1-Methyl-1H-2,1-benzothiazin-4(3H)-one 2,2-dioxide

In the crystal structure of the title compound, C9H9NO3S, there is distorted tetrahedral geometry around the S atom. The sulfonyl group is almost normal to the benzene ring, while the carbonyl O atom and methyl C atom are on opposite sides of this ring. The heterocyclic ring adopts a half-boat conformation with the S atom out of the plane. The molecules are dimerized by hydrogen bonding involving the benzene ring and the sulfonyl group. These dimers are linked to each other in the same way. There is an intramolecular hydrogen bond between a methyl C—H group and a sulfonyl O atom, and a π–π interaction between the aromatic rings of two dimers at a centroid-to-centroid distance of 3.6373 (13) Å.