Piperidine → 4-(2-carboxyethyl)-3-methyl-5-(6-methoxy-2-oxo-1,2-dihydroindol-3-ylidenemethyl)-1H-pyrrole-2-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

5-Formyl-4-(2-ethoxycarbonylethyl)-3-methyl-1H-pyrrole-2-carboxylic acid ethyl ester (591 mg), 6-methoxy-2-oxindole (333 mg) and piperidine (0.1 mL) in ethanol (4 mL) were stirred at 90° C for 2 hours. Potassium hydroxide (537 mg) was added to the mixture and it was then stirred at 95° C. for and additional hour. The reaction mixture was cooled and concentrated, dissolved in water, and acidified with 2 N hydrochloric acid to pH 2. The precipitate was filtered, washed with water, and dried in a vacuum oven overnight to give 730 mg (99%) of 4-(2-carboxyethyl)-3-methyl-5-(6-methoxy-2-oxo-1,2-dihydroindol-3-ylidenemethyl)-1H-pyrrole-2-carboxylic acid.

Provenance & Evidence