To a solution of trans-N1-(3-(3-chlorophenyl)imidazo[1,2-b]pyridazin-6-yl)cyclohexane-1,4-diamine (90 mg, 0.26 mmol) and pyridine (0.08 mL, 1.04 mmol) in CH2Cl2 (2.6 mL) was added dropwise chloroacetyl chloride (0.03 mL, 0.39 mmol). The resulting mixture was stirred at room temperature overnight. TLC (CH2Cl2:MeOH=10:1) showed the reaction was complete. The mixture was poured into sat. aq. NaHCO3 (100 mL) and extracted with EtOAc (50 mL*3). The extracts were dried over Na2SO4, filtered and concentrated in vacuo to give crude 2-chloro-N-(trans-4-((3-(3-chlorophenyl)imidazo[1,2-b]pyridazin-6-yl)amino)cyclohexyl)acetamide (110 mg, 101%) as a yellow solid.
