Used primarily as an intermediate in organic synthesis, especially in the preparation of sulfonamide derivatives with biological activity. Its reactive sulfonyl chloride group readily forms bonds with amines, making it valuable in pharmaceutical development for creating proteolysis-targeting chimeras (PROTACs) and other targeted protein degraders. It is also employed in the synthesis of fluorescent probes and labeling reagents due to its ability to link functional moieties to biomolecules. Its stable isoindoline-dione core supports conjugation strategies in medicinal chemistry and biochemical research.