To a solution of 2-fluoro-5-(3-fluorophenyl)benzoic acid (intermediate III(a)) (478 mg, 2.04 mmol, 1.1 eq) in DCM (9 mL) and DMF (3 drops) at 0° C. was added (COCl)2 (779 mg, 6.14 mmol, 3.3 eq) dropwise. The reaction mixture was stirred at room temperature for 1.5 h, then the solvent removed in vacuo. The residue obtained was dissolved in THF (7 mL) and added dropwise to a mixture of 3-amino-2-chloro-4-fluoro-phenol (intermediate X(f)) (300 mg, 1.86 mmol, 1.0 eq) and NaHCO3 (781 mg, 9.3 mmol, 5.0 eq) in THF (7 mL) at 0° C. After addition was completed, the reaction mixture was warmed to room temperature and stirred overnight. Water was added and the aqueous mixture was extracted with EtOAc. The organic extract was washed with 5% Na2CO3, water and brine, dried (Na2SO4), filtered, evaporated in vacuo and purified by column chromatography (EtOAc:petroleum ether, 3:20 to 1:4) to give the title as a yellow solid compound (180 mg, 26%).
