Hydrochloric Acid → 4-((4-(1-Methylcarbamoyl-1H-indol-5-yloxy)pyridin-2-yl)aminocarbonylamino)butyric acid

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Reaction Steps

Ethyl 4-aminobutyrate hydrochloride (1.0 g, 6.0 mmol) was suspended in N,N-dimethylformamide (6.7 ml), 5N aqueous solution of sodium hydroxide (1.2 ml, 6.0 mmol) was added and the reaction mixture was stirred at room temperature. Phenyl N-(4-(1-(methylamino)carbonyl-1H-indol-5-yloxy)pyridin-2-yl)-N-(phenoxycarbonyl)carbamate (700 mg, 1.3 mmol, Production example 5-2) was added thereto and the reaction mixture was stirred at room temperature for 1.2 hours. The reaction mixture was partitioned between ethyl acetate and water. The organic layer was dried over anhydrous magnesium sulfate, concentrated under reduced pressure. The residue was purified by silica gel column chromatography (Fuji Silysia BW-300, ethyl acetate) to yield a pale yellow oil. This oil was dissolved in tetrahydrofuran (6.0 ml) and methanol (3.0 ml); 4N lithium hydroxide (1.1 ml) was added thereto at room temperature; and the reaction mixture was stirred at room temperature for 3.5 hours. Moreover, 1N hydrochloric acid (4.4 ml) and water (2 ml) were added thereto while stirred at room temperature; and this was subjected to extraction with ethyl acetate, washed with brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. After the precipitated crystals were suspended in diethyl ether:hexane=1:1, the crystals were filtered off, washed with diethyl ether, and dried under aeration to yield the title compound (411 mg, 1.0 mmol, 75%) as colorless crystals.

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