反应详情

Lithium triethylborohydride (93 mL) was added to a solution of the product from step (ii) (5.0 g) in THF (25 mL) over 5 min and the reaction mixture was stirred at RT for 3.5 h. Water (60 mL) and 2M-hydrogen chloride (40 mL) was added to the mixture. The organic solvent was removed by evaporation. 2M-hydrogen chloride (16 mL) was added and the mixture was stirred at RT for 4 h. The mixture was neutralized by saturated aqueous sodium hydrogen carbonate. The precipitate was collected by filtration, washed with water and dried in vacuo at 50° C. to afford the sub-title compound (4.7 g) as a white solid; 1H NMR (300 MHz, d6-DMSO); 10.76 (1H, br s), 6.89 (1H, s), 6.77-6.70 (2H, m), 6.30 (2H, br s), 5.10 (1H, t), 4.42 (2H, d), 3.79 (3H, s), 3.51 (2H, s), 1.91 (3H, s).

1. customThe organic solvent was removed by evaporation
2. addition2M-hydrogen chloride (16 mL) was added
3. stirringthe mixture was stirred at RT for 4 h
4. filtrationThe precipitate was collected by filtration
5. washwashed with water
6. customdried in vacuo at 50° C.