反应详情

To a solution of [1-hydroxy-4-methyl-6-([1,3,4]thiadiazol-2-yloxy)-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl]-acetic acid ethyl ester (0.17 g, 0.5 mmol) in THF:H2O (1:1, 10 mL) at 0° C. was added a solution of LiOH (0.024 g, 1.01 mmol) in water (1 mL). The solution was allowed to warm to room temperature over 3 hours then acidified to pH 2 with 1N HCl (1 mL) at 0° C. The mixture was extracted with EtOAc (2×10 mL) and the organic extracts washed with water (10 mL), dried and concentrated in vacuo. The residue was purified by preparative HPLC to give [1-hydroxy-4-methyl-6-([1,3,4]thiadiazol-2-yloxy)-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl]-acetic acid (0.15 g, 96%). 1H NMR (400 MHz, DMSO): δ 9.24 (s, 1H), 9.15 (s, 1H), 7.43 (s, 1H), 7.30 (s, 1H), 5.51 (d, J=6.8 Hz, 1H), 3.06 (d, J=15.6 Hz, 1H), 2.30 (s, 3H), 2.18-2.12 (m, 1H). MS (ESI) m/z=305 [M−H]−.

1. extractionThe mixture was extracted with EtOAc (2×10 mL)
2. washthe organic extracts washed with water (10 mL)
3. customdried
4. concentrationconcentrated in vacuo
5. customThe residue was purified by preparative HPLC