Trans-6-(2-(4-Carboxyphenyl)ethenyl]-1(2H)-phthalazinone (46 g), thionyl chloride (315 ml) and DMF (2 ml) were mixed and heated slowly to 42° C. and maintained at 42°-48° C. until the gas evolution subsided. The reaction mixture was diluted with toluene and filtered to give the crude acid chloride (52 g). The crude acid chloride (25 g) was dissolved in THF (1250 ml) and 3-dimethylaminopropylamide (250 ml) was added dropwise. After stirring overnight at room temperature the precipitate was filtered, washed with ether (2 l) and then dried to give the amide (13.5 g). The amide was purified via the hydrochloride salt, mp 287° C.
