A Cationic Rhodium–Chiral Diene Complex as a High‐Performance Catalyst for the Intramolecular Asymmetric [4+2] Cycloaddition of Alkyne‐1,3‐Dienes

Two rings in one step: A rhodium–diene catalyst is more active than its rhodium–bisphosphine counterpart for the intramolecular [4+2] cycloaddition of alkyne-tethered 1,3-dienes (see scheme). A related complex with a C2-symmetric chiral diene ligand catalyzes an enantioselective asymmetric variant of this process. The intermolecular cycloaddition of 1,3-dienes and alkynes is also highly efficient.