6-Chloro-2H-1,4-benzoxazin-3(4H)-one

In the title compound, C8H6ClNO2, the conformation of the six-membered heterocyclic ring is close to screw boat and the molecules are linked via intermolecular N—H⋯O hydrogen bonds along the b axis.

In the title compound, C 8 H 6 ClNO 2 , the conformation of the six-membered heterocyclic ring is close to screw boat and the molecules are linked via intermolecular N-HÁ Á ÁO hydrogen bonds along the b axis.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WN2285). to exhibit a wide range of biological activities such as herbicidal (Huang et al., 2005) and antifungal (Macchiarulo et al., 2002). We report here the crystal structure of 6-chloro-

6-Chloro
The molecular structure is illustrated in Fig. 1. The conformation of the six-membered heterocyclic ring is close to screw boat, with atoms C1 and C2 out of the plane of the remaining four atoms by 0.301 (5) and 0.635 (5) Å, respectively. In a related compound containing the benzo[1,4]oxazin-3(4H)-one system (Pang et al., 2006), the heterocyclic ring also adopts a screw boat conformation. The molecules are connected via N -H ··· O hydrogen bonding into chains along the b axis.

Experimental
To a 25 ml round-bottomed flask equipped with a reflux condenser were added 2-chloro-N-(5-chloro-2hydroxyphenyl)acetamide (2.19 g, 10 mmol), potassium carbonate (2.76 g, 20 mmol) and anhydrous DMF (20 ml). The resulting mixture was heated under reflux for 90 min. After this time, the reaction mixture was poured into 80 g of water, and stirred for 15 min. The mixture was extracted with ethyl acetate (2 x 20 ml). The ethyl acetate extract was washed with saturated brine (10 ml). After drying over Na 2 SO 4 , the solvent was removed under vacuum and a colourless solid was obtained in 80% yield (1.46 g). Suitable crystals were grown by evaporation of a CH 2 Cl 2 solution at room temperature for 4 d.

Refinement
All H atoms were positioned geometrically (N -H = 0.86 Å, aromatic C -H = 0.93 Å, methylene C -H = 0.97 Å) and refined using a riding model; U iso (H) = 1.2 U eq (C, N). Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as spheres of arbitrary radius.