反应详情

温度

-78 °C

463 mg (2 mmol) of 7-bromo-5-chloro-1H-indazol were dissolved in 12 ml THF. The so-lution was cooled to −78° C. under argon. 3.75 ml (6 mmol) of a 1.6 M butyl lithium solution in hexane were added slowly within 10 min. The reaction mixture was warmed to 5° C. and stirred for 30 min at this temperature. A suspension was obtained, which was cooled to −78° C. Solid carbon dioxide was added and the reaction mixture was warmed to rt. At 10° C. the suspension became a clear solution. The solvent was evaporated and the residue was treated with water and diethyl ether. The aqueous layer was extracted once with diethyl ether, acidified with 1N aqueous HCl solution. A white solid precipitated, which was filtered off and washed with water. The solid was suspended in diethyl ether/heptane in order to remove pentanoic acid. 130 mg (33%) of 5-chloro-1H-indazole-7-carboxylic acid were obtained as a white solid after filtration and drying. MS (ISP) 195.1 (M−H)−.

1. temperatureThe reaction mixture was warmed to 5° C.
2. customA suspension was obtained
3. temperaturewhich was cooled to −78° C
4. temperaturethe reaction mixture was warmed to rt
5. customAt 10° C.
6. customThe solvent was evaporated
7. additionthe residue was treated with water and diethyl ether
8. extractionThe aqueous layer was extracted once with diethyl ether
9. customA white solid precipitated
10. filtrationwhich was filtered off
11. washwashed with water
12. customto remove pentanoic acid