(Z)-4-n-Butyl-2-(4-chloro­benzyl­idene)-2H-1,4-benzo­thia­zin-3(4H)-one

In the title compound, C19H18ClNOS, the thia­zin-3-one ring adopts a slightly distorted screw-boat conformation. An intra­molecular C—H⋯S hydrogen bond encloses an S(6) ring and affects the overall conformation of the mol­ecule. The dihedral angle between the two phenyl rings is 52.3 (2)°. In the crystal, weak C—H⋯O inter­molecular inter­actions stabilize the crystal packing.