Electrophilic Halospirocyclization of N‑Benzylacrylamides to Access 4‑Halomethyl-2-azaspiro[4.5]decanes

An electrophilic spirocyclization of N-benzylacrylamides with N-halosuccinimides (NXS) as the halogenating reagents has been developed. This reaction is carried out at room temperature under simple conditions without relying on metal reagents, photochemistry, or electrochemistry, providing a fast and efficient route to synthesize a wide variety of 4-halomethyl-2-azaspiro[4.5]­decanes with satisfactory yields. The approach is further highlighted through gram-scale synthesis and diverse transformations of the spiro products.