Hydrochloric Acid → 6-Fluoro-5-(4-methoxy-phenyl)-1H-indole-3-carboxylic acid

Participants

Reaction Steps

To a solution of 6-fluoro-5-(4-methoxy-phenyl)-1H-indole-3-carbaldehyde (106.0 mg, 0.39 mmol) in MeCN (5 mL) and water (3 mL) was added sodium phosphate monobasic hydrate (12.3 mg, 0.087 mmol), 25% hydrogen peroxide (56.3 mg, 0.41 mmol) and sodium chlorite (44.5 mg, 0.39 mmol). The reaction mixture was stirred for one hour at room temperature and additional MeCN (5 mL) and sodium chlorite (44.5 mg, 0.39 mmol) were added. The reaction mixture was heated to 50° C. for one hour, cooled to room temperature and stirred for another 16 hours. The reaction was quenched with sodium sulfite (405.0 mg, 3.15 mmol) and acidified with 3 N HCl (1 mL). The reaction solution was partially concentrated in vacuo, and extracted with EtOAc (10 mL). The organic layer was concentrated in vacuo and purified by reverse phase HPLC (Waters Sunfire C18 19×100, 5 μm; Mobile phase A: 0.05% TFA in water (v/v); Mobile phase B: 0.05% TFA in MeCN (v/v); Gradient: 80:20 A:B linear to 40:60 A:B in 8.5 min to 100% B to 9.0 min, hold at 100% B from 9.0 to 10.0 min. Flow: 25 mL/min) to give the title compound (6.8 mg, 6% yield). MS (ES+) 286.2 (M+1)+. Retention time=2.73 minutes (Waters Atlantis dC18 4.6×50, 5 μm; Mobile phase A: 0.05% TFA in water (v/v); Mobile phase B: 0.05% TFA in MeCN (v/v); Gradient: 95:5 A:B linear to 5:95 A:B in 4.0 min, hold at 5:95 A:B to 5.0 min. Flow: 2 mL/min).

Provenance & Evidence