To a solution of 5-bromo-N-(3,5-dichlorobenzyl)-8-hydroxy-1,6-naphthyridine-7-carboxamide from Example 50 (25 mg, 0.060 mmol), piperazine (30.25 mg, 0.35 mmol) in 1-methylpyrrolidinone (0.25 ml) was heated at 135 C for 18 hrs. The resulting mixture was further diluted with DMF (0.25 ml) and TFA (50 ul) and purified by preparative HPLC (Gilson Semi Preparative HPLC System and a YMC Combiprep Pro Column (50×20 mm i.d., C18, S-5 um, 120A) eluting with 5-95% acetonitrile/water (0.1%) at 15 ml/min) to afford the title compound as the piperazin-4-ium trifluoroacetate salt after lyophillization.
