反应详情

To a solution of (1-hydroxy-6-methoxy-4-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl)-acetic acid ethyl ester (0.85 g, 3.22 mmol) in THF (7 mL) was added a solution of LiOH (0.385 g, 16.1 mmol) in water (7 mL) at 0° C. The resulting mixture was stirred at room temperature for 1.5 hours then acidified to pH 2 using dilute hydrochloric acid. The mixture was concentrated to remove THF and the white precipitate collected and washed with water to give pure product as a white powder (0.571 g, 75.1%); mp 157-158° C. 1HNMR (400 MHz, DMSO-d δ 9.10 (s, 1H), 7.02 (d, J=2.34 Hz, 1H), 6.83 (d, J=1.76 Hz, 1H), 5.42 (dd, J=9.67, 2.64 Hz, 1H), 3.73 (s, 3H), 3.01 (dd, J=15.38, 2.49 Hz, 1H), 2.24 (s, 3H), 2.03 (dd, 1H). MS (ESI) m/z=235 [M−H]−.

1. concentrationThe mixture was concentrated
2. customto remove THF
3. customthe white precipitate collected
4. washwashed with water