Isatin

Isatin can be used as a reactant to prepare:

• Phthalazinone derivatives.
• Spirooxindole derivatives.
• Agents against multidrug-resistant cells expressing P-glycoprotein.
• Thiazolidinones spiro-fused to indolin-2-ones as potent and selective inhibitors of Mycobacterium tuberculosis protein tyrosine phosphatase B.
• Triazole-isatine compounds as potential antibacterial and antifungal agents.
• Biologically relevant scaffolds such as spiro[indole-thiazolidinones].

It can be a reactant for:

• Cascade reactions with heterocyclic ketene aminals.
• Knoevenagel condensation reactions.

Isatin can also be used as a chromatographic spray reagent for amino acids, and also as a reference material in the preparation of indigo and Maya Blue. It is responsible for the yellow color exhibited by the "Maya Yellow" pigment.

Isatin undergoes Pd(II)-catalyzed C-H addition by direct sp²/sp³ C-H bond activation to form 3-substituted-3-hydroxy-2-oxindoles. Isatin derivatives (bis-Schiff base) are synthesized by the condensation of the natural or synthetic isatins with hydrazine.