To a 0° C. solution of trans-N1-(3-(3-chlorophenyl)imidazo[1,2-b]pyridazin-6-yl)cyclohexane-1,4-diamine (50 mg, 0.146 mmol) and DIPEA (0.08 mL, 0.44 mmol) in DMSO (0.6 mL) was added dropwise MeSO3Cl (20 mg, 0.176 mmol). The resulting mixture was stirred at room temperature for 6 h. TLC (CH2Cl2:MeOH=10:1) showed most of starting material was converted. The mixture was partitioned between water (50 mL) and EtOAc (50 mL) and separated. The aqueous layer was extracted with EtOAc (50 mL×3). The combined extracts were dried over Na2SO4, filtered and concentrated in vacuo. The residue was purified by prep-HPLC to give EX. 8-80 (10.8 mg, 18%) as a white solid.
