1-Methyl-3-(2-methylphenyl)-3,3a,4,9b-tetrahydro-1H-chromeno[4,3-c][1,2]oxazole-3a-carbonitrile

In the title compound, C19H18N2O2, the five-membered isoxazole ring adopts an envelope conformation and the deviation of the N atom from the mean plane of the isoxazole ring is −0.3256 (11) Å. The pyran ring adopts a half-chair conformation. The isoxazole ring forms dihedral angles of 44.07 (7) and 84.23 (7)° with the pyran and methylbenzene rings, respectively. The molecular structure is stabilized by weak C—H⋯π interactions.

In the title compound, C 19 H 18 N 2 O 2 , the five-membered isoxazole ring adopts an envelope conformation and the deviation of the N atom from the mean plane of the isoxazole ring is À0.3256 (11) Å . The pyran ring adopts a half-chair conformation. The isoxazole ring forms dihedral angles of 44.07 (7) and 84.23 (7) with the pyran and methylbenzene rings, respectively. The molecular structure is stabilized by weak C-HÁ Á Á interactions.
Cg1 is the centroid of the C11-C16 phenyl ring.

Comment
The title compound is an angularly substituted fused tricyclic chromenoisoxazolidine framework, synthesized using Baylis-Hillman derivatives through in situ formation of nitrones followed by an intramolecular (3 + 2) dipolar cycloaddition reaction sequence (Bakthadoss & Murugan, 2010). It is well known that benzopyran and isoxazolidine derivatives possess interesting biological and pharmacological activities (Lin et al., 1996;Hu et al., 2004). Leflunomide is an isoxazole drug used for the treatment of rheumatoid arthritis (Rozman et al., 2002).

Experimental
A mixture of (E)-2-((2-formylphenoxy) methyl) -3-o-tolylacrylonitrile (1.0 mmol), N-methylhydroxylamine hydrochloride (1.1 mmol), pyridine (0.24 ml, 3 mmol) and ethanol (5 ml) were placed in a round bottom flask and refluxed for 6 h. After completion of the reaction as indicated by TLC, the reaction mixture was concentrated under reduced pressure. The crude product was diluted with water (10 ml) and dil HCl (5 ml) and extracted with ethylacetate (20 ml). The organic layer was washed with brine solution (10 ml) and concetrated. The crude product was purified by column chromatography to provide the pure title compound, as a colourless solid. Crystals of the title compound were grown from its solution in methanol by slow evaporation at room temperature.

Refinement
Hydrogen atoms were placed in calculated positions with C-H = 0.93, 0.96, 0.97 and 0.98 Å for aryl, methyl, methylene and methyne type H-atoms, respectively, and refined in riding model with fixed isotropic displacement parameters: U iso (H) = 1.5 U eq (methyl-C) and U iso (H) = 1.2 U eq (the rest of the C atoms).