反应详情

Intermediate (6f), 1-((S)-1-Phenyl-ethyl)-1H-pyrazole-4-carboxylic acid ethyl ester (1.525 g, 6.2 mmol) was stirred in a mixture of tetrahydrofuran (20 mL) and water (20 mL). Lithium hydroxide (0.524 g, 12.5 mmol) was added and the reaction stirred at ambient temperature for 24 hours. The reaction mixture was reduced in volume and extracted with diethyl ether (3×20 mL). The aqueous layer was carefully acidified using an aqueous 6N hydrochloric acid solution. The resulting precipitate was filtered, washed with copious amounts of water and dried in vacuo to afford intermediate (6g), 1-((S)-1-Phenyl-ethyl)-1H-pyrazole-4-carboxylic acid as a white solid, 0.664 g, 49%.

1. extractionextracted with diethyl ether (3×20 mL)
2. filtrationThe resulting precipitate was filtered
3. washwashed with copious amounts of water
4. customdried in vacuo