3-(4-Oxospiro[chroman-2,4′-piperidin]-6-yl)benzamide hydrochloride (224 mg), 1-cyclopropyl-4-(tetrazol-5-yl)-1H-indole-6-carboxylic acid (135 mg), EDCI (115 mg), HOBT (91.2 mg) and triethylamine (0.209 ml) were dissolved in DMF (3 mL), and stirred at 50° C. for 23 hours. 1N hydrochloric acid and water were added to the reaction liquid, the formed solid was taken out through filtration, and the resulting solid was purified through silica gel thin-layer column chromatography (chloroform/methanol) to obtain the title compound. 1H-NMR (400 MHz, DMSO-d6) δ: 8.17-8.10 (2.0H, br m), 8.05 (1.0H, d, J=2.2 Hz), 7.99 (1.0H, dd, J=8.5, 2.2 Hz), 7.86-7.78 (4.0H, m), 7.63 (1.0H, d, J=2.9 Hz), 7.52 (1.0H, dd, J=7.7, 7.7 Hz), 7.40 (1.0H, s), 7.25 (1.0H, d, J=8.5 Hz), 7.15-7.13 (1.0H, m), 4.50-4.08 (1.0H, br m), 3.88-3.08 (4.0H, m), 2.96 (2.0H, s), 2.23-1.68 (4.0H, m), 1.15-1.08 (2.0H, m), 1.06-0.96 (2.0H, m). MS [M+H]+=588.
