A mixture of methyl 4-[(4,5-dichloro-2-fluoro-benzoyl)amino]benzoate (34.21 mg, 0.1 mmol), 4-chloro-2-methoxyphenol (12.16 μl, 0.1 mmol), potassium carbonate 13.82 mg, 0.1 mmol) and N-methylpyrrolidinone (1 mL) were heated at 80° C. for 2.5 hours. Methanol (100 μL) and sodium hydroxide (3M, 100 μL, 0.3 mmol) were added and the reaction was stirred at 50° C. for 2 hours. An additional 100 μL of MeOH and 100 μL of 3M NaOH were added and the reactions were heated for another hour. The reaction mixture was filtered and purified by reverse phase preparative chromatography utilizing a gradient of 10-99% acetonitrile in water containing HCl as a modifier to yield 4-(4,5-dichloro-2-(4-chloro-2-methoxyphenoxy)benzamido)benzoic acid (18) (11.78 mg, 25%). ESI-MS m/z calc. 464.99, found 466.3 (M+1)+; Retention time: 2.20 minutes (3 minutes run).
