isatin

A compound (C₈H₅NO₂) obtained by oxidizing indigo.

An orange-red crystalline substance, C8H5NO2, obtained by the oxidation of indigo blue. It is also produced from certain derivatives of benzoic acid, and is one important source of artificial indigo.

The indole derivative 1H-indole-2,3-dione, used in the synthesis of dyes.