A solution of 4-chloro-1-(2-iodoethyl)-3,5-diphenyl-1H-pyrazolo[3,4-c]pyridazine (example 74 step 1 (Compound 81)) (100 mg, 0.21 mmol) in CH2Cl2 (1 ml) was added to piperazinone hydrochloride (160 mg, 1.05 mmol) and diisopropylethylamine (DIPEA) (220 μl, 12.6 mmol) in CH2Cl2 (0.5 ml) and the reaction stirred at ambient for 2 days. Further piperazinone hydrochloride (160 mg, 1.05 mmol) and diisopropylethylamine (DIPEA) (220 μl, 12.6 mmol) were added and the reaction stirred for a further 24 h. The resultant residue was purified using chromatography (silica gel, gradient 20 to 100% ethyl acetate/isohexane, then 0 to 100% ethyl acetate/acetone) followed by preparative HPLC to give Compound 84 as a yellow glass solid (17 mg).
