4-Methyl-2-oxo-2H-chromen-7-yl 4-methoxybenzenesulfonate

In the title compound, C17H14O6S, the 2H-chromene ring is essentially planar, with a maximum deviation of 0.016 (1) Å. The dihedral angle between the 2H-chromene and the benzene rings is 54.61 (5)°. The C atom of the methoxy group is close to coplanar with its attached ring [deviation = 0.082 (2) Å]. In the crystal, molecules are connected via C—H⋯O hydrogen bonds, forming sheets lying parallel to the bc plane. Weak C—H⋯π interactions are also observed.

In the title compound, C 17 H 14 O 6 S, the 2H-chromene ring is essentially planar, with a maximum deviation of 0.016 (1) Å . The dihedral angle between the 2H-chromene and the benzene rings is 54.61 (5) . The C atom of the methoxy group is close to coplanar with its attached ring [deviation = 0.082 (2) Å ]. In the crystal, molecules are connected via C-HÁ Á ÁO hydrogen bonds, forming sheets lying parallel to the bc plane. Weak C-HÁ Á Á interactions are also observed.   Table 1 Hydrogen-bond geometry (Å , ).

Related literature
Cg1 is the centroid of the O2/C9-C13 ring.   TNF-α (Cheng et al., 2004). Apart from these biological activity, this class of molecules is also widely used as fluorescent labels for molecular studies of nucleic acids and proteins.
In the crystal, (Fig. 2), the molecules are connected via weak intermolecular C-H···O hydrogen bonds (Table 1) to form two-dimensional networks parallel to the bc-plane. Furthermore, the crystal structure is stabilized by weak C-H···π interactions involving the Cg1 (O2/C9-C13) ring.

Experimental
The synthetic procedure followed is modified from the recent work by Fusegi et al. (2009). A mixture of 4-methylumbelliferone (0.176 g, 1.00 mmol), K 2 CO 3 (0.345 g, 2.5 mmol), and 4 Methoxybenzene sulphonyl chloride (0.130 g, 1.1 mmol) in ethyl acetate (10 ml) was refluxed for 5 hrs. After cooling, the solvent was evaporated under reduced pressure. H 2 O (30 ml) was added to the residue and the contents was extracted with AcOEt (3 × 100 ml). The combined organic layer was washed with H 2 O (3 × 80 ml) and brine (1 × 100 ml) and was dried over MgSO 4 . The solvent was evaporated in vacuo and the residue was recrystallized from hexane -AcOEt (7: 1) to give the title compound as colourless blocks.

Refinement
All hydrogen atoms were positioned geometrically [C-H = 0.93 or 0.96 Å] and were refined using a riding model, with U iso (H) = 1.2 or 1.5 U eq (C). A rotating group model was applied to the methyl groups.

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