To a solution of 5-bromo-6-fluoro-1-methyl-1H-indazole (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., 1-(6-chloroimidazo[1,2-b]pyridazin-3-yl)ethanone (1.691 g, 8.64 mmol) in THF (20 mL) was added dropwise. The reaction solution was stirred for additional 2 h and was quenched with NH4Cl (aq). The resulting mixture was extracted with EtOAc. Combined organic layers were washed with NH4Cl(aq), dried over Na2SO4 and concentrated in vacuo to afford a crude product, which was purified on silica gel column chromatography (Hexanes:EtOAc) to give the title compound in 34% yield. LCMS (method B): [MH]+=346, tR=2.14 min.
