[F:1][C:2]1[CH:7]=[C:6]([F:8])[CH:5]=[CH:4][C:3]=1[C:9]1[CH:14]=[CH:13][C:12]([OH:15])=[C:11]([C:16]([OH:18])=[O:17])[CH:10]=1.[CH2:19](O)[CH3:20]>S(=O)(=O)(O)O>[F:1][C:2]1[CH:7]=[C:6]([F:8])[CH:5]=[CH:4][C:3]=1[C:9]1[CH:14]=[CH:13][C:12]([OH:15])=[C:11]([C:16]([O:18][CH2:19][CH3:20])=[O:17])[CH:10]=12′,4′-difluoro-4-hydroxybiphenyl-3-carboxylic acid (1.0 g, 4.0 mmol) was dissolved in ethanol (30 mL) and sulfuric acid (8 mL). The solution was stirred (80° C., 18 h) and then concentrated under reduced pressure. The residue was dissolved in ethyl acetate and washed with water, brine and dried over MgSO4. Solvent evaporation afforded ethyl 2′,4′-difluoro-4-hydroxybiphenyl-3-carboxylate (1.0 g). Mass calculated for C15H12F2O3=278.25; found: [M+H]+=279.1.
Wird geladen…