A solution under stirring and dry N2 of 4-chloro-1-(3,5-dichloro-pyridin-4-ylmethyl)-6-methoxy-phthalazine (1 g, 2.82 mmoles), prepared as described in example 45, in DMF (25 ml), at room temperature, was added with morpholine (0.73 g, 8.46 mmoles) and the temperature was raised to 100° C. After 14 hours the whole was brought to dryness and the solid partitioned between water and CH2Cl2. The organic phase was washed with water, anhydrified and brought to dryness to give a solid which was flash chromatographed (eluent: hexane/ethyl acetate 6:4, then in gradient up to 3:7) to give 0.9 g of the title compound (yield: 79%). m.p.: 179-180° C.
