Carbon Dioxide → 4-Bromo-2,5-difluorobenzoic acid
反応式
Br[C:2]1[CH:7]=[C:6]([F:8])[C:5]([Br:9])=[CH:4][C:3]=1[F:10].C([Li])CCC.[C:16](=[O:18])=[O:17]>C(OCC)C>[Br:9][C:5]1[C:6]([F:8])=[CH:7][C:2]([C:16]([OH:18])=[O:17])=[C:3]([F:10])[CH:4]=1Br[C:2]1[CH:7]=[C:6]([F:8])[C:5]([Br:9])=[CH:4][C:3]=1[F:10].C([Li])CCC.[C:16](=[O:18])=[O:17]>C(OCC)C>[Br:9][C:5]1[C:6]([F:8])=[CH:7][C:2]([C:16]([OH:18])=[O:17])=[C:3]([F:10])[CH:4]=1A solution of 1,4-dibromo-2,5-difluorobenzene (640 mg, 2.35 mmol) in dry diethyl ether (10 mL) cooled in a dry ice-acetone bath was treated dropwise with 2.5 M n-butyllithium in hexanes (1.04 mL, 2.59 mmol). The solution was stirred at −78° C. for 30 min, then was treated with a piece of dry ice. The cooling bath was removed after 5 min and the mixture was stirred for another 30 min while warming to room temperature. The mixture was diluted with EtOAc and water. The organic phase was separated and washed twice with saturated aqueous NaHCO3. The combined aqueous phases were acidified with 1M aqueous HCl, extracted twice with DCM, and the combined organic phases were dried and concentrated to give 4-bromo-2,5-difluorobenzoic acid as a white solid (297 mg, 53% yield).
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