DMF (0.28 mL) was added dropwise to a solution of (COCl)2 (0.31 mL) in DCM (9 mL) at 0° C. The resulting mixture was stirred at 0° C. for 1 hour. Then a solution of 6-(5-{3-chloro-4-[(1-methylethyl)oxy]phenyl}-1,2,4-oxadiazol-3-yl)-1H-indole (D101) (1.06 g) in DCM (30 mL) was added. The reaction mixture was warmed to RT and stirred overnight. Then water and 2 M HCl was added. After stirred for 2 hours, the mixture was neutralized with 2 M aqueous NaOH solution until pH was between 8 and 9. The organic layer was separated and washed with brine, dried over anhydrous sodium sulfate. The dried solution was concentrated. The residue was purified by column chromatography to afford 6-(5-{5-chloro-6-[(1-methylethyl)oxy]-3-pyridinyl}-1,2,4-oxadiazol-3-yl)-1H-indole-3-carbaldehyde (D102) (620 mg) as a yellow solid. δH (DMSO-d6, 400 MHz): 1.46 (6H, d), 5.51 (1H, m), 7.99 (1H, d), 8.14 (1H, d), 8.30 (1H, s), 8.42 (1H, d), 8.46 (1H, d), 8.90 (1H, d), 8.98 (1H, br s), 10.12 (1H, d).
