To a solution of 5-(2-bromophenyl)-6-(1-isopropyl-6-oxo-1,6-dihydro-3-pyridazinyl)-2,3-pyrazinedicarbonitrile (3.00 g) in 1,3-dimethyl-2-imidazolidinone (6 ml), (4-methoxybenzyl)amine (0.96 ml) was added and the mixture was stirred at 25-30° C. for 100 hours. After addition of 0.5N aq. NaOH (15 ml), the mixture was stirred for one hour and a precipitate was collected by filtration to give a solid. The solid was dissolved in EtOAc, washed with water, dried over MgSO4 and concentrated under reduced pressure to give a residue. The residue was purified by column chromatography on silica gel eluting with a mixture of n-hexane and EtOAc (70:30 v/v) to give 5-(2-bromophenyl)-6-(1-isopropyl-6-oxo-1,6-dihydro-3-pyridazinyl)-3-[(4-methoxybenzyl)amino]-2-pyrazinecarbonitrile as an amorphous solid (2.58 g) containing 6-(2-bromophenyl)-5-(1-isopropyl-6-oxo-1,6-dihydro-3-pyridazinyl)-3-[(4-methoxybenzyl)amino]-2-pyrazinecarbonitrile.
