5—H50.9800C21—C201.531 (4)
C6—C71.523 (5)C21—H21A0.9700
C6—H6A0.9700C21—H21B0.9700
C6—H6B0.9700C20—C301.521 (5)
C7—C81.542 (5)C20—C291.522 (5)
C7—H7A0.9700C20—C191.534 (4)
C7—H7B0.9700C19—C181.528 (4)
C8—C261.548 (4)C19—H19A0.9700
C8—C91.552 (4)C19—H19B0.9700
C8—C141.597 (4)C18—H180.9800
C26—H26A0.9600C29—H29A0.9600
C26—H26B0.9600C29—H29B0.9600
C26—H26C0.9600C29—H29C0.9600
C9—C111.530 (4)C30—H30A0.9600
C9—C101.567 (4)C30—H30B0.9600
C9—H90.9800C30—H30C0.9600
C10—C251.544 (4)C25—H25A0.9600
C11—C121.520 (4)C25—H25B0.9600
C11—H11A0.9700C25—H25C0.9600
C28—O13—C13109.2 (2)O13—C13—C12107.7 (2)
C10—C1—C2113.9 (3)O13—C13—C18100.44 (19)
C10—C1—H1A108.8C12—C13—C18114.3 (2)
C2—C1—H1A108.8O13—C13—C14108.1 (2)
C10—C1—H1B108.8C12—C13—C14112.7 (2)
C2—C1—H1B108.8C18—C13—C14112.6 (2)
H1A—C1—H1B107.7C15—C14—C27107.8 (3)
C3—C2—C1111.5 (3)C15—C14—C13108.9 (2)
C3—C2—H2A109.3C27—C14—C13107.2 (2)
C1—C2—H2A109.3C15—C14—C8110.7 (2)
C3—C2—H2B109.3C27—C14—C8111.0 (2)
C1—C2—H2B109.3C13—C14—C8111.2 (2)
H2A—C2—H2B108.0C14—C27—H27A109.5
O3—C3—C2120.3 (4)C14—C27—H27B109.5
O3—C3—C4122.3 (4)H27A—C27—H27B109.5
C2—C3—C4117.4 (3)C14—C27—H27C109.5
C3—C4—C23108.7 (3)H27A—C27—H27C109.5
C3—C4—C24107.8 (3)H27B—C27—H27C109.5
C23—C4—C24108.5 (4)C16—C15—C14113.9 (3)
C3—C4—C5108.7 (3)C16—C15—H15A108.8
C23—C4—C5114.3 (3)C14—C15—H15A108.8
C24—C4—C5108.7 (3)C16—C15—H15B108.8
C4—C23—H23A109.5C14—C15—H15B108.8
C4—C23—H23B109.5H15A—C15—H15B107.7
H23A—C23—H23B109.5C15—C16—C17113.0 (3)
C4—C23—H23C109.5C15—C16—H16A109.0
H23A—C23—H23C109.5C17—C16—H16A109.0
H23B—C23—H23C109.5C15—C16—H16B109.0
C4—C24—H24A109.5C17—C16—H16B109.0
C4—C24—H24B109.5H16A—C16—H16B107.8
H24A—C24—H24B109.5C28—C17—C1899.8 (2)
C4—C24—H24C109.5C28—C17—C22112.5 (3)
H24A—C24—H24C109.5C18—C17—C22116.2 (3)
H24B—C24—H24C109.5C28—C17—C16108.1 (3)
C6—C5—C10110.6 (2)C18—C17—C16108.4 (2)
C6—C5—C4114.1 (3)C22—C17—C16111.1 (3)
C10—C5—C4117.5 (3)C21—C22—C17112.9 (3)
C6—C5—H5104.3C21—C22—H22A109.0
C10—C5—H5104.3C17—C22—H22A109.0
C4—C5—H5104.3C21—C22—H22B109.0
C5—C6—C7110.4 (3)C17—C22—H22B109.0
C5—C6—H6A109.6H22A—C22—H22B107.8
C7—C6—H6A109.6C22—C21—C20113.1 (3)
C5—C6—H6B109.6C22—C21—H21A109.0
C7—C6—H6B109.6C20—C21—H21A109.0
H6A—C6—H6B108.1C22—C21—H21B109.0
C6—C7—C8114.3 (3)C20—C21—H21B109.0
C6—C7—H7A108.7H21A—C21—H21B107.8
C8—C7—H7A108.7C30—C20—C29109.3 (3)
C6—C7—H7B108.7C30—C20—C21111.1 (3)
C8—C7—H7B108.7C29—C20—C21108.5 (3)
H7A—C7—H7B107.6C30—C20—C19110.7 (3)
C7—C8—C26105.8 (3)C29—C20—C19109.0 (3)
C7—C8—C9109.5 (2)C21—C20—C19108.2 (2)
C26—C8—C9111.4 (3)C18—C19—C20113.8 (3)
C7—C8—C14109.8 (3)C18—C19—H19A108.8
C26—C8—C14112.4 (2)C20—C19—H19A108.8
C9—C8—C14108.0 (2)C18—C19—H19B108.8
C8—C26—H26A109.5C20—C19—H19B108.8
C8—C26—H26B109.5H19A—C19—H19B107.7
H26A—C26—H26B109.5C17—C18—C19111.9 (2)
C8—C26—H26C109.5C17—C18—C1399.7 (2)
H26A—C26—H26C109.5C19—C18—C13114.1 (2)
H26B—C26—H26C109.5C17—C18—H18110.2
C11—C9—C8109.2 (2)C19—C18—H18110.2
C11—C9—C10114.1 (2)C13—C18—H18110.2
C8—C9—C10117.6 (2)C20—C29—H29A109.5
C11—C9—H9104.9C20—C29—H29B109.5
C8—C9—H9104.9H29A—C29—H29B109.5
C10—C9—H9104.9C20—C29—H29C109.5
C1—C10—C25107.7 (3)H29A—C29—H29C109.5
C1—C10—C5107.4 (2)H29B—C29—H29C109.5
C25—C10—C5114.4 (3)C20—C30—H30A109.5
C1—C10—C9107.8 (2)C20—C30—H30B109.5
C25—C10—C9113.3 (2)H30A—C30—H30B109.5
C5—C10—C9106.0 (2)C20—C30—H30C109.5
C12—C11—C9112.4 (3)H30A—C30—H30C109.5
C12—C11—H11A109.1H30B—C30—H30C109.5
C9—C11—H11A109.1O28—C28—O13121.1 (3)
C12—C11—H11B109.1O28—C28—C17129.2 (3)
C9—C11—H11B109.1O13—C28—C17109.6 (2)
H11A—C11—H11B107.9C10—C25—H25A109.5
C13—C12—C11115.7 (2)C10—C25—H25B109.5
C13—C12—H12A108.4H25A—C25—H25B109.5
C11—C12—H12A108.4C10—C25—H25C109.5
C13—C12—H12B108.4H25A—C25—H25C109.5
C11—C12—H12B108.4H25B—C25—H25C109.5
H12A—C12—H12B107.4
C10—C1—C2—C3−54.8 (4)O13—C13—C14—C27−168.8 (2)
C1—C2—C3—O3−128.1 (4)C12—C13—C14—C2772.3 (3)
C1—C2—C3—C451.3 (5)C18—C13—C14—C27−58.8 (3)
O3—C3—C4—C23−102.1 (4)O13—C13—C14—C869.8 (3)
C2—C3—C4—C2378.4 (4)C12—C13—C14—C8−49.1 (3)
O3—C3—C4—C2415.4 (5)C18—C13—C14—C8179.8 (2)
C2—C3—C4—C24−164.1 (3)C7—C8—C14—C15−61.7 (3)
O3—C3—C4—C5133.0 (4)C26—C8—C14—C1555.7 (4)
C2—C3—C4—C5−46.5 (4)C9—C8—C14—C15179.0 (3)
C3—C4—C5—C6179.5 (3)C7—C8—C14—C2758.0 (3)
C23—C4—C5—C657.9 (5)C26—C8—C14—C27175.4 (3)
C24—C4—C5—C6−63.5 (4)C9—C8—C14—C27−61.4 (3)
C3—C4—C5—C1047.6 (4)C7—C8—C14—C13177.2 (2)
C23—C4—C5—C10−74.0 (4)C26—C8—C14—C13−65.4 (3)
C24—C4—C5—C10164.6 (3)C9—C8—C14—C1357.8 (3)
C10—C5—C6—C7−63.9 (4)C27—C14—C15—C1674.8 (4)
C4—C5—C6—C7160.9 (3)C13—C14—C15—C16−41.1 (4)
C5—C6—C7—C856.5 (4)C8—C14—C15—C16−163.6 (3)
C6—C7—C8—C2674.0 (4)C14—C15—C16—C1744.9 (4)
C6—C7—C8—C9−46.1 (4)C15—C16—C17—C2845.6 (4)
C6—C7—C8—C14−164.5 (3)C15—C16—C17—C18−61.7 (4)
C7—C8—C9—C11178.4 (3)C15—C16—C17—C22169.5 (3)
C26—C8—C9—C1161.8 (3)C28—C17—C22—C21−70.9 (4)
C14—C8—C9—C11−62.0 (3)C18—C17—C22—C2143.2 (4)
C7—C8—C9—C1046.4 (3)C16—C17—C22—C21167.7 (3)
C26—C8—C9—C10−70.2 (3)C17—C22—C21—C20−51.3 (4)
C14—C8—C9—C10166.0 (2)C22—C21—C20—C30−63.9 (4)
C2—C1—C10—C25−70.1 (4)C22—C21—C20—C29176.0 (3)
C2—C1—C10—C553.6 (4)C22—C21—C20—C1957.8 (4)
C2—C1—C10—C9167.3 (3)C30—C20—C19—C1864.2 (3)
C6—C5—C10—C1174.8 (3)C29—C20—C19—C18−175.6 (3)
C4—C5—C10—C1−51.7 (3)C21—C20—C19—C18−57.7 (3)
C6—C5—C10—C25−65.7 (4)C28—C17—C18—C1978.8 (3)
C4—C5—C10—C2567.8 (4)C22—C17—C18—C19−42.3 (4)
C6—C5—C10—C959.8 (3)C16—C17—C18—C19−168.3 (3)
C4—C5—C10—C9−166.7 (2)C28—C17—C18—C13−42.3 (3)
C11—C9—C10—C162.4 (3)C22—C17—C18—C13−163.4 (3)
C8—C9—C10—C1−167.9 (3)C16—C17—C18—C1370.7 (3)
C11—C9—C10—C25−56.7 (4)C20—C19—C18—C1750.4 (3)
C8—C9—C10—C2573.1 (4)C20—C19—C18—C13162.7 (2)
C11—C9—C10—C5177.1 (2)O13—C13—C18—C1743.2 (3)
C8—C9—C10—C5−53.2 (3)C12—C13—C18—C17158.1 (2)
C8—C9—C11—C1258.6 (3)C14—C13—C18—C17−71.6 (3)
C10—C9—C11—C12−167.6 (2)O13—C13—C18—C19−76.3 (3)
C9—C11—C12—C13−50.4 (3)C12—C13—C18—C1938.7 (3)
C28—O13—C13—C12−147.8 (2)C14—C13—C18—C19169.0 (2)
C28—O13—C13—C18−27.9 (3)C13—O13—C28—O28−179.1 (3)
C28—O13—C13—C1490.2 (3)C13—O13—C28—C170.6 (3)
C11—C12—C13—O13−73.7 (3)C18—C17—C28—O28−153.0 (4)
C11—C12—C13—C18175.6 (2)C22—C17—C28—O28−29.3 (5)
C11—C12—C13—C1445.4 (3)C16—C17—C28—O2893.8 (4)
O13—C13—C14—C15−52.4 (3)C18—C17—C28—O1327.3 (3)
C12—C13—C14—C15−171.3 (3)C22—C17—C28—O13151.1 (3)
C18—C13—C14—C1557.6 (3)C16—C17—C28—O13−85.9 (3)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C26—H26B···O130.962.402.865 (4)109
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C26—H26B···O130.962.402.865 (4)109
Acknowledgements top

This work was supported by the Fundação para a Ciência e Tecnologia. RCS (SFRH/BD/23700/2005) and RMAP (SFRH/BD/18013/2004) thank the FCT for grants. We gratefully acknowledge LCA–UC for the grant of computer time in the Milipeia cluster and Mr Carlos Pereira for help in the analysis of the output of the GAMESS code.

references
References top

Bruker (2006). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.

Chang, H.-M., Chiang, T.-C. & Mak, T. C. W. (1982). Chem. Commun. pp. 1197–1198.

Cheriti, A., Babadjamian, A. & Balansard, G. (1994). J. Nat. Prod. 57, 1160–1163.

Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358.

Duax, W. L. & Norton, D. A. (1975). Atlas of Steroid Structure. New York: Plenum Press.

Dzubak, P., Hajduch, M., Vydra, D., Hustova, A., Kvasnica, M., Biedermann, D., Markova, L., Urban, M. & Sarek, J. (2006). Nat. Prod. Rep. 23, 294–411.

Eggleston, D. S. (1987). Acta Cryst. C43, 1229–1231.

Gershenzon, J. & Dudareva, N. (2007). Nat. Chem. Biol. 3, 408–414.

Horiuchi, K., Shiota, S., Hatano, T., Yoshida, T., Kuroda, T. & Tsuchiya, T. (2007). Biol. Pharm. Bull. 30, 1147–1149.

Koehn, F. E. & Carter, G. T. (2005). Nat. Rev. Drug Discov. 4, 206–220.

Lee, H. Y., Chung, H. Y., Kim, K. H., Lee, J. J. & Kim, K. W. (1994). J. Canc. Res. Clin. Oncol. 120, 513–518.

Ma, C. M., Nakamura, N., Hattori, M., Kakuda, H., Qiao, J. C. & Yu, H. L. (2000). J. Nat. Prod. 63, 238–242.

Ringbom, T., Segura, L., Noreen, Y., Perera, P. & Bohlin, L. (1998). J. Nat. Prod. 61, 1212–1215.

Salvador, J. A. R. (2010). Editor. Pentacyclic Triterpenes as Promising Agents in Cancer. New York: Nova Science Publishers. ISBN: 978-1-60876-973-5.

Salvador, J. A. R., Pinto, R. M. A., Santos, R. C., Le Roux, C., Beja, A. M. & Paixão, J. A. (2009). Org. Biomol. Chem. 7, 508–517.

Schmidt, M. W., Baldrige, K. K., Boatz, J. A., Elbert, S. T., Gordon, M. S., Jensen, J. J., Koseki, S., Matsunaga, N., Nguyen, K. A., Sue, S., Windus, T. L., Dupuis, M. & Montgomery, J. A. (1993). J. Comput. Chem. 14, 1347–1363.

Sheldrick, G. M. (2000). SADABS. University of Göttingen, Germany.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Sohn, K. H., Lee, H. Y., Chung, H. Y., Young, H. S., Yi, S. Y. & Kim, K. W. (1995). Cancer Lett. 94, 213–218.

Spek, A. L. (2009). Acta Cryst. D65, 148–155.

Sutthivaiyakit, S., Thongtan, J., Pisutjaroenpong, S., Jiaranantanont, K. & Kongsaeree, P. (2001). J. Nat. Prod. 64, 569–571.

Tokuda, H., Ohigashi, H., Koshimizu, K. & Ito, Y. (1986). Cancer Lett. 33, 279–285.

Wang, F., Hua, H., Pei, Y., Chen, D. & Jing, Y. (2006). J. Nat. Prod. 64, 807–810.