Sulfuric Acid → 5,6-difluoro-2,3-dihydro-1H-indole-2,3-dione

Participants

Reaction Steps

U.S. Pat. No. 4,833,270 also relates to the synthesis of 4,5-difluoroanthranilic acid by, first, reacting 3,4-difluoroaniline with hydroxylamine hydrochloride in the presence of chloral. The resulting intermediate is then cyclyzed using sulfuric acid to form 5,6-difluoroisatin. The 4,5-difluoroanthranilic acid is produced by oxidation of the aforementioned isatin with hydrogen peroxide. As before, however, 3,4-difluoroaniline is expensive and difficult to obtain.

Provenance & Evidence