Trimethylsilyldiazomethane → Methyl 3-({6-[(5-bromo-6-methoxypyridin-2-yl)oxy]-1-methyl-1H-benzimidazol-2-yl}methoxy)benzoate

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Reaction Steps

Methyl 3-({6-[(5-bromo-6-chloropyridin-2-yl)oxy]-1-methyl-1H-benzimidazol-2-yl}methoxy)benzoate produced in Example (3a) (0.74 g, 1.47 mmol), sodium methoxide (5.0 M solution in methanol, 2.94 mL, 14.7 mmol), water (10 mL) and 1,4-dioxane (20 mL) were stirred with heating under reflux for three days. After leaving to cool, the reaction mixture was concentrated and water (50 mL) was added. This aqueous solution was neutralized by adding 1 M hydrochloric acid and the precipitated solid was collected by filtration to obtain crude 3-({6-[(5-bromo-6-methoxypyridin-2-yl)oxy]-1-methyl-1H-benzimidazol-2-yl}methoxy)benzoic acid. Trimethylsilyldiazomethane (2.0 M solution in hexane) was added to a solution of the crude 3-({6-[(5-bromo-6-methoxypyridin-2-yl)oxy]-1-methyl-1H-benzimidazol-2-yl}methoxy)benzoic acid in toluene (20 mL) and methanol (10 mL) until the raw material disappeared. The reaction mixture was concentrated under reduced pressure. Then, the residue was purified by silica gel chromatography (hexane/ethyl acetate, 1:1) to obtain the title compound (0.36 g, 49%) as a white solid.

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