3-(1,3-Benzodioxol-5-yl)-3H-benzo[f]isobenzofuran-1-one

In the title compound, C19H12O4, the dioxole ring adopts a flattened envelope conformation with the methylene C at the flap [deviation = 0.104 (2) Å]. The benzene ring of the benzodioxole ring system makes a dihedral angle of 76.45 (5)° with the planar [maximum deviation = 0.016 (1) Å] 3H-benzo[f]isobenzofuran-1-one ring system. In the crystal structure, the molecules are linked into C(5) chains running along the b axis by intermolecular C—H⋯O hydrogen bonds. In addition, C—H⋯π interactions are observed.

In the title compound, C 19 H 12 O 4 , the dioxole ring adopts a flattened envelope conformation with the methylene C at the flap [deviation = 0.104 (2) Å ]. The benzene ring of the benzodioxole ring system makes a dihedral angle of 76.45 (5) with the planar [maximum deviation = 0.016 (1) Å ] 3H-benzo[f]isobenzofuran-1-one ring system. In the crystal structure, the molecules are linked into C(5) chains running along the b axis by intermolecular C-HÁ Á ÁO hydrogen bonds. In addition, C-HÁ Á Á interactions are observed.

Comment
Molecules containing a benzofuran ring system have attracted considerable interest in view of their biological and pharmacological properties (Howlett et al., 1999;Twyman & Allsop, 1999). Furan compounds exhibit antibacterial and antifungal activities (Valerga et al., 2009). Against this background and in order to obtain detailed information on molecular conformation in the solid state, an X-ray crystallographic study of the title compound has been carried out and the results are presented here.
In the crystal structure, intermolecular C-H···O hydrogen bonds (Table 1) involving atoms C12 and O1, link the molecules into chains which run parallel to the b axis and can be described by a graph set motif of C(5). In addition, the crystal packing is stabilized by C-H···π interactions involving the C13-C18 ring.

Experimental
NaBH 4 (1.6 g, 43.75 mmol) was carefully added in small portions to a solution of keto acid (3.5 g, 10.93 mmol) in THF-EtOH (2:5) at 273 K. The reaction mixture was refluxed for 12 h and then poured into ice water (200 ml). The reaction mixture was acidified using HCl (pH = 2-3) and then stirred for 0.5 h at room temperature. The solid formed was filtered and washed with methanol to afford lactone as a colourless solid.

Refinement
H atoms were positioned geometrically and allowed to ride on their parent C atoms, with C-H distances fixed in the range 0.93-0.98 Å and U iso (H) = 1.2U eq (C). Fig. 1

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds