7,7′,8,8′-Tetra­meth­oxy-4,4′-dimethyl-3,5′-bichromene-2,2′-dione

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

doi:10.1107/S1600536809018029

. 2009 May 20;65(Pt 6):o1322–o1323. doi: 10.1107/S1600536809018029

7,7′,8,8′-Tetramethoxy-4,4′-dimethyl-3,5′-bichromene-2,2′-dione

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

PMCID: PMC2969715 PMID: 21583178

Abstract

In the title molecule, C₂₄H₂₂O₈, the mean planes of the two coumarin units are inclined to each other at a dihedral angle of 79.93 (3)°. The attached methoxy groups form torsion angles of 7.65 (19) and 78.36 (14)° with respect to one coumarin unit, and angles of 9.01 (16) and 99.08 (11)° with respect to the other coumarin unit. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds connect pairs of molecules to form dimers, generating R ₂ ²(16) and R ₂ ²(18) rings; the dimers are linked by further weak intermolecular C—H⋯O hydrogen bonds, forming extended chains. Additional stabilization is provided by weak C—H⋯π interactions.

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 et al. (1999 ▶); Shaker (1996 ▶); Yang et al. (2005 ▶). For the pharmaceutical properties of coumarin derivatives, see: Kennedy et al. (1997 ▶). For related literature on natural and synthetic coumarins, see: Carlton et al. (1996 ▶); Zhou et al. (2000 ▶). For standard bond-length data, see: Allen et al. (1987 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₂₄H₂₂O₈
M _r = 438.42
Monoclinic,
a = 9.4724 (1) Å
b = 23.4766 (3) Å
c = 9.3525 (1) Å
β = 96.254 (1)°
V = 2067.43 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 100 K
0.50 × 0.27 × 0.14 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.949, T _max = 0.985
58385 measured reflections
7006 independent reflections
6023 reflections with I > 2σ(I)
R _int = 0.030

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.125
S = 1.07
7006 reflections
295 parameters
H-atom parameters constrained
Δρ_max = 0.47 e Å⁻³
Δρ_min = −0.24 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/S1600536809018029/lh2822sup1.cif

e-65-o1322-sup1.cif^{(24.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809018029/lh2822Isup2.hkl

e-65-o1322-Isup2.hkl^{(335.9KB, 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
C21—H21A⋯O6ⁱ	0.96	2.55	3.2921 (15)	134
C22—H22A⋯O6ⁱⁱ	0.96	2.52	3.4385 (14)	161
C22—H22B⋯O8ⁱ	0.96	2.56	3.4401 (15)	152
C6—H6A⋯Cg1ⁱⁱⁱ	0.93	2.92	3.6706 (12)	138
C19—H19A⋯Cg2^iv	0.96	2.60	3.5446 (14)	170

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) . Cg1 is the centroid of the O7/C14–C18 ring and Cg2 is the centroid of the C10–C18 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 derivatives. Many natural coumarins are reputed for their wide range of biological activites such as antibacterial (El-Agrody et al., 2001; Pratibha et al., 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). Bi and tri-coumarins are a comparatively new group of compounds which are widespread in nature and their biological properties are also well known (Laakso et al., 1994). One of the characteristic pharmacological properties of coumarin derivatives is anticoagulant action (Kennedy et al., 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 herein its crystal structure.

The molecular structure of the title compound is shown in Fig .1. In crystal structure of (I) molecules are linked by weak intermolecular C-H···O hydrogen bonds to form R₂²(16) and R₂²(18) rings (Bernstein et al., (1995). The two coumarin units are essentially planar with the maximum deviation from planarity of 0.0665 (11)Å for atom C9 in the ring (O3/C1–C9) and 0.0419 (12)Å for atom C16 in the ring (O7/C10–C18). The two coumarin units forming a dihedral angle of 79.93 (3)° (O3/C1–C9:O7/C10–C18), indicating that they are inclined to each other. Two of the methoxy units attached to the each coumarin units are twisted from the plane of coumarin unit as indicated by the torsion angles of C19–O1—C4–C5=-7.65 (19)°; C20–O2–C3–C2=78.36 (14)°; C22–O5–C12–C11=9.01 (16)° and C23–O6–C13–C14=99.08 (11)°, respectively. The bond lengths Allen et al. (1987) and bond angles are normal.

The crystal packing is illustrated in Fig. 2. In addition C—H···π interactions help stabilize the crystal structure.

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%).