反应详情

Methyl 3,4-dichloro-5-methoxybenzoate (5) (518 mg, 2.34 mmol) was suspended in DCM (10 mL) under a reflux condenser fitted with a CaCl2 drying tube. BBr3 (554 μL, 5.86 mmol) was added and the reaction mixture was stirred at RT for 15 h. The reaction mixture was cautiously poured in to iced water (20 mL) and the mixture stirred for 10 min. The product was extracted with EtOAc (50 mL), then the organic solution was washed with brine (2×50 mL) and dried over MgSO4 and filtered. The solvent was removed in vacuo and the residue purified by silica gel chromatogrpahy (40 g, 0-100% EtOAc in isohexane) to afford 3,4-dichloro-5-hydroxybenzoic acid (6) (260 mg, 51% yield) as a white solid: m/z 205 [M−H]− (ES−).

1. customfitted with a CaCl2 drying tube
2. stirringthe mixture stirred for 10 min
3. extractionThe product was extracted with EtOAc (50 mL)
4. washthe organic solution was washed with brine (2×50 mL)
5. dry with materialdried over MgSO4
6. filtrationfiltered
7. customThe solvent was removed in vacuo
8. customthe residue purified by silica gel chromatogrpahy (40 g, 0-100% EtOAc in isohexane)