Crystal structure of 5-benzyl-8-bromo-2-meth-yl-1,3-oxazolo[4,5-c][1,8]naphthyridin-4(5H)-one.

The title compound, C17H12BrN3O2, was unexpectedly isolated during an attempt to synthesize pyridodiazepinediones and identified as an oxazolonaphthyridinone derivative. The almost planar oxazolonaphthyridinone ring (r.m.s. deviation = 0.016 Å) makes a dihedral angle of 61.6 (2)° with the phenyl ring. In the crystal, columns of mol-ecules stacked along the a axis are formed by π-π inter-actions between the six-membered rings of the oxazolonaphthyridone moieties [centroid-to-centroid distances = 3.494 (2)-3.906 (3) Å], which further inter-act through C-H⋯π contacts with the phenyl rings.