Methanol → 2-(3-chloro-4-fluoro-phenyl)-7-hydroxy-1H-benzoimidazole-4-carboxylic acid methyl ester

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Reaction Steps

2-(3-chloro-4-fluoro-phenyl)-7-hydroxy-1H-benzoimidazole-4-carboxylic acid (800 mg, 2.64 mmol) obtained in step 3 was dissolved in methanol, SOCl2 (1.93 ml, 26.41 mmol) was added dropwise thereto and refluxed for 15 hours. The resulting solution was cooled to room temperature, concentrated under a reduced pressure to remove methanol, and the residue was neutralized with NaHCO3. Then, the neutralized residue was extracted with ethyl acetate and concentrated under a reduced pressure to obtain a residue which was purified by silica gel chromatography to obtain the title compound (690 mg, 2.15 mmol) in a yield of 81%.

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