反应详情

To a solution of 2-bromo-4-[({[(1E)-(4-tert-butylphenyl)methylidene]amino}oxy)methyl]benzoic acid methyl ester (0.43 g, 1.07 mmol), in 10/5/3 tetrahydrofuran/ethanol/water (24 mL) was added 2.5 M sodium hydroxide solution (4 mL). This mixture was heated to reflux for 3 hours and then allowed to cool back to room temperature. The mixture was concentrated to approximately ¼ volume and partitioned between ethyl acetate and brine. The aqueous layer was acidified to approximately pH 1 using 1 N hydrochloric acid. The layers were then separated. The aqueous layer was extracted with one additional portion of ethyl acetate. The organics were combined, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The crude material was dissolved in hot methylene chloride and crystallized out by the addition of room temperature hexanes (60 mL), and allowing the mixture to sit for 2 hours to give 2-bromo-4-[({[(1E)-(4-tert-butylphenyl)methylidene]amino}oxy)methyl]benzoic acid (0.39 g, 94%) as a white solid. mp=162-163° C. 1H NMR (500 MHz, DMSO-d6); δ 13.35 (bs, 1H), 8.31 (s, 1H), 7.74 (d, 1H), 7.71 (s, 1H), 7.52 (d, 2H), 7.46 (d, 1H), 7.42 (d, 2H), 5.19 (s, 2H), 1.26 (s, 9H). Mass spec (MW 390.28); (ES+) m/z 390.0, (ES−) m/z 388.3. Elemental analysis; Calculated for C19H20BrNO3: C, 58.47; H, 5.17; N, 3.59. Found: C, 57.99; H, 5.03; N, 3.41.

1. temperatureThis mixture was heated
2. temperatureto reflux for 3 hours
3. concentrationThe mixture was concentrated to approximately ¼ volume
4. custompartitioned between ethyl acetate and brine
5. customThe layers were then separated
6. extractionThe aqueous layer was extracted with one additional portion of ethyl acetate
7. dry with materialdried over anhydrous magnesium sulfate
8. filtrationfiltered
9. concentrationconcentrated under reduced pressure
10. dissolutionThe crude material was dissolved in hot methylene chloride
11. customcrystallized out by the addition of room temperature hexanes (60 mL)