tert-Butyl 5-chlorospiro[indoline-3,4'-piperidine]-1'-carboxylate is used as a key intermediate in the synthesis of pharmaceutical compounds, particularly in the development of kinase inhibitors and central nervous system (CNS) agents. Its spirocyclic structure provides conformational rigidity, enhancing selectivity and metabolic stability in drug candidates. The tert-butoxycarbonyl (Boc) protecting group on the piperidine nitrogen enables controlled reactivity in multi-step syntheses, protecting the nitrogen while allowing functionalization at other sites, and can be readily removed under mild acidic conditions. The 5-chloro substituent on the indoline ring offers additional synthetic versatility and potential for specific interactions in target molecules. Commonly employed in medicinal chemistry for structure-activity relationship (SAR) studies due to the ease of functionalization at the piperidine and indoline moieties. Also utilized in the preparation of bioactive molecules targeting psychiatric and neurological disorders.