5-Hy­droxy-8,8-dimethyl-10-(2-methyl­but-3-en-2-yl)-2H,6H-7,8-dihydro­pyrano[3,2-g]chromene-2,6-dione

Hoong-Kun Fun; Tawanun Sripisut; Surat Laphookhieo; Suchada Chantrapromma

doi:10.1107/S1600536811001565

. 2011 Jan 15;67(Pt 2):o422–o423. doi: 10.1107/S1600536811001565

5-Hydroxy-8,8-dimethyl-10-(2-methylbut-3-en-2-yl)-2H,6H-7,8-dihydropyrano[3,2-g]chromene-2,6-dione

Hoong-Kun Fun ^a,^*,^‡, Tawanun Sripisut ^b, Surat Laphookhieo ^b, Suchada Chantrapromma ^c,^§

PMCID: PMC3051790 PMID: 21523091

Abstract

In the title compound, C₁₉H₂₀O₅, the pyran ring is in an envelope conformation, whereas the benzene and dihydropyran ring system is planar with an r.m.s. deviation of 0.0190 (1) Å. The hydroxy group is coplanar with the attached benzene ring [r.m.s. deviation = 0.0106 (1) Å]. An intramolecular O—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, molecules are linked into chains along the b axis by weak C—H⋯O interactions. These chains are stacked along the a axis. C—H⋯π and weak π–π interactions [centroid–centroid distance = 3.7698 (7) Å] are also observed.

Related literature

For bond-length data, see: Allen et al. (1987 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶) and for ring conformations, see: Cremer & Pople (1975 ▶). For background to Rutaceae plants, coumarins and their biological activity, see: Kongkathip et al. (2005 ▶); Laphookhieo et al. (2009 ▶); Maneerat et al. (2010 ▶); Huang et al. (1997 ▶); Su et al. (2009 ▶); Tangyuenyongwatthana et al. (1992 ▶); Yenjai et al. (2000 ▶).

Experimental

Crystal data

C₁₉H₂₀O₅
M _r = 328.35
Monoclinic,
a = 10.2239 (2) Å
b = 11.3090 (3) Å
c = 13.8764 (3) Å
β = 93.108 (1)°
V = 1602.06 (6) Å³
Z = 4
Cu Kα radiation
μ = 0.81 mm⁻¹
T = 100 K
0.43 × 0.43 × 0.33 mm

Data collection

Bruker APEX DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.721, T _max = 0.774
48432 measured reflections
3114 independent reflections
3088 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.047
wR(F ²) = 0.147
S = 1.29
3114 reflections
234 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.71 e Å⁻³
Δρ_min = −0.84 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811001565/bq2271sup1.cif

e-67-0o422-sup1.cif^{(21.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811001565/bq2271Isup2.hkl

e-67-0o422-Isup2.hkl^{(152.8KB, hkl)}

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

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

Cg1 is the centroid of the C1–C5/O1ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H1O5⋯O4	0.93 (2)	1.66 (2)	2.5361 (14)	155 (2)
C9—H9B⋯O3ⁱ	0.97	2.36	3.2621 (17)	155
C16—H16B⋯O5ⁱⁱ	0.96	2.59	3.4982 (17)	159
C16—H16C⋯O2	0.96	2.34	2.9441 (16)	121
C15—H15B⋯Cg1ⁱⁱⁱ	0.97 (2)	2.83 (2)	3.5908 (16)	136.7 (15)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

SL and TS are grateful to the Thailand Research Fund through the Royal Golden Jubilee PhD Program and Mae Fah Luang University for financial support. SC thanks the Prince of Songkla University for generous support through the Crystal Materials Research Unit. The authors also thank Universiti Sains Malaysia for the Research University Grant No. 1001/PFIZIK/811160.

supplementary crystallographic information

Comment

Rutaceae plants are the rich sources of coumarins and carbazole alkaloids. Many of them have been isolated from several genera of Rutaceae especially from Clausena genus (Laphookhieo et al., 2009; Maneerat et al., 2010; Tangyuenyongwatthana et al., 1992) and some of these compounds show interesting pharmacological activities (Yenjai et al., 2000). During our on-going research on bioactive natural products from Thai medicinal plants, the title pyranocoumarin which known as clausenidin (Huang et al., 1997) was isolated from the roots of C. excavata which were collected from Suratthani province in the southern part of Thailand. Previous reports have found that clausenidin displayed anti-HIV-1 activity in a syncytial assay (Kongkathip et al., 2005) and cytotoxicity against four human cancer cell lines (A549, MCF7, KB and KB-VIN) (Su et al., 2009). We report herein the crystal structure of the title pyranocoumarin (I).

Fig. 1 shows that in the structure of (I), the pyran ring (C7–C11/O2) adopts an envelope conformation with the puckering atom C10 having deviation of 0.3279 (15) Å, and puckering parameters Q = 0.4648 (14) Å, θ = 123.32 (17)° and φ = 204.32° (Cremer & Pople, 1975). The benzene and dihydro-pyran ring system (C1–C7/C11-C12/O1) is planar with the r.m.s. 0.0190 (1) Å. The hydroxy group are planarly attached to the benzene ring. The orientation of the 2-methyl-but-3-enyl [C13–C17] side chain with respect to the benzene ring is indicated by the torsion angle of C12–C13–C14–C15 = 138.93 (16)°, indicating a (+)-anticlinal conformation (Fig. 1). Intramolecular O5—H1O5···O4 hydrogen bond (Table 1) generates an S(6) ring motif (Fig. 1 and Table 1) (Bernstein et al., 1995). The bond distances in (I) are within normal ranges (Allen et al., 1987).

The crystal packing of (I) is stabilized by intermolecular C—H···O and C—H···π weak interactions (Table 1). The molecules are linked into chains along the b axis and these chains are stacked along the a axis (Fig. 2 and Table 1). π–π interactions with the Cg₁···Cg₂ distance = 3.7698 (7) Å (symmetry code: -x, 2-y, 2-z) are observed; Cg₁ and Cg₂ are the centroids of C1–C5/O1 and C1/C5–C7/C11-C12 rings, respectively.

Experimental

The roots of C. excavata (3.98 Kg) were successively extracted with CH₂Cl₂ over the period of 3 days at room temperature to provide the crude CH₂Cl₂ extract which was subjected to quick column chromatography (QCC) over silica gel eluted with a gradient of hexane-EtOAc (100% hexane to 100% EtOAc) to provide twenty-one fractions (A-U). Fraction G (10.68 g) was further separated by QCC with a gradient of 10% EtOAc-hexane to 100% EtOAc to give seven subfractions (G1-G7). Subfraction G4 (1.82 g) was subjected to repeated column chromatography using 6% EtOAc-hexane to yield the yellow solid of the title compound (30.0 mg). Yellow block-shaped single crystals of the title compound suitable for x-ray structure determination were recrystallized from CH₂Cl₂/CH₃OH (4:1 v/v) by the slow evaporation of the solvent at room temperature after several days, Mp. 410-411 K (decomposition).