3-Chloro-2-methyl-1-propene → 4-Bromo-3-hydroxy-5-(2-methyl-allyloxy)-benzoic acid methyl ester
Reaction equation
[CH3:1][O:2][C:3](=[O:13])[C:4]1[CH:9]=[C:8]([OH:10])[C:7]([Br:11])=[C:6]([OH:12])[CH:5]=1.Cl[CH2:15][C:16]([CH3:18])=[CH2:17]>CO>[CH3:1][O:2][C:3](=[O:13])[C:4]1[CH:9]=[C:8]([O:10][CH2:17][C:16]([CH3:18])=[CH2:15])[C:7]([Br:11])=[C:6]([OH:12])[CH:5]=1Participants
4
Procedure
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).