The title compound, C21H18N2O4, crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. In both mol-ecules the oxazine ring has an envelope conformation with the hydroxyl-substituted C atom as the flap. The nitro-benzyl ring and the phenyl ring are almost normal to the mean plane of the benzooxazine ring system with dihdral angles of 85.72 (15) and 82.69 (15)°, respectively, in mol-ecule A, and 85.79 (15) and 87.72 (15)°, respectively, in mol-ecule B. The main difference in the conformation of the two mol-ecules concerns the dihedral angle between the nitro-benzyl ring and the phenyl ring, viz. 79.67 (18) in mol-ecule A and 71.13 (18)° in mol-ecule B. In the crystal, the A and B mol-ecules are linked by an O-H⋯O hydrogen bond. These units are then linked via C-H⋯O hydrogen bonds, forming sheets lying parallel to (010). Further C-H⋯O hydrogen bonds link the sheets to form a three-dimensional network. There are also O-H⋯π and C-H⋯π inter-actions present, reinforcing the three-dimensional structure.
Keywords: crystal structure.