To a solution of 4,6-difluoro-5-{4-[1-(hydroxymethyl)cyclopropyl]phenyl}-1H-indole-3-carbaldehyde (70 mg, 0.214 mmol) in acetonitrile (4.6 mL), t-Butanol (4.6 mL) and 2-methyl-2-butene (3.0 mL) was added a solution of sodium chlorite (289 mg, 4.28 mmol) and NaH2PO4 (590 mg, 4.28 mmol) in water (4.6 mL) at 0° C. The reaction mixture was stirred at room temperature for 18 h. The reaction was quenched with a solution of sodium sulfate (674 mg, 5.35 mmol) in water (5.0 mL), and extracted with ethyl acetate (20 mL×3). The organic layers were washed with brine (20 mL×1) and dried over sodium sulfate, filtered, concentrated, and purified which was purified by preparative HPLC to give the title compound (17.4 mg, 24%) as a white solid. MS (AP+) 343.9 (M+1)+. 1H NMR (400 MHz, CD3OD) δ 8.00 (s, 1 H), 7.48 (d, 2 H), 7.39 (d, 2 H), 7.11 (d, 1 H), 3.71 (s, 2 H), 0.91 (s, 4 H).
