Add indole-2-carboxylic acid (507 mg, 3.15 mmol) to a solution of 4-[4-(6-fluoro-benzo[b]thiophen-3-yl)-[1,4]diazapan-1-yl]butylamine (Example 6) (920 mg, 2.86 mmol), diisopropylethylamine (2.5 mL, 14.3 mmol), 1-hydroxy-1H-benzotriazole (503 mg, 3.72 mmol) and morpholinocarbodiimide (1.39 g, 3.29 mmol) in DMF (10 mL), and stir the solution overnight at room temperature. Remove the solvent under vacuum and dissolve the residue in EtOAc. Wash the organic phase with ether and saturated sodium chloride solution, and dry over MgSO4. Evaporate the solvent under vacuum and purify the crude product by column chromatography (EtOAc/MeOH 7:3) to obtain 716 mg of a colorless solid LC/MS, (LiChrospher 5μ, RP-18, 250 mm CH3CN/Water-gradient 20%→100% (25 min), Flow: 1.5 mL/min) tR=19.89 min, m/z=464.3.
