Palladium-Catalyzed [4+4] Cycloaddition of Homo-TMM All-Carbon 1,4-Dipole Precursors for Construction of Benzofuro[3,2-b]azocines and Furo[3,2-b]azocines

We developed a novel Pd-catalyzed [4 + 4] cycloaddition of (benzo)furan-derived azadienes with homo-TMM all-carbon 1,4-dipoles in situ generated from a-allyl malonate derivatives, affording an array of benzofuro[3,2-b]azocines and furo[3,2-b]azocines with good to excellent yields (up to 96%) and exclusive regioselectivities. This methodology featured mild reaction conditions and good functional group tolerance. The synthetic utility was demonstrated by a gram-scale reaction. Furthermore, the catalytic asymmetric [4 + 4] cycloaddition version has also been explored.