8-Iodo-5,7-dimethoxy-4-methyl-2H-chromen-2-one

In the title compound, C12H11IO4, the C and O atoms of both methoxy groups lie very close to the mean plane of the six C atoms of the benzene ring. The O and C atoms of the group lying closest to the I atom are 0.012 (3) and 0.022 (4) Å, respectively, out of the mean plane. For the other methoxy group, the corresponding distances are 0.020 (3) and 0.078 (4) Å. In the crystal, there are only very weak intermolecular C—H⋯O hydrogen bonds and O⋯I contacts [3.080 (2) Å]. The molecules are approximately parallel to (100), forming a layered structure.

In the title compound, C 12 H 11 IO 4 , the C and O atoms of both methoxy groups lie very close to the mean plane of the six C atoms of the benzene ring. The O and C atoms of the group lying closest to the I atom are 0.012 (3) and 0.022 (4) Å , respectively, out of the mean plane. For the other methoxy group, the corresponding distances are 0.020 (3) and 0.078 (4) Å . In the crystal, there are only very weak intermolecular C-HÁ Á ÁO hydrogen bonds and OÁ Á ÁI contacts [3.080 (2) Å ]. The molecules are approximately parallel to (100), forming a layered structure.

Comment
Coumarin is the simplest member of the group of oxygen heterocyclics called benzo-2-pyrone. Coumarins are an important class of compounds due to their presence in natural products as well as their medicinal applications such as anti-inflammatory (Lin et al., 2006), anti-viral (Massimo et al., 2003), antioxidant (Tyagi et al., 2003), antibacterial (Nawrot-Modranka et al., 2006), antifungal (Sardari et al., 1999), anti-HIV (Huang et al., 2005) and as anti-carcinogenic (Elinos-Baez et al., 2005). Besides the wide spectrum of biological applications of coumarin and its derivatives, there are also applications as cosmetics, optical brightening agents, and laser dyes. A recent report has revealed the anion sensing ability of some coumarin derivatives. Among various coumarin derivatives, recent pharmacological evaluation of iodocoumarins as cannabinoid receptor antagonists and inverse agonists has been done. Iodocoumarins such as 8-iodo-7-hydroxycoumarin exhibited moderate activity and 8-iodo-5,7-dihydroxycoumarin displayed good antimicrobial properties with MIC values <100 µg/ ml. Also, iodocoumarins had been successfully used for the optimization of reaction conditions and kinetic studies in high throughput format. Because of the biological and pharmaceutical importance of iodocoumarins, several protocols for the synthesis have been reported.
In the light of the mentioned above we planned to synthesize iodocoumarins by reaction of 5,7-dimethoxy-4-methylcoumarin with iodine in basic media (Ali & Ilyas, 1986).
In the molecule of the title compound ( Fig. 1), the best plane through the aromatic ring shows an r.m.s. deviation of 0.0059 Å; the O1-C2-C3-C4-C10-C9 ring shows a larger deviation from planarity, with an r.m.s. deviation of 0.0279 Å. The angle between these two planes is 2.85 (5) The iodine atom is approximately in the plane of the benzene ring and the methyl group is only slightly out of the pyrone ring plane.
In the crystal, the molecules are linked by very weak C-H···O hydrogen bonds and O···I contacts [3.080 (2) Å.]. There are no classic hydrogen bonds. The molecules are approximately parallel to (100), forming a layered structure (Fig. 2).

Experimental
To a stirred solution of 5,7-dimethoxy-4-methylcoumarin (2.20 g, 10 mmol) in 15-20 ml of methanol containing 8.2 g KOH was dropwise added to a solution of I 2 (2.56 g, 10 mmol) over a period of 30 min and stirred at room temperature for about which was removed by preparative thin layer chromatography (benzene:acetone; 3:2). The pure compound thus obtained was crystallized with CHCl 3 -MeOH as shining crystals of (I) (50 mg, m.p. 523 K).

Refinement
All H atoms were located in a difference Fourier synthesis, placed in calculated positions and refined as riding on their parent atoms, using SHELXL97 (Sheldrick, 2008) defaults. Fig. 1. A plot of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 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 (Å 2 )
x y z U iso */U eq I1 0.85918 (