supplementary materials


kj2193 scheme

Acta Cryst. (2012). E68, o32-o33    [ doi:10.1107/S1600536811051221 ]

4',5-Dihydroxy-7-methoxyflavanone dihydrate

I. Brito, J. Bórquez, M. Simirgiotis, A. Cárdenas and M. López-Rodríguez

Abstract top

The title compound, C16H14O5·2H2O [systematic name: 5-hydroxy-2-(4-hydroxyphenyl)-7-methoxychroman-4-one dihydrate], is a natural phytoalexin flavone isolated from the native chilean species Heliotropium taltalense and crystallizes with an organic molecule and two water molecules in the asymmetric unit. The 5-hydroxy group forms a strong intramolecular hydrogen bond with the carbonyl group, resulting in a six-membered ring. In the crystal, the components are linked by O-H...O hydrogen bonds, forming a three-dimensional network. The 4-hydroxyphenyl benzene ring is bonded equatorially to the pyrone ring, which adopts a slightly distorted sofa conformation. The title compound is the hydrated form of a previously reported structure [Shoja (1990). Acta Cryst. C46, 1969-1971]. There are only slight variations in the molecular geometry between the two compounds.

Comment top

The crystal structure of the flavanone (S)-sakuranetin (5,4'-di-hydroxy-7-methoxyflavanone dihydrate, C16H14O5.2H2O) which was isolated from the native Chilean shrub Heliotropium taltalense (Heliotropiaceae) collected in Quebrada de Paposo II Region of Chile, is presented in this paper. (S)-Sakuranetin is a methylated flavanone obtained from the bark of Prunuspuddum (Narasimhachari & Seshadri, 1949) and later from other Prunus species (Atkinson & Blakeman, 1982). This compound is a phytoalexin produced in response to infection in rice (Plowright et al., 1996) with several beneficial biological properties such as antimicrobial activity (Atkinson & Blakeman, 1982) and the induction of adipogenesis (Saito et al., 2008). H. taltalense, is an endemic shrub or bush that grows in arid regions which obtains survival water from condensation from the Chilean coastal fog. Several Heliotropium species grow freely mainly in the north of Chile and they have glandular secreting trichomes whose principal rol is to produce a gummy exudate aimed to protect the plant from environmental factors and predators. This exudate is composed mainly of waxes and a mixture of phenolic compounds, mainly flavonoids and aromatic geranyl derivatives (Modak et al., 2009). The title compound (Fig. 1) crystallizes with an organic molecule and two water molecules in the asymmetric unit. The hydroxy group at C5 forms a strong intramolecular hydrogen bond with the carbonyl group with graph-set notation S(6) (Bernstein, et al., 1995). This interaction is observed in the unsolvated compound too, (Shoja, 1990). In the crystal, the components are linked by intermolecular O—H···O hydrogen bonds with an average O···O distance of 2.86 (14) Å and O—H···O angles in the range 147–174°, forming a 3-D network (Fig. 2). The 4'-hydroxyphenyl ring is bonded equatorially to the pyrone ring which adopts a slightly distorted sofa conformation with the C2 atom 0.328 (5) Å out of plane defined by the C2/C3/C4/C9/C10/O1 atoms, [puckering amplitude QT= 0.465 (5) Å; θ =124.9 (6)° & φ = 245.3 (7)° (Cremer & Pople, 1975)]. The title compound is the hydrated form of a previously reported structure. There are only slight variations in the molecular geometry of both compounds, so when both compound are superimposed all atoms are fitted within RMSD 0.0715 Å, (with inversion & flexibility), (Macrae et al., 2008), as is shown in Fig. 3.

Related literature top

For the first study of the title compound, see: Narasimhachari & Seshadri (1949); Atkinson & Blakeman (1982). For its biological properties, see: Plowright et al. (1996); Atkinson & Blakeman (1982), Saito et al. (2008). For its spectroscopic properties, see: Agrawal (1989); Ogawa et al. (2007). For the structure of the unsolvated compound, see: Shoja (1990). For similar compounds, see: Modak et al. (2009). For graph-set notation, see: Bernstein et al. (1995). For puckering parameters, see: Cremer & Pople (1975). For molecular geometry calculations, see: Macrae et al. (2008).

Experimental top

Dried aerial parts of H. taltalense (1.8 kg) were immersed in ethyl acetate (EtOAc) for one minute (2 l) in order to obtain an extract from the exudate. The extract was immediately concentrated in vacuo and the resulting dark brown syrup (47 g) was adsorbed on to silicagel 60 G (50 g) and slurred onto the top of a column containing silica gel 60 H (0.5 kg), partitioned using a medium pressure pump with an isocratic eluent (n-hexane–EtOAc 8:2), to obtain six partitions (fractions A to F: n-hexane, n-hexane–EtOAc 95:5, n-hexane–EtOAc 90:10, n-hexane–EtOAc 80:20, n-hexane–EtOAc 50:50 and pure EtOAc). Further purification by a combination of chromatography on silicagel 60 H and permeation through Sephadex LH-20 (eluting with methanol-water 7:3) of the fraction 20% hexane-ethyl acetate (fraction D, 15 g) afforded the phytoalexin 5,4'-di-hydroxy-7-methoxyflavanone dihydrate for which 1-D and 2-D NMR data are consistent with literature (Agrawal, 1989; Ogawa, et al., 2007). Recrystallization from hexane-ethyl acetate (9:1) at -20 ° C yielded yellow crystals of (S)-sakuranetin dihydrate (0.039 g), suitable for X-ray diffraction analysis.

Refinement top

The parameters of the three H atoms bonded to atoms O5 (hydroxyl) and O6 (water) were located in difference maps and refined isotropically; all other H atoms were treated using a riding model, with C—H distances are in the range 0.93 – 0.98 Å and O—H distance of 0.82 and 0.85 Å, with Uiso(H) = 1.2Ueq(C,O) or 1.5Ueq(methyl C). The absolute configuration could not be established by the Flack method and the 772 observed Friedel opposites were merged.

Computing details top

Data collection: COLLECT (Nonius, 2000; cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN (Otwinowski & Minor, 1997); 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: WinGX (Farrugia, 1999) and publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. : Molecular structure of title compound. Displacement ellipsoids are shown at the 50% probability level.
[Figure 2] Fig. 2. : A view of the crystal packing of the title compound, showing the intermolecular and intramolecular hydrogen bonding.
[Figure 3] Fig. 3. Superimposed structures for the title compound (green) and the unsolvated compound (red).
5-hydroxy-2-(4-hydroxyphenyl)-7-methoxychroman-4-one dihydrate top
Crystal data top
C16H14O5·2H2OF(000) = 680
Mr = 322.30Dx = 1.376 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 2419 reflections
a = 5.0869 (10) Åθ = 3.3–28.4°
b = 9.4622 (19) ŵ = 0.11 mm1
c = 32.318 (7) ÅT = 293 K
V = 1555.6 (5) Å3Block, yellow
Z = 40.20 × 0.15 × 0.03 mm
Data collection top
Nonius KappaCCD area-detector
diffractometer
1623 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.068
graphiteθmax = 28.4°, θmin = 3.3°
φ and ω scans with κ offsetsh = 06
9743 measured reflectionsk = 012
2021 independent reflectionsl = 4042
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)] = 0.075Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.180H atoms treated by a mixture of independent and constrained refinement
S = 1.17 w = 1/[σ2(Fo2) + (0.0649P)2 + 1.4205P]
where P = (Fo2 + 2Fc2)/3
2021 reflections(Δ/σ)max < 0.001
224 parametersΔρmax = 0.38 e Å3
0 restraintsΔρmin = 0.29 e Å3
Crystal data top
C16H14O5·2H2OV = 1555.6 (5) Å3
Mr = 322.30Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 5.0869 (10) ŵ = 0.11 mm1
b = 9.4622 (19) ÅT = 293 K
c = 32.318 (7) Å0.20 × 0.15 × 0.03 mm
Data collection top
Nonius KappaCCD area-detector
diffractometer
1623 reflections with I > 2σ(I)
9743 measured reflectionsRint = 0.068
2021 independent reflectionsθmax = 28.4°
Refinement top
R[F2 > 2σ(F2)] = 0.075H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.180Δρmax = 0.38 e Å3
S = 1.17Δρmin = 0.29 e Å3
2021 reflectionsAbsolute structure: ?
224 parametersFlack parameter: ?
0 restraintsRogers 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 > 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
O10.1698 (7)0.3272 (3)0.39766 (8)0.0317 (8)
O20.3650 (7)0.5120 (4)0.31855 (10)0.0370 (9)
O30.1585 (7)0.3656 (4)0.25747 (9)0.0350 (8)
H30.25760.42240.26860.053*
O40.5380 (7)0.0576 (4)0.28692 (9)0.0341 (8)
O50.1305 (11)0.5341 (6)0.58135 (12)0.0610 (15)
H50.247 (18)0.564 (8)0.593 (2)0.07 (3)*
C20.0708 (9)0.4690 (5)0.40716 (13)0.0266 (10)
H20.18930.53810.39450.032*
C30.2023 (9)0.4877 (6)0.38806 (13)0.0345 (12)
H3A0.32540.42500.40180.041*
H3B0.26130.58400.39240.041*
C40.2002 (9)0.4562 (5)0.34223 (13)0.0265 (10)
C100.0071 (9)0.3561 (5)0.32828 (12)0.0247 (9)
C50.0125 (9)0.3128 (5)0.28607 (12)0.0248 (10)
C60.1952 (10)0.2153 (5)0.27344 (13)0.0278 (10)
H60.20630.18990.24570.033*
C70.3658 (9)0.1537 (5)0.30263 (13)0.0251 (9)
C80.3505 (9)0.1902 (5)0.34455 (13)0.0267 (9)
H80.45860.14650.36390.032*
C90.1720 (8)0.2925 (5)0.35667 (12)0.0221 (9)
C1'0.0839 (9)0.4870 (5)0.45324 (13)0.0265 (10)
C2'0.0739 (11)0.4059 (6)0.48002 (14)0.0379 (12)
H2'0.19230.34100.46910.046*
C3'0.0542 (12)0.4220 (6)0.52256 (15)0.0439 (14)
H3'0.15810.36730.54000.053*
C4'0.1203 (10)0.5197 (6)0.53925 (13)0.0367 (12)
C5'0.2769 (12)0.6004 (6)0.51347 (15)0.0441 (14)
H5'0.39400.66560.52460.053*
C6'0.2585 (11)0.5837 (6)0.47061 (14)0.0361 (12)
H6'0.36450.63810.45340.043*
C110.7076 (11)0.0153 (6)0.31527 (15)0.0364 (12)
H11A0.60390.07340.33340.055*
H11B0.80430.05230.33140.055*
H11C0.82800.07370.30010.055*
O60.2193 (9)0.7134 (5)0.32036 (13)0.0500 (11)
H6A0.354 (18)0.659 (8)0.316 (2)0.07 (2)*
H6B0.209 (15)0.761 (6)0.2996 (19)0.06 (2)*
O70.5931 (9)0.6486 (6)0.60698 (12)0.0586 (13)
H7A0.74500.64410.59610.088*
H7B0.63060.67360.63150.088*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0332 (19)0.0370 (19)0.0248 (15)0.0105 (18)0.0035 (13)0.0066 (13)
O20.0244 (17)0.046 (2)0.0406 (18)0.0133 (18)0.0064 (14)0.0006 (16)
O30.0334 (19)0.039 (2)0.0324 (16)0.0081 (19)0.0069 (14)0.0014 (14)
O40.0292 (18)0.041 (2)0.0324 (16)0.0126 (17)0.0009 (14)0.0085 (14)
O50.061 (3)0.096 (4)0.0258 (18)0.028 (3)0.0028 (19)0.006 (2)
C20.018 (2)0.032 (2)0.030 (2)0.001 (2)0.0035 (17)0.0057 (18)
C30.022 (2)0.044 (3)0.038 (2)0.012 (3)0.0049 (19)0.006 (2)
C40.018 (2)0.029 (2)0.032 (2)0.000 (2)0.0033 (18)0.0001 (18)
C100.018 (2)0.028 (2)0.028 (2)0.001 (2)0.0005 (17)0.0006 (17)
C50.023 (2)0.027 (2)0.025 (2)0.005 (2)0.0066 (17)0.0041 (17)
C60.032 (2)0.031 (2)0.0204 (19)0.002 (2)0.0008 (18)0.0029 (17)
C70.017 (2)0.026 (2)0.032 (2)0.002 (2)0.0021 (17)0.0008 (18)
C80.023 (2)0.031 (2)0.026 (2)0.002 (2)0.0012 (17)0.0009 (18)
C90.0115 (18)0.029 (2)0.0259 (19)0.0042 (19)0.0017 (15)0.0002 (17)
C1'0.022 (2)0.029 (2)0.028 (2)0.001 (2)0.0004 (17)0.0030 (18)
C2'0.032 (3)0.048 (3)0.033 (2)0.008 (3)0.002 (2)0.006 (2)
C3'0.039 (3)0.054 (4)0.039 (3)0.012 (3)0.012 (2)0.003 (2)
C4'0.034 (3)0.050 (3)0.027 (2)0.001 (3)0.005 (2)0.000 (2)
C5'0.039 (3)0.057 (4)0.036 (3)0.008 (3)0.003 (2)0.009 (2)
C6'0.029 (3)0.047 (3)0.031 (2)0.012 (2)0.0050 (19)0.001 (2)
C110.027 (3)0.040 (3)0.042 (3)0.014 (3)0.000 (2)0.001 (2)
O60.048 (3)0.058 (3)0.044 (2)0.020 (2)0.007 (2)0.001 (2)
O70.049 (3)0.084 (3)0.042 (2)0.008 (3)0.0053 (19)0.007 (2)
Geometric parameters (Å, °) top
O1—C91.365 (5)C7—C81.400 (6)
O1—C21.465 (5)C8—C91.383 (6)
O2—C41.252 (5)C8—H80.9300
O3—C51.364 (5)C1'—C6'1.393 (6)
O3—H30.8200C1'—C2'1.408 (7)
O4—C71.361 (5)C2'—C3'1.387 (7)
O4—C111.435 (6)C2'—H2'0.9300
O5—C4'1.369 (6)C3'—C4'1.391 (7)
O5—H50.75 (8)C3'—H3'0.9300
C2—C1'1.501 (6)C4'—C5'1.382 (7)
C2—C31.530 (6)C5'—C6'1.397 (6)
C2—H20.9800C5'—H5'0.9300
C3—C41.511 (6)C6'—H6'0.9300
C3—H3A0.9700C11—H11A0.9600
C3—H3B0.9700C11—H11B0.9600
C4—C101.437 (6)C11—H11C0.9600
C10—C91.426 (6)O6—H6A0.87 (9)
C10—C51.427 (6)O6—H6B0.81 (6)
C5—C61.372 (6)O7—H7A0.8500
C6—C71.408 (6)O7—H7B0.8501
C6—H60.9300
C9—O1—C2115.3 (3)C9—C8—H8120.6
C5—O3—H3109.5C7—C8—H8120.6
C7—O4—C11118.0 (4)O1—C9—C8116.7 (4)
C4'—O5—H5123 (6)O1—C9—C10121.2 (4)
O1—C2—C1'107.3 (4)C8—C9—C10122.2 (4)
O1—C2—C3109.5 (4)C6'—C1'—C2'118.3 (4)
C1'—C2—C3115.3 (4)C6'—C1'—C2120.2 (4)
O1—C2—H2108.2C2'—C1'—C2121.5 (4)
C1'—C2—H2108.2C3'—C2'—C1'120.6 (5)
C3—C2—H2108.2C3'—C2'—H2'119.7
C4—C3—C2111.5 (4)C1'—C2'—H2'119.7
C4—C3—H3A109.3C2'—C3'—C4'120.2 (5)
C2—C3—H3A109.3C2'—C3'—H3'119.9
C4—C3—H3B109.3C4'—C3'—H3'119.9
C2—C3—H3B109.3O5—C4'—C5'121.5 (5)
H3A—C3—H3B108.0O5—C4'—C3'118.4 (5)
O2—C4—C10123.0 (4)C5'—C4'—C3'120.1 (5)
O2—C4—C3120.7 (4)C4'—C5'—C6'119.8 (5)
C10—C4—C3116.3 (4)C4'—C5'—H5'120.1
C9—C10—C5116.7 (4)C6'—C5'—H5'120.1
C9—C10—C4120.9 (4)C1'—C6'—C5'121.1 (4)
C5—C10—C4122.4 (4)C1'—C6'—H6'119.5
O3—C5—C6118.5 (4)C5'—C6'—H6'119.5
O3—C5—C10119.9 (4)O4—C11—H11A109.5
C6—C5—C10121.6 (4)O4—C11—H11B109.5
C5—C6—C7119.8 (4)H11A—C11—H11B109.5
C5—C6—H6120.1O4—C11—H11C109.5
C7—C6—H6120.1H11A—C11—H11C109.5
O4—C7—C8124.2 (4)H11B—C11—H11C109.5
O4—C7—C6115.0 (4)H6A—O6—H6B105 (6)
C8—C7—C6120.8 (4)H7A—O7—H7B101.2
C9—C8—C7118.9 (4)
C9—O1—C2—C1'180.0 (4)C2—O1—C9—C8155.2 (4)
C9—O1—C2—C354.2 (5)C2—O1—C9—C1026.6 (6)
O1—C2—C3—C454.4 (5)C7—C8—C9—O1178.2 (4)
C1'—C2—C3—C4175.4 (4)C7—C8—C9—C103.6 (6)
C2—C3—C4—O2153.5 (5)C5—C10—C9—O1179.7 (4)
C2—C3—C4—C1028.6 (6)C4—C10—C9—O11.7 (6)
O2—C4—C10—C9178.3 (4)C5—C10—C9—C82.2 (6)
C3—C4—C10—C90.5 (6)C4—C10—C9—C8176.4 (4)
O2—C4—C10—C50.3 (7)O1—C2—C1'—C6'112.6 (5)
C3—C4—C10—C5178.0 (4)C3—C2—C1'—C6'125.2 (5)
C9—C10—C5—O3177.7 (4)O1—C2—C1'—C2'66.1 (6)
C4—C10—C5—O30.9 (7)C3—C2—C1'—C2'56.1 (6)
C9—C10—C5—C60.2 (6)C6'—C1'—C2'—C3'0.3 (8)
C4—C10—C5—C6178.8 (4)C2—C1'—C2'—C3'178.5 (5)
O3—C5—C6—C7176.9 (4)C1'—C2'—C3'—C4'0.6 (8)
C10—C5—C6—C71.1 (7)C2'—C3'—C4'—O5178.9 (5)
C11—O4—C7—C82.6 (7)C2'—C3'—C4'—C5'0.6 (9)
C11—O4—C7—C6176.5 (4)O5—C4'—C5'—C6'179.3 (5)
C5—C6—C7—O4179.5 (4)C3'—C4'—C5'—C6'0.2 (9)
C5—C6—C7—C80.4 (7)C2'—C1'—C6'—C5'0.1 (8)
O4—C7—C8—C9178.2 (4)C2—C1'—C6'—C5'178.9 (5)
C6—C7—C8—C92.7 (7)C4'—C5'—C6'—C1'0.2 (9)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O20.821.902.630 (5)147
O5—H5···O70.76 (9)1.99 (9)2.720 (7)163 (7)
O6—H6A···O2i0.87 (9)2.00 (8)2.847 (6)166 (7)
O6—H6B···O3ii0.81 (6)2.11 (6)2.915 (5)174 (8)
O7—H7A···O5i0.852.273.055 (7)153
O7—H7B···O6iii0.851.942.763 (6)163
Symmetry codes: (i) x+1, y, z; (ii) −x, y+1/2, −z+1/2; (iii) x+1/2, −y+3/2, −z+1.
Table 1
Hydrogen-bond geometry (Å, °)
top
D—H···AD—HH···AD···AD—H···A
O3—H3···O20.821.902.630 (5)147
O5—H5···O70.76 (9)1.99 (9)2.720 (7)163 (7)
O6—H6A···O2i0.87 (9)2.00 (8)2.847 (6)166 (7)
O6—H6B···O3ii0.81 (6)2.11 (6)2.915 (5)174 (8)
O7—H7A···O5i0.852.273.055 (7)153
O7—H7B···O6iii0.851.942.763 (6)163
Symmetry codes: (i) x+1, y, z; (ii) −x, y+1/2, −z+1/2; (iii) x+1/2, −y+3/2, −z+1.
Acknowledgements top

IB thanks the Spanish Research Council (CSIC) for providing us with a free-of-charge licence for the CSD system. The authors acknowdledge funds from FONDECYT (1110068) and U. Antofagasta (CODEI N° 1383).

references
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