Palladium‐Catalyzed Intermolecular [4+1] Spiroannulation via C(sp3)–H Activation and Naphthol Dearomatization

A novel palladium‐catalyzed [4+1] spiroannulation was developed by using a C(sp3)–H activation/naphthol dearomatization approach. This bimolecular domino reaction of two aryl halides was realized through a sequence of cyclometallation‐facilitated C(sp3)–H activation, biaryl cross‐coupling, and naphthol dearomatization, thus rendering the rapid assembly of a new class of spirocyclic molecules in good yields with broad functional group tolerance. Preliminary mechanistic studies indicated that C‐H cleavage is likely involved in the rate‐determining step, and the five‐membered palladacycle was identified as the key intermediate for the intermolecular coupling.

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