Hydrochloric Acid → 1-{1-[2-(7-methoxy-2,2-dimethyl-4-oxochroman-8-yl)ethyl]piperidin-4-yl}-1H-indole-6-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

3.5 g of the above crude product of methyl 1-{1-[2-(7-methoxy-2,2-dimethyl-4-oxochroman-8-yl)ethyl]piperidin-4-yl}-1H-indole-6-carboxylate was dissolved in 28.0 mL of tetrahydrofuran and added with 14 mL of 1 N aqueous sodium hydroxide. 14 mL of methanol was added and the mixture was heated to 40° C. and stirred for 30 minutes. 7 mL of tetrahydrofuran and 3.5 mL of methanol were added and the mixture was stirred for 2 hours and further stirred at the same temperature for about 16 hours. When the reaction mixture was cooled with an ice-water bath and the pH was adjusted to 7 with 12.2 mL of 1 N hydrochloric acid and 0.5 mL of 1 N sodium hydroxide, crystals precipitated. 10 mL of water was further added to this slurry, and crystals were obtained by filtration and the crystals were washed with 21 mL of a mixture of 2-propanol and water (5:1). The crystals were dried in vacuo and 2.45 g of the title compound was obtained.

Provenance & Evidence