A suspension of 1.0 g of 3-[N-(p-chlorobenzyl)-3-(t-butylthio)-5-methoxyindol-2-yl]-2,2-dimethylpropanoic acid (from Example 1 Step B) in 50 mL of CH2Cl2 was treated with 1.3 mL of ethanethiol and 3.47 g of AlCl3 at 0° C. under argon. After 40 min the mixture was poured onto 50 mL 1N HCl, extracted with 3×50 mL of CH2Cl2 washed with 2×50 mL of H2O, dried with MgSO4 and the solvent removed. The residue was dissolved in 10 mL ether and ethereal diazomethane added until all the acid was consumed. The excess solvent was removed and the residue chromatographed on silica gel to afford the title compound.
