3-Chloro-2-methyl-1-propene → 4-Bromo-3-hydroxy-5-(2-methyl-allyloxy)-benzoic acid methyl ester

Participants

Reaction Steps

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, 1 H), 7.06 (s, 1 H), 5.72 (s, 1 H), 5.11 (s, 1 H), 4.96 (s, 1 H), 4.47 (s, 2 H), 3.84 (s, 3 H), 1.79 (s, 3 H).

Provenance & Evidence