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.
Comprehensive Summary
A general and efficient strategy for the synthesis of γ‐lactams has been reported. The hydroxylamines form Lossen rearrangement products of electron‐deficient group migration with base and then undergo [3+2] cycloaddition reaction with vinyl cyclopropane, which could be performed with broad substrate scope, excellent functional group tolerance and high efficiency to produce the desired products. It also allowed further modification to other derivatives of these γ‐lactams.
Herein, we disclose a novel reorganization/cycloaddition between two imine units catalyzed by In(OTf)3 Lewis acid, which is sharply distinguished from the well-recognized [4+2] cycloaddition version with Povarov reaction. By means...
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