A mixture of ethyl 4-(methylsulfonyl)-γ,ζ-dioxobenzeneheptanoate (Step 3), (270 mg, 0.79 mmol), 4-fluoroaniline (83 μl, 0.87 mmol) and p-toluenesulfonic acid (25 mg) in toluene (40 ml) was heated at reflux for 24 hours. The reaction mixture was cooled, filtered and concentrated. The crude solid (360 mg) was purified by chromatography (silica gel, hexane/ethyl acetate, 1/1) to give ethyl 1-(4-fluorophenyl)-5-[4-(methylsulfonyl)phenyl]-1H-pyrrole-2-propanoate (246 mg, 75%) as a white solid: mp (DSC) 134° C. Anal Calc'd. for C22H22NSFO4 : C, 63.60; H, 5.34; N, 3.37; S, 7.72. Found: C, 63.29; H, 5.51; N, 3.38; S, 8.05.
