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

Article abstract of DOI:10.1002/anie.201506483

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 Cp^xIr^III complexes equipped with an atropchiral Cp scaffold. A robust complexation procedure reliably provides Cp^xIr^III 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.