A mixture of 6-hydroxy-2-(2-pyridyl)-4H-1,3-benzothiazine-4-one (0.30 g, 1.1 mmol), benzyl bromide (0.61 g, 3.5 mmol) and potassium carbonate (0.32 g, 2.3 mmol) and DMF (10 ml) was stirred at room temperature for 2 hrs. The reaction mixture was diluted with water and extracted with ethyl acetate. The extract was washed with water and dried. The solvent was evaporated under reduced pressure. The obtained crystals were recrystallized from tetrahydrofuran-hexane to give the titled compound (0.39 g, 95%).
