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Acta Cryst. (2010). E66, o1366    [ doi:10.1107/S1600536810017502 ]

Alternariol

D. Siegel, S. Troyanov, J. Noack, F. Emmerling and I. Nehls

Abstract top

In the title compound (systematic name: 3,7,9-trihydroxy-1-methyl-6H-benzo[c]chromen-6-one), C14H10O5, the methyl group is shifted out of the molecular plane due to a steric collision, thus causing a slight twist of the benzene rings. The molecular structure is stabilized by an intramolecular O-H...O hydrogen bond, generating an S(6) ring. In the crystal, molecules are connected by intermolecular O-H...O hydrogen bonds into a three-dimensional network.

Comment top

Alternariol is a cytotoxic, fetotoxic, teratogenic (Weidenbörner, 2001), mutagenic (Brugger et al., 2006, Wollenhaupt et al., 2008) and genotoxic (Fehr et al., 2009) mycotoxin produced by ubiquitous Alternaria fungi. It naturally occurs on fruits, vegetables and cereals like apples, tomatoes or wheat (Weidenbörner, 2001) and has also been obtained by total synthesis (Koch et al., 2005). The molecular structure of the title compound and the atom-labeling scheme are shown in Fig. 1. It is noteworthy that the benzene rings are not fully coplanar. This phenomenon is not observed for the benzo[c]chromen-6-one analogue 2-chloro-7-hydroxy-8-methyl-6H-benzo[c]chromen-6-one (Appel et al., 2006). Hence, the lacking planarity of the alternariol molecule may be attributed to a steric effect caused by the proximity of the H6A hydrogen to the C14 methyl group, which is not present in the planar analogue. This explanation is corroborated by the fact that the C8—C13—C14 angle is increased to 124.93 (17)°. The absolute configuration cannot be derived confidently since the molecule is a weak anomalous scatterer, which is documented by a large s.u. value for the Flack X parameter. Besides the intramolecular hydrogen bonds between O3—H3 and O2 (see dashed blue bonds in fig. 2), each molecule is connected to four adjacent molecules via intermolecular hydrogen bonds (see dashed green bonds in fig. 2). As a result undulated layers in the the ac plane are formed.

Related literature top

For information on alternariol, see: Weidenbörner (2001); Brugger et al. (2006); Wollenhaupt et al. (2008); Fehr et al. (2009). For the total synthesis of alternariol, see: Koch et al. (2005). For a comparable structure, (2-chloro-7-hydroxy-8-methyl-6H-benzo[c]chromen-6-one), see: Appel et al. (2006).

Experimental top

Alternariol was supplied by the workgroup of Prof. R. Faust (University of Kassel, Germany) by total synthesis according to a literature procedure (Koch et al., 2005). Alternariol crystals were grown by sublimation in argon atmosphere. To do so, 100 mg of crude alternariol were heated to 380 °C for 2.5 h under a slow argon flow (atmospheric pressure). After cooling to room temperature, colourless needles could be collected from the water cooled compartment of the reaction vessel.

Refinement top

In the absence of anomalous scatterers, the absolute structure cannot be determined therefore Friedel pairs were merged prior to refinement. The hydrogen atoms were located in difference maps and refined with Uiso(H) set to 1.2 Ueq of the parent atom (1.5 for methyl groups).

Computing details top

Data collection: X-AREA (Stoe & Cie, 2006); cell refinement: X-AREA (Stoe & Cie, 2006); data reduction: X-AREA (Stoe & Cie, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2010) and ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. : ORTEP representation of the title compound with atomic labeling shown with 30% probability displacement ellipsoids.
[Figure 2] Fig. 2. : View of the unit cell of the title compound along [010], showing the hydrogen-bonded layers.
3,7,9-trihydroxy-1-methyl-6H-benzo[c]chromen-6-one top
Crystal data top
C14H10O5F(000) = 536
Mr = 258.22Dx = 1.594 Mg m−3
Orthorhombic, Pca21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2acCell parameters from 1894 reflections
a = 18.969 (3) Åθ = 5–26°
b = 3.7244 (6) ŵ = 0.12 mm−1
c = 15.235 (3) ÅT = 150 K
V = 1076.3 (3) Å3Needle, colourless
Z = 40.40 × 0.10 × 0.02 mm
Data collection top
Stoe IPDS
diffractometer		1053 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.067
graphiteθmax = 28.1°, θmin = 2.5°
rotation method scansh = −24→22
6072 measured reflectionsk = −4→4
1338 independent reflectionsl = −20→20
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)] = 0.035Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.069H atoms treated by a mixture of independent and constrained refinement
S = 0.99 w = 1/[σ2(Fo2) + (0.0314P)2]
where P = (Fo2 + 2Fc2)/3
1338 reflections(Δ/σ)max < 0.001
191 parametersΔρmax = 0.16 e Å−3
1 restraintΔρmin = −0.23 e Å−3
Crystal data top
C14H10O5V = 1076.3 (3) Å3
Mr = 258.22Z = 4
Orthorhombic, Pca21Mo Kα radiation
a = 18.969 (3) ŵ = 0.12 mm−1
b = 3.7244 (6) ÅT = 150 K
c = 15.235 (3) Å0.40 × 0.10 × 0.02 mm
Data collection top
Stoe IPDS
diffractometer		1053 reflections with I > 2σ(I)
6072 measured reflectionsRint = 0.067
1338 independent reflectionsθmax = 28.1°
Refinement top
R[F2 > 2σ(F2)] = 0.035H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.069Δρmax = 0.16 e Å−3
S = 0.99Δρmin = −0.23 e Å−3
1338 reflectionsAbsolute structure: ?
191 parametersFlack parameter: ?
1 restraintRogers parameter: ?
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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
O10.54295 (9)0.3728 (6)0.78417 (11)0.0213 (4)
O20.44464 (9)0.1215 (6)0.74006 (11)0.0272 (5)
O30.42666 (9)−0.0612 (6)0.57652 (13)0.0277 (5)
H30.4192 (17)−0.038 (10)0.632 (2)0.033*
O40.61983 (10)0.1209 (7)0.38531 (11)0.0275 (5)
H40.5946 (18)0.002 (10)0.344 (2)0.033*
O50.74389 (10)0.8553 (6)0.91670 (10)0.0260 (5)
H50.78430.93070.90380.031*
C10.50516 (13)0.2203 (8)0.71956 (16)0.0193 (6)
C20.53589 (13)0.1856 (8)0.63425 (15)0.0167 (6)
C30.49365 (13)0.0493 (8)0.56447 (16)0.0192 (6)
C40.52045 (14)0.0246 (8)0.48049 (17)0.0194 (6)
H4A0.4917 (15)−0.072 (8)0.4295 (19)0.023*
C50.58935 (13)0.1357 (9)0.46651 (15)0.0183 (6)
C60.63205 (15)0.2688 (8)0.53304 (15)0.0178 (6)
H6A0.6788 (15)0.341 (8)0.5183 (18)0.021*
C70.60688 (12)0.2911 (7)0.61830 (15)0.0135 (5)
C80.64850 (13)0.4228 (7)0.69286 (14)0.0141 (5)
C90.61339 (12)0.4710 (8)0.77287 (16)0.0166 (6)
C100.64335 (14)0.6136 (8)0.84775 (16)0.0194 (6)
H100.6189 (14)0.644 (8)0.9006 (18)0.023*
C110.71326 (13)0.7093 (8)0.84418 (16)0.0186 (6)
C120.75199 (13)0.6479 (8)0.76803 (16)0.0159 (5)
H120.7968 (16)0.696 (8)0.7685 (17)0.019*
C130.72187 (13)0.5072 (7)0.69300 (15)0.0146 (5)
C140.77182 (13)0.4380 (8)0.61791 (16)0.0198 (6)
H14A0.82050.46830.63820.030*
H14B0.76220.60830.57040.030*
H14C0.76520.19230.59640.030*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0154 (8)0.0343 (13)0.0141 (8)−0.0028 (8)0.0031 (6)−0.0013 (9)
O20.0164 (9)0.0475 (14)0.0177 (8)−0.0068 (9)0.0028 (7)0.0060 (9)
O30.0125 (9)0.0439 (14)0.0268 (10)−0.0096 (9)0.0011 (8)−0.0021 (11)
O40.0164 (9)0.0518 (15)0.0143 (9)−0.0034 (10)−0.0002 (7)−0.0092 (9)
O50.0244 (10)0.0405 (13)0.0131 (8)−0.0053 (9)−0.0034 (7)−0.0063 (9)
C10.0152 (13)0.0243 (18)0.0183 (13)−0.0006 (11)−0.0013 (9)0.0027 (11)
C20.0139 (12)0.0187 (16)0.0176 (12)0.0002 (10)0.0010 (9)0.0038 (11)
C30.0113 (12)0.0239 (17)0.0222 (13)−0.0027 (11)−0.0021 (10)0.0012 (12)
C40.0166 (13)0.0218 (17)0.0200 (12)0.0027 (11)−0.0052 (10)−0.0022 (11)
C50.0149 (13)0.0277 (17)0.0123 (11)0.0025 (12)0.0021 (9)−0.0019 (12)
C60.0134 (12)0.0226 (17)0.0175 (12)0.0001 (10)0.0012 (9)−0.0003 (11)
C70.0124 (11)0.0153 (15)0.0127 (11)0.0024 (9)0.0007 (9)0.0026 (11)
C80.0170 (12)0.0150 (14)0.0102 (10)0.0036 (10)−0.0006 (9)−0.0001 (10)
C90.0129 (11)0.0216 (17)0.0153 (10)0.0008 (10)−0.0006 (10)0.0035 (11)
C100.0207 (14)0.0257 (17)0.0117 (11)0.0037 (11)0.0030 (9)0.0001 (11)
C110.0205 (13)0.0227 (17)0.0125 (11)0.0014 (11)−0.0061 (10)−0.0013 (11)
C120.0124 (11)0.0191 (15)0.0163 (11)0.0014 (10)−0.0020 (9)0.0014 (11)
C130.0166 (12)0.0139 (15)0.0133 (10)0.0023 (10)0.0015 (9)0.0030 (10)
C140.0130 (12)0.0279 (17)0.0184 (11)−0.0009 (10)0.0004 (9)−0.0038 (12)
Geometric parameters (Å, °) top
O1—C11.343 (3)C6—C71.386 (3)
O1—C91.396 (3)C6—H6A0.95 (3)
O2—C11.245 (3)C7—C81.468 (3)
O3—C31.348 (3)C8—C91.401 (3)
O3—H30.86 (3)C8—C131.427 (4)
O4—C51.367 (3)C9—C101.381 (4)
O4—H40.91 (4)C10—C111.374 (4)
O5—C111.362 (3)C10—H100.94 (3)
O5—H50.8400C11—C121.392 (4)
C1—C21.430 (3)C12—C131.381 (4)
C2—C71.424 (3)C12—H120.87 (3)
C2—C31.425 (4)C13—C141.508 (3)
C3—C41.380 (3)C14—H14A0.9800
C4—C51.387 (4)C14—H14B0.9800
C4—H4A1.01 (3)C14—H14C0.9800
C5—C61.389 (4)
C1—O1—C9122.07 (19)C9—C8—C13115.7 (2)
C3—O3—H3105 (2)C9—C8—C7117.4 (2)
C5—O4—H4115 (2)C13—C8—C7126.8 (2)
C11—O5—H5109.5C10—C9—O1113.1 (2)
O2—C1—O1115.6 (2)C10—C9—C8124.9 (2)
O2—C1—C2125.2 (2)O1—C9—C8121.9 (2)
O1—C1—C2119.1 (2)C11—C10—C9117.7 (2)
C7—C2—C3120.2 (2)C11—C10—H10118.7 (17)
C7—C2—C1121.0 (2)C9—C10—H10123.6 (17)
C3—C2—C1118.8 (2)O5—C11—C10118.9 (2)
O3—C3—C4116.9 (2)O5—C11—C12121.1 (2)
O3—C3—C2122.5 (2)C10—C11—C12120.0 (2)
C4—C3—C2120.6 (2)C13—C12—C11122.2 (2)
C3—C4—C5118.0 (2)C13—C12—H12119.3 (18)
C3—C4—H4A122.4 (16)C11—C12—H12118.4 (18)
C5—C4—H4A119.6 (16)C12—C13—C8119.2 (2)
O4—C5—C4121.7 (2)C12—C13—C14115.6 (2)
O4—C5—C6115.4 (2)C8—C13—C14125.1 (2)
C4—C5—C6122.9 (2)C13—C14—H14A109.5
C7—C6—C5120.3 (2)C13—C14—H14B109.5
C7—C6—H6A121.6 (17)H14A—C14—H14B109.5
C5—C6—H6A118.1 (17)C13—C14—H14C109.5
C6—C7—C2118.0 (2)H14A—C14—H14C109.5
C6—C7—C8124.1 (2)H14B—C14—H14C109.5
C2—C7—C8118.0 (2)
C9—O1—C1—O2174.9 (2)C6—C7—C8—C9172.4 (3)
C9—O1—C1—C2−5.6 (4)C2—C7—C8—C9−6.5 (4)
O2—C1—C2—C7−176.9 (3)C6—C7—C8—C13−7.9 (4)
O1—C1—C2—C73.6 (4)C2—C7—C8—C13173.3 (3)
O2—C1—C2—C34.3 (4)C1—O1—C9—C10−178.2 (3)
O1—C1—C2—C3−175.2 (3)C1—O1—C9—C81.3 (4)
C7—C2—C3—O3178.6 (3)C13—C8—C9—C104.5 (4)
C1—C2—C3—O3−2.6 (4)C7—C8—C9—C10−175.7 (3)
C7—C2—C3—C4−1.3 (4)C13—C8—C9—O1−174.9 (2)
C1—C2—C3—C4177.5 (3)C7—C8—C9—O14.8 (4)
O3—C3—C4—C5−179.8 (3)O1—C9—C10—C11178.2 (3)
C2—C3—C4—C50.1 (4)C8—C9—C10—C11−1.3 (4)
C3—C4—C5—O4−179.9 (3)C9—C10—C11—O5179.1 (2)
C3—C4—C5—C60.1 (5)C9—C10—C11—C12−2.6 (4)
O4—C5—C6—C7−179.1 (3)O5—C11—C12—C13−178.6 (3)
C4—C5—C6—C70.9 (5)C10—C11—C12—C133.1 (4)
C5—C6—C7—C2−2.1 (4)C11—C12—C13—C80.3 (4)
C5—C6—C7—C8179.1 (3)C11—C12—C13—C14−176.7 (3)
C3—C2—C7—C62.3 (4)C9—C8—C13—C12−3.9 (4)
C1—C2—C7—C6−176.5 (3)C7—C8—C13—C12176.4 (3)
C3—C2—C7—C8−178.8 (3)C9—C8—C13—C14172.9 (3)
C1—C2—C7—C82.5 (4)C7—C8—C13—C14−6.8 (4)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O20.86 (3)1.82 (3)2.605 (3)152 (3)
O4—H4···O2i0.91 (3)1.81 (3)2.685 (3)162 (3)
O5—H5···O4ii0.841.972.809 (2)175
Symmetry codes: (i) −x+1, −y, z−1/2; (ii) −x+3/2, y+1, z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O20.86 (3)1.82 (3)2.605 (3)152 (3)
O4—H4···O2i0.91 (3)1.81 (3)2.685 (3)162 (3)
O5—H5···O4ii0.841.972.809 (2)175
Symmetry codes: (i) −x+1, −y, z−1/2; (ii) −x+3/2, y+1, z+1/2.
references
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