反应详情

Lithium hydroxide (17.1 g, 407 mmol) was added to a solution of ethyl 5-{2-[(tert-butoxycarbonyl)amino]-2-methylpropyl}-1-(2-methoxyethyl)-1H-pyrazole-3-carboxylate (37.6 g, 102 mmol) in methanol (141 mL) and water (47 mL). The reaction mixture was stirred for 2 days and then most of the methanol was removed under reduced pressure. The aqueous residue was cooled in an ice bath and then combined with 1 N hydrochloric acid (350 mL) and tert-butyl methyl ether. The layers were separated. The volume of the organic layer was reduced under vacuum and then diluted with hexanes. A precipitate was isolated by filtration, washed with water, and suction dried to provide 13.09 g of 5-{2-[(tert-butoxycarbonyl)amino]-2-methylpropyl}-1-(2-methoxyethyl)-1H-pyrazole-3-carboxylic acid as a white solid. The aqueous layer was extracted with chloroform while maintaining the pH of the aqueous layer at pH 4-5 by the addition of 1 N hydrochloric acid. The chloroform extracts were combined, dried over sodium sulfate and magnesium sulfate, filtered, and concentrated under reduced pressure. The residue was dissolved in tert-butyl methyl ether, diluted with hexanes, and then concentrated under reduced pressure. A white solid was isolated by filtration, washed with hexanes, and suction dried to provide an additional 21.8 g of product.

1. custommost of the methanol was removed under reduced pressure
2. temperatureThe aqueous residue was cooled in an ice bath
3. customThe layers were separated
4. additiondiluted with hexanes
5. customA precipitate was isolated by filtration
6. washwashed with water, and suction
7. customdried