7,7′,8,8′-Tetra­meth­oxy-4,4′-dimethyl-3,3′-bicoumarin

Hoong-Kun Fun; Samuel Robinson Jebas; Mehtab Parveen; Zakia Khanam; Raza Murad Ghalib

doi:10.1107/S1600536809017334

. 2009 May 14;65(Pt 6):o1294–o1295. doi: 10.1107/S1600536809017334

7,7′,8,8′-Tetramethoxy-4,4′-dimethyl-3,3′-bicoumarin

Hoong-Kun Fun ^a,^*,^‡, Samuel Robinson Jebas ^a,^§, Mehtab Parveen ^b, Zakia Khanam ^b, Raza Murad Ghalib ^b

PMCID: PMC2969639 PMID: 21583154

Abstract

In the crystal structure, the title compound, C₂₄H₂₂O₈, lies on a twofold rotation axis and the asymmetric unit comprises one half-molecule. The dihedral angle formed by the coumarin unit with the symmetry-related part is 74.78 (14)°. One of the methoxy groups attached to the coumarin unit is considerably twisted, making an angle of 87.17 (17)° with respect to the coumarin unit; the other is twisted by 0.66 (19)°. No classical hydrogen bonds are found in the sturcture; only a weak C—H⋯π interaction and short intramolecular O⋯O contacts [2.683 (2)–2.701 (2) Å] are observed.

Related literature

For the biological activity of coumarins, see: El-Agrody et al. (2001 ▶); El-Farargy (1991 ▶); Emmanuel-Giota et al. (2001 ▶); Ghate et al. (2005 ▶); Laakso et al. (1994 ▶); Nofal et al. (2000 ▶); Pratibha & Shreeya (1999 ▶); Shaker (1996 ▶); Yang et al. (2005 ▶). For the pharmaceutical properties of coumarin derivatives, see: Kennedy & Thornes (1997 ▶). For natural and synthetic coumarins, see: Carlton et al. (1996 ▶); Zhou et al. (2000 ▶). For related bond-length data, see: Allen et al. (1987 ▶). For stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₂₄H₂₂O₈
M _r = 438.42
Monoclinic,
a = 21.715 (9) Å
b = 7.138 (3) Å
c = 15.511 (6) Å
β = 121.801 (5)°
V = 2043.3 (14) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 100 K
0.28 × 0.19 × 0.06 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.971, T _max = 0.994
27961 measured reflections
3527 independent reflections
2710 reflections with I > 2σ(I)
R _int = 0.065

Refinement

R[F ² > 2σ(F ²)] = 0.059
wR(F ²) = 0.155
S = 1.08
3527 reflections
189 parameters
All H-atom parameters refined
Δρ_max = 0.50 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); 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/S1600536809017334/is2417sup1.cif

e-65-o1294-sup1.cif^{(17.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809017334/is2417Isup2.hkl

e-65-o1294-Isup2.hkl^{(169.5KB, 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
C6—H6⋯Cg1ⁱ	0.96 (2)	2.86 (2)	3.676 (2)	143.5 (18)

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Symmetry code: (i) Inline graphic . Cg1 is the centroid of the C4–C9 ring.

Acknowledgments

HKF and SRJ thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. SRJ thanks Universiti Sains Malaysia for a post–doctoral research fellowship. HKF also thanks Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012.

supplementary crystallographic information

Comment

Coumarins are a large group of naturally occurring oxygen heterocycles representing 2H-1-benzopyran-2-one derivative. Many natural coumarins are reputed for their wide range of biological activites such as antibacterial (El-Agrody et al., 2001; Pratibha & Shreeya, 1999), antifungal (Shaker, 1996; El-Farargy, 1991), antioxidant (Yang et al., 2005), analgesic (Ghate et al., 2005), anti-inflammatory (Emmanuel-Giota et al., 2001) and antitumor (Nofal et al., 2000) properties. Bi and tri-coumarins are comparatively new groups which are widely spread in nature and their biological properties are also well known (Laakso et al., 1994). One of the characteristic pharmacological properties of coumarin derivatives is the anticoagulant action (Kennedy & Thornes, 1997). A large number of natural and semisynthetic coumarin and bicoumarin derivatives have been reported to demonstrate chemopreventive (Carlton et al., 1996) and anti-HIV (Zhou et al., 2000) activities. Keeping in view of these biological importance of coumarins and their dimers, we have synthesized the title compound (I) and report here its structure.

The asymmetric unit of (I) (Fig. 1), contains half of the 7,7',8,8'-4,4'-dimethyl-3,3'-bicoumarin molecule. The other half is symmetry generated [symmetry code: -x, y, -z + 1/2]. The coumarin unit is planar with the maximum deviation from the mean plane of 0.0295 (15) Å for atom C2. One of the methyl group attached to the coumarin unit is twisted as evidenced by the torsion angle of C10—O3—C8—C9 = 87.17 (17)°. The dihedral angle formed by the coumarin unit (O1/C1—C9) with the symmetry related coumarin unit (O1A/C1A—C9A) is 74.78 (14)°, indicating that they are almost perpendicular to each other. The bond lengths (Allen et al., 1987) and bond angles are normal.

The crystal packing (Fig. 2) (Table 1) is stabilized by weak C—H···π interactions and intramolecular O···O = 2.683 (2) to 2.701 (2) Å short contacts.

Experimental

A mixture of 7,8-dimethoxy-4-methyl coumarin (2.20 g, 10 mmol) and manganese(III) acetate (0.774 g, 1 mmol) was stirred at room temperature, then 70% perchloric acid (0.8 g, 6 mmol) was added. The reaction mixture was heated under reflux at 114°C with stirring in the atmosphere of nitrogen for 3 h. The reaction mixture was cooled and diluted with 50 ml of benzene. The benzene solution was washed with water and aq. NaHCO₃, dried over anhydrous Na₂SO₄ and left to evaporate. The residue showed two major compounds which were separated by column chromatography followed by preparative thin layer chromatography (Benzene: EtOAc, 9:1) into the title compound (I) (260 mg, 12%).