Potassium Hydroxide → 7-(5-{3-chloro-4-[(1-methylethyl)oxy]phenyl}-1,2,4-oxadiazol-3-yl)-1H-indole-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 7-(5-{3-chloro-4-[(1-methylethyl)oxy]phenyl}-1,2,4-oxadiazol-3-yl)-1H-indole-3-carbaldehyde (D71) (1.1 g) in THF (20 mL) was added KMnO4 (0.9 g) and aqueous KOH (10 mL). The reaction was stirred at 55° C. overnight. After cooled to room temperature, the mixture was diluted with THF (20 mL) and filtered. The filtrate was concentrated and the aqueous suspension was acidified with aqueous HCl (2 M) to pH 5-6. The resulting solid was collected by filtration, washed with water, dried in vacuo to give the crude compound, which was purified by column chromatography (20% ethyl acetate in hexane) to afford 7-(5-{3-chloro-4-[(1-methylethyl)oxy]phenyl}-1,2,4-oxadiazol-3-yl)-1H-indole-3-carboxylic acid as a white solid (D94) (1.0 g). δH (DMSO-d6, 400 MHz): 1.36 (6H, d), 4.90 (1H, m), 7.38 (1H, t), 7.46 (1H, d), 8.02 (2H, m), 8.22 (1H, dd), 8.30 (1H, dd), 8.41 (1H, d), 11.66 (1H, br s). MS (ES): C20H16ClN3O4 requires 397; found 398.1 (M+H+).

Provenance & Evidence