4-Bromo-3-hydroxy-5-(2-methyl-allyloxy)-benzoic acid methyl ester → 4-Bromo-3,5-dihydroxy-2-(2-methyl-allyl)-benzoic acid methyl ester
Reaction equation
[CH3:1][O:2][C:3](=[O:17])[C:4]1[CH:9]=[C:8]([O:10]CC(C)=C)[C:7]([Br:15])=[C:6]([OH:16])[CH:5]=1>CN1C(=O)CCC1>[CH3:1][O:2][C:3](=[O:17])[C:4]1[CH:5]=[C:6]([OH:16])[C:7]([Br:15])=[C:8]([OH:10])[C:9]=1[CH2:5][C:4]([CH3:9])=[CH2:3]Participants
3
Procedure
A solution of 4-bromo-3-hydroxy-5-(2-methyl-allyloxy)-benzoic acid methyl ester (197b) (148 g, 0.49 mol) in NMP (1.5 L) was refluxed for 0.5 h. After TLC (petroleum ether/EtOAc=5/1) indicated complete consumption of 197b, the reaction mixture was cooled to room temperature and 20% aq. HCl was added until pH=1. The resulting mixture was extracted with EtOAc (3×500 mL). The combined organic phases were dried over Na2SO4 and concentrated to give a brown oil. The crude oil was purified by column chromatography (petroleum ether/EtOAc=15/1) to give the title compound (139 g, 94% yield) as a white solid.