To a solution of 5-hydroxy-4-propyl-N-(4-chlorophenyl)indole (Step D; 500 mg, 1.75 mmol) and potassium carbonate (484 mg, 3.50 mmol) in 7 mL of dimethylformamide (DMF) was added 1,3-dibromopropane (1.77 g, 8.75 mmol). The mixture was stirred at ambient temperature for 2 hours and diluted with ethyl acetate and saturated aqueous ammonium chloride. The aqueous phase was extracted with ethyl acetate and the combined organic extracts were washed brine, dried over magnesium sulfate, filtered, concentrated in vacuo, and the crude residue was used as is in the next step.
