反应详情

Na pieces (41.4 g, 1.82 mol) were added slowly to MeOH (3 L). The resulting mixture was stirred at room temperature for 30 min and then 4-bromo-3,5-dihydroxy-benzoic acid methyl ester (197a) (450 g, 1.82 mol) was added portion wise. The mixture was warmed to 60° C. 3-Chloro-2-methyl-propene (202.5 mL, 2 mol) was added drop wise. The mixture was refluxed for 6 h. TLC (petroleum ether/EtOAc=5/1) showed the reaction was complete. The solvent was removed and the residue was purified by column chromatography (petroleum ether/EtOAc=15/1) to give the title compound (75 g, 13.6% yield). 1H NMR (400 MHz, CDCl3) δ 7.27 (s, 1H), 7.06(s, 1H), 5.72(s, 1H), 5.11(s, 1H), 4.96(s, 1H), 4.47(s, 2H), 3.84(s, 3H), 1.79(s, 3H).

1. temperatureThe mixture was warmed to 60° C
2. temperatureThe mixture was refluxed for 6 h
3. customThe solvent was removed
4. customthe residue was purified by column chromatography (petroleum ether/EtOAc=15/1)