E-Notopterol

Andreas Schinkovitz; Ferdinand Belaj; Olaf Kunert; Rudolf Bauer

doi:10.1107/S1600536809005030

. 2009 Feb 18;65(Pt 3):o545. doi: 10.1107/S1600536809005030

E-Notopterol

Andreas Schinkovitz ^a, Ferdinand Belaj ^b,^*, Olaf Kunert ^c, Rudolf Bauer ^a

PMCID: PMC2968663 PMID: 21582204

Abstract

The title compound (systematic name: 4-{[(2E)-5-hydroxy-3,7-dimethylocta-2,6-dien-1-yl]oxy}-7H-furo[3,2-g][1]benzopyran-7-one), C₂₁H₂₂O₅, is a known furanocoumarin, which was isolated from the Chinese herbal product Radix seu Rhizoma Notopterygii. The crystal structure shows a weak O—H⋯O hydrogen bond.

Related literature

For the isolation, see: Yang et al. (1994 ▶); Xiao et al. (1994 ▶). For NMR shifts and coupling constants of related compounds, see: Hasegawa et al. (1999 ▶); Chemical Abstract Service (2009 ▶).

Experimental

Crystal data

C₂₁H₂₂O₅
M _r = 354.39
Triclinic,
a = 6.4317 (10) Å
b = 8.0912 (16) Å
c = 17.206 (3) Å
α = 91.802 (15)°
β = 94.240 (13)°
γ = 97.473 (15)°
V = 884.6 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 95 K
0.48 × 0.44 × 0.32 mm

Data collection

Stoe four-circle diffractometer
Absorption correction: none
4234 measured reflections
3462 independent reflections
2941 reflections with I > 2σ(I)
R _int = 0.023
3 standard reflections every 100 reflections intensity decay: 0.4%

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.113
S = 1.04
3462 reflections
249 parameters
Only H-atom displacement parameters refined
Δρ_max = 0.38 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: local software; cell refinement: local software; data reduction: local software; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: modified ORTEP (Johnson, 1965 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809005030/bt2871sup1.cif

e-65-0o545-sup1.cif^{(22.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809005030/bt2871Isup2.hkl

e-65-0o545-Isup2.hkl^{(169.8KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H51⋯O8ⁱ	0.84	2.57	3.2193 (16)	135

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Symmetry code: (i) Inline graphic .

Acknowledgments

Funding provided by the Austrian Science Fund (FWF) within project S107 (Drugs from Nature Targeting Inflammation) is gratefully acknowledged.

supplementary crystallographic information

Comment

Rhizoma seu Radix Notopterygii is a herbal preparation commonly used in traditional Chinese medicine. It may either contain roots or rhizomes of N. incisum or N. forbesii (Apiaceae) or a mixture of both plants. The isolation of E-Notopterol (Fig.1) has been previously reported for both species (Yang et al., 1994; Xiao et al. 1994), which naturally occur in the region of South Central Asia, but the crystal structure has not been reported until now. In the process of structure elucidation, the title compound was primarily identified by ¹H and ¹³C NMR experiments. Observed chemical shifts and coupling constants were in compliance with previously published literature (Hasegawa et al., 1999; Chemical Abstract Service, 2009). Further support was provided by the ESI-MS analysis, indicating the pseudo molecular ion at 377.29 m/z [M—Na⁺].

The crystal structure analysis confirmed the proposed structure as 4-{[(2E)-5-hydroxy-3,7-dimethyl- octa-2,6-dien-1-yl]oxy}-7H-furo[3,2-g][1]benzopyran-7-one. All the atoms are lying on general positions. In Fig. 1 the S-enantiomer of the racemate is shown. The least-squares plane through the non-H atoms around the double bond C42=C43 enclose an angle of 12.36 (9)° with the plane through the atoms around C46=C47, and further an angle of 41.35 (6)° with the plane through the tricycle. The packing is dominated by an antiparallel stacking of the tricycles (s. Fig. 2) preventing the formation of a strong hydrogen bond of the OH group [O5—H51···.O8ⁱ 134.5°, O5···.O8ⁱ 3.2193 (16) Å; symmetry transformation used to generate the equivalent atom: (i) 1 - x, 2 - y, 1 - z].

Experimental

Plant Material: Rhizoma seu Radix Notopterygii was purchased from Plantasia (Oberndorf, Austria).

Isolation and purification: Plant material (2000 g) was grinded and extracted with 11 L dichloromethane at room temperature, yielding 381.87 g of dried extract after vacuum evaporation. Next 100 g dried extract were fractionated on a Silicagel 60 column (230–400 mesh, Merck, Darmstadt, Germany; size: 8.5 x 20 cm). In the process a stepwise gradient elution starting from 100% hexane (Hex) and going to 100% ethylacetate (EtOAc) was performed. For each step (2400 ml) the content of Hex in the eluent was reduced by 16.7 vol.%, and 6–8 subfractions were collected. Subfraction D7 collected between 2030 ml and 2400 ml from eluent D (Hex:EtOAc: 50:50, v:v) yielded in the isolation of 86.49 mg crystallized 1. Finally the colourless block crystals were washed with eluent C (Hex:EtOAc: 67:33, v:v) before being analyzed.

NMR analysis: ¹H and ¹³C NMR spectra were recorded at 293 K on a Varian UnityInova 400 NMR spectrometer with a 5 mm broadband probe. E-Notpterol was dissolved in chloroform-d (Aldrich, USA) and TMS was used as internal standard.

NMR results: ¹H NMR (CDCl₃, 400 MHz) δ 1.70 (3H, d, J = 1.2, H-50), 1.72 (3H, d, J = 1.2, H-48), 1.77 (3H, s, H-49), 2.22 (1H, dd, J = 13.7, 5.0, H-44b), 2.31 (1H, dd, J = 13.7, 8.2, H-44a), 4.52 (1H, m, H-45), 4.98 (2H, d, J = 6.9, H-41), 5.18 (1H, pseudo td, J = 8.4, 1.3, H-46), 5.65 (1H, pseudo dt, J = 6.7, 1.0, H-42), 6.28 (1H, d, J = 9.8, H-6), 6.98 (1H, dd, J = 2.4, 0.8, H-3), 7.16 (1H, s, H-9), 7.60 (1H, d, J = 2.4, H-2), 8.16 (1H, d, J = 9.8, H-5); ¹³C NMR (CDCl₃, 400 MHz) δ 17.0 (CH3, C-49), 18.2 (CH3, C-50), 25.7 (CH3, C-48), 47.7 (CH2, C-44), 66.4 (CH, C-45), 69.4 (CH2, C-41), 94.3 (CH, C-9), 105.0 (CH, C-3), 107.4 (C, C-14), 112.6 (CH, C-6), 114.0 (C, C-13), 122.4 (CH, C-42), 127.3 (CH, C-46), 135.6 (C, C-47), 139.5 (C, C-43), 139.5 (CH, C-5), 145.0 (CH, C-2), 148.7 (C, C-4), 152.6 (C, C-18), 158.1 (C, C-19), 161.3 (C, C-7).

LC—MS-analysis: Experiments were performed on a Thermo Finnigan Surveyor liquid chromatograph interfaced with a LCQ^TM Deca XP^PLUS mass detector. E-Notopterol was dissolved in methanol (HPLC grade, Merck, Darmstadt, Germany) and analyzed in the ESI+ mode under following conditions: Sheath gas flow: 70 units, ionization voltage: 5,50 kV, capillary voltage 15 V, tube lens offset: 50 V, capillary temperature: 623 K.