2-{[1-(Phenylsulfonyl)-1H-indol-5-yl]oxy}ethanamine (Intermediate 24, 0.20 g, 0.63 mmol) in DCM (100 mL) was treated with triethylamine (0.27 mL, 1.9 mmol) and 4-dimethylaminopyridine (39 mg, 0.32 mmol). The solution was cooled to 0° C. and was treated with isobutyryl chloride (0.14 g, 0.13 mmol). The mixture was stirred at room temperature for 1 hour. The mixture was washed with saturated aqueous NaHCO3 (50 mL) and 1 M HCl (2×40 mL). The organic phase was dried (MgSO4) and concentrated in vacuo to give the title compound (133 mg). MS m/z 387 [M+H]+.
