A mixture of 256 mg (1.00 mmol) 1-chloro-4-(4-pyridylmethyl)phthalazine and 556 mg (3.00 mmol) 4-phenoxyaniline (Aldrich) is heated for 2 h at 90° C. The melt is cooled and stirred with 6 ml NH3 solution (10% in water or 10 ml sat. NaHCO3 solution) and 15 ml dichloromethane/methanol 50:1 for 30 min. The aqueous phase is then separated off and extracted again with dichloromethane. The organic phase is dried (Na2SO4), concentrated by evaporation, and chromatographed (SiO2; ethyl acetate→ethyl acetate/CH3OH, 19:1→10:1). Crystallization from acetonitrile yields the title compound: m.p.: 186-189° C.; Anal. calc. (C26H21N4O) C, 77.02%; H, 5.22%; N, 13.82%. found C, 77.2%; H, 4.9%; N, 13.8%. The starting material is prepared as follows:
