A mixture of 2-[2-methanesulfonyloxy)ethyl]-3-methyl-1-(benzenesulfonyl)indole (4.32 g), (-)-4-(1-aminoethyl)-5-methyl-1-trityl-1H-imidazole (3.67 g), sodium iodide (456 mg) and potassium carbonate [1.51 g) in benzene (43 ml) was stirred at reflux for 24 hours. The reaction mixture was diluted with cold water and extracted twice with ethyl acetate. The extracts were washed with brine, dried over anhydrous magnesium sulfate and evaporated in vacuo. The residue was chromatographed on silica gel (eluted with 5% methanol in chloroform) to give (-)-3-methyl-2-[2-[[1-(5-methyl-1-trityl-1H-imidazol-4-yl)ethyl]amino]ethyl]-1-(benzenesulfonyl)indole (4.82 g) as amorphous powder.
