Methyl 1-phenyl-3-p-tolyl-1,9b-dihydro-3H-chromeno[4,3-c]isoxazole-3a(4H)-carboxylate

In the title compound, C25H23NO4, the pyran ring of the chroman moiety has an envelope conformation with the methylene C atom as the flap. The isoxazole ring has a twist conformation on the O—C bond. The dihedral angle between their mean planes is 57.87 (9)°. The attached phenyl and benzene rings are twisted away from its mean plane by 56.19 (10) and 50.57 (10)°, respectively. These two rings are normal to each other, subtending a dihedral angle of 89.2 (1)°. In the crystal, there are no classical hydrogen bonds; the molecules are linked via C—H⋯π interactions, forming a two-dimensional network lying parallel to (10-1).

In the title compound, C 25 H 23 NO 4 , the pyran ring of the chroman moiety has an envelope conformation with the methylene C atom as the flap. The isoxazole ring has a twist conformation on the O-C bond. The dihedral angle between their mean planes is 57.87 (9) . The attached phenyl and benzene rings are twisted away from its mean plane by 56.19 (10) and 50.57 (10) , respectively. These two rings are normal to each other, subtending a dihedral angle of 89.2 (1) . In the crystal, there are no classical hydrogen bonds; the molecules are linked via C-HÁ Á Á interactions, forming a two-dimensional network lying parallel to (101).

Comment
Isoxazoline derivatives have been shown to be efficient precursors for the preparation of many synthetic intermediates including γ-amino alcohols and β-hydroxy ketones (Kozikowski, 1984). They display interesting biological properties such as herbicidal, plant growth regulators and antitumour activities (Howe & Shelton, 1990). The title compound in which a chromane and isoxazole ring are fused was synthesized by (Bakthadoss & Murugan, 2010), and we report herein on its crystal structure.
The carboxylate group assumes an extended conformation which can be seen from the torsion angle C8-C24-O4- In the crystal, there are no classical hydrogen bonds. The molecules are linked via C-H···π interactions (Table 1), forming a two-dimensional network lying parallel to plane (1 0 -1).

Experimental
The title compound was synthesized according to the published procedure (Bakthadoss & Murugan, 2010). A mixture of (E)-methyl 2-((2-formylphenoxy)methyl)-3-p-tolylacrylate (2 mmol, 0.60 g) and N-phenylhydroxylamine (3 mmol, 0.33 g) in ethanol (10 ml) was refluxed for 6 h. After the completion of the reaction, as indicated by TLC, the reaction mixture was concentrated under reduced pressure and the resulting crude mass was diluted with water (15 ml) and extracted with ethyl acetate (3 × 15 ml). The organic layers were combined and washed with brine (3 × 15 ml) and dried over anhydrous Na 2 SO 4 , and the solvent was removed under reduced pressure. The crude mass was purified by column chromatography on silica gel (Acme 100-200 mesh), using ethyl acetate-hexane (0.5: 9.5) to afford the pure compound as a colourless solid in 92% yield. Colourless block-like crystals were obtained by slow evaporation of a solution in ethyl acetate-hexane (0.5: 9.5).

Figure 1
The molecular structure of the title molecule, with atom labelling. The displacement ellipsoids are drawn at 30% probability level. the H atoms have been omitted for clarity. 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 R-factors(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.