反应详情

To a solution of ethyl 2-(4-chloro-1,6-dihydroxy-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetate (150 mg, 0.55 mmol) in THF (2 mL) was added an aqueous solution of lithium hydroxide (116 mg, 2.77 mmol) in water (1 mL) at 0° C. The resulting mixture was stirred at ambient temperature for 3 h and acidified with diluted hydrochloric acid at 0° C. to pH=1˜2. The mixture was extracted with EtOAc (2×20 mL) and the combined organic layers were dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was purified by prep HPLC to give the title compound as a white powder (78 mg. Yield: 69%). 1H NMR (400 MHz, DMSO-d6) δ 9.95 (s, 1H), 9.40 (s, 1H), 8.15 (s, 1H), 7.06 (d, J=1.6 Hz, 1H), 6.91 (d, J=1.6 Hz, 1H), 5.38-5.41 (m, 1H), 3.14-3.19 (m, 1H), 2.15-2.22 (m, 1H). MS (ESI) m/z=243 [M+H]+.

1. extractionThe mixture was extracted with EtOAc (2×20 mL)
2. dry with materialthe combined organic layers were dried over anhydrous Na2SO4
3. concentrationconcentrated in vacuo
4. customThe residue was purified by prep HPLC