organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

Methyl 2-(8a-hy­dr­oxy-4a-methyl-8-methyl­enedeca­hydro­naphthalen-2-yl)acrylate

abLaboratoire de Chimie Biomoléculaire, Substances Naturelles et Réactivité, URAC 16, Faculté des Sciences Semlalia, BP 2390, Bd My Abdellah, 40000 Marrakech, Morocco, bUniversite Blaise Pascal, Laboratoire des Mate'riaux Inorganiques, UMR CNRS 6002, 24 Avenue des Landais, 63177 Aubie`re, France, and cLaboratoire de Chimie Bioorganique et Analytique, URAC 22, BP 146, FSTM, Université Hassan II, Mohammedia-Casablanca 20810 Mohammedia, Morocco
*Correspondence e-mail: mberraho@yahoo.fr

(Received 12 December 2011; accepted 13 December 2011; online 17 December 2011)

The title compound, C16H24O3, was synthesized from ilicic acid which was isolated from the aerial part of Inula Viscosa­ (L) Aiton [or Dittrichia Viscosa­ (L) Greuter]. The mol­ecule contains two fused six-membered rings both in chair conformations. In the crystal, mol­ecules are linked into chains running parallel to the a axis by O—H⋯O hydrogen bonds.

Related literature

For the synthesis, see: Barrero et al. (2009[Barrero, A. F., Herrador, M. M., Arteaga, J. & Catalań, V. (2009). Eur. J. Org. Chem. pp. 3589-3594.]). For the medicinal and pharmacological properties of Inula Viscosa (L) Aiton [or Dittrichia Viscosa­ (L) Greuter], see: Shtacher & Kasshman (1970[Shtacher, G. & Kasshman, Y. (1970). J. Med. Chem. 13, 1221-1223.]); Bohlmann et al. (1977[Bohlmann, F., Czerson, H. & Schoneweib, S. (1977). Chem. Ber. 110, 1330-1334.]); Chiappini et al. (1982[Chiappini, I., Fardella, G., Menghini, A. & Rossi, C. (1982). Planta Med. 44, 159-161.]); Azoulay et al. (1986[Azoulay, P., Reynier, J. P., Balansard, G., Gasquet, M. & Timon-David, P. (1986). Pharm. Acta Helv. 61, 345-352.]); Bohlmann et al. (1977[Bohlmann, F., Czerson, H. & Schoneweib, S. (1977). Chem. Ber. 110, 1330-1334.]); Ceccherelli et al. (1988[Ceccherelli, P., Curini, M. & Marcotullio, M. C. (1988). J. Nat. Prod. 51, 1006-1009.]). For background to phytochemical studies of plants, see: Geissman & Toribio (1967[Geissman, T. A. & Toribio, F. P. (1967). Phytochemistry, 6, 1563-1567.]). For conformational analysis, see: Cremer & Pople (1975[Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354-1358.]).

[Scheme 1]

Experimental

Crystal data
  • C16H24O3

  • Mr = 264.35

  • Orthorhombic, P 21 21 21

  • a = 6.0666 (5) Å

  • b = 10.0900 (9) Å

  • c = 23.747 (2) Å

  • V = 1453.6 (2) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.08 mm−1

  • T = 296 K

  • 0.65 × 0.45 × 0.26 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • 6831 measured reflections

  • 1745 independent reflections

  • 1202 reflections with I > 2σ(I)

  • Rint = 0.050

Refinement
  • R[F2 > 2σ(F2)] = 0.046

  • wR(F2) = 0.114

  • S = 1.04

  • 1745 reflections

  • 176 parameters

  • H-atom parameters constrained

  • Δρmax = 0.18 e Å−3

  • Δρmin = −0.19 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O1—H1⋯O3i 0.82 2.24 3.033 (4) 161
Symmetry code: (i) [x+{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+2].

Data collection: APEX2 (Bruker, 2005[Bruker, (2005). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2005[Bruker, (2005). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information


Comment top

The Inula Viscosa (L) is widespread in Mediterranean area and extends to the Atlantic cost of Morocco. It is a well known medicinal plant (Shtacher & Kasshman, 1970; Chiappini et al., 1982) and has some pharmacological activities (Azoulay et al., 1986). This plant has been the subject of chemical investigation in terms of isolating sesquiterpene lactones (Bohlmann et al., 1977), sesquiterpene acids (Ceccherelli et al., 1988; Geissman & Toribio, 1967). The ilicic acid is one of the main components of the dichloromethane extract of the Inula Viscosa (L) Aiton or Dittrichia Viscosa (L) Greuter]. The literature report one article on the transformation of the ilicic acid (Barrero et al., 2009). In order to prepare products with high added value, that can be used in the pharmacologycal industry, we have studied the reactivity of this sesquiterpene acid. Thus, from this acid, we have prepared by the method of Barrero et al. (2009), 2-(4a,8-Dimethyl-1, 2,3,4,4 a,5,6,7- octahydro naphthalen-2-yl)-acrylic acid methyl ester. The epoxidation of the latter compound by metachloroperbenzoic acid (mCPBA), followed by the opening of the epoxide obtained by Bi(OTf)3 leads to the title compound (I) with a yield of 50%.

The molecule is built up from two fused six-membered rings. The molecular structure of (Fig. 1) shows the two rings to adopt a perfect chair conformation as indicated by Cremer & Pople (1975) puckering parameters Q(T)= 0.573 (3)Å and spherical polar angle θ = 176.9 (3)° with ϕ = 281 (8)° for the first ring (C1,C6··· C10) and Q(T)= 0.571 (3)Å with a spherical polar angle θ = 173.0 (3)° and ϕ = 144 (3)° for the second ring (C1, C6···C10) (Cremer and Pople,1975). Molecules are linked by intermolecular O—H···O hydrogen bonds (Table 1, Figure 2) to chains running parallel to the a axis.

Related literature top

For the synthesis, see: Barrero et al. (2009). For the medicinal and pharmacological properties of Inula Viscosa (L) Aiton [or Dittrichia Viscosa (L) Greuter], see: Shtacher & Kasshman (1970); Bohlmann et al. (1977); Chiappini et al. (1982); Azoulay et al. (1986); Bohlmann et al. (1977); Ceccherelli et al. (1988). For background to phytochemical studies of plants, see: Geissman & Toribio (1967). For conformational analysis, see: Cremer & Pople (1975).

Experimental top

To 1 g (4 mmol) of 2-(4a,8-Dimethyl-1,2,3,4,4a,5,6,7-octahydro- naphthalen-2-yl)- acrylic acid methyl ester dissolved in 40 ml of dichloromethane was added one equivalent of m-chloroperbenzoic acid at 70%. The reaction mixture was stirred at room temperature for 3 h, then treated three times with a solution of sodium bisulfite at 10%. The organic layer was then washed with distilled water three times until neutralization, dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue obtained was chromatographed on silica gel eluting with hexane/ ethyl acetate (98/2) to give quantitatively the corresponding epoxide. 500 mg (1,89 mmol) of this epoxyde is dissolved with 5% of Para-toluene sulfonic acid (APTS) in 20 ml of dichloromethane. The reaction mixture was left stirring for a period of half an hour and then treated with 10 ml of a solution of sodium bicarbonate to 10%. The organic layer was dried filtered and concentrated under reduced pressure. Chromatography on silica gel, eluting with hexane/ethyl acetate (98/2) of the residue obtained, allowed us to obtain 250 mg (94.5 mmol) of the title compound which was recrystallized in dichloromethane.

Refinement top

All H atoms were fixed geometrically and treated as riding with O—H = 0.82Å, C—H = 0.93 Å(aromatic), 0.96Å (methyl), 0.97 Å (methylene), 0.98Å (methine) with Uiso(H) = 1.2Ueq (Caromatic, Cmethylene, Cmethine) or Uiso(H) = 1.5Ueq (O, Cmethyl). In the absence of significant anomalous scattering, the absolute configuration could not be determined and thus Friedel pairs were merged and any references to the Flack parameter were removed.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. : Molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii.
[Figure 2] Fig. 2. : Partial packing view showing the O–H···O interactions (dashed lines) and the formation of a chain parallel to the a axis. H atoms not involved in hydrogen bonding have been omitted for clarity.
Methyl 2-(8a-hydroxy-4a-methyl-8-methylenedecahydronaphthalen-2-yl)acrylate top
Crystal data top
C16H24O3F(000) = 576
Mr = 264.35Dx = 1.208 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 6881 reflections
a = 6.0666 (5) Åθ = 3.5–26.4°
b = 10.0900 (9) ŵ = 0.08 mm1
c = 23.747 (2) ÅT = 296 K
V = 1453.6 (2) Å3Prism, colourless
Z = 40.65 × 0.45 × 0.26 mm
Data collection top
Bruker APEXII CCD
diffractometer
1202 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.050
Graphite monochromatorθmax = 26.4°, θmin = 3.5°
ϕ and ω scansh = 77
6831 measured reflectionsk = 1112
1745 independent reflectionsl = 2929
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.046H-atom parameters constrained
wR(F2) = 0.114 w = 1/[σ2(Fo2) + (0.056P)2 + 0.0754P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max = 0.001
1745 reflectionsΔρmax = 0.18 e Å3
176 parametersΔρmin = 0.19 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.009 (2)
Crystal data top
C16H24O3V = 1453.6 (2) Å3
Mr = 264.35Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 6.0666 (5) ŵ = 0.08 mm1
b = 10.0900 (9) ÅT = 296 K
c = 23.747 (2) Å0.65 × 0.45 × 0.26 mm
Data collection top
Bruker APEXII CCD
diffractometer
1202 reflections with I > 2σ(I)
6831 measured reflectionsRint = 0.050
1745 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0460 restraints
wR(F2) = 0.114H-atom parameters constrained
S = 1.04Δρmax = 0.18 e Å3
1745 reflectionsΔρmin = 0.19 e Å3
176 parameters
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 > 2σ(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
C10.1942 (5)0.9387 (3)0.90963 (10)0.0356 (7)
H1A0.06010.98830.90260.043*
H1B0.15980.84510.90640.043*
C20.2754 (5)0.9680 (3)0.96934 (11)0.0383 (7)
H20.40890.91530.97560.046*
C30.3401 (6)1.1152 (3)0.97421 (12)0.0471 (8)
H3A0.20931.16970.97020.056*
H3B0.40191.13151.01120.056*
C40.5077 (5)1.1547 (3)0.92942 (12)0.0443 (8)
H4A0.64481.10820.93650.053*
H4B0.53691.24890.93260.053*
C4A0.4312 (5)1.1240 (3)0.86892 (11)0.0347 (7)
C50.6221 (5)1.1502 (3)0.82769 (12)0.0449 (8)
H5A0.66041.24350.82910.054*
H5B0.75001.10000.83970.054*
C60.5660 (6)1.1129 (4)0.76711 (13)0.0538 (9)
H6A0.69671.12220.74390.065*
H6B0.45491.17330.75280.065*
C70.4804 (5)0.9707 (3)0.76277 (12)0.0458 (8)
H7A0.42420.95540.72510.055*
H7B0.60120.90940.76910.055*
C80.3005 (5)0.9442 (3)0.80496 (11)0.0364 (7)
C8A0.3675 (4)0.9758 (3)0.86540 (11)0.0323 (7)
C90.1081 (5)0.9271 (3)1.01354 (12)0.0417 (8)
C100.1797 (6)0.9201 (3)1.07371 (12)0.0438 (8)
C110.4791 (6)0.9357 (4)1.13715 (12)0.0622 (10)
H11A0.43071.01401.15650.093*
H11B0.63730.93371.13640.093*
H11C0.42510.85861.15640.093*
C120.2369 (5)1.2136 (3)0.85384 (14)0.0507 (9)
H12A0.28441.30440.85370.076*
H12B0.12171.20240.88110.076*
H12C0.18241.19040.81720.076*
C130.1041 (5)0.8994 (3)0.79041 (12)0.0480 (8)
H13A0.07230.88290.75270.058*
H13B0.00250.88430.81780.058*
C150.0984 (6)0.8966 (4)1.00336 (14)0.0586 (10)
H15A0.19100.87241.03280.070*
H15B0.15200.89920.96670.070*
O10.5665 (3)0.9020 (2)0.87737 (8)0.0406 (5)
H10.54250.82250.87340.061*
O20.3955 (4)0.9371 (2)1.08027 (8)0.0514 (6)
O30.0589 (4)0.8972 (3)1.11270 (9)0.0684 (8)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0353 (17)0.0361 (17)0.0354 (15)0.0003 (14)0.0008 (12)0.0014 (14)
C20.0363 (17)0.0434 (19)0.0352 (15)0.0013 (15)0.0007 (12)0.0009 (14)
C30.056 (2)0.047 (2)0.0380 (15)0.0083 (17)0.0031 (15)0.0083 (15)
C40.049 (2)0.0409 (18)0.0430 (17)0.0123 (16)0.0021 (15)0.0041 (14)
C4A0.0386 (17)0.0309 (16)0.0344 (13)0.0028 (13)0.0020 (13)0.0018 (12)
C50.046 (2)0.0416 (19)0.0469 (17)0.0073 (16)0.0046 (15)0.0040 (15)
C60.060 (2)0.057 (2)0.0444 (16)0.0056 (19)0.0084 (17)0.0056 (17)
C70.055 (2)0.051 (2)0.0320 (14)0.0024 (17)0.0040 (14)0.0020 (15)
C80.0417 (18)0.0327 (17)0.0348 (14)0.0041 (15)0.0043 (13)0.0010 (14)
C8A0.0308 (17)0.0316 (16)0.0347 (14)0.0022 (12)0.0012 (12)0.0023 (13)
C90.0396 (19)0.047 (2)0.0387 (14)0.0005 (16)0.0036 (13)0.0008 (15)
C100.047 (2)0.046 (2)0.0386 (16)0.0012 (16)0.0038 (15)0.0002 (15)
C110.062 (2)0.086 (3)0.0396 (16)0.001 (2)0.0049 (15)0.0004 (18)
C120.055 (2)0.0378 (19)0.059 (2)0.0032 (16)0.0014 (16)0.0036 (17)
C130.049 (2)0.056 (2)0.0389 (15)0.0014 (18)0.0085 (14)0.0026 (16)
C150.044 (2)0.080 (3)0.0513 (19)0.008 (2)0.0048 (16)0.0058 (19)
O10.0377 (12)0.0393 (12)0.0447 (11)0.0068 (10)0.0038 (9)0.0005 (11)
O20.0436 (14)0.0750 (17)0.0354 (10)0.0031 (13)0.0001 (9)0.0007 (12)
O30.0595 (16)0.103 (2)0.0431 (12)0.0137 (16)0.0125 (11)0.0082 (13)
Geometric parameters (Å, º) top
C1—C21.530 (4)C7—C81.506 (4)
C1—C8A1.533 (4)C7—H7A0.9700
C1—H1A0.9700C7—H7B0.9700
C1—H1B0.9700C8—C131.320 (4)
C2—C91.518 (4)C8—C8A1.525 (4)
C2—C31.541 (4)C8A—O11.446 (3)
C2—H20.9800C9—C151.312 (5)
C3—C41.524 (4)C9—C101.495 (4)
C3—H3A0.9700C10—O31.203 (4)
C3—H3B0.9700C10—O21.330 (4)
C4—C4A1.541 (4)C11—O21.443 (3)
C4—H4A0.9700C11—H11A0.9600
C4—H4B0.9700C11—H11B0.9600
C4A—C121.528 (4)C11—H11C0.9600
C4A—C51.539 (4)C12—H12A0.9600
C4A—C8A1.547 (4)C12—H12B0.9600
C5—C61.526 (4)C12—H12C0.9600
C5—H5A0.9700C13—H13A0.9300
C5—H5B0.9700C13—H13B0.9300
C6—C71.530 (5)C15—H15A0.9300
C6—H6A0.9700C15—H15B0.9300
C6—H6B0.9700O1—H10.8200
C2—C1—C8A111.5 (2)C8—C7—C6111.6 (3)
C2—C1—H1A109.3C8—C7—H7A109.3
C8A—C1—H1A109.3C6—C7—H7A109.3
C2—C1—H1B109.3C8—C7—H7B109.3
C8A—C1—H1B109.3C6—C7—H7B109.3
H1A—C1—H1B108.0H7A—C7—H7B108.0
C9—C2—C1111.9 (2)C13—C8—C7122.7 (3)
C9—C2—C3112.4 (2)C13—C8—C8A124.0 (3)
C1—C2—C3109.8 (2)C7—C8—C8A113.3 (2)
C9—C2—H2107.5O1—C8A—C8107.5 (2)
C1—C2—H2107.5O1—C8A—C1108.2 (2)
C3—C2—H2107.5C8—C8A—C1114.2 (2)
C4—C3—C2111.7 (2)O1—C8A—C4A106.2 (2)
C4—C3—H3A109.3C8—C8A—C4A108.6 (2)
C2—C3—H3A109.3C1—C8A—C4A111.7 (2)
C4—C3—H3B109.3C15—C9—C10116.3 (3)
C2—C3—H3B109.3C15—C9—C2125.1 (3)
H3A—C3—H3B107.9C10—C9—C2118.7 (3)
C3—C4—C4A113.4 (3)O3—C10—O2122.3 (3)
C3—C4—H4A108.9O3—C10—C9124.6 (3)
C4A—C4—H4A108.9O2—C10—C9113.1 (3)
C3—C4—H4B108.9O2—C11—H11A109.5
C4A—C4—H4B108.9O2—C11—H11B109.5
H4A—C4—H4B107.7H11A—C11—H11B109.5
C12—C4A—C5109.2 (2)O2—C11—H11C109.5
C12—C4A—C4109.4 (2)H11A—C11—H11C109.5
C5—C4A—C4109.4 (2)H11B—C11—H11C109.5
C12—C4A—C8A111.5 (2)C4A—C12—H12A109.5
C5—C4A—C8A108.6 (2)C4A—C12—H12B109.5
C4—C4A—C8A108.6 (2)H12A—C12—H12B109.5
C6—C5—C4A112.9 (3)C4A—C12—H12C109.5
C6—C5—H5A109.0H12A—C12—H12C109.5
C4A—C5—H5A109.0H12B—C12—H12C109.5
C6—C5—H5B109.0C8—C13—H13A120.0
C4A—C5—H5B109.0C8—C13—H13B120.0
H5A—C5—H5B107.8H13A—C13—H13B120.0
C5—C6—C7111.8 (3)C9—C15—H15A120.0
C5—C6—H6A109.3C9—C15—H15B120.0
C7—C6—H6A109.3H15A—C15—H15B120.0
C5—C6—H6B109.3C8A—O1—H1109.5
C7—C6—H6B109.3C10—O2—C11117.1 (2)
H6A—C6—H6B107.9
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O3i0.822.243.033 (4)161
Symmetry code: (i) x+1/2, y+3/2, z+2.

Experimental details

Crystal data
Chemical formulaC16H24O3
Mr264.35
Crystal system, space groupOrthorhombic, P212121
Temperature (K)296
a, b, c (Å)6.0666 (5), 10.0900 (9), 23.747 (2)
V3)1453.6 (2)
Z4
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.65 × 0.45 × 0.26
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
6831, 1745, 1202
Rint0.050
(sin θ/λ)max1)0.625
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.114, 1.04
No. of reflections1745
No. of parameters176
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.18, 0.19

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O3i0.822.243.033 (4)161
Symmetry code: (i) x+1/2, y+3/2, z+2.
 

Acknowledgements

We thank Professor Daniel Avignant for the data collection.

References

First citationAzoulay, P., Reynier, J. P., Balansard, G., Gasquet, M. & Timon-David, P. (1986). Pharm. Acta Helv. 61, 345–352.  CAS PubMed Web of Science
First citationBarrero, A. F., Herrador, M. M., Arteaga, J. & Catalań, V. (2009). Eur. J. Org. Chem. pp. 3589–3594.  Web of Science CrossRef
First citationBohlmann, F., Czerson, H. & Schoneweib, S. (1977). Chem. Ber. 110, 1330–1334.  CrossRef CAS Web of Science
First citationBruker, (2005). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationCeccherelli, P., Curini, M. & Marcotullio, M. C. (1988). J. Nat. Prod. 51, 1006–1009.  CrossRef CAS PubMed Web of Science
First citationChiappini, I., Fardella, G., Menghini, A. & Rossi, C. (1982). Planta Med. 44, 159–161.  CrossRef PubMed CAS Web of Science
First citationCremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358.  CrossRef CAS Web of Science
First citationFarrugia, L. J. (1997). J. Appl. Cryst. 30, 565.  CrossRef IUCr Journals
First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals
First citationGeissman, T. A. & Toribio, F. P. (1967). Phytochemistry, 6, 1563–1567.  CrossRef CAS Web of Science
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationShtacher, G. & Kasshman, Y. (1970). J. Med. Chem. 13, 1221–1223.  CrossRef CAS PubMed Web of Science
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals

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