To a solution of 4-[5-(4-fluorophenyl)-1-methyl-3-oxido-2-phenyl-1H-imidazol-4-yl]pyridin-2(1H)-one of Step A (56 mg, 0.155 mmol) in CHCl3 (2 mL) was added phosphorous trichloride (16 μL, 0.186 mmol) dropwise at room temperature. The reaction mixture was heated at 60° C. for 2 hours, cooled, and poured into 1N NaOH/ice solution. The aqueous layer was extracted with CH2Cl2, and the combined organic extracts were washed with H2O followed by brine. After drying over Na2SO4, the solvent was removed in vacuo. The crude material was purified by preparative thin layer chromatography (1:10 MeOH:CH2Cl2 as an eluent) to obtain 21.8 mg of the title compound.
