Piperidine → 3-(3-methyl-1H-indol-2-ylmethylene)-2-oxo-2,3-dihydro-1H-indole-5-carboxylic acid

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Reaction Steps

A mixture of 5-carboxy-2-oxindole (113 mg), 3-methylindole-2-carbaldehyde (56 mg) (prepared according to Synthetic Communications, 1986, 16, 1799) and piperidine (30 mg) in ethanol (1 mL) was held in a sealed tube at 90° C. overnight. The mixture was cooled to room temperature. The solid was collected by vacuum filtration, washed with cold ethanol and dried in a vacuum oven to give 75 mg (58% yield) of 3-(3-methyl-1H-indol-2-ylmethylene)-2-oxo-2,3-dihydro-1H-indole-5-carboxylic acid (piperidine salt).

Provenance & Evidence