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

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Reaction Steps

A mixture of 5-aminosulfonyl-2-oxindole (106 mg), indole-2-carbaldehyde (87 mg) (prepared according to Synthetic Communications, 1993, 23, 3109) and piperidine (4 mg) in ethanol (2 mL) was held in a sealed tube at 90° C. for 3 hours. 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 140 mg (83% yield) of 3-(1H-indol-2-ylmethylene)-2-oxo-2,3-dihydro-1H-indole-5-sulfonic acid amide as an orange solid.

Provenance & Evidence