A mixture of 1-{2-chloro-4-fluoro-5-[(tetrahydro-3-oxo-1H,3H-[1,3,4]thiadiazolo[3,4-a]pyridazin-1-ylidene)-amino]phenyl}-3-methyl-s-triazine-2,4,6(1H,3H,5H)-trione (1.00 g, 2.27 mmol), potassium carbonate (0.627 g, 4.54 mmol) and allyl bromide (0.329 g, 2.72 mmol) in acetone is stirred overnight at 40° C. and poured into water. The aqueous mixture is extracted with ethyl acetate. The organic extract is washed with water, dried over anhydrous magnesium sulfate, and concentrated in vacuo to give the title product as a white glass (0.8 g) which is identified by NMR spectral analyses.
