Chiral Cyclopentadienyl Iridium(III) Complexes Promote Enantioselective Cycloisomerizations Giving Fused Cyclopropanes

The cyclopentadienyl (Cp) group is a very important ligand for many transition-metal complexes which have been applied in catalysis. The availability of chiral cyclopentadienyl ligands (Cp-x) lags behind other ligand classes, thus hampering the investigation of enantioselective processes. We report a library of chiral (CpIrIII)-Ir-x complexes equipped with an atropchiral Cp scaffold. A robust complexation procedure reliably provides (CpIrIII)-Ir-x complexes with tunable counterions. In a proof-of-concept application, the iodide-bearing members are shown to be highly selective for enyne cycloisomerization reactions. The dehydropiperidine-fused cyclopropane products are formed in good yields and enantioselectivities.