Ethyl 5-oxo-4-phenyl-5,6-di-hydro-4H-1,3,4-oxadiazine-2-carboxyl-ate

The asymmetric unit of title compound, C12H12N2O4, consists of two independent mol-ecules. In each mol-ecule, the oxadiazine ring has a flattened envelope conformation with the methyl-ene C atom as the flap atom, and the eth-oxy-carbonyl unit is in a syn-periplanar conformation with respect to the oxadiazine ring as indicated by O-C-C=O torsion angles of 1.9 (4) and 2.5 (4)°. The dihedral angles between the mean plane of the oxadiazine ring and the phenyl ring are 80.07 (13) and 42.98 (14)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds and stacked in a double-column along the a-axis direction.