Triethylamine → 4-chloro-N-[3-(4-oxo-3,4-dihydrophthalazin-1-ylmethyl)phenyl]butyramide

4-Chlorobutyryl chloride (5.42 g, 38.4 mmol) was added dropwise at ambient temperature to a stirred mixture of 4-(3-aminobenzyl)-2H-phthalazin-1-one (8 g, 32 mmol; prepared in a manner similar to that described above), triethylamine (5.35 ml, 38.4 mmol) and 1,4-dioxane (40 ml), the mixture was stirred at ambient temperature for 1 hour, then it was poured into ice-water (100 ml). The resulting solid was collected by filtration, washed with water (30 ml) and dried in vacuo to give 4-chloro-N-[3-(4-oxo-3,4-dihydrophthalazin-1-ylmethyl)phenyl]butyramide (12.34 g) as an off-white solid, m.pt. 180–184° C.