(Z)-3-(3,4-Di­meth­oxy­benz­yl)-1,5-benzo­thia­zepin-4(5H)-one

In the title compound, C(18)H(17)NO(3)S, the thia­zepine ring adopts a slightly distorted twist-boat conformation. The dihedral angle between the mean plane of the benzo­thia­zepin ring system and the benzene ring is 60.3 (1)°. In the crystal, mol­ecules are linked by two pairs of inversion-related N—H⋯O and C—H⋯O hydrogen bonds, generating alternating R (2) (2)(8) and R (2) (2)(6) ring motifs, respectively, in a zigzag supra­molecular chain that runs along the c axis. These chains stack along the a axis via S⋯C [3.424 (2) Å] contacts. A three-dimensional supra­molecular network is consolidated by C—H⋯π and π–π inter­actions [inter-centroid distance between di­meth­oxy­benzene rings = 3.815 (1) Å]. The crystal studied was a non-merohedral twin, with a refined value of the minor twin fraction of 0.2477 (6) .