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

Two types of halides: A palladium‐catalyzed [4+1] spiroannulation of two types of aryl halides has been developed for the rapid construction of a new class of spirocycles. This intermolecular domino process was realized through a sequence of C(sp³)−H cleavage, unsymmetrical biaryl coupling, and naphthol dearomatization.

Abstract

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 indicate that C−H cleavage is likely involved in the rate‐determining step, and a five‐membered palladacycle was identified as the key intermediate for the intermolecular coupling.

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