Rhodium(I)-catalyzed decarbonylative spirocyclization through C-C bond cleavage of benzocyclobutenones: an efficient approach to functionalized spirocycles.

The rhodium-catalyzed formation of all-carbon spirocenters involves a decarbonylative coupling of trisubstituted cyclic olefins and benzocyclobutenones through CC activation. The metal-ligand combination [{Rh(CO)2 Cl}2 ]/P(C6 F5 )3 catalyzed this transformation most efficiently. A range of diverse spirocycles were synthesized in good to excellent yields and many sensitive functional groups were tolerated. A mechanistic study supports a hydrogen-transfer process that occurs through a β-H elimination/decarbonylation pathway.