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0 °C

0.2 g (0.49 mmol) of 4-Bromo-3-[2-(2,4-dichlorophenyl)-ethoxy]-5-hydroxy-benzoic acid was dissolved in 5 ml DMF and 0.272 mg (1.97 mmol) of potassium carbonate was added. The solution was cooled to 0° C. and 0.699 g (4.9 mmol) methyl bromide was added. The solution was stirred for 16 h at RT. The solvent was removed under reduced pressure. The residue was chromatographed on silica gel eluting with ethyl acetate/n-heptane (1/1). The resulting compound was dissolved in 10 ml dioxan and 1 ml water. 2N aqueous NaOH was added to the solution to give a pH of 13. The reaction solution was heated at 60° C. for 4 h. 5 ml water was added, followed by concentrated hydrochloric acid to give a pH of 1-2, whereupon the product precipitated from solution. The suspension was stirred for 30 min, then the product was filtered off and dried under reduced pressure.

1. customThe solvent was removed under reduced pressure
2. customThe residue was chromatographed on silica gel eluting with ethyl acetate/n-heptane (1/1)
3. dissolutionThe resulting compound was dissolved in 10 ml dioxan
4. addition2N aqueous NaOH was added to the solution
5. customto give a pH of 13
6. temperatureThe reaction solution was heated at 60° C. for 4 h
7. customto give a pH of 1-2
8. customwhereupon the product precipitated from solution
9. stirringThe suspension was stirred for 30 min
10. filtrationthe product was filtered off
11. customdried under reduced pressure