1-(5,5-Dioxido-10H-phenothiazin-10-yl)ethanone

In the title compound, C14H11NO3S, the six-membered thiazine ring fused to two benzene rings adopts a distorted boat conformation. The dihedral angle between the mean planes of the two benzene rings is 45.8 (1)degrees. The crystal packing is stabilized by weak intermolecular C-H center dot center dot center dot O interactions