A mixture of 209 mg of 1-(6-{[6-(4-fluorophenyl)[1,2,4]triazolo[4,3-b]pyridazin-3-yl]sulphanyl}-1,3-benzothiazol-2-yl)-3-(2-morpholin-4-ylethyl)urea and 241 mg of zinc in 7 cm3 of acetic acid is stirred at 20° C. for 1.5 h and then heated at 50° C. for 3.5 h. 241 mg of zinc are again added and the mixture is again left for 1 h at 50° C. After stirring overnight at 20° C., aqueous ammonia is added so that the reaction mixture changes to an alkaline pH. This mixture is extracted with ethyl acetate. The organic phase is washed with a saturated solution of sodium bicarbonate and then with brine and is then dried with magnesium sulphate and evaporated to dryness under vacuum. The residue is purified by chromatography on a Merck cartridge of 25 g of silica 15-40 μm by solid deposit, elution being carried out with a 9/1 mixture of dichloromethane/(dichloromethane:38/methanol:17/aqueous ammonia:2). 48 mg of 1-(6-{[6-(4-fluorophenyl)-7,8-dihydro-[1,2,4]triazolo[4,3-b]pyridazin-3-yl]sulphanyl}-1,3-benzothiazol-2-yl)-3-[2-(morpholin-4-yl)ethyl]urea are thus obtained in the form of a white solid, the characteristics of which are as follows:
