A mixture of 5-bromo-indazole-1-carboxylic acid tert-butyl ester (3.37 mmol), 2-fluoro-4-(4,4,5,5-tetramethyl-[1,3] dioxolan-2-yl)-benzaldehyde (1.01 g, 4.04 mmol)) PdCl2(dppf).DCM (27 mg, 0.03 mmol) in 16 mL of dioxane was degassed (evacuate in vacuo and pressurize with argon, three times); cesium carbonate in water (2M, 6.73 mL, 13.46 mmol) was added and the mixture degassed three more times as described above. The resulting mixture was heated at 85° C. for 6 h, then it was allowed to cool to room temperature and left overnight. The mixture was diluted with dichloromethane and washed with brine. The aqueous phase was extracted with dichloromethane and the combined organic phases were washed with brine, dried over MgSO4, filtered and evaporated to give crude product. Chromatography on silica gel (elution with diethyl ether/heptane) gave 820 mg of the title compound.
