反应详情

To a stirred solution of the ester from step 1 (756 mg, 1.95 mmol) in 2:1:1 tetrahydrofuran/methanol/water (12 mL) is added lithium hydroxide (170 mg, 4 mmol). The reaction mixture is stirred at room temperature for 42 h, and concentrated under reduced pressure. The residue is partitioned between water (10 mL) and chloroform (10 mL). The aqueous layer is acidified to pH 4-5 with 1 N hydrochloric acid and extracted with 3:1 chloroform/2-propanol (3×30 mL). The combined organic layers are dried (sodium sulfate), filtered, and concentrated under reduced pressure to provide the title compound. 1H NMR (300 MHz, CD3OD) δ 8.51 (s, 1H), 8.06 (s, 1H), 8.00 (s, 1H), 7.49 (s, 1H), 7.17 (s, 1H), 5.39 (s, 2H), 3.62 (q, J=7 Hz, 2H), 3.51 (m, 2H), 3.27 (m, 2H), 1.72 (m, 2H), 1.59 (m, 2H), 1.21 (t, J=7 Hz, 3H), 1.00 (m, 3H), 0.75 (m, 3H).

1. concentrationconcentrated under reduced pressure
2. customThe residue is partitioned between water (10 mL) and chloroform (10 mL)
3. extractionextracted with 3:1 chloroform/2-propanol (3×30 mL)
4. dry with materialThe combined organic layers are dried (sodium sulfate)
5. filtrationfiltered
6. concentrationconcentrated under reduced pressure