1-(10H-phenothia­zin-10-yl)ethanone

In the title compound, C₁₄H₁₁NOS, the phenothia­zine unit has a butterfly conformation and the central six-membered ring has a boat form. The fold angle between the benzene rings is 46.39 (7)°, which is larger than found in similar compounds, probably as a result of steric repulsion between the phenothia­zine fragment and the acetyl group.