Dual Au(I) Catalysis in Regioselective Cycloaddition of Bicyclo[1.1.0]butanes with Allenes

A formal [2π+2σ] cycloaddition between electron-rich allenes and bicyclobutanes (BCBs), under a gold-catalyzed regime, is reported. A dual gold activation mechanism was revealed through kinetic studies and further supported by detailed DFT analysis, introducing intriguing paradigms into the dual activation strategy of homogeneous Au catalysis. This protocol enables the synthesis of a broad array of densely functionalized bicyclohexanes (32 examples) in high yields (up to 93%) with complete regioselectivity and stereoselectivity.