Visible Light-Mediated Spiroannulation of o-Alkynyl Acrylamides Using Excited-State Palladium Catalysis

A photoinduced, Pd-catalyzed spiroannulation of 1,7-enynes has been developed. This reaction employs simple alkyl halides as radical precursors to initiate a radical addition/cyclization cascade of o-alkynyl acrylamides, resulting in spiroannulated tetracyclic systems. Using a widely available and simple palladium catalyst, this protocol demonstrates good scope and functional group tolerance under mild reaction conditions and provides expedient access to complex spirocyclic molecular architectures.