In methylene chloride (10 ml) was dissolved 1-(4-methoxybenzyl)-3-indazolylcarboxylic acid (630 mg, 2.23 mmol). To the resulting solution were added oxalyl chloride (292 μl, 3.53 mmol) and DMF (1 drop). The resulting mixture was stirred until the mixture became uniform. From the reaction mixture, the solvent was distilled off under reduced pressure. The residue was dissolved in methylene chloride (20 ml). Ethyl (4-amino-5-chloro-2-fluorophenyl)acetate (517 mg, 2.23 mmol) and triethylamine (621 μl, 4.46 mmol) were added to the resulting solution. The resulting mixture was heated under reflux for 15 hours. After cooling, the reaction mixture was added with water (50 ml), followed by extraction with chloroform (200 ml). The extract was dried over anhydrous magnesium sulfate and distilled under reduced pressure to remove the solvent. The residue was purified by chromatography on a silica gel column, whereby from hexane-ethyl acetate (4:1) eluate fractions, ethyl (5-chloro-2-fluoro-4-(1-(4-methoxybenzyl)-3-indazolylcarbonylamino)phenyl)acetate (881 mg, 80%) was obtained as a pale yellow amorphous substance.
