Lewis Acid-Mediated Intermolecular [2π+2σ] Cycloaddition Between Enol Ethers and Bicyclo[1.1.0]butanes

A Lewis acid-promoted [2π+2σ] cycloaddition strategy enables the construction of bicyclo[2.1.1]hexanes (BCHs) from enol ethers and bicyclo[1.1.0]butanes (BCBs), with excellent functional group tolerance observed for both reactants. Successful scale-up experiments and further derivatization of BCHs demonstrate the robustness of this methodology for accessing complex carbocyclic frameworks.