3-(4-Chlorophenyl)-5-phenyl-4,5-dihydro-1,3-oxazole

In the title compound, C15H12ClNO, the isoxazoline ring adopts an envelope conformation with the C atom bearing an unsubstituted phenyl ring as the flap atom. The chlorinated phenyl group is nearly in-plane with the four coplanar atoms of the heterocycle and the corresponding mean planes enclosing an angle of 1.16 (7)°. The unsubstituted phenyl group attached to the envelope flap atom approaches a nearly perpendicular orientation relative to the isoxazoline ring with a dihedral angle of 74.93 (7)°. In the crystal, weak C—H⋯O, C—H⋯N and C—H⋯π interactions connect the molecules into layers perpendicular to the a axis.

In the title compound, C 15 H 12 ClNO, the isoxazoline ring adopts an envelope conformation with the C atom bearing an unsubstituted phenyl ring as the flap atom. The chlorinated phenyl group is nearly in-plane with the four coplanar atoms of the heterocycle and the corresponding mean planes enclosing an angle of 1.16 (7) . The unsubstituted phenyl group attached to the envelope flap atom approaches a nearly perpendicular orientation relative to the isoxazoline ring with a dihedral angle of 74.93 (7) . In the crystal, weak C-HÁ Á ÁO, C-HÁ Á ÁN and C-HÁ Á Á interactions connect the molecules into layers perpendicular to the a axis.

Experimental
Cg is the centroid of the C11-C16 ring.
Isoxazoles appear in numerous medicinally active compounds and natural products of biological significance.
Additionally, they are valuable as synthetic intermediates or protecting groups in organic synthesis. Also, isoxazoles serve as monomers for the synthesis of substituted poly(imine)s by cationic ring-opening polymerization (Wiesbrock et al., 2005). Due to our interest in developing new isoxazole-based heterocycles, we have synthesized the title compound to study its crystal structure.
The title molecule features a chlorinated as well as a non-halogenated phenyl group as substituents on a central isoxazole core. The latter one adopts a 5 E conformation with the flap atom on C3 (Cremer & Pople, 1975). While the halogenated phenyl group is nearly in-plane with the isoxazoline moiety -the least-squares planes defined by the respective intracyclic atoms intersect at an angle of 7.16 (7) ° only -the non-substituted phenyl group adopts a nearly perpendicular orientation towards the isoxazole moiety. The corresponding least-squares planes in the latter case enclose an angle of 74.93 (7) ° ( Fig. 1).
In the crystal, only weak C-H···O and C-H···N contacts whose range falls slightly below the sum of van-der-Waals radii of the atoms participating in them are observed. The hydrogen atom that is part of the C-H···N contact stems from the chlorinated phenyl substituent and is also the origin of a bifuracated hydrogen bond that extends to the oxygen atom as acceptor. The C-H···O contacts are supported by the intracyclic methylene group as well as a hydrogen atom on the nonsubstituted phenyl group. Taking into account the latter two findings, the oxygen atom acts as threefold acceptor. Metrical parameters as well as information about the symmetry codes for these contacts are summarized in Table 1. In total, the molecules are connected to layers perpendicular to the crystallographic a axis. In terms of graph-set analysis (Etter et al., 1990;Bernstein et al., 1995), the descriptor for these contacts is C 1 1 (4)C 1 1 (5)C 1 1 (5)C 1 1 (6) on the unary level. The shortest intercentroid distance between two aromatic systems was measured at 4.709 (3) Å and is observed between the halogenated phenyl group and its symmetry-generated equivalent (Fig. 2).
The packing of the title compound in the crystal structure is shown in Figure 3.

Experimental
An equimolar mixture of 1-(4-chlorophenyl)-N-hydroxymethanimine (0.5 g, 0.0032 mol), N-chloro succinamide (0.58 g, 0.0032 mol) and sodium bicarbonate (0.537 g, 0,0064 mol) in dichloromethane (10 ml) and water (10 ml) was stirred at 0 °C for 1 h. Styrene (0.366 g, 0.0035 mol) was then added to the reaction mixture and stirring was continued for another 12 h at room temperature. After completion of the reaction, the reaction mixture was concentrated and purified by column chromatography using petrol ether and ethyl acetate (v/v = 1:1) as the eluent to afford the title compound as a white solid, yield: 0.63 g (76.8%) (ChemSpider ID: 10496235).

Refinement
Carbon-bound H atoms were placed in calculated positions (C-H 0.95 Å for aromatic carbon atoms, C-H 1.00 Å for methine groups and C-H 0.99 Å for methylene groups) and were included in the refinement in the riding model approximation, with U(H) set to 1.2U eq (C).

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