To a solution of 5-bromo-6-fluoro-1-methyl-1H-indazole (intermediate L) (1.800 g, 7.86 mmol) in THF (79 mL) at −100° C. was added n-BuLi (5.40 mL, 8.64 mmol) dropwise. After stirring for 1 h at −100° C., a solution of 1-(6-chloroimidazo[1,2-b]pyridazin-3-yl)ethanone (intermediate M) (1.691 g, 8.64 mmol) in THF (20 mL) was added dropwise. The reaction solution was stirred for additional 2 h and quenched with NH4Cl (aq). The resulting mixture was extracted with EtOAc. The combined organic layers were washed with NH4Cl (aq), dried over Na2SO4 and concentrated in vacuo to afford the crude product which was purified by column chromatography (hexanes:EtOAc) to give the title compound in 34% yield. LCMS (method B): [MH]+=346, tR=2.14 min.
