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Acta Crystallogr Sect E Struct Rep Online. 2010 February 1; 66(Pt 2): o356–o357.
Published online 2010 January 16. doi:  10.1107/S1600536810001169
PMCID: PMC2979771

(1R,3aR,5aS,6S,8aR,8bR,9aS)-1-Hydr­oxy-6-isopropyl-1,3a,5a-trimethyl­perhydro­cyclo­penta­[a]cyclo­propa[i]naphthalen-4-one

Abstract

The title compound (also know as azorellanone), C20H32O2, is built up from three fused carbocycles, one five-membered ring and two six-membered rings. The five membered-ring has an envelope conformation, whereas the six-membered rings have a distorted half-chair and a twist–boat conformation. In the crystal, mol­ecules are linked by O—H(...)O inter­actions into zigzag chains with graph-set notation C(8) along [010]. The absolute configuration was assigned on the basis of earlier chemical studies.

Related literature

For related structures, see: Loyola et al. (1998 [triangle], 2000 [triangle], 2001 [triangle], 2004 [triangle]); Borquez et al. (2007 [triangle]). For the biological properties of diterpenoids with azorellane and mulinane skeletons, see: Chiaramello et al. (2003 [triangle]); Fuentes et al. (2005 [triangle]); Delporte et al. (2003 [triangle]); Morales et al. (2003 [triangle]); Neira et al. (1998 [triangle]). For graph-set notation, see: Bernstein et al. (1995 [triangle]). For a description of the Cambridge Structural Database, see: Allen (2002 [triangle]). For puckering parameters, see: Cremer & Pople (1975 [triangle]).

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Object name is e-66-0o356-scheme1.jpg

Experimental

Crystal data

  • C20H32O2
  • M r = 304.46
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-0o356-efi1.jpg
  • a = 6.0073 (5) Å
  • b = 13.3348 (11) Å
  • c = 11.2743 (8) Å
  • β = 99.271 (6)°
  • V = 891.34 (12) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.07 mm−1
  • T = 173 K
  • 0.37 × 0.36 × 0.36 mm

Data collection

  • Stoe IPDSII two-circle diffractometer
  • 6336 measured reflections
  • 2107 independent reflections
  • 1876 reflections with I > 2σ(I)
  • R int = 0.066

Refinement

  • R[F 2 > 2σ(F 2)] = 0.041
  • wR(F 2) = 0.100
  • S = 1.00
  • 2107 reflections
  • 204 parameters
  • 1 restraint
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.2 e Å−3
  • Δρmin = −0.16 e Å−3

Data collection: X-AREA (Stoe & Cie, 2001 [triangle]); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: XP in SHELXTL-Plus (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXL97.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810001169/fl2288sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810001169/fl2288Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

We thank the Spanish Research Council (CSIC) for providing us with a free-of-charge licence for the CSD system.

supplementary crystallographic information

Comment

Compounds belonging to the Azorella, Laretia y Mulinum genus are recognized as important sources of novel diterpenoids with azorellane and mulinane skeletons (Loyola et al., 1998, 2000; Chiaramello et al., 2003). These metabolites display a wide variety of biological activities, including trichomonicidal, (Loyola et al., 2001), anti-inflammatory and analgesic, (Delporte et al., 2003; Borquez et al., 2007) contraceptive, (Morales et al., 2003) trypanocidal, (Neira et al., 1998) anti-plasmodial (Loyola et al., 2004) and anti-hyperglycemic (Fuentes et al., 2005).

The title compound (Fig. 1) is built up from three fused carbocycles: a six membered ring (A) with a methylene bridge between C9 and C12 with a second six membered ring (B) trans-fused to a five membered ring (C). The five- membered ring has an envelope conformation whereas the six-membered rings have a distorted half-chair (A) and atwist boat conformation (B) respectively [Q2=0.441 (2) Å, [var phi] =112.5 (3)°; QT= 0.518 (2) Å, θ = 48.8 (2)°, [var phi] =272.2 (3)°; QT= 0.677 (2) Å, θ = 97.1 (2)°, [var phi]2 = 131.5 (2)°] (Cremer & Pople, 1975). The cyclopropane ring (C9, C11 and C12) features an almost regular triangle with the C9 and C12 distance being slightly longer than the others. The isopropyl, methyl groups at C3, C8, C13 and cyclopropane ring are β-oriented, whereas the hydroxyl group is α-oriented.

A search of the Cambridge Structural Database (CSD, Version 5.31; Allen, 2002) shows no significant variations of the molecular geometry of (I) and the conformations of two closely related compound, azorellanol (CSD refcode FIHYAW; Loyola, et al., 1998) and 7-deacetylazorellanol (CSD refcode NEMXUY; Loyola, et al., 2001).

In the crystal, the molecules are linked by O—H···O interactions into zigzag chains with graph-set notation C(8) along [010] (Bernstein et al., 1995). Atom O1 at (x, y, z) acts as a hydrogen-bond donor to atom O2 at (-x + 2,y + 1/2,-z + 1), (Table1, Fig. 2). The absolute configuration was assigned on the basis of early chemical studies (Loyola et al., 1998).

Experimental

Azorella yareta Hauman plants were collected in Quebradas de las llaretas in Vallenar, Chile. The dried and finely powdered whole plant (1.5 kg) was extracted with petrol ether at room temperature to give a gum (85 g). The concentrated petrol ether extract was fractionated on a silica gel column with hexane-ethyl acetate mixtures of increasing polarity as elution solvents. The fraction (3.45 g) eluted was further separated and purified by silica gel chromatography to give 155 mg of the title compound (also know as azorellanone). Recrystallization from hexane-ethyl acetate (1:1) at room temperature afforded colourless crystals suitable for X-ray diffraction analysis.

Refinement

In the absence of anomalous scatterers the absolute configuration could not be determined and therefore Friedel pairs were merged. The hydroxyl H atom was refined isotropically. Other H atoms were placed in idealized positions and treated as riding atoms with C—H distances in the range 0.98–1.00 Å and Uiso(H) = 1.2Ueq(C) or 1.5Ueq(Cmethyl).

Figures

Fig. 1.
Molecular structure of the title compound with displacement ellipsoids at the 50% probability level showing atom-labelling scheme.
Fig. 2.
Part of the crystal structure of (I), showing the formation of a C(8) chain along [010]. Hydrogen bond shown as dashed lines.

Crystal data

C20H32O2F(000) = 336
Mr = 304.46Dx = 1.134 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from 6216 reflections
a = 6.0073 (5) Åθ = 3.5–27.8°
b = 13.3348 (11) ŵ = 0.07 mm1
c = 11.2743 (8) ÅT = 173 K
β = 99.271 (6)°Block, colourless
V = 891.34 (12) Å30.37 × 0.36 × 0.36 mm
Z = 2

Data collection

Stoe IPDSII two-circle diffractometerRint = 0.066
graphiteθmax = 27.5°, θmin = 3.4°
ω scansh = −7→7
6336 measured reflectionsk = −17→17
2107 independent reflectionsl = −13→14
1876 reflections with I > 2σ(I)

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.041H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.100w = 1/[σ2(Fo2) + (0.065P)2] where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max < 0.001
2107 reflectionsΔρmax = 0.2 e Å3
204 parametersΔρmin = −0.16 e Å3
1 restraintExtinction correction: SHELXL97 (Sheldrick, 2008)
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.035 (6)

Special details

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)

xyzUiso*/Ueq
O11.0462 (3)0.74056 (12)0.32053 (17)0.0400 (4)
H11.088 (5)0.801 (2)0.369 (3)0.053 (8)*
O20.8592 (3)0.42953 (12)0.55110 (15)0.0470 (5)
C10.8182 (4)0.44374 (16)0.0885 (2)0.0340 (4)
H1A0.95690.47970.07610.041*
H1B0.6880.47270.03440.041*
C20.8394 (3)0.33017 (15)0.06515 (19)0.0313 (4)
H2A0.99120.31440.04670.038*
H2B0.72530.3089−0.00360.038*
C30.8004 (3)0.27562 (15)0.18129 (18)0.0261 (4)
H30.95060.26840.23360.031*
C40.7041 (3)0.16952 (15)0.1557 (2)0.0311 (4)
H40.56640.17510.09310.037*
C50.6621 (3)0.35294 (14)0.24246 (18)0.0246 (4)
C60.6819 (4)0.34028 (15)0.38011 (19)0.0308 (4)
H6A0.53530.31640.39870.037*
H6B0.79560.28780.40680.037*
C70.7475 (3)0.43507 (15)0.45144 (19)0.0302 (4)
C80.6549 (3)0.53588 (15)0.40016 (18)0.0271 (4)
C90.6806 (3)0.54398 (14)0.26617 (18)0.0272 (4)
C100.7838 (3)0.45080 (14)0.21941 (18)0.0254 (4)
H100.9380.44510.26790.03*
C110.5111 (4)0.60649 (17)0.1836 (2)0.0364 (5)
H11A0.46390.58230.10030.044*
H11B0.39160.64090.21920.044*
C120.7496 (4)0.64378 (15)0.2178 (2)0.0340 (5)
H120.84330.63740.15250.041*
C130.8031 (4)0.73557 (15)0.2965 (2)0.0356 (5)
C140.7134 (4)0.72394 (15)0.4149 (2)0.0357 (5)
H14A0.77520.77820.47060.043*
H14B0.54710.73050.40.043*
C150.7781 (3)0.62273 (15)0.47304 (19)0.0307 (4)
H15A0.74020.62210.55530.037*
H15B0.9430.6130.47950.037*
C160.7113 (5)0.83020 (18)0.2302 (3)0.0524 (7)
H16A0.74720.88850.28270.079*
H16B0.54730.82450.20750.079*
H16C0.78030.83840.15770.079*
C170.4059 (4)0.53345 (18)0.4215 (2)0.0370 (5)
H17A0.33060.59590.39210.055*
H17B0.4020.52640.50770.055*
H17C0.32810.47650.37820.055*
C180.8759 (4)0.10463 (17)0.1047 (2)0.0425 (5)
H18A0.91960.13790.03440.064*
H18B0.80870.03920.08090.064*
H18C1.00950.09510.16610.064*
C190.6366 (5)0.11760 (17)0.2651 (2)0.0429 (5)
H19A0.52750.15940.29850.064*
H19B0.77060.10760.32610.064*
H19C0.56820.05250.24110.064*
C200.4160 (3)0.35344 (16)0.1790 (2)0.0338 (4)
H20A0.41190.3610.09220.051*
H20B0.33560.40950.20920.051*
H20C0.34350.29020.19520.051*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0403 (8)0.0284 (7)0.0521 (10)−0.0029 (6)0.0101 (7)−0.0037 (7)
O20.0642 (10)0.0364 (8)0.0347 (9)0.0084 (8)−0.0096 (8)0.0001 (7)
C10.0422 (10)0.0317 (10)0.0303 (11)−0.0025 (8)0.0127 (8)0.0006 (8)
C20.0327 (9)0.0345 (10)0.0287 (10)−0.0030 (7)0.0109 (8)−0.0038 (8)
C30.0235 (8)0.0298 (9)0.0251 (9)0.0000 (7)0.0041 (7)−0.0019 (7)
C40.0317 (10)0.0282 (9)0.0325 (11)−0.0004 (7)0.0028 (8)−0.0044 (8)
C50.0214 (8)0.0275 (8)0.0253 (10)−0.0013 (6)0.0055 (6)−0.0015 (7)
C60.0375 (10)0.0303 (9)0.0261 (10)−0.0009 (8)0.0099 (8)0.0006 (8)
C70.0330 (9)0.0331 (10)0.0257 (10)0.0025 (8)0.0084 (7)0.0008 (8)
C80.0255 (9)0.0299 (9)0.0261 (10)0.0024 (7)0.0048 (7)−0.0035 (7)
C90.0271 (9)0.0286 (9)0.0251 (10)0.0010 (7)0.0020 (7)−0.0001 (7)
C100.0230 (7)0.0274 (8)0.0261 (10)−0.0010 (7)0.0054 (6)0.0006 (7)
C110.0400 (11)0.0332 (10)0.0326 (11)0.0057 (9)−0.0041 (8)0.0012 (8)
C120.0414 (11)0.0271 (9)0.0328 (11)0.0005 (8)0.0041 (9)0.0021 (8)
C130.0393 (11)0.0255 (9)0.0406 (12)0.0021 (8)0.0020 (9)−0.0017 (9)
C140.0347 (10)0.0319 (11)0.0397 (12)0.0048 (8)0.0034 (9)−0.0086 (8)
C150.0312 (9)0.0332 (10)0.0278 (10)0.0008 (8)0.0047 (7)−0.0048 (8)
C160.0708 (17)0.0302 (11)0.0520 (16)0.0069 (11)−0.0024 (13)0.0029 (11)
C170.0303 (10)0.0403 (11)0.0425 (13)0.0010 (8)0.0126 (8)−0.0066 (10)
C180.0462 (12)0.0343 (11)0.0475 (15)0.0059 (9)0.0095 (10)−0.0106 (10)
C190.0560 (14)0.0314 (10)0.0429 (14)−0.0048 (10)0.0130 (11)−0.0010 (10)
C200.0227 (8)0.0373 (10)0.0413 (12)−0.0006 (8)0.0046 (8)−0.0054 (9)

Geometric parameters (Å, °)

O1—C131.443 (3)C10—H101.00
O1—H10.99 (3)C11—C121.507 (3)
O2—C71.215 (3)C11—H11A0.99
C1—C101.525 (3)C11—H11B0.99
C1—C21.546 (3)C12—C131.516 (3)
C1—H1A0.99C12—H121.00
C1—H1B0.99C13—C161.524 (3)
C2—C31.548 (3)C13—C141.525 (4)
C2—H2A0.99C14—C151.523 (3)
C2—H2B0.99C14—H14A0.99
C3—C41.538 (3)C14—H14B0.99
C3—C51.553 (3)C15—H15A0.99
C3—H31.00C15—H15B0.99
C4—C191.525 (3)C16—H16A0.98
C4—C181.529 (3)C16—H16B0.98
C4—H41.00C16—H16C0.98
C5—C201.535 (2)C17—H17A0.98
C5—C101.538 (3)C17—H17B0.98
C5—C61.547 (3)C17—H17C0.98
C6—C71.516 (3)C18—H18A0.98
C6—H6A0.99C18—H18B0.98
C6—H6B0.99C18—H18C0.98
C7—C81.532 (3)C19—H19A0.98
C8—C151.539 (3)C19—H19B0.98
C8—C91.547 (3)C19—H19C0.98
C8—C171.553 (3)C20—H20A0.98
C9—C111.514 (3)C20—H20B0.98
C9—C101.520 (3)C20—H20C0.98
C9—C121.521 (3)
C13—O1—H1107.5 (18)C12—C11—H11A117.7
C10—C1—C2104.67 (16)C9—C11—H11A117.7
C10—C1—H1A110.8C12—C11—H11B117.7
C2—C1—H1A110.8C9—C11—H11B117.7
C10—C1—H1B110.8H11A—C11—H11B114.8
C2—C1—H1B110.8C11—C12—C13121.3 (2)
H1A—C1—H1B108.9C11—C12—C960.01 (14)
C1—C2—C3106.74 (17)C13—C12—C9122.7 (2)
C1—C2—H2A110.4C11—C12—H12114.1
C3—C2—H2A110.4C13—C12—H12114.1
C1—C2—H2B110.4C9—C12—H12114.1
C3—C2—H2B110.4O1—C13—C12105.05 (18)
H2A—C2—H2B108.6O1—C13—C16109.21 (19)
C4—C3—C2112.18 (16)C12—C13—C16110.81 (19)
C4—C3—C5118.79 (15)O1—C13—C14109.27 (18)
C2—C3—C5103.20 (15)C12—C13—C14111.03 (18)
C4—C3—H3107.4C16—C13—C14111.26 (19)
C2—C3—H3107.4C15—C14—C13111.42 (17)
C5—C3—H3107.4C15—C14—H14A109.3
C19—C4—C18109.33 (18)C13—C14—H14A109.3
C19—C4—C3114.03 (18)C15—C14—H14B109.3
C18—C4—C3109.55 (17)C13—C14—H14B109.3
C19—C4—H4107.9H14A—C14—H14B108
C18—C4—H4107.9C14—C15—C8111.71 (16)
C3—C4—H4107.9C14—C15—H15A109.3
C20—C5—C10111.46 (15)C8—C15—H15A109.3
C20—C5—C6112.37 (17)C14—C15—H15B109.3
C10—C5—C6107.48 (15)C8—C15—H15B109.3
C20—C5—C3109.86 (16)H15A—C15—H15B107.9
C10—C5—C3100.68 (14)C13—C16—H16A109.5
C6—C5—C3114.39 (16)C13—C16—H16B109.5
C7—C6—C5114.38 (16)H16A—C16—H16B109.5
C7—C6—H6A108.7C13—C16—H16C109.5
C5—C6—H6A108.7H16A—C16—H16C109.5
C7—C6—H6B108.7H16B—C16—H16C109.5
C5—C6—H6B108.7C8—C17—H17A109.5
H6A—C6—H6B107.6C8—C17—H17B109.5
O2—C7—C6119.85 (18)H17A—C17—H17B109.5
O2—C7—C8121.02 (18)C8—C17—H17C109.5
C6—C7—C8118.94 (17)H17A—C17—H17C109.5
C7—C8—C15110.17 (16)H17B—C17—H17C109.5
C7—C8—C9110.04 (15)C4—C18—H18A109.5
C15—C8—C9110.73 (16)C4—C18—H18B109.5
C7—C8—C17102.90 (17)H18A—C18—H18B109.5
C15—C8—C17108.97 (16)C4—C18—H18C109.5
C9—C8—C17113.75 (17)H18A—C18—H18C109.5
C11—C9—C10120.53 (17)H18B—C18—H18C109.5
C11—C9—C1259.54 (14)C4—C19—H19A109.5
C10—C9—C12116.15 (17)C4—C19—H19B109.5
C11—C9—C8118.43 (17)H19A—C19—H19B109.5
C10—C9—C8113.08 (16)C4—C19—H19C109.5
C12—C9—C8119.15 (17)H19A—C19—H19C109.5
C9—C10—C1120.82 (17)H19B—C19—H19C109.5
C9—C10—C5113.78 (16)C5—C20—H20A109.5
C1—C10—C5104.67 (15)C5—C20—H20B109.5
C9—C10—H10105.4H20A—C20—H20B109.5
C1—C10—H10105.4C5—C20—H20C109.5
C5—C10—H10105.4H20A—C20—H20C109.5
C12—C11—C960.45 (13)H20B—C20—H20C109.5
C10—C1—C2—C33.7 (2)C12—C9—C10—C1−38.2 (2)
C1—C2—C3—C4152.34 (17)C8—C9—C10—C1178.76 (16)
C1—C2—C3—C523.3 (2)C11—C9—C10—C5−95.5 (2)
C2—C3—C4—C19−173.09 (18)C12—C9—C10—C5−164.01 (16)
C5—C3—C4—C19−52.7 (2)C8—C9—C10—C553.0 (2)
C2—C3—C4—C1864.0 (2)C2—C1—C10—C9−159.73 (17)
C5—C3—C4—C18−175.61 (18)C2—C1—C10—C5−29.8 (2)
C4—C3—C5—C20−48.0 (2)C20—C5—C10—C961.6 (2)
C2—C3—C5—C2076.87 (19)C6—C5—C10—C9−62.0 (2)
C4—C3—C5—C10−165.61 (16)C3—C5—C10—C9178.04 (16)
C2—C3—C5—C10−40.77 (17)C20—C5—C10—C1−72.4 (2)
C4—C3—C5—C679.5 (2)C6—C5—C10—C1164.08 (15)
C2—C3—C5—C6−155.67 (15)C3—C5—C10—C144.09 (17)
C20—C5—C6—C7−106.20 (19)C10—C9—C11—C12−104.3 (2)
C10—C5—C6—C716.8 (2)C8—C9—C11—C12108.9 (2)
C3—C5—C6—C7127.63 (17)C9—C11—C12—C13−112.3 (2)
C5—C6—C7—O2−148.2 (2)C10—C9—C12—C11111.6 (2)
C5—C6—C7—C836.7 (3)C8—C9—C12—C11−107.7 (2)
O2—C7—C8—C1516.3 (3)C11—C9—C12—C13110.0 (2)
C6—C7—C8—C15−168.73 (18)C10—C9—C12—C13−138.4 (2)
O2—C7—C8—C9138.6 (2)C8—C9—C12—C132.3 (3)
C6—C7—C8—C9−46.4 (2)C11—C12—C13—O1173.55 (19)
O2—C7—C8—C17−99.8 (2)C9—C12—C13—O1101.3 (2)
C6—C7—C8—C1775.2 (2)C11—C12—C13—C16−68.6 (3)
C7—C8—C9—C11150.51 (18)C9—C12—C13—C16−140.9 (2)
C15—C8—C9—C11−87.4 (2)C11—C12—C13—C1455.5 (3)
C17—C8—C9—C1135.7 (3)C9—C12—C13—C14−16.7 (3)
C7—C8—C9—C101.4 (2)O1—C13—C14—C15−67.2 (2)
C15—C8—C9—C10123.40 (17)C12—C13—C14—C1548.2 (2)
C17—C8—C9—C10−113.48 (19)C16—C13—C14—C15172.11 (18)
C7—C8—C9—C12−140.47 (18)C13—C14—C15—C8−68.4 (2)
C15—C8—C9—C12−18.4 (2)C7—C8—C15—C14172.31 (18)
C17—C8—C9—C12104.7 (2)C9—C8—C15—C1450.3 (2)
C11—C9—C10—C130.3 (3)C17—C8—C15—C14−75.5 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1—H1···O2i0.99 (3)1.93 (3)2.916 (2)172 (3)

Symmetry codes: (i) −x+2, y+1/2, −z+1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FL2288).

References

  • Allen, F. H. (2002). Acta Cryst. B58, 380–388. [PubMed]
  • Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl.34, 1555–1573.
  • Borquez, J., Loyola, L. A., Morales, G., San-Martín, A., Roldan, R., Marquez, N. & Muñoz, E. (2007). Phytother. Res.21, 1082–1086. [PubMed]
  • Chiaramello, A. I., Ardanaz, C. E., García, E. E. & Rossomando, P. C. (2003). Phytochemistry, 63, 883–886. [PubMed]
  • Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc.97, 1354–1358.
  • Delporte, C., Backhouse, N., Salinas, P., San-Martin, A., Borquez, J. & Loyola, A. (2003). Bioorg. Med. Chem.11, 1187–1190. [PubMed]
  • Fuentes, N. L., Sagua, H., Morales, G., Borquez, J., San-Martín, A., Soto, J. & Loyola, L. A. (2005). Phytother. Res.19, 713–716. [PubMed]
  • Loyola, L. A., Borquez, J., Morales, G., Araya, J., González, J., Neira, I., Sagua, H. & San-Martín, A. (2001). Phytochemistry, 56, 177–180. [PubMed]
  • Loyola, L. A., Bórquez, J., Morales, G. & San-Martín, A. (2000). Phytochemistry, 53, 961–963. [PubMed]
  • Loyola, L. A., Borquez, J., Morales, G., San-Martin, A., Darias, J., Flores, N. & Gimenez, A. (2004). Phytochemistry, 65, 1931–1935. [PubMed]
  • Loyola, L. A., Bórquez, J., Morales, G., San Martin, A., Manríquez, V. & Wittke, O. (1998). Tetrahedron, 54, 15533–15540.
  • Morales, P., Kong, M., Pizarro, E., Pasten, C., Morales, G., Borquez, J. & Loyola, L. A. (2003). J. Androl.24, 364–370. [PubMed]
  • Neira, I., Pobleta, L., Porcille, P., Silva, P., Araya, J., Bórquez, J., Morales, G., Loyola, L. A. & Sagua, H. (1998). Bol. Chil. Parasitol 53, 9–13 [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Stoe & Cie (2001). X-AREA Stoe & Cie, Darmstadt, Germany

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