Used as a key intermediate in the synthesis of pharmaceutical compounds, particularly in the development of kinase inhibitors and other bioactive molecules. Its spirocyclic structure provides structural rigidity and stereochemical control, making it valuable in medicinal chemistry for optimizing drug potency and metabolic stability. Commonly employed in the preparation of analogs for structure-activity relationship (SAR) studies. Also utilized in the construction of complex heterocyclic systems through selective functionalization of the oxindole and pyrrolidine moieties.