Ligand-Controlled Enantioselective [2 + 2] Cycloaddition of Oxabicyclic Alkenes with Terminal Alkynes Using Chiral Iridium Catalysts

The first catalytic asymmetric [2 + 2] cycloaddition of oxabicyclic alkenes and terminal alkynes has been developed. This iridium-catalyzed enantioselective [2 + 2] cycloaddition allows the formation of four stereocenters in a single step with excellent enantioselectivity (94-->99% ee).