A mixture of 2-(2,3-dihydro-1,4-benzothiazin-4-yl)ethyl methanesulfonate (0.49 g, 1.82 mmol), 2-hydroxy-6-cyanonaphthalene (0.28, 1.65 mmol) and potassium carbonate (1.15 g, 8.28 mmol) in dry dimethyl formamide (15 mL) was stirred at 80° C. for 12 h. Water (50 mL) was added and extracted with ethyl acetate (2×25 mL). The combined ethyl acetate layer was washed with water (25 mL), brine (20 mL), dried (Na2SO4), filtered and the solvent was evaporated under reduced pressure. The residue was chromatographed over silica gel using a mixture of ethyl acetate and pet. ether to afford the title compound (0.41 g, 72%) as a pale yellow solid. mp: 94-96° C.
