反应详情

To a stirred solution of 2 (7.0 g, 41.3 mmol) in anhydrous THF (100 mL) at −78° C. under a nitrogen atmosphere was added n-BuLi (24.7 mL, 2.5 M in hexanes, 61.8 mmol). After 1 hour, methyl chloroforrnate (9.6 ml, 124 mmol) was added and the reaction mixture was stirred for an extra hour at the same temperature, quenched with excess methanol and allowed to warm to room temperature. The solvent was then evaporated and the residue was purified by flash chromatography using hexane —AcOEt (70:30) as an eluent. The product from the column was re-crystallized from ethyl acetate to afford title compound 37 (4.3g, 46% yield) as a white solid. 1H NMR (400 MHz, DMSO-d6) δ(ppm): 8.75 (dd, J=0.8 and 4.8 Hz, 1H), 8.26 (d, J=0.8 Hz, 1H), 7.74 (dd, J=0.8 and 5.2 Hz, 1H), 3.93 (s, 3H).

1. customquenched with excess methanol
2. customThe solvent was then evaporated
3. customthe residue was purified by flash chromatography
4. customThe product from the column was re-crystallized from ethyl acetate