Dimethylcarbamoyl Chloride → N,N-Dimethyl-N'-[2-[6-(4-oxo-4H-1,3-benzothiazin-2-yl)-2-pyridyl]ethyl]urea

A mixture of 2-[6-(2-aminoethyl)-2-pyridyl]-4H-1,3-benzothiazine-4-one trifluoroacetic acid salt (0.45 g, 1.1 mmol), potassium carbonate (0.46 g, 3.3 mmol) and acetonitrile (20 ml) was stirred at room temperature for 20 minutes. Successively N,N-dimethylcarbamoyl chloride (0.47 g, 4.3 mmol) was added to the mixture, and the mixture was stirred at room temperature for 3 hrs. The precipitates were filtered, and the filtrate was concentrated. The residue was subjected to a silica gel column chromatography. The fractions eluted with chloroform-ethanol (20:1, v/v) were collected, concentrated and recrystallized from chloroform-hexane to give the titled compound (0.31 g, 77%) as white crystals.