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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 64| Part 2| February 2008| Page o529
doi:10.1107/S1600536808002729

Aromaticine, a sesquiterpene lactone from Amblyopappus pusillus

Iván Brito,a* Jorge Bórquez,a Luis Alberto Loyolaa and Matías López-Rodríguezb

aDepartamento de Química, Facultad de Ciencias Básicas, Universidad de Antofagasta, Casilla 170, Antofagasta, Chile, and bInstituto de Bio-Orgánica 'Antonio González', Universidad de La Laguna, Astrofísico Francisco Sánchez No. 2, La Laguna, Tenerife, Spain
*Correspondence e-mail: ivanbritob@yahoo.com

(Received 20 December 2007; accepted 24 January 2008; online 30 January 2008)

Aromaticine (systematic name: 4a,8-dimethyl-3-methyl­ene-3,3a,4,4a,7a,8,9,9a-octa­hydro­azuleno[6,5-b]furan-2,5-dione), C15H18O3, is a natural lactone isolated from Amblyopappus pusillus. The mol­ecular structure and conformation agree with the results of Romo, Joseph-Nathan & Díaz [(1964[Romo, J., Joseph-Nathan, J. & Díaz, F. (1964). Tetrahedron, 20, 79-85.]). Tetra­hedron, 20, 79–85]. The fused-ring system contains a seven-membered ring in a twist-boat conformation and two five-membered rings trans fused in envelope conformations.

Related literature

For related literature, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]); Bórquez (2006[Bórquez, J. (2006). Unpublished results.]); Bernstein et al. (1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]); Cremer & Pople (1975[Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354-1358.]); Rodríguez et al. (1976[Rodríguez, E., Towers, G. H. N. & Mitchell, J. C. (1976). Phytochemistry, 15, 1573-1580.]); Romo et al. (1964[Romo, J., Joseph-Nathan, J. & Díaz, F. (1964). Tetrahedron, 20, 79-85.]).

[Scheme 1]

Experimental

Crystal data

  • C15H18O3

  • Mr = 246.29

  • Orthorhombic, P 21 21 21

  • a = 6.763 (4) Å

  • b = 9.932 (5) Å

  • c = 18.685 (7) Å

  • V = 1255.1 (11) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 295 (2) K

  • 0.40 × 0.10 × 0.08 mm
Data collection

  • Nonius KappaCCD area-detector diffractometer

  • Absorption correction: none

  • 16315 measured reflections

  • 1667 independent reflections

  • 1432 reflections with I > 2σ(I)

  • Rint = 0.051
Refinement

  • R[F2 > 2σ(F2)] = 0.057

  • wR(F2) = 0.148

  • S = 1.20

  • 1667 reflections

  • 167 parameters

  • H-atom parameters constrained

  • Δρmax = 0.24 e Å−3

  • Δρmin = −0.23 e Å−3

Data collection: COLLECT (Nonius, 1998[Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: DENZO-SMN; program(s) used to solve structure: SIR97 (Altomare et al., 1999[Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.]); 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, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808002729/om2203sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808002729/om2203Isup2.hkl

checkCIF report


Comment top

Sesquiterpene lactones are known to have biological activity, and some guaianolides have antitumor and citotoxic activities (Rodríguez et al., 1976). The title compound was isolated from aerial parts of Amblyopappus pusillus (Bórquez, 2006), which was originally isolated from Helenium Aromaticum (Romo et al., 1964).In order to ascertain the structure and secure the assignment of the stereochemistry, an X-ray structure determination was performed. The absolute configuration was not determined. The structure confirms the previously proposed molecular structure and molecular conformation (Romo et al., 1964). The molecule (Fig. 1) involves a seven-membered ring in a twisted- boat conformation. Deviations of atoms in this ring from the plane (Cremer & Pople, 1975) were less than 0.1 Å for atoms C4 and C9 and more than 0.38 Å, for the remaining atoms of the ring. Using the same definition, for the two five-membered rings, the lactone is present in an envelope conformation with C3a in the flap position and a maximun deviation of -0.144 (3) Å for C3a. The other five-membered ring also adopts an envelope conformation, with C4a 0.137 (3) Å out of the plane. The crystal structure consists of discrete molecules. The molecules are linked into chains by one weak intermolecular C—H···O hydrogen bond [H···O =2.65 Å, C···O = 3.552 (4) Å and C—H···O =163°]. Atom C7 acts as a hydrogen bond donor via atom H7 to atom O2 in the molecule at (-x + 1/2,-y + 1, z + 1/2), so generating a C(9) chain running parallel to the [001] direction, (Bernstein, et al., 1995). Bond lengths are within expected ranges (Allen et al., 1987), with average values (Å): O-Csp2 =1.205 (4); Csp2—Csp2 = 1.440 (5); Csp3—Csp2 =1.501 (5) and Csp3—Csp3= 1.516 (4).

Related literature top

For related literature, see: Allen et al. (1987); Bórquez (2006); Bernstein et al. (1995); Cremer & Pople (1975); Rodríguez et al. (1976); Romo et al. (1964).

Experimental top

The whole fresh plants (200 g) was submerged in chloroform at room temperature for 4 hrs. After filtration, the solvent was avaporated to dryness under reduced pressure, yielding 10 g. The chloroform extract was chromatographed on silica gel column using diethyl ether, giving 800 mg of the title compound (m.p 505–527 K). Optical rotation: [α] D20 +20.6. The title compound was identified by comparing the spectroscopic data with the previously published data (Romo et al., 1964). Crystal suitable for X-ray analysis were obtained for recrystallization from diethyl ether at room temperature.

Refinement top

H atoms were located from difference Fourier maps and placed in geometrically idealized positions (C—H = 0.93–0.98 Å), and were constrained to ride on their parents atoms with Uiso (H) = 1.5Ueq(C) for methyl H atoms and 1.2 Ueq(C) for the other H atoms.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. View of the title compound showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level, and H-atom radii are arbitrary.
[Figure 2] Fig. 2. Part of the crystal structure showing the formation of C(9) along [001]. For the sake of clarity, H atoms not involved in hydrogen bonding have been omitted. [Symmetry code: (i) 1/2 - x, 1 - y, 1/2 + z.]
4a,8-dimethyl-3-methylene-3,3a,4,4a,7a,8,9,9a-octahydroazuleno[6,5-b]furan-\ 2,5-dione top
Crystal data top
C15H18O3F(000) = 528
Mr = 246.29Dx = 1.303 Mg m−3
Orthorhombic, P212121Mo Kα radiation, λ = 0.7107 Å
Hall symbol: P 2ac 2abCell parameters from 1595 reflections
a = 6.763 (4) Åθ = 2.3–27.5°
b = 9.932 (5) ŵ = 0.09 mm−1
c = 18.685 (7) ÅT = 295 K
V = 1255.1 (11) Å3Needle, colourless
Z = 40.40 × 0.10 × 0.08 mm
Data collection top
Nonius KappaCCD area-detector
diffractometer		1432 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.051
Graphite monochromatorθmax = 27.5°, θmin = 2.3°
ϕ and ω scans with κ offsetsh = −8→8
16315 measured reflectionsk = −12→12
1667 independent reflectionsl = −22→24
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.057 w = 1/[σ2(Fo2) + (0.0749P)2 + 0.1397P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.148(Δ/σ)max < 0.001
S = 1.20Δρmax = 0.24 e Å−3
1667 reflectionsΔρmin = −0.23 e Å−3
167 parameters
Crystal data top
C15H18O3V = 1255.1 (11) Å3
Mr = 246.29Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 6.763 (4) ŵ = 0.09 mm−1
b = 9.932 (5) ÅT = 295 K
c = 18.685 (7) Å0.40 × 0.10 × 0.08 mm
Data collection top
Nonius KappaCCD area-detector
diffractometer		1432 reflections with I > 2σ(I)
16315 measured reflectionsRint = 0.051
1667 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0570 restraints
wR(F2) = 0.148H-atom parameters constrained
S = 1.20Δρmax = 0.24 e Å−3
1667 reflectionsΔρmin = −0.23 e Å−3
167 parameters
Special details top

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
O10.5372 (3)0.6338 (2)0.19079 (12)0.0407 (6)
O20.5286 (4)0.6343 (3)0.07133 (13)0.0575 (8)
O3−0.2760 (3)0.8586 (3)0.34464 (13)0.0411 (6)
C20.4451 (5)0.6506 (3)0.12748 (18)0.0388 (8)
C30.2351 (5)0.6883 (3)0.14092 (17)0.0352 (8)
C3A0.1973 (4)0.6661 (3)0.21918 (14)0.0266 (7)
H3A0.1470.57420.22480.032 (3)*
C40.0484 (4)0.7610 (3)0.25401 (15)0.0327 (7)
H4A−0.08350.73550.23880.032 (3)*
H4B0.07280.85170.23690.032 (3)*
C4A0.0554 (4)0.7616 (3)0.33662 (15)0.0246 (6)
C5−0.1505 (4)0.7855 (3)0.36921 (16)0.0290 (7)
C6−0.1602 (5)0.7054 (4)0.43487 (17)0.0398 (8)
H6−0.2570.71410.46990.032 (3)*
C7−0.0114 (4)0.6190 (3)0.43729 (17)0.0362 (8)
H70.01050.56020.47520.032 (3)*
C7A0.1190 (4)0.6263 (3)0.37165 (15)0.0270 (7)
H7A0.07290.5550.33940.032 (3)*
C80.3431 (4)0.6025 (3)0.38199 (16)0.0294 (7)
H80.4010.68540.40120.032 (3)*
C90.4455 (5)0.5710 (3)0.31060 (17)0.0335 (7)
H9A0.58680.56660.3190.032 (3)*
H9B0.40320.48240.2950.032 (3)*
C9A0.4083 (4)0.6694 (3)0.25025 (15)0.0301 (7)
H9C0.43910.76080.26650.032 (3)*
C100.3856 (5)0.4889 (4)0.43484 (19)0.0461 (9)
H10A0.32610.40710.41790.045 (4)*
H10B0.33150.51160.48080.045 (4)*
H10C0.52590.47660.43910.045 (4)*
C110.1178 (6)0.7350 (4)0.09104 (18)0.0545 (10)
H11A0.16450.74590.04460.065*
H11B−0.01230.75720.1020.065*
C120.1774 (5)0.8833 (3)0.36430 (17)0.0316 (7)
H12A0.12020.96540.34680.045 (4)*
H12B0.31120.8760.34750.045 (4)*
H12C0.17640.88380.41570.045 (4)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0379 (12)0.0473 (14)0.0370 (13)0.0043 (12)0.0092 (10)−0.0058 (11)
O20.0744 (17)0.0583 (17)0.0399 (14)0.0075 (16)0.0252 (13)0.0018 (13)
O30.0294 (11)0.0432 (14)0.0507 (14)0.0076 (11)0.0000 (11)−0.0008 (12)
C20.0501 (19)0.0310 (18)0.0353 (19)0.0002 (16)0.0102 (15)0.0002 (15)
C30.0500 (19)0.0281 (17)0.0274 (17)0.0009 (15)0.0029 (14)−0.0045 (14)
C3A0.0305 (14)0.0260 (16)0.0233 (15)−0.0010 (13)−0.0010 (11)−0.0018 (13)
C40.0326 (16)0.0393 (18)0.0261 (15)0.0081 (14)−0.0029 (12)0.0022 (14)
C4A0.0240 (13)0.0245 (15)0.0252 (14)0.0024 (12)0.0008 (11)−0.0011 (12)
C50.0255 (14)0.0283 (17)0.0330 (17)−0.0014 (13)−0.0005 (12)−0.0081 (13)
C60.0352 (16)0.054 (2)0.0303 (17)−0.0053 (16)0.0080 (13)0.0012 (16)
C70.0379 (16)0.0404 (19)0.0304 (17)−0.0079 (15)−0.0037 (13)0.0074 (15)
C7A0.0319 (15)0.0249 (16)0.0242 (15)−0.0043 (12)−0.0046 (12)0.0003 (13)
C80.0327 (15)0.0254 (16)0.0300 (16)0.0023 (13)−0.0054 (12)0.0027 (13)
C90.0312 (15)0.0315 (17)0.0378 (18)0.0063 (14)−0.0044 (14)−0.0028 (14)
C9A0.0296 (14)0.0312 (17)0.0295 (16)0.0037 (12)0.0026 (12)−0.0045 (14)
C100.047 (2)0.043 (2)0.048 (2)0.0062 (17)−0.0088 (18)0.0134 (18)
C110.073 (3)0.063 (3)0.0277 (18)0.017 (2)−0.0028 (17)0.0011 (18)
C120.0318 (15)0.0259 (17)0.0369 (18)−0.0006 (13)0.0002 (13)0.0009 (14)
Geometric parameters (Å, º) top
O1—C21.347 (4)C7—C7A1.512 (4)
O1—C9A1.456 (3)C7—H70.93
O2—C21.202 (4)C7A—C81.546 (4)
O3—C51.208 (4)C7A—H7A0.98
C2—C31.490 (5)C8—C101.526 (4)
C3—C111.309 (5)C8—C91.535 (4)
C3—C3A1.501 (4)C8—H80.98
C3A—C41.525 (4)C9—C9A1.513 (4)
C3A—C9A1.541 (4)C9—H9A0.97
C3A—H3A0.98C9—H9B0.97
C4—C4A1.544 (4)C9A—H9C0.98
C4—H4A0.97C10—H10A0.96
C4—H4B0.97C10—H10B0.96
C4A—C51.538 (4)C10—H10C0.96
C4A—C121.552 (4)C11—H11A0.93
C4A—C7A1.555 (4)C11—H11B0.93
C5—C61.463 (5)C12—H12A0.96
C6—C71.323 (5)C12—H12B0.96
C6—H60.93C12—H12C0.96
C2—O1—C9A111.3 (2)C7—C7A—H7A106.1
O2—C2—O1122.2 (3)C8—C7A—H7A106.1
O2—C2—C3128.9 (3)C4A—C7A—H7A106.1
O1—C2—C3108.9 (3)C10—C8—C9109.1 (3)
C11—C3—C2123.2 (3)C10—C8—C7A112.2 (3)
C11—C3—C3A130.0 (3)C9—C8—C7A111.4 (2)
C2—C3—C3A106.8 (3)C10—C8—H8108
C3—C3A—C4115.9 (3)C9—C8—H8108
C3—C3A—C9A101.9 (2)C7A—C8—H8108
C4—C3A—C9A116.0 (2)C9A—C9—C8116.2 (2)
C3—C3A—H3A107.5C9A—C9—H9A108.2
C4—C3A—H3A107.5C8—C9—H9A108.2
C9A—C3A—H3A107.5C9A—C9—H9B108.2
C3A—C4—C4A114.1 (2)C8—C9—H9B108.2
C3A—C4—H4A108.7H9A—C9—H9B107.4
C4A—C4—H4A108.7O1—C9A—C9108.2 (2)
C3A—C4—H4B108.7O1—C9A—C3A105.2 (2)
C4A—C4—H4B108.7C9—C9A—C3A114.9 (3)
H4A—C4—H4B107.6O1—C9A—H9C109.4
C5—C4A—C4111.6 (2)C9—C9A—H9C109.4
C5—C4A—C12103.2 (2)C3A—C9A—H9C109.4
C4—C4A—C12110.6 (2)C8—C10—H10A109.5
C5—C4A—C7A102.5 (2)C8—C10—H10B109.5
C4—C4A—C7A115.2 (2)H10A—C10—H10B109.5
C12—C4A—C7A112.7 (2)C8—C10—H10C109.5
O3—C5—C6127.9 (3)H10A—C10—H10C109.5
O3—C5—C4A125.4 (3)H10B—C10—H10C109.5
C6—C5—C4A106.8 (3)C3—C11—H11A120
C7—C6—C5110.3 (3)C3—C11—H11B120
C7—C6—H6124.8H11A—C11—H11B120
C5—C6—H6124.8C4A—C12—H12A109.5
C6—C7—C7A112.6 (3)C4A—C12—H12B109.5
C6—C7—H7123.7H12A—C12—H12B109.5
C7A—C7—H7123.7C4A—C12—H12C109.5
C7—C7A—C8117.6 (2)H12A—C12—H12C109.5
C7—C7A—C4A102.8 (2)H12B—C12—H12C109.5
C8—C7A—C4A117.1 (2)
C9A—O1—C2—O2175.7 (3)C5—C6—C7—C7A−1.4 (4)
C9A—O1—C2—C3−5.1 (4)C6—C7—C7A—C8145.1 (3)
O2—C2—C3—C11−13.6 (6)C6—C7—C7A—C4A14.8 (3)
O1—C2—C3—C11167.1 (3)C5—C4A—C7A—C7−20.9 (3)
O2—C2—C3—C3A168.1 (4)C4—C4A—C7A—C7−142.3 (3)
O1—C2—C3—C3A−11.1 (4)C12—C4A—C7A—C789.5 (3)
C11—C3—C3A—C4−30.1 (5)C5—C4A—C7A—C8−151.4 (3)
C2—C3—C3A—C4148.0 (3)C4—C4A—C7A—C887.2 (3)
C11—C3—C3A—C9A−157.0 (4)C12—C4A—C7A—C8−41.0 (4)
C2—C3—C3A—C9A21.1 (3)C7—C7A—C8—C1040.3 (4)
C3—C3A—C4—C4A−164.1 (3)C4A—C7A—C8—C10163.6 (3)
C9A—C3A—C4—C4A−44.6 (4)C7—C7A—C8—C9163.0 (3)
C3A—C4—C4A—C5−147.0 (3)C4A—C7A—C8—C9−73.8 (3)
C3A—C4—C4A—C1298.7 (3)C10—C8—C9—C9A176.3 (3)
C3A—C4—C4A—C7A−30.6 (4)C7A—C8—C9—C9A51.9 (4)
C4—C4A—C5—O3−36.1 (4)C2—O1—C9A—C9142.0 (3)
C12—C4A—C5—O382.7 (3)C2—O1—C9A—C3A18.7 (3)
C7A—C4A—C5—O3−160.0 (3)C8—C9—C9A—O1172.3 (2)
C4—C4A—C5—C6144.9 (3)C8—C9—C9A—C3A−70.5 (4)
C12—C4A—C5—C6−96.3 (3)C3—C3A—C9A—O1−23.8 (3)
C7A—C4A—C5—C621.0 (3)C4—C3A—C9A—O1−150.6 (3)
O3—C5—C6—C7168.1 (3)C3—C3A—C9A—C9−142.7 (3)
C4A—C5—C6—C7−13.0 (4)C4—C3A—C9A—C990.5 (3)

Experimental details

Crystal data
Chemical formulaC15H18O3
Mr246.29
Crystal system, space groupOrthorhombic, P212121
Temperature (K)295
a, b, c (Å)6.763 (4), 9.932 (5), 18.685 (7)
V (Å3)1255.1 (11)
Z4
Radiation typeMo Kα
µ (mm−1)0.09
Crystal size (mm)0.40 × 0.10 × 0.08
Data collection
DiffractometerNonius KappaCCD area-detector
diffractometer
Absorption correction–
No. of measured, independent and
observed [I > 2σ(I)] reflections		16315, 1667, 1432
Rint0.051
(sin θ/λ)max (Å−1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.057, 0.148, 1.20
No. of reflections1667
No. of parameters167
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)0.24, −0.23

Computer programs: COLLECT (Nonius, 1998), DENZO-SMN (Otwinowski & Minor, 1997), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003), WinGX (Farrugia, 1999).

 

Acknowledgements

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

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ISSN: 2056-9890
Volume 64| Part 2| February 2008| Page o529
doi:10.1107/S1600536808002729
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