Sodium Hydroxide → 7-Benzoyl-2-oxindole

Participants

Reaction Steps

The hydrolysis of an indolin-2-one (II) is carried out in dilute aqueous base as, for example, 3N sodium hydroxide solution, for a period of from about 0.5 hour to about 1.0 hour. The hydrolysis may be run in an inert atmosphere using nitrogen. The hydrolysis mixture may be filtered to remove base-insoluble materials and the pH of the basic solution is adjusted to pH 6-pH 7 by the addition of a weak organic acid such as glacial acetic acid or a dilute mineral acid such as hydrochloric acid. When (I) is a 2-amino-5-benzoylphenylacetic acid or a 2-amino-6-benzoylphenylacetic acid the product can be readily recrystallized from a suitable solvent. When (I) is a 2-amino-3-benzoylphenylacetic acid, recrystallization may result in partial cyclization to the precursor 7-benzoylindolin-2-one (II). Therefore, in the preparation of a 2-amino-3-benzoylphenylacetic acid (I) theproduct is preferably not recrystallized and is isolated by careful acidification of the filtered basic hydrolysis mixture.

Provenance & Evidence