Crystal structure of 4-methoxyphenyl 2-oxo-2H-chromene-3-carboxylate

In the title compound, C17H12O5, the dihedral angle between the planes of the coumarin ring system (r.m.s. deviation = 0.015 Å) and the benzene ring is 48.04 (10)°. The central CO2 group subtends a dihedral angle of 27.15 (11)° with the coumarin ring system and 74.86 (13)° with the benzene ring. In the crystal, molecules are linked by C—H⋯O interactions, which generate a three-dimensional network. Very weak C—H⋯π interactions are also observed.


S1. Chemical context
The 2-oxo-2H-chromene is a useful starting material for the construction of heterocyclic compounds with a broad spectrum of biological activities. Especially the 3-substituted derivatives exhibits pharmacological effects such as analgesic, anti-arthritis, anti-inflammatory, anti-pyretic, anti-viral, anti-cancer and anticoagulant properties (Chimenti et al., 2009;Traven et al., 2004;Lacy et al., 2004). Moreover, these derivatives are well known for their anti-microbial activity toward different microorganisms, they show anti-microbial activity with reference to anti-H. pylori activity. (Kawase et al., 2001).
2-oxo-2H-chromenes (coumarins) have been also used in the field of medicine, cosmetics and fluorescent dyes. They are efficient fluorophores characterized by good emission quantum yields and are used as materials for lasers in organic light emitting devices, non-linear optical chromophores and fluorescent labels. Keeping these facts in mind and in continuation of our work on 2-oxo-2H-chromene derivatives Devarajegowda, et al.,2013), herein we report the synthesis and crystal structure of 4-Methoxyphenyl 2-oxo-2H-chromene-3-carboxylate (I).

S2. Structural commentary
In the title molecule (I), C 17 H 12 O 5 , the coumarin ring is almost planar, the rms deviation (considering non Hydrogen atom)

S3. Supramolecular features
In the crystal structure, the molecules are linked into zig-zag C9 chains along c axis via C3-H3···O3 intermolecular interactions. Further, C12-H12···O2 interactions between the molecules in the neighbouring chains leads to C8 chains along a axis, and thus forming sheets in the ac plane. These sheets are interconnected via an intermolecular C15-H15···O2 interactions which form helical C7 chains running along b axis, and hence a three dimensional architecture is displayed. An additional C17-H17B···O5 interactions between the molecules in the neighbouring C7 helical chains leading to the formation of C3 chains along a axis results in sheets along ab plane. Thus, a grid like three dimensional supporting information structure is observed. Packing of the molecules displaying the columns formed along a axis is shown in Figure 2.

S4. Synthesis and crystallization
A solution of dicyclohexylcarbodiimide (DCC) dissolved in dried CH 2 Cl 2 was added to a solution containing coumarin 3carboxylic acid (1.0 mmol) and 4-methoxyphenol (1.0 mmol) and a catalytic amount of N-N-Dimethylaminopyrimidine (DMAP) in anhydrous dichloromethane (CH 2 Cl 2 ), under stirring, After 24 hrs of stirring, dicyclohexylurea was filtered off and the solution was concentrated. The solid residue was purified by column chromatography on silica gel (60-120) using chloroform (CHCl 3 ) as an eluent. Colourless prisms of the title compound were grown by slow evaporation of an ethanol solution at room temperature.

S5. Refinement details
Crystal data, data collection and structure refinement details are summarized in Table 1. The H atoms were positioned with idealized geometry using a riding model with C-H = 0.93-0.99 Å. All H-atoms were refined with isotropic displacement parameters (set to 1.2-1.5 times of the U eq of the parent atom).

Figure 1
The molecular structure of the title compound, showing displacement ellipsoids drawn at the 50% probability level.

Figure 2
The packing of (I) showing grid like structure when viewed along a axis.

Figure 3
The packing of (I) showing C-H···π interactions when viewed along a axis.

Figure 4
The formation of the title compound.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )