反应详情

A solution of 3-hydroxy-2-nitrobenzoic acid (51 g) and con.H2SO4 (5 mL) in anhydrous methanol (450 mL) was heated to reflux for 48 hr. The mixture was concentrated to remove methanol, and the residue was partitioned between water (500 mL) and ethyl acetate (800 mL). The organic layer was washed with brine (300 mL), dried over anhydrous sodium sulfate, and concentrated to give crude compound. The crude product was purified by chromatography (silica gel, petroleum ether/ethyl acetate=40:1 to 5:1) to give methyl 3-hydroxy-2-nitrobenzoate (28 g) 1H-NMR (400 MHz, CDCl3) δ 3.8 (s, 3H), 7.32-7.34 (d, J=8.4 Hz, 1H), 7.39-7.41 (d, J=8.0 Hz, 1H), 7.48-7.52 (t, J=8.0 Hz, 1H), 11.37 (s, 1H); LC-MS (m/z) 198 [M+1]+.

1. temperatureto reflux for 48 hr
2. concentrationThe mixture was concentrated
3. customto remove methanol
4. customthe residue was partitioned between water (500 mL) and ethyl acetate (800 mL)
5. washThe organic layer was washed with brine (300 mL)
6. dry with materialdried over anhydrous sodium sulfate
7. concentrationconcentrated
8. customto give crude compound
9. customThe crude product was purified by chromatography (silica gel, petroleum ether/ethyl acetate=40:1 to 5:1)