Used in pharmaceutical synthesis as a protected heterocyclic amine building block. Its spirocyclic structure, featuring a 1-oxa-4,9-diazaspiro[5.5]undecane core with a tert-butyl carbamate (Boc) protecting group on one nitrogen, makes it valuable for constructing complex nitrogen-containing molecules, particularly in drug discovery targeting central nervous system disorders and kinase inhibitors. The Boc group allows for selective protection during multi-step syntheses, enabling controlled reactions at other reactive sites, including the secondary amine. Commonly employed in the development of bioactive compounds where structural rigidity and specific stereochemistry are required for target binding.