A microwave tube was charged with 6-chloro-8-(cyclopropyl(4-methoxybenzyl)amino)-N-(3-fluoropyridin-4-yl)imidazo[1,2-b]pyridazine-3-carboxamide (35 mg, 0.075 mmol), 1-methylpiperidin-4-amine (86 mg, 0.750 mmol) and NMP (1 mL). The reaction mixture was irradiated in a microwave (300 W) for 20 minutes at 100° C. The crude reaction mixture was dissolved in a small amount of MeOH and purified by reversed phase HPLC (YMC ODS-A 5 um 30×250 mm, 10-90% aqueous methanol containing 0.1% TFA, 25 mL/min, 30 min gradient, monitored at 220 nm). The product (retention time=30.463 minutes) was isolated and lyophilized to dryness. The crude material was dissolved in CH2Cl2 (2 mL) and treated with TFA (0.5 mL) and stirred at room temperature for 2 hours, then concentrated to dryness. The crude reaction product was dissolved in a small amount of MeOH and purified by reversed phase HPLC (YMC ODS-A 5 um 30×250 mm, 10-90% aqueous methanol containing 0.1% TFA, 25 mL/min, 30 min gradient, monitored at 220 nm). The product (retention time=24.643 minutes) was isolated and lyophilized to dryness to afford 8-(cyclopropylamino)-N-(3-fluoropyridin-4-yl)-6-(1-methylpiperidin-4-ylamino)imidazo[1,2-b]pyridazine-3-carboxamide (8.5 mg, 14.42%). HPLC Rt=2.681 min (YMC S5 ODS 4.6×50 mm, 10-90% aqueous methanol containing 0.2% H3PO4, 4 min gradient, monitored at 220 nm). [M+H+]=425.0.
