Acetic Acid → 3-[2-(5-bromo-2-oxo-1,2-dihydroindol-3-ylidenemethyl)-4,5,6,7-tetrahydro-1H-indol-3-yl]-propionic acid

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Reaction Steps

A mixture of 3-(2-Formyl-4,5,6,7-tetrahydro-1H-indol-3-yl)-propionic acid (3.4 g), 2.7 g of 5-bromo-2-oxindole and 1.4 g of pyrrolidine in 25 mL of ethanol was refluxed for 4 hours. Upon slow addition of acetic acid (8 mL), a precipitate formed. The mixture was refluxed for 5 minutes and cooled to ambient temperature. The precipitate was collected by vacuum filtration and washed with 20 mL of ethanol. The solids were slurry-washed by refluxing in 30 mL of ethanol, cooled, collected by vacuum filtration, washed with 30 mL of ethanol and dried under vacuum to give 5.2 g (98% yield) of 3-[2-(5-bromo-2-oxo-1,2-dihydroindol-3-ylidenemethyl)-4,5,6,7-tetrahydro-1H-indol-3-yl]-propionic acid as a red-orange solid, mp 286-289° C.

Provenance & Evidence